Đặc điểm nứt nẻ trong đá móng granitoid mỏ Hải Sư Đen trên cơ sở phân tích tổng hợp tài liệu ĐVLGK và thuộc tính địa chấnc

B GIO DC V O TO

TRNG I HC M - A CHT

NGUYN ANH C

C IM NT N TRONG MNG GRANITOID

M HI S EN TRN C S PHN TCH TNG

HP TI LIU A VT L GING KHOAN V

THUC TNH A CHN

LUN N TIN S A CHT

H NI 2015

B GIO DC V O TO

TRNG I HC M - A CHT

NGUYN ANH C

C IM NT N TRONG MNG GRANITOID

M HI S EN TRN C S PHN TCH TNG

HP TI LIU A VT L GING KHOAN V

THUC TNH A CHN

Ngnh. K thut a vt l

M s. 62520502

LUN N TIN S A VT L

NGI HNG DN KHOA HC.

1. PGS. TS. NGUYN VN PHN

2. TS. NGUYN HUY NGC

H NI 2015

i

LI CAM OAN

Ti xin cam oan y l cng trnh nghin cu ca ring tc gi. Cc s liu, kt

qu trnh by trong lun n l hon ton trung thc v cha tng c ai cng b trong

mt cng trnh no khc.

Tc gi

Nguyn Anh c

ii

MC LC

Li cam oan .................................................................................................................. i

Mc lc .......................................................................................................................... ii

Danh mc cc bng ....................................................................................................... iv

Danh mc cc hnh v .................................................................................................... v

Danh mc cc k hiu, vit tt ..................................................................................... xvi

M u ........................................................................................................................ xix

Li cm n ................................................................................................................ xxiv

CHNG 1 C IM A CHT - A VT L VNG NGHIN CU

TRONG KHUNG CU TRC B CU LONG

1.1 . V tr a l ........................................................................................................ 1

1.2 . Lch s tm kim thm d ................................................................................. 1

1.3 . c im a cht, kin to ............................................................................... 8

1.3.1. Lch s pht trin a cht ....................................................................... 8

1.3.2. Cc pha bin dng hnh thnh t gy, i ph hy trong mng Hi S en

............................................................................................................... 11

1.3.3. Cu trc a cht khu vc ...................................................................... 14

1.3.4. a tng khu vc nghin cu ................................................................. 17

1.3.5. H thng du kh .................................................................................... 24

CHNG 2 - PHNG PHP M HNH HA RNG NT N TRONG

MNG M HI S EN

2.1. Tng quan v mng nt n ......................................................................... 32

2.1.1. Hin trng v phng php nghin cu mng nt n ........................ 32

2.1.2. C ch hnh thnh nt n trong mng granitoid ................................ 37

2.1.3. Cc yu t nh hng n kh nng cha ca mng nt n. ............ 43

2.2. c im a cht kin to tng mng granitoid cu to Hi S en ...... 45

2.2.1. c im hnh thi cu trc mng .......................................................... 45

2.2.2. Thnh phn thch hc ............................................................................. 46

iii

2.2.3. H thng t gy ..................................................................................... 46

2.3. Cc phng php nghin cu c im nt n trong mng. ...................... 50

2.3.1. Cc phng php a Cht ..................................................................... 50

2.3.2. Cc phng php a Vt L Ging Khoan ........................................... 51

2.3.3. Cc phng php a Chn .................................................................... 59

2.3.4. Cc phng php ton hc t hp s liu .......................................... 65

2.4. Phng php, quy trnh xy dng m hnh rng nt n trong mng m

Hi S en. ............................................................................................................ 71

2.4.1. C s d liu ........................................................................................... 71

2.4.2. Cc bc thc hin ................................................................................. 71

CHNG 3 - C IM NT N TRONG MNG GRANITOID M HI S

EN THEO TI LIU A VT L

3.1 . c im nt n theo ti liu a Vt L Ging Khoan ................................ 75

3.2 . c im nt n theo ti liu a chn ........................................................... 85

CHNG 4 - M HNH RNG NT N V NH GI C IM NT

N TRONG MNG M HI S EN

4.1. M hnh rng nt n theo phng php mng n-ron nhn to (Artificial

Neural Network ANN) ...................................................................................... 103

4.2. p dng phng php Co-Kriging xy dng m hnh rng nt n. ... 109

4.3. Kim tra, so snh, i chiu kt qu ............................................................. 115

4.4. nh gi c im v phn vng khu vc nt n m Hi S en . ............. 122

KT LUN V KIN NGH .................................................................................. 131

DANH MC CC CNG TRNH CA NCS ........................................................ 133

TI LIU THAM KHO ........................................................................................ 134

iv

DANH MC CC BNG

STT Tn hnh Ni dung Trang

1 Bng 1.1 su cc ngng hin ti ca m Oligoxen b

Cu Long

26

2 Bng 3.1 Nhn bit cc i nt n v mch phun tro thng

qua c tnh cc ng cong a vt l ging khoan

77

3 Bng 3.2 c trng vt l cc nhm mng v cc i nt

n b Cu Long

78

4 Bng 4.1 Bng so snh h s tng quan gia rng t m

hnh v rng t ging khoan VD-2X v HSD-

5XP

117

v

DANH MC CC HNH V, TH

STT Tn hnh Ni dung Trang

CHNG 1

1 Hnh 1.1 V tr a l b Cu Long 2

2 Hnh 1.2 V tr a l m Hi S en - L 15-2/01 2

3 Hnh 1.3 Cc kho st a chn 2D v 3D ti khu vc m Hi S

en

7

4 Hnh 1.4 Bn ng su nc mng m Hi S en v v tr cc

ging khoan.

7

5 Hnh 1.5 S v tr kin to ca b Cu Long trong bnh kin

to khu vc ng Nam

8

6 Hnh 1.6 S a cht i Lt ch ra s phn b ca cc phc

h Granitoid nh Qun, C N (Ankroet), o C

9

7 Hnh 1.7

S minh ha cc hot ng kin to khu vc ng

Nam thi k cui Eoxen u Oligoxen. Khu vc

nghin cu ang ch kin to tch gin

10

8 Hnh 1.8 Cc giai on bin dng b Cu Long 12

9 Hnh 1.9 Cc pha bin dng khu vc Hi S en 13

10 Hnh 1.10 S phn chia cc n v cu trc bc II trong b Cu

Long

14

11 Hnh 1.11 Bn cu trc trng chnh b Cu Long 15

12 Hnh 1.12 Cc mt ct i qua cc i cu trc ca trng chnh b

Cu Long

16

13 Hnh 1.13

Biu phn loi thch hc cho cc mu mng theo

ging khoan ti cu to Hi S en (Vng ng) v ln

cn

19

vi

14 Hnh 1.14

So snh mu mng ti cu to Hi S en vi cc

mu ca phc h nh Qun, o C v Ankroet ly

ti cc im l trn khu vc i Lt

20

15 Hnh 1.15 Ct a tng tng hp ti b Cu Long 21

16 Hnh 1.16 Biu tim nng sinh du v phn loi vt cht hu c

trm tch Oligoxen

25

17 Hnh 1.17 Biu tim nng sinh du v phn loi VCHC trm tch

Mioxen sm

25

18 Hnh 1.18 th th hin trng thnh ca vt cht hu c ti

thi im hin ti

26

19 Hnh 1.19 th th hin phn loi ct kt v mi quan h gia

rng v thm, tp BI

27


rng v thm, tp C

29


rng v thm, tp E

29

22 Hnh 1.22 th th hin phn loi magma trong khu vc nghin

cu

30

23 Hnh 1.23 M hnh tng qut h thng du kh b Cu Long 31

CHNG 2

24 Hnh 2.1 S phn b tr lng trong mng b Cu Long 33

25 Hnh 2.2

Cc i mch ht mn (gouge) xut hin trn mt t gy

c th ng vai tr l cc nm chn, ngn s di chuyn

ca cht lu ln cc va bn trn

35

26 Hnh 2.3

M hnh by du kh mng nt n b Cu Long: (1)

cha mng nt n; (2) Tp st D tng chn v tng

sinh; (3) cha ct kt.

37

vii

27 Hnh 2.4 Phn loi cc mng theo phn v a cht v thch hc 38

28 Hnh 2.5 Phn loi granitoid mt s ging khoan b Cu Long 38

29 Hnh 2.6 Cc kiu khe nt nguyn sinh ca magma xm nhp 39

30 Hnh 2.7

Phn loi khe nt trong m hnh elipxoit bin dng. Cc

trc ng sut chnh c k hiu l 1, 2, 3 (vi quy

c 1 > 2 > 3)

40

31 Hnh 2.8 Mi quan h gia trng ng sut v cc loi t gy. 41

32 Hnh 2.9 Mi quan h gia cc loi t gy v cc khe nt sinh

km

41

33 Hnh 2.10 Bin i rng mng nt n m Bch H theo chiu

su

44

34 Hnh 2.11 Bn chiu su nc mng cu to Hi S en 45

35 Hnh 2.12 Mt ct a dc theo cu to Hi S en 45

36 Hnh 2.13

Thnh phn thch hc trong mng cu to Hi S en

dc theo ging khoan HSD-3X: t nc mng n su

4200m gp granodiorit, t su 4200m tr xung

gp monzogranit

46

37 Hnh 2.14 H thng t gy v tuyn ti m Hi S en. 47

38 Hnh 2.15 H thng t gy ng Bc Ty Nam ti m Hi S

en.

48

39 Hnh 2.16 H thng t gy Ty Bc ng Nam ti m Hi S

en

49

40 Hnh 2.17

Mt ct a chn dc theo cc ging khoan HSD-1X v

HSD-5XP vi h thng t gy v tuyn v kt qu o

PLT

49

41 Hnh 2.18 Mu li ti cc ging khoan m Hi S en 50

viii

42 Hnh 2.19

Mu phn tch lt mng thch hc ca granit, bao gm

cc thnh phn khong vt thch anh, Feldspar,

plagioclase v mica

51

43 Hnh 2.20 M hnh mng in hnh 55

44 Hnh 2.21 Quy trnh tnh ton rng trong mng bng phng

php th tch

56

45 Hnh 2.22 Hnh nh ging khoan 58

46 Hnh 2.23 Mch a chn phc (Taner et al., 1979) 61

47 Hnh 2.24 Cng phn x tc thi v Tn s tc thi ca xung

sng a chn (Partyka, 2000)

62

48 Hnh 2.25 Mng n-ron in hnh 66

49 Hnh 2.26 M hnh ca mt n-ron 68

50 Hnh 2.27 Hm kch hot sigmoid 68

51 Hnh 2.28 S biu din cc bc ca phng php Co-Kriging 70

52 Hnh 2.29

S biu din cc bc thc hin trong phng php

xy dng m hnh rng bng phng php ANN v

Co-Kriging

72

CHNG 3

53 Hnh 3.1 c trng ng cong a vt l ging khoan i vi

tng loi

75

54 Hnh 3.2 c trng t hp cc ng cong VLGK ca

granite, granodiorite v i nt n

79

55 Hnh 3.3 c trng t hp cc ng cong VLGK ca cc

mch tr.

80

56 Hnh 3.4 c trng t hp cc ng cong VLGK ca cc mch

xm nhp nng Aplit

81

ix

57 Hnh 3.5 ng FMI cho gi tr mc nt n cao (FMI

intensity) im ch v tr cc i nt n

82

58 Hnh 3.6 Biu th hin hng dc v gc dc theo phn loi h

thng nt n trn ti liu FMI khu vc m Hi S en

82

59 Hnh 3.7

So snh khong phn b ca cc i nt n trn ti liu

FMI v kt qu minh gii rng ca ging khoan HSD-

2X v HSD-3X

83

60 Hnh 3.8

So snh khong phn b ca cc i nt n trn ti liu

FMI v kt qu minh gii rng ca ging khoan HSD-

4X v HSD-5XP

83

61 Hnh 3.9 th th hin mi quan h gia gi tr Vp/Vs theo

su ti cc ging khoan trn cu to hi S en.

84

62 Hnh 3.10 th th hin mi quan h gia gi tr rng v gi tr

AI ti cc ging khoan trn cu to hi S en.

85

63 Hnh 3.11 rng ca i nt n c th quan st c trn ti liu

a chn khu vc m Hi S en l 14m.

86

64 Hnh 3.12 c im phn x a chn trong mng ghi nhn s tn

ti h thng khe nt

87

65 Hnh 3.13 Cc cube a chn c trong khu vc m Hi S en 87

66 Hnh 3.14 Cube a chn AI inversion t cube CBM 2009 cho hnh

nh trong mng tt hn so vi cube CBM 2009

87

67 Hnh 3.15 Mt ct th hin thuc tnh relative acoustic impedance. 89

68 Hnh 3.16

Mt ct a chn dc theo ging khoan HSD-5XP v cc

mt ct ngang ti cc su khc nhau th hin s trng

khp gia kt qu minh gii rng t ti liu a vt l

ging khoan (ng mu ) v thuc tnh Relative AI

89

69 Hnh 3.17 Mt ct a chn dc theo ging khoan HSD-5XP v

HSD-1X th hin s trng khp gia kt qu minh gii

90

x

rng t ti liu a vt l ging khoan (ng mu )

v thuc tnh Relative AI

70 Hnh 3.18 Mt ct th hin thuc tnh bin ngoi (Envelope). 90

71 Hnh 3.19




ging khoan (ng mu ) v thuc tnh Envelope

91

72 Hnh 3.20

Mt ct a chn dc theo ging khoan HSD-5XP v



v thuc tnh Envelope.

91

73 Hnh 3.21 Mt ct th hin thuc tnh bin d (variance). 92

74 Hnh 3.22




ging khoan (ng mu ) v thuc tnh Variance

92

75 Hnh 3.23




v thuc tnh Variance

93

76 Hnh 3.24 Mt ct th hin thuc sweetness. 93

77 Hnh 3.25




ging khoan (ng mu ) v thuc tnh sweetness.

94

78 Hnh 3.26




94

xi

v thuc tnh sweetness.

79 Hnh 3.27 Mt ct th hin thuc Reflection intensity. 95

80 Hnh 3.28




ging khoan (ng mu ) v thuc tnh Reflection

Intensity.

95

81 Hnh 3.29




v thuc tnh Reflection Intensity.

96

82 Hnh 3.30 Mt ct th hin thuc tnh csin ca pha 96

83 Hnh 3.31




ging khoan (ng mu ) v thuc tnh Cosine of

phase.

97

84 Hnh 3.32




v thuc tnh Cosine of phase.

97

85 Hnh 3.33 Mt ct th hin thuc tnh Gradient magnitude. 98

86 Hnh 3.34




ging khoan (ng mu ) v thuc tnh gradient

magnitude.

98

xii

87 Hnh 3.35




v thuc tnh gradient magnitude.

99

88 Hnh 3.36 Mt ct th hin thuc tnh bin RMS 99

89 Hnh 3.37




ging khoan (ng mu ) v thuc tnh RMS

amplitude.

100

90 Hnh 3.38




v thuc tnh RMS Amplitude.

100

91 Hnh 3.39 Mt ct th hin thuc tnh Ant-tracking. 101

92 Hnh 3.40




ging khoan (ng mu ) v thuc tnh Ant tracking

101

93 Hnh 3.41




v thuc tnh Ant tracking.

102

CHNG 4

94 Hnh 4.1 Lt ct ngang ti su 3424m t m hnh rng

ANN.

105


ANN.

105

xiii


ANN.

106

97 Hnh 4.4 Phn b rng dc theo nc mng t m hnh ANN. 106

98 Hnh 4.5 M hnh rng t phng php ANN. 107

99 Hnh 4.6 Kim chng kt qu gia m hnh rng theo phng

php ANN v rng t ging khoan HSD-1X

107


php ANN v rng t ging khoan HSD-4X.

108


php ANN v rng t ging khoan HSD-5XP.

108

102 Hnh 4.9 th th hin mi quan h ca rng theo su t

nc mng

110

103 Hnh 4.10 Bn mt mng biu din thuc tnh Variance gip xc

nh gi tr khong ti thiu.

110

104 Hnh 4.11 Mt ct dc qua cc ging khoan HSD-4X, VD-1X, VD-

2X, HSD-2X v HSD-3X t m hnh rng Co-Kriging

110

105 Hnh 4.12 Mt ct dc qua cc ging khoan HSD-4X v HSD-1X t

m hnh rng Co-Kriging.

112

106 Hnh 4.13 Lt ct ngang ti su 3424m t m hnh rng Co-

Kriging.

112


Kriging.

113


Kriging.

113

109 Hnh 4.16 Phn b rng dc theo nc mng t m hnh Co-

Kriging.

114

110 Hnh 4.17 Cc mt ct ngang t m hnh rng Co-Kriging. 114

xiv

111 Hnh 4.18

Mt ct qua ging khoan HSD-1X cho thy c s tng

ng gia m hnh rng t Co-Kriging v rng t

ging khoan.

115

112 Hnh 4.19

Mt ct qua ging khoan HSD-5XP cho thy c s tng


ging khoan

116

113 Hnh 4.20

Mt ct qua ging khoan HSD-4X cho thy c s tng


ging khoan.

116

114 Hnh 4.21 So snh rng t cc phng php ANN v Co-Kriging

vi rng t ging khoan HSD-1X

118



118



119


vi rng t ging khoan VD-1X

119


vi rng t ging khoan VD-2X

120


vi rng t ging khoan HSD-5XP

121

120 Hnh 4.27 S phn chia cc phn vng cc c im nt n khc

nhau trong mng m Hi S en.

122

121 Hnh 4.28 Mt ct dc qua 06 phn vng 123

122 Hnh 4.29 Mt ct dc qua phn vng 2,3 v 4 123



xv

125 Hnh 4.32

Mt ct dc theo ging khoan HSD-4X t m hnh

rng Co-Kriging ti phn vng 1v kt qu minh gii

FMI cho thy h thng khe nt ch yu phn b theo

phng Ty Bc ng Nam.

125

126 Hnh 4.33

Mt ct dc theo ging khoan HSD-1X v HSD-5XP t

m hnh rng Co-Kriging ti phn vng 2 v kt qu

minh gii FMI cho thy h thng khe nt ch yu phn

b theo phng ng Ty

126

127 Hnh 4.34 Kt qu minh gii FMI ca ging HSD-5XP. 126

128 Hnh 4.35 Mt ct dc theo ging khoan HSD-1X v VD-2X t m

hnh rng Co-Kriging ti phn vng 3

127

129 Hnh 4.36

Mt ct dc t m hnh rng Co-Kriging qua phn

vng 3 v phn vng 4 cho thy phn vng 4 c rng

km, h thng nt n tha tht, ri rc

128

130 Hnh 4.37 Mt ct dc t m hnh rng Co-Kriging qua phn

vng 4 v phn vng 5

129

131 Hnh 4.38 Mt ct dc t m hnh rng Co-Kriging qua phn

vng 4, 5 v 6

130

132 Hnh 4.39 Kt qu minh gii FMI ca ging HSD-2X. 130

xvi

DANH MC CC K HIU, CC CH VIT TT

STT K hiu Ch thch

1 ANN Mng n-ron nhn to (Artificial Neural Network)

2 HSD Hi S en

3 BCH Bt chnh hp

4 BLI Di tn s hu hn

5 CALI ng knh ging khoan (Caliper)

6 CNL Phng php ntron

7 DLL Phng php o su sn

8 DT Thi gian truyn sng siu m (DT)

9 DST Th va cn khoan

10 VLGK a vt l ging khoan

11 GR Cng bc x gamma (Gamma ray)

12 I Tr sng

13 HC Hydrocacbon

14 K thm

15 km Kilmet

16 LLD Phng php o in kp su

17 LLS Phng php o in kp nng

18 MD Chiu su o dc ging khoan

19 MLFN Mng n-ron nhiu lp (Multi Layer Feedforward Neural

Netword)

20 PLT o trong qu trnh th va (production logging test)

21 m Mt

22 mD Mili ac-xi

23 ms Mili giy

24 NGS Ph gamma t nhin

25 NPHI rng bng phng php ntron

xvii

26 PHIE rng hiu dng

27 PNN Mng n ron xc sut (Probabilistic Neural Network)

28 PP Phng php

29 PSC Hp ng phn chia sn phm

30 R in tr sut

31 RHOB Mt

32 RMS Trung bnh bnh phng

33 Rt in tr sut thc

34 Rw in tr sut nc va

35 Shl St (Shale)

36 SNA Tng bin m

37 SPA Tng bin dng

38 Sw bo ha nc

39 TKTD Tm kim thm d

28 CBM Dch chuyn chm tia (Control beam migration)

29 TVDSS Chiu su thc thng ng di mc nc bin (True Vertical

depth sub- Sea)

30 TWT Thi gian truyn sng hai chiu (Two Way Time)

31 VCHC Vt cht hu c

32 Vshl Th tch st

33 @ Ti

34 ft B (foot)

35 s Micro giy

36 m m mt

37 in tr sut

38 FMI Hnh nh thnh ging khoan (Fullbore Formation

MicroImager)

39 PLT Production logging tool

40 TKTD&KT Tm kim thm d v khai thc

xviii

41 BH Bch H

42 PSTM Dch chuyn trc cng trong min thi gian (pre stack time

migration)

43 PSDM Dch chuyn trc cng trong min su (pre stack depth

migration)

44 B-TN ng Bc Ty Nam

45 TB-N Ty Bc ng Nam

46 -N ng ng Nam

47 Vp Vn tc sng dc

48 Vs Vn tc sng ngang

xix

M U

1. Tnh cp thit ca ti

Trong nhng nm gn y, du kh c tm thy ngy cng nhiu hn trong cc

mng nt n khc nhau trn th gii. Ti Vit Nam nhiu m du c pht hin v

khai thc trong mng granitoid nt n nh cc m: Bch H, Rng, S T en, S T

Vng, S T Nu, C Ng Vng, Rng ng, Phng ng, Hi S en, Diamond,

Ruby, H Xm South, Thng Long, ng , i Mi, Knh Ng Trng, Knh Ng Trng

Nam, Knh Ng Vng Nam.

Tim nng du kh cn li b Cu Long l rt ln, trong khi m li nh, h

thng nt n phc tp dn n vic khoan thm d thm lng v khai thc gp nhiu ri

ro (v d nh Rng ng, Phng ng, C Ng Vng, Azurite, H Xm v Hi S

en). C nhiu nguyn nhn m trong ni bt nht l do khoan khng vo cc i nt

n tt ca m gy thit hi kinh t rt ln. Chnh v th vic nghin cu d on h

thng nt n l rt cn v cp thit.

gp phn gii quyt nhu cu cp thit trn, NCS chn ti lun n nghin cu

c im nt n trong mng granitoid m Hi S en trn c s phn tch tng

hp ti liu VLGK v thuc tnh a chn. y l mt cng trnh nghin cu thc

tin, c tnh cp thit cao, s ng gp nht nh trong sn xut v nghin cu, gp phn

m bo sn lng du kh trong nhng nm ti.

thc hin ti lun n, NCS tp trung phn tch, nh gi cc cng trnh nghin

cu hin c, nu ra cc vn cn tn ti trong cng tc nghin cu c im nt n ca

mng granitoid ti b Cu Long ni chung v m Hi S en ni ring nhm nh

hng cho cc cng vic s gii quyt ca lun n: la chn cc phng php hin i

nghin cu cha mng nt n v xy dng m hnh rng nt n cho mng m

Hi S en.

2. Mc ch

Mc tiu chnh ca lun n l nghin cu c tnh nt n ca mng da trn ti liu

a cht, a vt l ging khoan v ti liu a chn, t la chn phng php v tin hnh

xy dng m hnh rng trong mng nt n ca m Hi S en b Cu Long.

xx

3. Nhim v ca lun n.

t c mc ch nu trn cc nhim v cn c gii quyt bao gm:

Tm hiu tnh cht ca nt n trong mng granitoid, c ch hnh thnh v nh

hng ca chng ln ti liu VLGK v a chn.

T hp ti liu a cht, a vt l ging khoan, a chn v quan st thc a lm

sng t s tn ti ca h thng nt n cha du kh trong mng granitoid m Hi

S en.

Nghin cu p dng cc phng php m hnh ha nhm t hp v la chn cc

thuc tnh a chn vi kt qu phn tch tng hp ti liu a vt l ging khoan, o

kim tra khai thc (PLT), xy dng m hnh rng cha du kh trong mng

granitoid trong khu vc nghin cu.

4. Phm vi, i tng nghin cu v c s ti liu

Phm vi nghin cu l vng m Hi S en thuc L 15-2/01, nm sn Ty Bc b

Cu Long. i tng nghin cu chnh l mng granitoid.

Ti liu dng trong lun n.

Ti liu a cht b Cu Long.

Ti liu a chn 3D x l bng CBM (controlled beam migration) v APSDM

(Anisotropy pre stack depth migration) nm 2009 ca m Hi S en.

Ti liu a vt l ging khoan ca 7 ging: HSD-1X, HSD-2X/ST, HSD-3X,

HSD-4X, HSD-5XP, VD-1X, VD-2X, o kim tra khai thc, th va ti khu vc

m Hi S en.

Cc ti liu nghin cu a cht v kin to l 15-2/01.

5. Ni dung nghin cu

Tng hp ti liu a cht, kin to, a vt l v ging khoan khu vc m Hi

S en nhm lm sng t cc c im a cht, a vt l, c ch hnh thnh v

bin i ca nt n trong mng m Hi S en.

Phn tch, minh gii ti liu a vt l ging khoan v mu li xc nh rng

nt n trong mng ca cc ging khoan khu vc m Hi S en.

xxi

Minh gii ti liu a chn 3D v phn tch kh nng ca cc thuc tnh a chn

trong d bo nt n m Hi S en.

ng dng cc phn mm hin c (Petrel) la chn t hp ti u cc thuc tnh

a chn trong xy dng m hnh rng nt n cho mng granitoid.

Nghin cu tch hp cc kt qu minh gii rng t ti liu ging khoan v phn

tch thuc tnh a chn kt hp vi cc thng tin a cht v kin to trong vng

bng phng php kt hp cc cng c ton hc: a thng k v mng nron.

6. Phng php nghin cu.

Phn tch tng hp ti liu a vt l ging khoan, o kim tra khai thc, th va

trong khu vc nghin cu xc nh c im ca cc h thng nt n, tnh ton

rng.

Phn tch t hp ti liu a chn ba chiu (thuc tnh a chn) vi ti liu a vt

l ging khoan xc nh s phn b v c tnh ca cc i nt n trong mng

granitoid.

Xy dng m hnh rng bng cch kt hp phng php mng nron nhn to

ANN v thut ton a thng k Co-Kriging.

7. ngha khoa hc v thc tin ca lun n

ngha khoa hc.

Lm sng t kh nng, cng ngh v k thut p dng cc phng php minh gii

a chn hin i (thuc tnh a chn) tch hp vi phn tch ti liu a vt l ging

khoan v cc ti liu a cht kin to khc xy dng c m hnh rng nt

n trong mng granitoid.

ngha thc tin.

Gp phn lm sng t c im phn b cc i nt n v xy dng m hnh

rng trong mng granitoid, t gip nng cao hiu qu khai thc du kh m

Hi S en.

Cc kt qu nghin cu ca lun n khng ch cung cp thng tin b sung phc

v trc tip cho vic khai thc du kh m Hi S en, m cn c th ng dng

nghin ca cho cc m khai thc du kh trong mng nt n b Cu Long.

xxii

8. Lun im bo v.

Lun im 1: mng m Hi S en l khi magma a khong, b xuyn

ct bi cc ai mch phun tro, tn ti cc i nt n rt phc tp. Cc i nt n

trong mng c nhng c im ring bit th hin qua ti liu a vt l ging

khoan v cc thuc tnh a chn. Vi ti liu a chn thu c t cng ngh thu

n v x l hin i, la chn cc thuc tnh a chn cn thit tch hp vi ti

liu a vt l ging khoan, cho php ta khng nhng pht hin, khoanh nh cc

i nt n trong mng granitoid m cn d on c cc c im ca chng

nh phng pht trin v hng cm.

Lun im 2: Php kt hp gia phng php mng nron nhn to (ANN) v

phng php a thng k (Co-Kriging) v kh nng t hp c trng s cc thuc

tnh a chn, kt qu minh gii ti liu a vt l ging khoan v cc thng tin a

cht kin to c c trong vng nghin cho php xy dng c m hnh

rng nt n trong mng granitoid m Hi S en vi chnh xc v tin

cy cao.

9. Nhng im mi ca lun n

- Ln u tin m hnh rng nt n trong mng granitoid m Hi S en

c xy dng bng phng php mng nron nhn to v phng php a

thng k. M hnh c s ph hp tt vi kt qu khoan, minh gii ti liu a vt

l ging khoan v th va.

- Khng nh kh nng v vai tr quan trng ca cc thuc tnh a chn v ti liu

a vt l ging khoan trong nghin cu cc h thng nt n trong mng granitoid

m Hi S en v cc khu vc khc c cc c im a cht du kh tng t.

10. Cu trc lun n.

Ni dung lun n bao gm: phn m u, 4 chng , kt lun v kin ngh, danh sch ti

liu tham kho v cc cng trnh khoa hc. Ton b lun n c trnh by trong 137 trang

nh my kh giy A4, 132 hnh v, 4 biu bng v 33 ti liu tham kho.

xxiii

LI CM N.

Trong qu trnh tin hnh nghin cu lun n, NCS nhn c s gip tn tnh

ca cc thy gio hng dn. NCS xin c by t s bit n su sc n tp th gio vin

thuc b mn a Vt L trng i Hc M - a cht v c bit l PGS. TS. Nguyn

Vn Phn v TS. Nguyn Huy Ngc.

NCS xin trn trng cm n cc thy c trong hi ng cng cc phn bin ng

gp kin qu bu cho lun n. Xin c chn thnh cm n Ban lnh o trng i Hc

M - a cht v Tng Cng Ty Thm D Khai Thc Du Kh (PVEP) to mi iu kin

thun li v thi gian, phng tin NCS c th hon thnh lun n ca mnh.

Cui cng, NCS xin by t lng bit n chn thnh n cc ng nghip ng gp

nhng kin b ch v gip lun n c th c hon thnh tt p.

1

CHNG 1

C IM A CHT- A VT L VNG NGHIN CU

TRONG KHUNG CU TRC B CU LONG

Cu to Hi S en thuc l 15-2/01 nm sn Ty Bc b Cu Long, y l b

trm tch cha du kh quan trng nht cho ti thi im hin ti ca Vit Nam. Trong

khu vc b tin hnh kho st a chn 2D v 3D vi khi lng rt ln, khoan tng

cng hn 500 ging khoan thm d, thm lng v khai thc, pht hin 18 m trong

c 11 m ang c khai thc (Bch H, S T en, C Ng Vng, Rng) vi tng

sn lng khai thc cng dn t 344,8 triu m3 du quy i tnh n thi im hin ti.

Ngoi ra ti y cn tn ti rt nhiu cc pht hin v cu to tim nng ang c tin

hnh thm lng v thm d.

1.1. V tr a l

B Cu Long nm ngoi khi thm lc a Nam Vit Nam v mt phn t lin

thuc khu vc ca sng Cu Long. B c hnh bu dc, vng ra v pha bin v nm dc

theo b bin Vng Tu - Bnh Thun, c gii hn trong khung ta a l t 9

o n

11o v Bc v t 106

o30 n 109

o kinh ng. B Cu Long tip gip vi t lin v pha

Ty Bc, ngn cch vi b Nam Cn Sn bi i nng Cn Sn, pha Ty Nam l i

nng Khorat - Natuna v pha ng Bc l i ct trt Tuy Ha ngn cch vi b Ph

Khnh. B c din tch khong 36.000 km2, bao gm cc l: 01&02, 01&02/97, 15-1/01,

15-1/05, 15-2, 15-2/01; 16-1/03, 16-1, 16-2, 09-1, 09-2, 09-2/09, 09-3, 17 v mt phn

ca cc l: 127, 01&02/10, 25 v 31 (hnh 1.1). [16]

Cu to Hi S en thuc l 15-2/01, cch TP. Vng Tu 75 km v pha ng

(Hnh 1.2). Cu to c din tch khong 64,7 km2 tnh theo din tch cu to mng.

1.2 Lch s tm kim thm d

Qu trnh tm kim thm d v khai thc (TKTD & KT) du kh b Cu Long bt

u t nhng nm trc 1975 vi cc hot ng kho st, thm d khu vc. khu vc l

15-2/01 ni chung v cu to Hi S en c hai nh thu du kh JVPC (t nm 1994)

v Thng Long JOC (t 2005) ln lt trin khai hot ng tm kim thm d.

2

Hnh 1.1. V tr a l b Cu Long

Hnh 1.2. V tr a l m Hi S en - L 15-2/01.

Cho n thi im hin nay lch s tm kim thm d b Cu Long c th chia

thnh 4 giai on [15]:

3

Giai on trc nm 1975

Giai on trc nm 1975 l giai on to nn tng pht trin cho qu trnh tm

kim thm d v khai thc du kh. Thi k ny bt u bng kho st a vt l mang

tnh cht khu vc nh t, trng lc v a chn phn chia cc l, chun b cho cng tc

u thu v k kt cc hp ng du kh.

Nm 1967 US Navy Oceanographic Office tin hnh kho st t hng khng gn

khp lnh th Min Nam.

Nm 1967-1968: o ghi 19.500 km tuyn a chn 2D pha Nam Bin ng,

trong c tuyn ct qua b Cu Long.

Nm 1969: o a vt l bin bng tu N.V.Robray I do cng ty Ray Geophysical

Mandrel tin hnh vng thm lc a Min Nam v vng pha Nam ca Bin ng vi

tng s 3.482 km tuyn 2D trong c tuyn ct qua b Cu Long.

Nm 1969: US Navy Oceanographic cng tin hnh o song song 20.000 km tuyn

a chn 2D bng hai tu R/V E.V Hunt vnh Thi Lan v pha Nam Bin ng trong

c tuyn ct qua b Cu Long.

n u nm 1970, Cng ty Ray Geophysical Mandrel li tin hnh o t hai

Nam Bin ng v dc b bin 8.639 km tuyn a chn 2D vi mng li 30x50 km,

kt hp vi kho st t, trng lc v hng khng trong c tuyn ct qua b Cu Long.

Nm 1973-1974: u thu trn 11 l, trong c 3 l thuc b Cu Long l l

09, l 15 v l 16.

Nm 1974: Cng ty Mobil trng thu trn l 09 v tin hnh kho st a vt l,

ch yu l a chn phn x, cng vi t v trng lc vi khi lng l 3.000 km tuyn

2D. Cui nm 1974 v u nm 1975, cng ty Mobil khoan ging khoan tm kim u

tin BH-1X trong b Cu Long phn nh ca cu to Bch H. Kt qu th va ti i

tng ct kt Mioxen di chiu su 2.755-2.819m cho dng du cng nghip, lu

lng du t 342m3/ngy. Kt qu ny khng nh trin vng v tim nng du kh

ca b Cu Long.

4

Giai on 1975-1980

Nm 1976, c nh du bng vic cng ty a vt l CGG ca Php tin hnh

kho st 1.210,9 km tuyn a chn 2D theo cc con sng ca ng bng sng Cu Long

v vng ven bin Vng Tu-Cn Sn. Kt qu xc nh c cc tng phn x chnh: t

CL 20 n CL 80 v khng nh s tn ti ca b Cu Long vi mt lt ct dy ca trm

tch Tam.

Nm 1978, Cng ty Geco ca Nauy thu n 11.898,5 km tuyn a chn 2D trn

cc l 09, 10, 16, 19, 20, 21 v lm chi tit trn cu to Bch H vi mng li tuyn

2x2km v 1x1km. Ring i vi l 15, Cng ty Deminex hp ng vi Geco kho st

3.221,7 km tuyn a chn 2D vi mng li 3,5x3,5km trn l 15 v cu to Cu Long

(nay l Rng ng). Cn c vo kt qu minh gii ti liu a chn ny Deminex

khoan 4 ging khoan tm kim trn cc cu to trin vng nht l Tr Tn (15-A-1X),

Sng Ba (15-B-1X), Cu Long (15-C-1X) v ng Nai (15-G-1X). Kt qu khoan

cho thy cc ging ny u gp cc biu hin du kh trong ct kt tui Mioxen sm v

Oligoxen, nhng vi dng du yu, khng c ngha cng nghip.

Giai on 1980-1988

y l giai on m cng tc tm kim, thm d du kh thm lc a Vit Nam

trin khai rng khp, nhng tp trung ch yu vo mt n v l x nghip lin doanh du

kh Vit-X. Nm 1980 tu nghin cu POISK tin hnh kho st 4.057 km tuyn a

chn 2D im su chung, v 3.250 km tuyn t, trng lc. Kt qu ca t kho st ny

phn chia ra c tp a chn B (CL4-1, CL4-2), C (CL5-1), D (CL5-2), E (CL5-3)

v F (CL6-2), xy dng c mt s s cu to d thng t v trng lc Bouguer.

Nm 1981 tu nghin cu Iskatel tin hnh kho st a vt l vi mng li

2x2, 2-3x2-3 km a chn 2D MOB-OGT-48, trng lc, t phm vi l 09, 15 v 16 vi

tng s 2.248 km.

Nm 1983-1984 tu vin s Gamburxev tin hnh kho st 4.000 km tuyn a

chn 2D nghin cu phn su nht ca b Cu Long.

Trong thi gian ny x nghip lin doanh du kh Vit-X khoan 4 ging trn cc

cu to Bch H v Rng: R-1X, BH-3X, BH-4X, BH-5X v ging khoan T-1X trn

5

cu to Tam o. Tr ging khoan T-1X, tt c 4 ging cn li u pht hin va du

cng nghip t cc va ct kt Mioxen di v Oligoxen (BH-4X).

Cui giai on 1980-1988 c nh du bng vic Vietsovpetro khai thc

nhng tn du u tin t hai i tng Mioxen, Oligoxen di ca m Bch H vo

nm 1986 v pht hin ra du trong mng granite nt n vo thng 9 nm 1988.

Giai on 1988 - ngy nay

Giai on t nm 1988 cho ti ngy nay l giai on pht trin mnh m nht ca

cng tc tm kim, thm d v khai thc du kh b Cu Long.

Song song vi l s ra i ca Lut u t nc ngoi v Lut Du kh, hng

lot cc cng ty du nc ngoi k hp ng phn chia sn phm hoc cng u t

vo cc l m v c trin vng ti b Cu Long.

Trin khai cc hp ng k v cng tc kho st a vt l thm d, cc cng ty

du kh k hp ng vi cc cng ty dch v kho st a chn c nhiu kinh nghim

trn th gii nh: CGG, Geco-Prakla, Western Geophysical Company, PGS v.v. Hu ht

cc l trong b c kho st a chn t m khng ch phc v cho cng tc thm d

m c cho vic chnh xc m hnh va cha. Kho st a chn 3D c tin hnh trn

hu ht cc din tch c trin vng v trn tt c cc vng m pht hin.

Trong lnh vc x l ti liu a chn 3D c nhng tin b r rt khi p dng quy

trnh x l dch chuyn thi gian v su trc cng (PreSTM, PreSDM).

Nm 2001, Vietsovpetro k nim khai thc tn du th th 100 triu. y l

mt du n quan trng trong bc tin ca ngnh cng nghip du kh Vit Nam.

Cho n ht nm 2003, tng s ging khoan thm d, thm lng v khai thc

khoan b Cu Long khong 300 ging, trong ring Vietsovpetro chim 70%. Bng

kt qu khoan, nhiu pht hin du kh c pht hin: Rng ng (l 15-2), Topaz

North, Diamond, Pearl, Emerald (l 01), C Ng Vng (l 09-2), Voi Trng (l 16-1),

ng Rng, ng Nam Rng (l 09-1). Trong s pht hin tnh n nm 2005 c nm

m du: Bch H, Rng (bao gm c ng Rng v ng Nam Rng), Rng ng, S

T en, Hng Ngc c khai thc vi tng sn lng t khong 45.000 tn/ngy.

6

Tng lng du thu hi t 5 m k t khi a vo khai thc cho n u nm 2005 l

khong 170 triu tn.

Tnh n cui nm 2010 ti b trm tch Cu Long phn ra 18 l hp ng,

khoan tng cng hn 500 ging khoan thm d, thm lng v khai thc, pht hin tng

cng 18 m trong c 11 m ang c khai thc (Bch H, S T en, C Ng Vng,

Rng) vi tng sn lng khai thc cng dn t khong 280 triu tn du quy i,

cng nhiu pht hin v cc cu to trin vng.

Tnh n thi im hin ti, c tt c hn 58.000 km a chn 2D v hn 15.000

km2 a chn 3D c thu n trn khu vc b Cu Long (Hnh 1.3).

Trong khu vc l 15-2/01 v cu to Hi S en, nm 1994, sau khi tin hnh thu

n 492km a chn 2D, JVPC tin hnh khoan ging VD-1X ( su TD 3410m).

Nm 1999, vi 192 km2 ti liu a chn 3D thu c nm 1998, JVPC tip tc khoan

ging VD-2X ( su 4000m). C 02 ging khoan u c biu hin du kh trong mng,

tuy nhin kt qu th va khng pht hin dng du thng mi.

Sau khi thnh lp nm 2005, TLJOC tin hnh khoan ging HSD-1X vo thng

09 nm 2007 trn khi B ca cu to Hi S en, kt qu th DST#1 v DST#2 trong

mng cho dng cc i ln n 21660 thng du/ngy m. Sau thnh cng ca ging

khoan HSD-1X, thng 08/2009, TLJOC tin hnh khoan 02 ging thm lng khi D v

mt phn khi C l HSD-2X v HSD-2XST, kt qu th va trong mng ca HSD-2XST

cho dng 700 thng/ngy m. Ging khoan HSD-3X khoan vo khi E cho dng t

nhin trong mng t 200-400 thng/ngy.

Thng 06/2009, ging khoan HSD-4X c khoan trong khi A, th DST trong

mng cho dng t nhin 1500 thng/ngy. Tip theo , thng 02/2010, tin hnh khoan

ging khoan thm lng HSD-5XP, kt qu th va trong mng cho dng 1350

thng/ngy m (Hnh 1.4).

7

Hnh 1.3. Cc kho st a chn 2D v 3D ti khu vc m Hi S en.

Hnh 1.4. Bn ng su nc mng m Hi S en v v tr cc ging khoan.

8

1.3. c im a cht, kin to

1.3.1. Lch s pht trin a cht

Trn bnh kin to khu vc hin ti, b Cu Long nm v pha nam ca phn

ng nam mng u-. y l b trm tch kiu tch gin (rift) pht trin min v lc a

c tui trc Tam b thoi ha mnh trong thi k Paleogen v chuyn sang ch

ra lc a th ng nh ngy nay bt u t thi k Neogen [7, 11, 16,31] (hnh 1.5).

Hnh 1.5. S v tr kin to ca b Cu Long trong bnh kin to khu vc ng

Nam [15].

Lch s pht trin a cht ca b c th chia ra 3 thi k: 1) Trc to rift (Pre-

rift): thnh to tng mng trc Tam; 2) ng to rift (Syn-rift) trong Paleogen n

u Neogen thnh to cc trm tch ca tp F(?)/E, D, C v B1; 3) Sau to rift: t Neogen

n hin nay, thnh to cc trm tch tp B2, B3 v A [7, 11, 16].

9

Thi k trc to rift: Thi k Jura sm-gia, vng nghin cu thuc phn ng

nam ca bn to ni Jura sm-gia. Lp y b ny l cc thnh to trm tch lc nguyn,

lc nguyn-carbonat. n Mesozoic mun, khu vc b Cu Long thuc bi cnh kin to

ra lc a tch cc do s ht chm ca mng Thi Bnh Dng xung di mng Indosini

(Hnh 1.6).

Hnh 1.6. S a cht i Lt ch ra s phn b ca cc phc h Granitoid nh

Qun, C N (Ankroet), o C [30]

Qu trnh ht chm gy nn cc hot ng magma xm nhp v phun tro hnh

thnh cung ni la pluton. Cc loi magma c tui Jura-Creta pht trin rng ri khu

vc i Lt v vng ln cn nh gp ti cc vt l trn t lin cng nh trong cc

10

ging khoan ngoi khi thuc b Cu Long l kt qu ca hot ng kin to ny. Ph

bin l cc diorite, granodiorite, granite thuc phc h nh Qun, o C, Ankroet

(C N) v cc magma phun tro andezite, riolite... thuc cc h tng o Bo Lc,

Nha Trang, n Dng tng ng.

Thi k ng to rift: Vo cui Creta u Paleogen, hot ng nng v bo mn

tri rng trn ton khu vc, to ra s ph hy mnh m cc granite tui Mesozoic

mun, mt trong nhng i tng cha du kh chnh trong khu vc. V lc a va

c c kt bt u b ph v thnh cc khi nng v vng st do tch gin. B Cu

Long c hnh thnh trn cc vng st khu vc thuc thi k Paleoxen - Eoxen. Cui

thi k ny l qu trnh hnh thnh trm tch tp F lp y cc trng mt s khu vc

trong b Cu Long. Hot ng t gy - kin to t Eoxen n Oligoxen c lin quan

n qu trnh tch gin (hnh 1.7) to nn cc khi t gy v cc trng b Cu

Long. Cc t gy ni chung c phng ng Ty, ng Bc - Ty Nam v Bc Nam.

Hnh 1.7. S minh ha cc hot ng kin to khu vc ng Nam thi k cui

Eoxen u Oligoxen. Khu vc nghin cu ang ch kin to tch gin [7]

11

Thi k ng tch gin to nn cc bn a ho c lp y bi cc trm tch

ca tp E c tui Eoxen Oligoxen sm. Trong giai on u, ngun cung cp vt liu

trm tch t, iu kin kh hu thun li to nn h su vi s tch t cc tng trm tch

st h dy trn din rng (trm tch ca tp E). Qu trnh tch gin tip tc m rng b v

gia tng su hnh thnh nn nhng h ln trong lng ng ch yu st m h ca

tp D, tip sau l cc trm tch nhiu ct hn lng ng trong mi trng sng, h,

delta ca tp C sau nh du giai on lp y b rift. Trm tch Eoxen-Oligoxen

trong cc trng chnh c th dy n 5000m. S kt thc hot ng ca phn ln cc t

gy v bt chnh hp nc trm tch Oligoxen nh du s kt thc thi k ny.

Bt u t Mioxen sm qu trnh tch gin gim dn, ch c cc hot ng yu t

ca cc t gy (th hin l 16-2). Giai on bin tin khu vc bt u xut hin (thnh

to trm tch tp B.1). Vo cui Mioxen sm, cc trng trung tm tip tc st ln phn

ln din tch b b chm su di mc nc bin, v tng st rotalite - tng chn khu vc

ca b - c hnh thnh vo thi gian ny. Cc trm tch Mioxen di ph chm hu ht

ln a hnh Oligoxen.

Thi k sau to rift: Thi k Mioxen gia l thi k nng ln ca b Cu Long,

mi trng bin nh hng t hn, phn ng Bc b ch yu chu nh hng ca cc

iu kin ven b. Thi k Mioxen mun, bin trn ngp ton b b Cu Long. Cng vo

cui thi k ny, do sng M Kng vo b Cu Long lm thay i mi trng trm

tch, ngun cung cp vt liu, kiu tch t v c hnh thi cu trc ca b. Bn trng m

rng hn v pha Ty Nam, vo pha ng bng chu th sng M Kng ngy nay v

thng vi b Nam Cn Sn. Trm tch chu th c hnh thnh do sng l ch yu.

Thi k Plioxen - T, l giai on tch cc kin to mi to nn bnh cu

trc hin ti ca thm lc a Vit Nam. B Cu Long khng cn hnh dng cu trc

ring m ho chung vo cu trc ton thm. Nguyn nhn l y bin ng tip tc st

ln do b cun ht xung di cung o Luson, mt khc, t lin ng Dng c

nng cao cng vi s hot ng ca ni la basalt kim, do v i dng n ang

y lc a ng Dng v Ty Nam ng Nam ln cao.

12

1.3.2. Cc pha bin dng hnh thnh cc t gy, i ph hy trong mng

khu vc Hi S en.

Tng ng vi thi k lch s pht trin kin to, trong b Cu Long v vng ln

cn, xc nh c cc giai on bin dng chnh t Jura n hin ny gm 4 giai on:

(D1) Giai on Jura sm-gia; (D2) Giai on Jura mun-Kreta; (D3) Giai on

Paleogen-Neogen sm v (D4) t Neogen n hin nay (Hnh 1.8) [19].

Hnh 1.8. Cc giai on bin dng b Cu Long [18]

Trong mi giai on ln ny li c chia thnh cc pha (phase). Trong , giai

on tch gin (rifting) (D3) c chia chi tit gm 6 pha (t D3.1 n D3.6) tng ng

vi cc thi k tch gin v nn p. Kt qu ca cc giai on v cc pha bin dng l cc

13

i cu trc a cht, b mt bt chnh hp, h thng t gy, un np vi cc phng

cu trc c trng, nguyn nhn gy ra bi trng ng sut kin to.

Trong khu vc m Hi S en, hot ng kin to gy nn cc t gy ch yu

din ra trong giai on (D3). Cc pha tch gin D3.1, D3.3 v D3.5 to nn cc t gy

thun, ng trm tch v cc bn a ho. Cc pha nn p D3.2, D3.4 v D3.6 to nn cc

t gy trt bng, cc t gy thun, cc t gy nghch v cc thnh to trm tch b

un np. Hu ht cc t gy hot ng mnh trong D3.4, D3.6 v cc t gy hot ng

t trc trong D3.1 v D3.2 u ti hot ng li trong cc pha t gy ny.

Trng ng sut kin to qua cc giai on trong khu vc ny v c bn cng xy

ra nh b Cu Long ngoi tr pha D3.4, c s xoay trc nn p t phng ty bc-

ng nam sang phng kinh tuyn (bc nam) khu vc HS v phng v tuyn (ng

ty) khu vc cu to Gi ng (Hnh 1.9).

Hnh 1.9. Cc pha bin dng khu vc Hi S en [19].

14

Tc ng vo mng mnh nht l trng ng sut kin to D3.2 c phng nn p

TB-N to ra cc h thng t gy trt bng c ng phng theo phng kinh tuyn

v v tuyn, h thng t gy nghch ng phng theo phng ng bc-ty nam.

Trong pha D3.4, trng ng sut kin to ti khu vc HS c phng kinh tuyn (hnh

1.9), mang tnh cc b so vi hng chung ca ton b l ty bc-ng nam (hnh 1.8)

hnh thnh cc h thng t gy theo phng ty bc-ng nam, kinh tuyn v v tuyn

1.3.3. Cu trc a cht khu vc

B Cu Long tip gip vi t lin v pha Ty Bc, ngn cch vi b Nam Cn

Sn pha ng nam bng i nng Cn Sn, pha Ty Nam l i nng Khorat - Natuna

v pha ng Bc l i ct trt Tuy Ha ngn cch vi b Ph Khnh. B Cu Long

c xem l b trm tch Kainozoi khp kn in hnh ca Vit Nam. Tuy nhin, nu tnh

theo ng ng dy trm tch 1000m th b c xu hng m v pha ng bc. Theo ti

liu a cht v Ti Nguyn Du Kh Vit Nam, 2007 [16], b Cu Long c xc nh

l n v cu trc bc I. n v cu trc bc I ny c chia thnh cc n v cu trc bc

II bao gm: 1) Trng phn d Bc Liu, 2) Trng phn d C Ci, 3) i nng Cu Long,

4) i nng Ph Qu v 5) Trng chnh b Cu Long (Hnh 1.10) [16].

Hnh 1.10. S phn chia cc n v cu trc bc II trong b Cu Long [15].

15

Trong cc n v cu trc bc II ny th Trng chnh b Cu Long tip tc c

phn chia chi tit thnh cc n v cu trc bc III da trn c im cu trc a cht ca

tng khu vc vi s khc bit v chiu dy trm tch v thng c gii hn bi nhng

t gy hoc h thng t gy c bin ng k. Trng chnh b Cu Long phn chia

thnh 8 n v cu trc a cht cp III gm: 1) i sn nghing Ty Bc, 2) i nng

Ty Bc, 3) Trng Trung tm (gm trng Ty Bch H v trng ng Bc), 4) i nng

Trung tm, 5) Trng pha ng Bch H, 6) i sn nghing ng Nam, 7) i phn

d ng Bc v 8) i phn d Ty Nam (Hnh 1.11-1.12).

Hnh 1.11. Bn cu trc Trng chnh b Cu Long [15]

1) Sn nghing Ty Bc: l di sn b Ty Bc ca b ko di theo hng

B-TN, chiu dy trm tch tng dn v pha Ty Nam t 1 n 2.5km. Sn nghing b

ct x bi cc t gy kin to c hng B-TN hoc TB-N, to thnh cc mi nh.

16

Trm tch Tam ca b thng c xu hng vt nhn v g y ln mng c granitoid

trc Kainozoi.

2) i nng Ty Bc: nm v pha Ty Bc trng ng Bc v c khng ch

bi cc t gy chnh phng B-TN. V pha TB i nng b ngn cch vi sn

nghing Ty Bc bi mt a ho nh c chiu dy trm tch khong 6km. i nng bao

gm cu to Vng ng (Hi S en) v di nng ko di v pha ng Bc.

3) Trung Trung tm: trong mt s ti liu trng ny c ghp chung vi trng

ng Bc. Tuy nhin, v c th kin to gia 2 trng c s khc bit ng k c bit l

phng ca cc t gy chnh. Trng trung tm b khng ch bi cc t gy kin to c

phng v tuyn, to s gp khc ca b. Chiu dy trm tch ca trng ny c th t

ti 7-8 km [15].

Hnh 1.12. Cc mt ct i qua cc i cu trc ca Trng chnh b Cu Long [16]

17

4) i nng Trung Tm: l i nng nm kep gia hai trng ng v Ty Bch

H v c gii hn bi cc t gy c bin ln vi hng ch yu v pha ng

Nam. i nng bao gm cc cu to dng v c lin quan n nhng khi nng c ca

mng trc Kainozoi nh: Bch H, Rng. Cc cu to b chi phi khng ch bi cc t

thun hnh thnh trong qu trnh tch gin, m cn bi cc t gy trt bng v chm

nghch do nh hng ca s sit p vo Oligoxen mun.

5) Trung pha ng Bch H: nm kep gia i nng Trung Tm v pha Ty,

sn nghing ng Nam v pha -N v i nng ng Bc v pha Bc. Trng c

chiu dy trm tch t ti 7 km v l mt trong ba trung tm tch gin ca b.

6) i sn nghing ng Nam: l di sn b ng Nam ca b, tip gip vi

i nng Cn Sn. Trm tch ca i ny c xu hng vt nhn v g y vi chiu dy

dao ng t 1 n 2.5 km. Sn nghing ny cng b phc tp bi cc t gy kin to

c phng B-TN v v tuyn to nn cc cu to a phng nh cu to Amethyst,

C ng i, Opal, Si.

7) i phn d ng Bc (phn u ng Bc ca b): nm kep gia i nng

ng Ph Qu v Sn nghing Ty Bc. y l khu vc c chiu dy trm tch trung

bnh v b phn d mnh bi cc h thng t gy c ng phng TB-N, B-TN v

v tuyn to thnh nhiu a ho, a luy nh (theo b mt mng). Mt s cc cu to

dng a phng xc nh nh: Ruby, Pearl, Turquoise, Diamond, Agate.

8) i phn d Ty Nam: nm v u Ty Nam ca trng chnh. Khc vi i

phn d B, i ny b phn d mnh bi h thng nhng t gy vi ng phng ch

yu l v tuyn to thnh nhng a ho, a luy, hoc bn a ho, bn a luy xen k

nhau. Nhng cu to c quy m ln trong i ny phi k n: u , Tam o, B en

v Ba V. Cc cu to a phng dng bc 4 l i tng tm kim v thm d du kh

chnh ca b.

1.3.4. a tng khu vc nghin cu

Theo ti liu khoan, a tng c m ra ca b Cu Long gm mng c trc

Kainozoi v trm tch lp ph Kainozoi [1, 2, 3, 5].

18

MNG TRC KAINOZOI

b Cu Long cho n nay khoan hng trm ging khoan su vo mng trc

Kainozoi ti nhiu v tr khc nhau trn ton b. Thnh phn thch hc ca mng gp

ph bin l cc magma xm nhp granite v granodiorite-diorite. Cc granite c gp

ti nhiu cu to nh Bch H (khi Trung Tm), Rng v Ruby, Rng ng, Hi S

en, Ngoi ra, cn c th gp cc phun tro, bin cht v trm tch c tui trc

Kainozoi nh l ra trn i Lt v vng ph cn.

So snh kt qu nghin cu cc phc h magma xm nhp trn t lin vi

mng kt tinh ngoi khi b Cu Long, theo c trng thch hc v tui tuyt i c th

xp tng ng vi 3 phc h: nh Qun, o C v C N. Ngoi ra, cnh pha

ng Bc m Bch H, mng magma xm nhp y ang c lin h vo thnh

phn ca phc h Hn Khoai, phc h magma c nht trong mng ca b Cu Long,

phc h c tui Trias mun, tng ng khong 240 n 250 tr. nm, thnh phn thch

hc gm ch yu l diorite, monzonite v adamelite. b bin i, c nt mnh. Phn

ln cc khe nt b lp y bi khong vt th sinh: calcite-epidote-zeolite.

Phc h nh Qun v o C gp kh ph bin nhiu cu to Bch H (vm

Bc), Ba V, Tam o v Si. cc m Hng Ngc, Rng ng, S T en v S T

Vng ( pha Bc b), ch yu l granodiorite, i ch gp monzonite biotite-thch

anh a sc. thuc loi kim vi, c thnh phn axit va phi SiO2 dao ng 63-67%.

Cc thnh to ca phc h xm nhp ny c mc gip v v bin i cao. Hu ht cc

khe nt u c lp y bi cc khong vt th sinh: calcite, zeolite, thch anh v

clorite. Trong i bin i mnh biotite thng b clorite ho. Phc h nh Qun c tui

Jura mun-Creta sm, phc h o C tui Creta. Tui tuyt i ca cc thuc cc

phc h ny dao ng t 90 n 130-155tr. nm. Phc h C N l phc h magma pht

trin v gp ph bin nht trn ton b Cu Long. Phc h c trng l granite hai mica,

thuc loi Natri-Kali, d nhm (Al=2.98%), Si (~69%) v t Ca. c tui tuyt i

khong 90-100 tr. nm, thuc Creta mun. Cc khi granitoid phc h magma xm nhp

ny thnh to ng to ni v phn b dc theo hng trc ca b. b dp v, nhng

mc bin i th sinh yu hn so vi hai phc h va nu.Trong mt ct magma

19

xm nhp bit thng gp cc ai mch c thnh phn thch hc khc nhau t axit n

trung tnh - baz, baz v thch anh. Ti mt s ni, nh khu vc m Rng cn gp

bin cht nhit ng kiu paragneis hoc orthogneis. Cc ny thng c mc gip

v v bin i km hn so vi xm nhp (Hnh 1.13).

Hnh 1.13. Biu phn loi thch hc cho cc mu mng theo ging khoan ti

cu to Hi S en (Vng ng) v ln cn [19]

Ti khu vc Hi S en, tng mng l mt i tng giu tim nng. Cc kt

qu th va trong i tng mng nt n ti y u cho dng kh quan. Ti cc ging

khoan trong phm vi cu to, mng trc Kainozoi gm cc granitoid phc h o C

tui Creta. Ch yu thuc nhm granite v monzonite thch anh (Hnh 1.14).

TRM TCH KAINOZOI

Trm tch Kainozoi trong khu vc b Cu Long ni chung bao gm cc trm tch

c tui t Eoxen ti nay v c chia thnh cc h tng: h tng C Ci (Eoxen), h tng

Tr C (Oligoxen sm), h tng Tr Tn (Oligoxen), h tng Bch H (Mioxen sm), h

tng Cn Sn (Mioxen gia), h tng ng Nai (Mioxen mun) v h tng Bin ng

(Plioxen-Pleitoxen) (hnh 1.15). Ti khu vc Hi S en, c mt cc phn v a tng

c m t theo th t t c n tr nh sau:

H PALEOGEN

Eoxen- Oligoxen sm. H tng Tr C (E2-E31 tc) - tp F

H tng Tr C xc lp ging khoan (GK) Cu Long-1X. Trm tch gm ch

yu l st kt, bt kt v ct kt, c cha cc va than mng v st vi, c tch t trong

20

iu kin sng h. i khi gp cc ni la. Chiu dy ca h tng ti phn trng su,

phn sn cc khi nng Trung tm nh Bch H, Rng v S T Trng c th t ti

500m. Tui ca h tng c xc nh da trn phc h bo t, phn hoa trong mu ly

ti ging khoan Cu Long-1X (Nguyn Giao, L Trng Cn v nnk 1987) [16]. khu

vc ln cn M Hi S en, trm tch ca tp F gp trong cc ging khoan cu to S

T Trng (L 15-1, Cu Long JOC). H tng Tr C c tim nng cha v sinh du kh

kh cao [16]. Cc va ct kt ca h tng l cc va cha du kh ch yu trn m ng

Nam Rng, S T Trng v l i tng khai thc th hai sau mng nt n trn m Bch

H. Chiu dy ca h tng dao ng t 0 n 800m.

Hnh 1.14. So snh mu mng ti cu to Hi S en vi cc mu ca phc h

nh Qun, o C v Ankroet ly ti cc im l trn khu vc i Lt [19]

21

Hnh 1.15. Ct a tng tng hp ti b Cu Long [16]

22

Oligoxen. H tng Tr Tn (E32 tt) - tp E, D v C

H tng Tr Tn c xc lp GK 15A-1X. ca h tng Tr Tn i ch nm

bt chnh hp trn h tng Tr C. Mt ct h tng c chia thnh ba tp:

Tp E: trong khu vc nghin cu, tp E gp trong cc ging khoan HSD-4X (L

15-02/1) v HSN-1X (L 15-2 m). Chng thng b bc mn ti nhng khu vc mng

nh cao. Thnh phn thch hc: ct kt ht mn n th, i ch c sn, cui kt xen st

kt, bt kt. Trm tch tp E c xc nh thnh to trong bi cnh kin to ng to

rift. Mi trng trm tch sng (aluvi/fluvi/channel/turbidite).

Tp D: y l tp trm tch giu st bao gm st kt, bt kt xen kep ct kt. St

kt mu en nu, nu m giu hu c l ngun sinh chnh trong b Cu Long. Mi

trng tch t l m h nc l v m h nc ngt c nh hng nc l.

Tp C (Oligoxen mun): trm tch ca tp C cha thnh phn ct nhiu hn so vi

tp D. Thnh phn thch hc bao gm st kt xen kep vi ct kt v vi. Mi trng

tch t l iu kin m h nc ngt vi nh hng nc l v m h nc ngt gn

b.

Trong mt ct h tng gp nhng ho thch bo t phn: F. Trilobata,

Verutricolporites, Cicatricosiporites, xc nh tui Oligoxen mun.

H NEOGEN

Mioxen sm. H tng Bch H (N11 bh) - tp BI

H tng Bch H c xc lp ging khoan BH-1X. khu vc nghin cu, H

tng Bch H c chia thnh hai phn tp BI.1 (phn di) v BI.2 (phn trn) c m

t theo t t t di ln nh sau:

Tp BI.1: tp BI.1 c chia lm th t t di ln nh sau:

BI.1 di ph tp 5.2: Intra Bch H di 5.2 bao gm ct kt xen kep vi bt

kt v st kt xm. Mi trng trm tch l iu kin m h nc ngt vi nh hng

ca nc l v iu kin h nc ngt gn b.

BI.1 di ph tp 5.1: Intra Bch H di 5.1 bao gm st kt nu dy xen

kep vi st kt xm mng, bt kt v ct kt mng (phn di); st kt xm dy xen kep

23

vi ct kt v bt kt mng (phn trn). Mi trng trm tch l iu kin h nc ngt

vi nh hng ca nc l v iu kin ng bng ph sa vi kh hu kh.

Tp BI.2: phn nc tp BI.2 c c trng bi mt lp st kt to nn tng chn

rng ln bao ph ton b b Cu Long c gi l tng st Bch H hay st Rotalit.

Thnh phn thch hc bao gm phin st/st kt mu xm xanh lc sm, xm xanh vi

bt kt mng (phn trn), phin st/st kt xm xanh lc sm, xm xanh lc vi ct kt

mng, bt kt v mt t vi. Mi trng trm tch gn b, bin b gii hn, iu kin

ph nc l v h nc ngt vi nng lng thp.

Mioxen trung. H tng Cn Sn (N12 cs) - tp BII

H tng Cn Sn c xc lp ging khoan 15B-1X. H tng Cn Sn gm ch

yu ct kt ht th-trung, bt kt (chim n 75-80%), xen k vi cc lp st kt mu

xm, nhiu mu dy 5-15m, i ni c lp than mng. B dy h tng thay i t 250 -

900m. Trm tch ca h tng c thnh to trong mi trng sng (aluvi) pha Ty,

m ly - ng bng ven b pha ng, ng Bc. Trm tch ca h tng nm gn nh

ngang hoc un nhe theo cu trc b mt nc h tng Bch H, nghing thoi v ng v

Trung tm b. Trong mt ct h tng gp ph bin cc bo t phn: F. Meridionalis,

Plorschuetzia levipoli, Acrostichum, Compositea... v cc trng l, rong to nh h tng

Bch H.

Mioxen mun. H tng ng Nai (N13 n) - tp BIII

H tng ng Nai c m ging khoan 15G-1X. H tng ng Nai ch yu l

ct ht trung xen k vi bt v cc lp mng st mu xm hay nhiu mu, i khi gp cc

va carbonat hoc than mng, mi trng trm tch m ly - ng bng ven b phn

Ty b, ng bng ven b - bin nng phn ng v Bc b. Tui ca h tng c xc

nh theo tp hp phong ph bo t v Nannoplakton: Stenoclaena Palustris Carya,

Florschuetzia Meridionalis, ngho ho foraminifera. B dy ca h tng thay i trong

khong t 500 - 750m.

H NEOGEN - T

Plioxen-Pleitoxen. H tng Bin ng (N2-Q b) - tp A

24

H tng Bin ng ch yu l ct ht trung-mn vi t lp mng bn, st mu xm

nht cha phong ph ha bin v glauconit thuc mi trng trm tch bin nng, ven

b, mt s ni c gp carbonat. Chng phn b v tri u khp ton b, vi b dy

kh n nh trong khong 400 700m. Trong mt ct ca h tng gp kh ph bin cc

ho foraminifera: Pseudorotalia, Globorotalia, Dng ru (Bryozoar), Molusca, san h,

rong to v bo t phn: Dacrydium, Polocarpus imbricatus...

Tm li: a tng khu vc cu to Hi S en bao gm cc granitoid tui

Mesozoi mun to nn mng trc Kainozoi v cc trm tch Kainozoi bao gm cc

tp a chn E, D, C, BI.5.2, BI.5.1, BII, BIII & A. Nhn chung b dy ca cc thnh to

trm tch tui cui Mioxen sm- T kh n nh thay i trong khong t 1800-

2100m. B dy ca trm tch Eoxen Mioxen sm thay i rt r t 1100m trung tm

kin trc Hi S en n trn 6000m trng lin k.

1.3.5. H thng du kh.

1.3.5.1. c im tng sinh. B Cu Long tn ti 2 tng me: trm tch tui

Oligoxen v Mioxen sm [16, 19].

m tui Oligoxen:

- giu VCHC t trung bnh n rt tt, tim nng sinh cao, tp trung vng ln

cn cu to m Bch H-Rng.

- Trng trung tm, giu VCHC c bit cao su trn 3100m, gi tr tim

nng sinh HC t t tt n rt tt vi sn phm l du chim ch yu.

- Cht lng me tt hn ti tp D, E so vi tp C.

- me Oligoxen khu vc b Cu Long th hin tnh tri VCHC m h, cho

tim nng sinh du cao (Bng 1.1, Hnh 1.16).

m tui Mioxen sm: Ngho VCHC, tim nng sinh km v cha t

trng thnh cha iu kin tham gia vo qu trnh sinh du, kh b Cu Long

(Hnh 1.18).

25

Hnh 1.16. Biu tim nng sinh du v phn loi vt cht hu c trm tch Oligoxen

[19]

Hnh 1.17. Biu tim nng sinh du v phn loi VCHC trm tch Mioxen sm [19]

26

Bng 1.1: su cc ngng hin ti ca m Oligoxen b Cu Long [19]

Hnh 1.18. th th hin trng thnh ca vt cht hu c ti thi im hin ti

[19]

27

1.3.5.2. c im cha. cha B Cu Long bao gm: ct kt tui Mioxen,

Oligoxen v mng granitoid nt n trc Tam [14, 16, 19].

cha Mioxen:

- cha tp BII: cc tp ct kt c chiu dy kh ln, ht t mn n th,

chn lc t km n kh. Mi trng ven bin, bin, nc l. cha c cht lng t

tt ti rt tt vi rng, thm cao, c th t > 30% v tng ng hng trm mD.

- cha tp BI: l tng cha quan trng, c mt tt c cc ging khoan trong

b Cu Long. Ct kt c ht t trung bnh n tt. chn lc t km ti rt tt.

rng v thm vn c bo tn, rng gia ht bin i t 15% n hn 20%. (Hnh

1.19)

Hnh 1.19. th th hin phn loi ct kt v mi quan h gia rng v thm,

tp BI [19]

cha Oligoxen:

Tp C (Oligoxen mun - H tng Tr Tn trn). Ct kt tp C ht t mn ti th,

c ni rt th hoc c cui si, ht t gc cnh n trn cnh. chn lc t km ti rt

tt. thm km hn so vi tp BI nhng cng c ch ln ti 1000mD do s lin thng

tt. Khu vc Hi S en v ln cn, trm tch tp C kh phong ph ct kt sng ngi-ph

sa. T s N/G ca tp C thng kh cao, khong 60-65% nh ti T Gic Trng/Hi S

Trng, nhng ti ging 15-GD-1X t s ny ch khong 12%. Ti cc ging khoan trong

28

l 15-2/01, b dy tp C khong 250m, cht lng cha trung bnh, rng khong 14-

17% (Hnh 1.20).

Tp D (Oligoxen mun H tng Tr Tn gia). Ct kt thuc loi arkose v

arkose lithic, cc mnh ch yu gm granite, vi t ni la. Ct kt tp D c

trng bi kch thc ht t trung bnh ti mn, ti mt s ni c ht th, lin thng kh

tt. cha c hm lng st trung bnh l 25%, rng thp hn so vi ct kt tp BI

v tp C (t 10% n 20). Nhn chung, tp D cha rt nhiu trm tch st m h nn

khng phi l va cha chnh trong b v khu vc nghin cu.

Tp E (Oligoxen di). Kt qu phn tch mu li cho thy rng v thm

thp. rng tp trung ch yu trong khong 8-15%, thm t 0.01 n 100 mD cho

thy cht lng cha tp E km hn nhiu so vi cc tp khc. Ti m Hi S en,

ging khoan HSD-4X bt gp tp E vi chiu dy 350m, kt qu phn tch ti liu a

vt l ging khoan cho thy cc va c rng t 13-14% (hnh 1.21), kt qu th va

cho dng du 700 thng/ngy m sau khi tin hnh lm nt va bng thy lc.

Tp F (Oligoxen di). Ct kt tp F khng xut hin nhiu trong b Cu Long.

Khu vc Hi S en vng mt trm tch ca tp F. nhng khu vc c cha tp F,

thnh phn ch yu l arkose v arkose lithic vi ht t trung bnh ti th hoc rt th,

i ch c si cui, chn lc t km ti trung bnh. Kt qu phn tch rng v

thm ca trong tp F cho thy rng thng nh hn 10%, thm nh hn 10 mD.

cha tp F c cht lng t km n trung bnh.

Mng trc Tam: cha mng granitoid nt n-hang hc l loi cha

c bit rt ph bin b Cu Long, ch yu gm granite v granodiorit. Mt s nt n,

hang hc b lp y bi cc khong vt th sinh nh calcit, thch anh, clorit, epidot, pyrit,

zeolit, i ch lp y bi l oxit st [13,14]. Granite b bin i c cha kaolinit chim

t 10 ti 30% v cc khong vt kim. c c trng rng thp (trung bnh 1-3%)

thm rt cao (hng nghn mD). Ti nhiu ging khoan kt qu th va cho dng ti

hn 1.000m3/ngy, thm ch t 2.000m

3/ngy. y l tng cha du kh quan trng nht

b Cu Long (hnh 1.22).

29

Trong khu vc Hi S en, JVPC khoan 2 ging 15-VD-1X v 15-VD-2X bt

gp i tng mng vi biu hin du kh tt, tuy nhin, do y l nhng ging thng

ng nn khng th xc nh c lin thng ca cc t gy m. Vi nhng ging

khoan xin sau ca TLJOC (HSD-1X, HSD-5XP.) khoan gn vung gc c

vi nhng hng t gy m em li nhng thnh cng trong vic nh gi mng.

Hnh 1.20. th th hin phn loi ct kt v mi quan h gia rng v thm,

tp C [19]

Hnh 1.21. th th hin phn loi ct kt v mi quan h gia rng v thm, tp

E [19]

30

Hnh 1.22. th th hin phn loi magma trong khu vc nghin cu [19]

1.3.5.3. c im chn

chn du kh b Cu Long c xem l nhng va hoc tp st nm trong

khong a tng t Mioxen ti Oligoxen, bao gm 1 tng chn khu vc v 3 tng chn a

phng [16, 19]:

Tng chn khu vc tng st thuc nc h tng Bch H hay cn gi l tp st

Rotalit kh dy, pht trin rng khp b Cu Long. Chiu dy kh n nh cc l thuc

trung tm b v mng dn v ra b.

Tng chn a phng I - tng st nm trong tng Mioxen h. Chiu dy tng

chn ny dao ng t 60 n 150m, gm nhiu va st vi chiu dy 5-10m v hm lng

st trung bnh khong 60%.

Tng chn a phng II - tng st thuc h tng Tr Tn (tp D v C) bao gm

cc va st ring l, ph kn ton b din tch v c bit l phn nh mng vi tng

chiu dy cc va st t ti hng trm mt.

Tng chn a phng III - tng st thuc h tng Tr C. y l tng chn

mang tnh cc b, c din phn b hep, bao quanh cc khi nh mng c, rt him khi

ph kn c phn nh ca khi nng mng. St phn lp dy, c kh nng chn kh tt.

1.3.5.4. c im by cha. By cha du kh b Cu Long bao gm: by cu

trc, by phi cu to v by hn hp [16, 19]:

31

By cu trc: gp hu ht cc m trong b Cu Long c chia lm 2 loi:

By np li: hot ng kin to un cong cc lp t nm ngang ban u to

nn loi by ny.

By bn t gy: by loi ny c hnh thnh do np li b t gy.

By phi cu to: By phi cu to c chia ra do cc nguyn nhn thch hc (mt

thm trong cha), trm tch (vt nhn, thu knh) hoc c a l (bo mn, lng

sng c, bt chnh hp a tng) nh gp ti cc m C Ng Vng, Knh Ng Trng...

By hn hp: By c hnh thnh do s kt hp ca by cu trc v by a

tng trong b Cu Long, dng by ny gp ch yu trong trm tch Oligoxen.

1.3.5.5. Thi gian dch chuyn du kh

Ti y tp E (Oligoxen di), me ch yu ang trong pha sinh du & kh m-

condensat ngoi tr phn nh thuc trng ng Bc v trng Ty Bch H ( su vt

5800m). Trong khi ti nc tp D, C (Oligoxen trn) me ang trong pha sinh du

[19].

Du kh di c mnh theo phng thng ng qua cc t gy ln ti tng cha

pha trn hoc dch chuyn dc tng theo va ct xen kep trong chnh tng me hoc

theo cc tp tip xc trc tip vi tng sinh.

By c hnh thnh ch yu trong giai on to rift v u giai on sau rift

(Mioxen sm), sm hn vi giai on sinh mnh v di c chnh ca du, kh.

Hnh 1.23. M hnh tng qut h thng du kh b Cu Long [19]

32

CHNG 2

PHNG PHP M HNH HA RNG NT N

TRONG MNG M HI S EN

2.1. Tng quan v mng nt n.

Mng granitoid nt n l i tng cha du c bit trong b Cu Long ni

chung v ca cu to Hi S en ni ring. Bn thn granitoid khng c rng

nguyn sinh, v khng c thm. Cc qu trnh a cht trong v sau to hnh

thnh cc nt n, hang hc, vi rnh ra la v c bit l cc nt n m to rng

v thm th sinh hnh thnh nn "tng cha mng granite nt n" vi rng trung

bnh 1-3%, thm ln ti hng nghn mD ti cc i nt n tt.

2.1.1. Hin trng v phng php nghin cu mng nt n

Hin trng nghin cu mng nt n

Du kh trong mng nt n c pht hin trong nhng nm u ca th

k 20. Cho n nay, du kh c pht hin hn 30 nc trn th gii ti hu ht

cc chu lc v trong hu ht cc loi mng, t nhng tr granite tui Mezozoi

(ti bn trng Cu Long hoc cc khu vc khc thuc ng nam Chu ) cho n

nhng trm tch bin cht tin Cambri (mt s m thuc Trung ng nh Azura, Libi)

hay trong nhng c nht tui Proterozoi ( khu vc ng Xibieri). Mt s v d

in hnh ca du kh c tm thy trong mng c th k n nh: b trm tch

Argentina (Cuyo v Neuquen), b trm tch Yemen (DNO l 43, Nexen l 14, Total

l 10, ONV l S2), b trm tch Vit Nam (Cu Long)...

C th nhn thy, du kh c pht hin trong mng, cc loi t trm

tch bin cht mc thp cho n cc trm tch bin cht mc cao hay trong cc

loi magma. Tnh cht cho dng trong cc nhm mng khc nhau cng khc

nhau, trong kh nng cho dng ln nht l i tng mng granitoid nt n. Mt

s m in hnh ca nhm mng granitoid trn th gii c th k n nh: mng

granitoid c tui Mezozoi thuc m Kora ca New Zealand.

33

Ti Vit Nam, cc m ln trong i tng mng garnitoid nt n c th k

n nh: mng granitoid trc Tam ti cc m Bch H, Rng, S T en, S

T Trng, S T Vng, Hi S en, C Ng Vng, Phng ng, Rng ng... Du

cha trong mng ln nht thuc v b Cu Long, tim nng c tnh 6.400 triu

thng. Cho n nay pht hin 25 cu to trong tng s 42 cu to c khoan thm

d n i tng mng, trong 16 cu to c a vo pht trin.

Hnh 2.1. S phn b tr lng trong mng b Cu Long

Cc phng php nghin cu mng nt n

Vit Nam l nc c sn lng khai thc du t mng nt n ng hng u

th gii. Du kh t mng nt n Vit Nam ch yu c khai thc t khu vc b

Cu Long. Trong khu vc ny, in hnh phi k n m Bch H vi tr lng thu

hi ln n 1.4 t thng du. Bn cnh cn c cc m Rng, Rng ng, Ruby v

S T en vi tr lng t 100 n 400 triu thng du [26].

Tuy nhin vic nghin cu mng Vit Nam mi ch mc nghin cu

s hnh thnh nt n, d on s tn ti ca cc i nt n, c tnh thm cha v cc

34

nguyn nhn nh hng n kh nng thm cha ca mng nt n. Cng tc tm

kim thm d v khai thc du kh trong mng nt n hin nay vn gp nhiu kh

khn trong vic minh gii, d on s phn b v c tnh chm cha ca cc i nt

n.

Mc d du kh trong mng l rt tim nng, nhng vic tm kim, phn tch,

nh gi tr lng thu hi ca cc m ny li rt kh khn do tnh cht phc tp ca

mng. C mt s trng hp mc d ban u m cho sn lng rt cao, nhng li

gim xung rt nhanh. Nguyn nhn l do cha phn tch, nh gi, v nm bt c

h thng rng, tnh cht lu thng ca du. V vy vic xy dng m hnh rng

cho mng nt n l rt cn thit trong vic nh gi tim nng cng nh tr lng

ca cc m dng ny.

Vic xy dng m hnh rng trong mng hin nay c 3 phng php

chnh l phng php Halo, phng php DFN (Discrete Fracture Network),

phng php ANN (Artificial Neural Network) ang c ng dng. Mi phng

php u c nhng u im v nhc im khc nhau. Bn cnh , vic chn la

phng php cho vic xy dng m hnh cn b khng ch bi cht lng v s lng

ca s liu u vo.

Phng php Halo: y l phng php u tin c s dng Vit Nam v

hin nay vn ang c s dng rng ri, ti nhng khu vc c cht lng ti liu a

chn t trung bnh n km. Phng php ny ch yu da vo minh gii t gy, nn

ph thuc vo s ch quan ca ngi minh gii. Nhc im ca phng php ny l

gi thuyt h thng t gy l ng nht dc theo mt t gy. Vit Nam, phng

php ny c s dng nhiu trong vic nh gi gia tng tr lng trong mng nt

n, v d nh trong m S T en SW [29]. Nhm khc phc cc yu im ca

phng php Halo, phng php Halo ci tin c p dng bng cch s dng thm

thuc tnh a chn v phn loi cc t gy c th nh gi c mc bt ng

nht ca rng nt n v s lin thng gia chng dc theo mt t gy.

35

Hnh 2.2. Cc i mch ht mn (gouge) xut hin trn mt t gy c th ng vai tr

l cc nm chn, ngn s di chuyn ca cht lu ln cc va bn trn

Phng php DFN (Discrete Fracture Network): c s dng khi c nhiu

ti liu ging khoan v thng tin a cht ca khu vc. M hnh xy dng theo phng

php ny da vo thng k cc thng s ca nt n nh: hng, chiu di, m, hnh

dng. Phng php ny xy dng m hnh kt ni ca cc t gy v h thng nt n,

t ta c c cc c tnh ca dng trong cha. y l phng php c gii

thiu t nhng nm 1970 v c s dng nhiu trong xy dng m hnh vi nhiu ci

tin trong sut qu trnh t n nay. Phng php DFN c dng nhiu trong

nghin cu nt n ni chung. V d nh xy dng m hnh trong mng nt n

Olkiluoto, Phn Lan hay Soultz-Sous-Forest, Php hay m hnh nghin cu dng

nc thi cha Chloride chy trong mch nc ngm qua nt n [24].

36

Phng php ANN (Artificial Neural Network): l phng php mi v nhn

c nhiu s quan tm gn y trong cng nghip du kh. Phng php ny c kh

nng s dng ti cc khu vc c ti liu a chn cht lng t trung bnh n tt,

cc khu vc ang trong giai on thm d, pht trin v c s lng ging khoan hn

ch. Mt s m in hnh c ng dng phng php ANN nh Bch H, Hi S

en. i vi phng php ny, ngi s dng s tin hnh hun luyn phng php

bng cc ti liu u vo ca ging khoan. Phng php dng ti liu a chn l chnh

ni suy. Chnh v th, i vi nhng m ang giai on cha pht trin, ang

trong giai on thm d thm lng, c ti liu a chn tt th phng php ANN s

t ra hu hiu hn v phng php ny c th kt hp c ti liu a chn v t

ng ni suy theo cc ti liu thc t ch dn c a vo. Chnh v th phng php

c th trnh c cc sai s do ch quan ca ngi minh gii. c im ni bt nht

ca phng php ny chnh l kh nng t hp c trng s cc s liu u vo. Trng

s ny c xc nh chnh trong qu trnh hun luyn cc thuc tnh bng ti liu ca

cc ging khoan.

ANN cho php t hp lot cc thuc tnh a chn c hun luyn theo ti liu

ging khoan, hot ng trn c s p dng thut ton phi tuyn. Tng thuc tnh s

c nhn vi trng s tng ng v cng ra nhm tnh ton ra rng.

tng chnh xc ca m hnh, thuc ton a thng k (Co-Kriging) c

s dng trn c s t hp kt hp mt s ti liu ging khoan khc nh FMI, PLT, cc

thng tin a cht kin to ca vng nghin cu.

Co-Kriging l phng php ni suy da vo mt s ti liu u vo. Phng

php s dng c trng thng k khng ch phng php ni suy. Da trn cc c

im ca c hai phng php Co-Kriging v ANN, nu kt hp c hai phng php

ny th s to ra c mt t hp cc s liu: ti liu a chn, ti liu a vt l ging

khoan v cc thng tin a cht kin to c trong khu vc nghin cu. Chnh v th,

u im ni tri ca phng php c xut ng dng chnh l t hp c tt c

cc s liu c c vo m hnh rng.

37

Hin nay vic xy dng m hnh rng cho mng nt n bng cch kt hp

phng php ANN v Co-Kriging cha nhn c s quan tm v p dng rng ri

Vit Nam.

2.1.2. C ch hnh thnh nt n trong mng granitoid

mng l khi nim chung ch tt c cc thnh to t trc khi hnh

thnh b v to thnh y ca b. mng c th pht trin ra ngoi phm vi b v l

trn mt t.

B Cu Long bt u hnh thnh vo giai on gia Eoxen, do qu trnh tch

gin pht trin trn v lc a pha ng i Lt [16]. Thnh to nn mng ca

b l cc trm tch, trm tch b bin cht, magma xm nhp v phun tro trc

Kainozoi nh gp trn i Lt. Trong cc thnh to mng ny, magma

xm nhp l mt i tng cha ht sc c bit, c bit vi tn gi tng cha

mng granitoid nt n (hnh 2.3). Thnh phn thch hc ca granitoid bao gm

granite, monzonite, granodiorite, diorite thch anh, monzodiorite, diorite,

gabrodiorite Chng c phn chia vo cc phc h magma c tui t Triat mun

n Jura mun - Kreta: 1) Phc h Hn Khoai (183-208 tr. n) tui Triat mun; 2) Phc

h nh Qun, phc h o C tui Jura mun-Kreta, v phc h Ankroet (C N)

(100-130 tr. n) [9].

Hnh 2.3. M hnh by du kh mng nt n b Cu Long: (1) cha mng nt n;

(2) Tp st D tng chn v tng sinh; (3) cha ct kt.

38

Hnh 2.4. Phn loi cc mng theo phn v a cht v thch hc.

Hnh 2.5. Phn loi granitoid mt s ging khoan b Cu Long (theo phn loi ca

Streckeisen, 1976).

39

Cc nt n hnh thnh trong cng c th do nhiu nguyn nhn khc nhau,

hay tng hp ca mt s nguyn nhn no . i vi cc nt n, hang hc trong

mng granite m Bch H v Rng, cc nh nghin cu Areshev E.G., Trn L

ng v nnk (1992), Ng Xun Vinh (1999), Phan Trung in (2000), Phm Anh

Tun (2001), Trnh Xun Cng (2013)..., u c nhn nh chung l c cc nguyn

nhn chnh sau [13, 17, 18, 21, 22]:

- S ng ngui v co rt th tch ca khi magma: Do khi magma xm nhp

tip xc vi vy quanh. Km theo qu trnh l s co rt th tch ca magma hnh

thnh khe nt nguyn sinh gm cc loi tiu biu sau: 1) Khe nt ngang (Q) vung gc

vi mt tip xc gia khi magma v vy quanh, ng thi vung gc vi phng

sp xp nh hng ca khong vt i tip xc. Chng thng tng i thng, mt

bng phng. Trong cc ai mch, khe nt Q xe nh nan qut, c m ln; 2) Khe

nt dc (S) vung gc vi (Q). Khe nt dc thng ngn, mt khng phng, rt dc

hoc dc ng v l khe nt kn; 3) Khe nt dng lp (L) hay khe nt thoi thng

song song vi mt tip xc; 4) Khe nt cho (P) ct cho v nhn (Q) lm ng phn

gic, thng pht trin khng ng u.

Hnh 2.6. Cc kiu khe nt nguyn sinh ca magma xm nhp (ngun ti liu: biu

khi ca Cloos.E).

40

- Qu trnh ph hy do kin to: Cc chuyn ng kin to v trng ng sut

khu vc c tnh cht quyt nh trong s hnh thnh cc h thng nt n trong khi

mng. Hot ng kin to dn n hnh thnh cc h thng t gy, nt n v i

c nt. Trong b Cu Long gp cc loi dm kt c rng ln ti 10% trn cc

mu li cc su kh ln so vi mt mng.

Trng ng sut do hot ng kin to gy nn cc lc nn p (1) v ko cng

(3) tc ng nn khi mng to ra cc nt v /t gy. Cc loi khe nt gy nn bi

trng ng sut kin to bao gm: 1) Khe nt ct (S1, S2): to thnh 2 h thng ct

nhau (hnh 2.7). Cc mt cu to ct l nhng mt phng, nhn rt kht nhau khng

thun li cho s xuyn nhp cc th magma. 2) Khe nt tch (Kt): pht trin theo

phng vung gc vi lc tc dng ko (3) v song song vi phng ca lc p

(1). Cc khe nt tch c b mt g gh, c nhiu khe nt nh ven ra v c m

ln thun li cho s xuyn nhp ca cc th magma hoc nhit dch; 3) Khe nt p dp

(Kd): pht trin theo phng song song vi lc tc dng ko (3) v vung gc vi

phng ca lc p (1). Cc khe nt p dp thng gp trong bin dng do.

Hnh 2.7. Phn loi khe nt trong m hnh elipxoit bin dng. Cc trc ng sut chnh

c k hiu l 1, 2, 3 (vi quy c 1 > 2 > 3).

Cc mt khe nt S1, S2 t nhiu c s dch chuyn nn cn gi l mt chuyn

ng, trong trng hp khi s dch chuyn c gi tr ln chng tr thnh cc t gy;

Tng ng vi v tr v phng khc nhau ca cc trc ng sut chnh s hnh thnh

41

cc kiu t gy thun, t gy nghch, t gy trt bng (hnh 2.8 2.9).

Hnh 2.8. Mi quan h gia trng ng sut v cc loi t gy.

Hnh 2.9. Mi quan h gia cc loi t gy v cc khe nt sinh km (After

Mikhailov)[24]

42

Trong b Cu Long, cc pha kin to hot ng trong nhiu thi k. Nhng nt

n to ra trong pha u tin thng b lp kn bi qu trnh nhit dch, v cc qu

trnh trao i nhit dch xy ra. Kt qu l cc nt n b lp y bng cc khong vt

th sinh c thnh phn chnh l calcite, zeolite, thch anh. Cc pha hot ng kin to

v sau c th tip tc m rng cc khe nt c hoc to ra cc khe nt mi. Cc nt

n c l ch xung yu nht v cha cc khong vt gin s d b ph v vn, nghin

nt. Kt qu l cc khng gian rng m trong nt n c c hnh thnh v c bo

tn trong iu kin khng c dung dch nhit dch trn vo hoc khng b cc trm tch

ht mn lp kn. L rng nt n tn ti trong khi mng vng m Bch H v m

Rng ch yu do tc ng ca lc kin to trong cc pha mun v sau, lm cho cc t

gy ti hot ng c l vo cui Oligoxen mun v u Mioxen sm. Trong khi

magma xm nhp, cc khe nt ban u hoc b lp kn bi cc khong vt th sinh,

hoc c m rt b cho nn gn nh khng c l rng nt n ng k. Tuy nhin,

di tc dng ca lc ng sut ko xy ra trong pha hot ng kin to sau , cc nt

n s ti hot ng to nn l rng hiu dng. Nu pha hot ng kin to ny xy ra

trc hoc trong thi gian dch chuyn du kh s c ngha cha du kh [13, 17].

- Hot ng nhit dch: Cc hot ng ca qu trnh nhit dch c lin quan

cht ch vi cc hot ng kin to v dn n cc bin i trong thnh phn cng nh

cu trc khng gian rng trong mng b Cu Long.

Ngoi vic c th to ra cc khong vt th sinh nh zeolite, calcite lp kn

hoc gn kn cc khe nt, cc dung dch thy nhit cn ha tan ra la bo mn to ra

cc hang hc c bit l ti nhng giao ct cc nt n ln nh. Tuy nhin cng c

kin cho rng hot ng nhit dch khng nhng khng lm m rng thm cc khe nt

n c trc m ngc li chng cn b lp y mt phn hay ton b [18]. Qu trnh

thy nhit hu nh khng c tc dng n s hnh thnh l rng trong mng m

Bch H.

- Qu trnh phong ha: din ra khi khi magma xm nhp c hnh thnh,

kt tinh di su trong iu kin p sut cao, c nng cao ln b mt dn n hin

tng gim ti do tng t nm trn b bc mn, gim p iu kin p sut b mt

43

v cc qu trnh phong ha l nguyn nhn quan trng dn n hin tng nt n,

phong ha lm cho b ph hy, bo mn, ra tri hnh thnh rng th sinh trong

mng. Theo ti liu khoan mt s m nh Bch H, Rng ng, Hi S en...

ch khong 20m tnh t mt mng. Ni chung qu trnh phong ha nh hng khng

ng k ln s bin i th sinh ca mng m ch yu lm gim bn c hc ca

v hnh thnh i thm trn b mt khi granitoid vn khng c tnh thm [13].

- Mi quan h gia tui ca nt n v thi gian sinh du kh: mi quan h gia

thi im nt n c hnh thnh v thi im du kh dch chuyn ng vai tr quan

trng trong vic nh gi rng ca nt n trong mng. Khi nt n c hnh thnh

v cha b lp nht, sau du khi dch chuyn vo v lp y cc l rng ny th qu

trnh nhit dch xy ra sau khng nh hng n rng ca nt n. Tuy nhin khi

nt n c hnh thnh v ngay ti thi im xy ra qu trnh nhit dch th cc l

rng ny b lp nht, lm gim rng ca nt n trong mng.

2.1.3. Cc yu t nh hng n kh nng cha ca mng nt n.

Cc yu t nh hng n kh nng thm cha ca mng bao gm thnh

phn thch hc - khong vt, cc bin i nhit dch, hot ng kin to v su,

hot ng magma tr (volcanic activity), mi quan h gia qu trnh hnh thnh nt n

v dch chuyn du kh. Nhng yu t ny tc ng tng h quyt nh n cht

lng tng cha [13, 15, 31].

Thnh phn khong vt chnh ca mng granitoid gm c thch anh v

feldspar (plagioclas v feldspar kali) ngoi ra cn c cc khong vt mu nh pyroxen,

hornblend, biotit, muscovit v cc khong vt ph, qung. T l % khong vt khc

nhau ty theo tng loi .

Phn ln cc khong vt to magma u c phn ng di tc dng ca

dung dch nhit dch sau magma, ngay c thch anh cng b gm mn, ha tan. Qu

trnh ny hnh thnh cc hang hc kch thc t vi chc micromet n hng chc

milimet. Dung dch nhit dch trong qu trnh dch chuyn dc theo cc khe nt, t

gy c th hnh thnh cc khong vt nh zeolite v calcite... lp nht vo khng gian

rng. Thnh phn khong vt ca mng l yu t cn bn n phn ng vi dung

44

dch nhit dch v c xc nh d bin i nht trong diorite, t hn l

granodiorite v t nht l granite. Qu trnh nhit dch c tnh hai mt: m rng cc nt

n v hang hc tn ti trc hoc lp y, lm gim khng gian rng bng cc

khong vt th sinh. Nhng nhn chung, qu trnh ny khi xy ra mnh s c tc ng

xu lm gim mnh khng gian rng trong .

Thnh phn thch hc cng c nh hng rt ln n mt , tnh cht v quy

m pht trin cc h thng nt n. Cc h thng nt n hiu dng a phn u c

ngun gc kin to, hnh thnh i km h thng t gy, cc i ph hy kin to v

cc vng chu nh hng cao ca trng ng sut kin to. Mc d mng lun b

tc ng bi cc t gy, nt n nhng c th nhn thy cc nt n m, c lin

thng tt thng gp nhiu trong cc magma acid (granite, granodiorite) hn trong

trung tnh-baz (diorite, gabro). iu ny lin quan n c tnh gin (cha nhiu

thch anh) ca granite hn so vi diorite c tnh do (nhiu thnh phn feldspar) nhiu

hn [13].

V phn b theo chiu su, kt qu nghin cu m Bch H v S T en c

th cho thy xu th bin i rng c tnh quy lut gim dn theo chiu su so vi

mt mng. (hnh 2.10).

Hnh 2.10. Bin i rng mng nt n theo chiu su so vi mt mng ca b

Cu Long.

45

2.2. c im a cht - kin to tng cha granitoid cu to Hi S en.

2.2.1. c im hnh thi cu trc mng

Nc mng trc Kainozoi ca cu to Hi S en l mt cu trc nng c

ng khp kn 4100m, ko di theo phng ng bc-ty nam vi chiu di khong

16km, chiu rng khong 5,3km, m rng v pha ty bc, nam, ng nam v thu hp

dn li v pha ng bc [19]. Khi nng mng b chia ct bi cc t gy c phng

v tuyn, ty bc - ng nam v ng bc - ty nam (hnh 2.11). Ti khu vc pha Ty

Nam, b mt nc mng nm thp hn phn cn li v c tch bit bi h thng t

gy phng v tuyn. Ph trn mng trc Kainozoi khu vc ny l cc trm tch

c tui t Oligoxen (tp E) n T (tp A) (hnh 2.12).

Hnh 2.11. Bn chiu su nc mng cu to Hi S en [19].

Hnh 2.12. Mt ct dc theo cu to Hi S en [19].

46

2.2.2. Thnh phn thch hc

Tham gia vo cu trc a cht cu to Hi S en bao gm cc mng

granitoid tui Mesozoi mun v lp ph trm tch, trm tch-phun tro Cenozoi (gm

cc tp a chn E, D, C, BI, BII, BIII & A). Theo kt qu phn tch thch hc cc mu

ly t 8 ging khoan cho thy cc granitoid trong mng Hi S en ch yu l

monzogranite v granodiorite (hnh 2.13). Ngoi ra cn gp cc ai mch trung tnh

xuyn ct qua mng [19].

Hnh 2.13. Thnh phn thch hc trong mng cu to Hi S en dc theo ging

khoan HSD-3X: t nc mng n su 4200m gp granodiorite, t su 4200m

tr xung gp monzogranite [19].

2.2.3. H thng t gy

Kt qu minh gii ti liu a chn cho thy trong mng ca cu to Hi S en

tn ti 06 h thng t gy chnh c phn chia theo ng phng v loi t gy,

bao gm (Hnh 2.14 2.16) [19]:

47

- H thng ng phng 20-30o (ng Bc Ty Nam) phn b ch yu

trung tm ca cu to.

- H thng ng phng 40-50o (ng Bc Ty Nam) phn b ch yu ra

ty nam v trung tm.

- H thng ng phng 60-70o (ng Bc Ty Nam) pht trin mnh trong

ton cu to.

- H thng ng phng v tuyn v v tuyn (ng Ty) pht trin mnh

trong ton cu to.

- H thng ng phng 300-320o (Ty Bc - ng Nam) phn b trung

tm v ty nam cu to.

- H thng ng phng 330-340o (Ty Bc - ng Nam) phn b trung

tm v ty nam cu to.

Hnh 2.14. H thng t gy v tuyn ti m Hi S en.

48

Hnh 2.15. H thng t gy ng Bc Ty Nam ti m Hi S en.

Trong cu to Hi S en, c 08 ging khoan thm d vo i tng mng

bao gm HSD-1X, HSD-2X/2XST, HSD-3X, HSD-4X, HSD-5XP, VD-1X v VD-

2X. Kt qu th va trong cc ging khoan ny cho thy kt qu cho dng tt nht

trong cc h thng t gy phng v tuyn (ng phng ng ty) so vi cc

hng cn li (hnh 2.17). Ti khu vc m Hi S en, h thng t gy theo phng

ng Ty c hnh thnh trong giai on nn p D3.2 v giai on tch gin D3.3.

Trong cc pha hot ng kin to t D3.4 tr v sau tip tc m rng cc khe nt

c v to ra cc khe nt mi v to nn l rng hiu dng. Thi gian cc t gy

phng ng ty hnh thnh v ti hot ng xy ra trc v cng thi im vi thi

gian dch chuyn ca du kh khin cho cc h thng nt n v t gy phng

ng ty trong vng nghin cu c ngha cha du kh tt hn so vi cc h thng

t gy, nt n theo phng khc.

49

Hnh 2.16. H thng t gy Ty Bc ng Nam ti m Hi S en.

Hnh 2.17. Mt ct a chn dc theo cc ging khoan HSD-1X v HSD-5XP vi h

thng t gy v tuyn v kt qu o PLT [18].

50

2.3. Cc phng php nghin cu c im nt n trong mng.

C nhiu phng php nghin cu c im v tip cn xy dng m hnh

rng cha nt n khc nhau. Trong nghin cu ny, NCS s dng mt s phng

php c in kt hp vi hin i nh phng php a cht, phng php a vt l

ging khoan, phng php a chn v cc phng php ton hc: mng nron nhn

to (ANN) v phng php a thng k (Co-Kriging).

2.3.1. Cc phng php a cht.

Phng php a cht nghin cu nt n bao gm phng php nghin cu mu

li, o v trn thc a v nh hng khng/v tinh.

Nghin cu trn cc mu li khoan

i vi mng nt n, nghin cu mu li ca cc thnh h nt n c th

gip: phn loi khe nt macro v micro, thnh phn thch hc, mi quan h gia ai

mch vi gc, phn loi khe nt m v khe nt kn, m ca khe nt, lp nht.

Cc mu li c o trong phng th nghim xc nh rng, thm v

cc tham s vt l thch hc khc nh mt , vn tc truyn sng, c tnh mao dn,

cc h s thnh h ca phng trnh Archie, thm pha, gip cho nh gi c tnh

rng-thm v cht lng ca tng cha. Ngoi ra, m t chi tit lt mng thch hc

bng knh hin vi in t qut nghin cu thch hc v da vo cc kt qu xc

nh thnh phn khong vt to , kin trc ca , thnh phn khong vt th sinh

v cc giai on bin i sau magma t xc nh cc yu t nh hng n rng

v thm ca cng nh cht lng cha.

Hnh 2.18. Mu li ti cc ging khoan m Hi S en

51

Hnh 2.19. Mu phn tch lt mng thch hc ca granite, bao gm cc thnh phn

khong vt thch anh, Feldspar, plagioclase v mica [18]

nh hng khng

Phng php phn tch nh vin thm c s dng phn tch v xc nh

cc yu t dng tuyn (photolinement), thng qua c th gii on cc t gy v

quy lut phn b ca chng trong khu vc nghin cu. Phng php ny kt hp vi

o v thc a thng xuyn c s dng trong nghin cu t gy, khe nt.

o v thc a

o c tnh cht ca cc h thng nt n trn im l nhm xc nh mi quan

h gia c im ca nt n v t gy, thng k tnh cht ca cc nt n m, mi

quan h gia nt n m v lp nht.

2.3.2. Cc phng php a Vt L Ging Khoan.

a vt l ging khoan l mt phn ca a vt l thm d, bao gm vic s

dng nhiu phng php a vt l hin i nghin cu vt cht kho st lt ct a

cht thnh ging khoan nhm pht hin v nh gi v thu thp cc thng tin v vn

hnh khai thc m v trng thi k thut ca ging khoan. Cng vi s pht trin ca

khoa hc cng ngh, c bit l 30 nm gn y, a vt l ging khoan p dng cc

thnh tu mi nht ca ngnh t ng ha v cng ngh thng tin trong cc hot ng

ca mnh. a vt l ging khoan bao gm nhiu nhm phng php, trong mi nhm

li c nhiu phng php ring r p ng cc i hi khc nhau khi nghin cu cc

iu kin a cht khc nhau. Ngy trc, a vt l ging khoan trong nghin cu du

kh c i tng ch yu l trm tch. Tuy nhin, hin nay, khi ngy cng nhiu m

52

du v ang c khai thc trong i tng mng nt n, a vt l ging khoan

vi nhng ci tin ca mnh gp phn khng nh trong vic nghin cu mng.

V c bn, a vt l ging khoan trong mng cng p dng nhng quy lut v

nguyn l hot ng ca cc thit b o nh trong i tng trm tch nhng c kt

hp thm cc hiu bit v c im ca mng.

Khc vi trm tch, trong i tng mng th rng trong cc khe nt l

quan trng v c lu tm hng u. Cc loi magma khc nhau th c thnh phn

khong vt khc nhau dn n cc c trng thm cha hay nt n khc nhau. Cc

phng php a vt l ging khoan tn dng cc c tnh ny nghin cu v

phn tch cc thnh h mng.

Mt s phng pho a vt l ging khoan c th k n trong vic nghin cu

c tnh ca mng nt n bao gm: phng php gamma t

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