ham luong set

TP ON DU KH VIT NAM

TRNG I HC DU KH VIT NAM

-----------

BO CO N CHUYN NGNH

XC NH RNG CHA OLIGOCEN

M BCH H

THEO TI LIU A VT L GING KHOAN

Gio vin hng dn :

TS Nguyn Trung Ch

Th.S Nguyn Th Hi H

Sinh vin thc hin:

Trnh Xun Linh

Nguyn Vit Thun

Nguyn Tin Thanh Tng

B Ra, thng 06, nm 2015

Xc nh rng cha Oligocen m Bch H theo ti liu DVLGK

1


2

Nhn Xt ca gio vin hng dn TS Nguyn Trung Ch:

im bi n :


3

LI CM N

n chuyn ngnh 1 l mn hc ch yu da vo kh nng tm ti ca sinh

vin, vic nghin cu n ny gip sinh vin i su vo chuyn nghnh du kh,

nghin cu su vo qu trnh lm vic sau ny ca 1 ngi k s.

hon thnh c n ny, nhm chng em xin xin chn thnh gi li cm

n n Khoa Du Kh Trng i Hc Du Kh Vit Nam to iu kin vt cht v

lun ng h qu trnh nghin cu ca nhm chng em.

c nhng kin thc v k nng qu bu lm n, nhn y nhm em xin

gi li cm n chn thnh n TS. Nguyn Trung Ch, Th.s Nguyn Th Hi H, nhng

ngi trc tip hng dn rt tn tnh v kp thi ch ra nhng thiu st, a ra nhng

kin qu bu cho chng em trong sut qu trnh thc hin hon chnh n ny.

Qua ti ny, nhm em c thm kinh nghim bc u v tht s t tin sau

ny tip tc pht huy v nghin cu thm nhiu ti hu ch cho cng cuc k thut

thm d, tm hiu, minh gii ti liu a vt l cho sau ny.

Do mi bc u tip cn nghin cu n, v thi gian khng nhiu, kin thc

cn tng i hn ch nn chc rng ti ny s c nhiu sai st. Knh mong qu thy

c ng gp kin thm nhm c th lm tt nhng bi n tip theo v n tt

nghip sau ny.

Chng em xin chn thnh cm n!

Cc thnh vin


4

Mc Lc

LI CM N ................................................................................................................ 3

M U ......................................................................................................................... 7

CHNG 1: KHI QUT V VNG NGHIN CU............................................ 9

1.1. TNG QUAN V B CU LONG ..................................................................... 9

1.2. TNG QUAN V M BCH H ..................................................................... 10

1.2.1. V tr a l. ................................................................................................... 10

1.2.2 c im kh hu. ........................................................................................... 11

1.2.3. Ch hi vn ............................................................................................... 11

1.2.4. c im a cht .......................................................................................... 11

1.2.4.1 a tng ...................................................................................... 11

1.2.4.2. c im cha du kh .............................................................. 16

1.2.5. Tr lng du kh .......................................................................................... 16

1.3. C IM A CHT TRM TCH TNG OLIGOCEN ............................. 17

1.3.1. Thi k Oligocen (to bn trm tch) ............................................................ 17

1.3.1.1 Giai on Oligocen sm:............................................................ 18

1.3.1.2 Giai on Oligocen mun .......................................................... 19

1.3.2. Trin vng du kh ........................................................................................ 20

1.3.2.1. c im tng sinh Oligocen .................................................... 20

1.3.2.2. c im tng cha Oligocen ................................................... 21

1.3.2.3. c im tng chn Oligocen ................................................... 22

CHNG 2: C S L THUYT CHUNG V RNG ................................ 23

CHNG 3: CC PHNG PHP NGHIN CU ............................................ 25

3.1 CC PHNG PHP CHUNG V PHNG X ......................................... 25

3.1.1 Phng php Gamma Gamma (Density): ...................................................... 25


5

3.1.1.1 Nguyn l: .................................................................................. 25

3.1.1.2 ng cong mt (bulk density log) ................................... 26

3.1.1.3. Phng php dng o gamma tn x mt ....................... 28

3.1.1.4. Chiu su nghin cu v phn gii ca cc Zond o

gamma gamma: ...................................................................................... 31

3.1.1.5. ng dng ca phng php Gamma Gamma: ......................... 31

3.1.2 Phng php Neutron: ................................................................................... 31

3.1.2.1. Nguyn l chung: ...................................................................... 32

3.1.2.2 Phng php Neutron Gamma:.................................................. 33

3.1.2.3 Phng php Neutron Neutron: ................................................. 35

3.1.2.4. Cc yu t nh hng ti kt qu o: ...................................... 39

3.1.2.5. ng dng ca phng php neutron: ....................................... 39

3.2.1. Bn cht ca phng php: .......................................................................... 39

3.2. PHNG PHP SNG SIU M (SONIC LOG - DT): ................................ 41

3.2.2. Thit b ......................................................................................................... 41

3.2.3. Cc yu t nh hng n kt qu o: ......................................................... 43

3.2.4. Loi tr nh hng ca ng knh ging khoan ........................................ 43

3.2.5. n v o ....................................................................................................... 43

3.2.6 Minh gii v x l ti liu ............................................................................ 44

3.2.7. ng dng ca phng php siu m: ............................................................ 45

CHNG 4: KT QU TNH TON .................................................................... 46

4.1. Tnh ton rng hiu dng theo ng Density:............................................. 46

4.2. Tnh ton rng bng phng php neutron .................................................. 47

4.3. Tnh ton rng theo phng php sonic (DT) ............................................... 47

KT LUN V KIN NGH ..................................................................................... 54


6

TI LIU THAM KHO .......................................................................................... 55


7

M U

M Bch H l m du ln nht ca Vit Nam thuc bn trng Cu Long, chng

ta pht hin du kh c trong mng trc Kainozoi, trm tch Paleogen v

Miocen, v nhiu m c a vo khai thc hn 20 nm. Tuy nhin hiu r thm

du kh c sinh thnh t u th i tng tng cha Oligocen l i tng quan trng

ta cn phi nghin cu

Xc nh rng l vic khng th thiu trong tm kim v thm d du kh. Nh

a cht mun xc nh c va cha c tim nng hay mun tnh ton tr lng du

kh th vic xc nh chnh xc rng l mt trong nhng vic cn hon thnh v yu

cu vi chun xc ti a. Hin nay, vic xc nh rng trong lnh vc tm kim

thm d pht trin vt bc vi rt nhiu phng php ti u, hin i v mang li

hiu qu kinh t cao. Trong phm vi nghin cu, chng ti ch a ra ba phng php

c dng ph bin trn th gii.

ti: Xc nh rng cha tng Oligocen ca ging khoan BH 129 m Bch

H theo ti liu a vt l ging khoan (DVLGK)

n gm 4 chng chnh, khng k m u v kt lun. Ton b ni dung n

c trnh by nh sau:

Chng 1: Khi qut v vng nghin cu

Chng 2: C s l thuyt chung v rng

Chng 3: Cc phng php nghin cu

Chng 4: Kt qu tnh ton

Nhn thy ti xc nh rng cha ca tng Oligocen m Bch H theo ti

liu a vt l ging khoan l mt ti mang ngha thc tin rt cao v ph hp vi

nhu cu thc t, sau ti ny chng em d nh s tip tc nghin cu su rng hn v

gii thiu n thy c v cc bn nhng phng php khc tnh rng

Trong qu trnh thc hin n, nhm chng em nhn c s gip c bit

ca cc thy c: TS Nguyn Trung Ch, Th.s Nguyn Th Hi H, v cc Thy c gio

b mn khoa a cht a vt l du kh trng H Du kh Vit Nam, v cc bn

cng lp. Chnh nh nhng s quan tm, gip tn tnh m nhm c th hon

thin n. Ngoi ra nhm n xin gi li cm n chn thnh nht ti PGS.TS Hong


8

Vn Qu, cng qu Thy c cng cc bn gip v to iu kin tt nht cho nhm

n trong sut thi gian thc hin.

Knh chc Qu thy c sc khe v hnh phc!

Trong thi gian tm hiu v su tm ti liu, do s lng ti liu v thi gian nghin

cu hon thnh n cng nh kin thc v kinh nghim cn hn ch s khng trnh

khi nhng thiu st. Nhm rt mong nhn c s ng gp kin ca Qu thy c

gio, cc nh chuyn mn v cc bn sinh vin cng ngnh n ca nhm hon

thin hn trong thi gian ti.

Nhm n


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CHNG 1: KHI QUT V VNG NGHIN CU

1.1. TNG QUAN V B CU LONG

Trong kin to chung ca ng Nam , bn trng Cu Long l mt b phn nm pha

ng ca thm lc a Sunda vi ta a l 90 110 v Bc, 10630 - 109 kinh

ng ko di dc theo b bin Phan Thit n ca sng Hu. B c hnh bu dc, nm

dc theo b bin Vng Tu Bnh Thun.

Bn trng Cu Long c din tch 36000 km2 v v:

Pha Ty Nam gip vi n nghing Tr Tn.

Pha ng Nam c ngn cch vi trng Nam Cn Sn bi khi nng Cn Sn.

Pha Ty Nam c ngn cch vi bn trng vnh Thi Lan bi khi nng Korat.

Pha ng Bc l i ct trt Tuy Ha ngn cch vi b Ph Khnh

Hnh 1: Bn v tr a l ca B Cu Long


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1.2. TNG QUAN V M BCH H

1.2.1. V tr a l.

M du Bch H L mt m du kh ln nm trong thm lc a pha Nam nc

ta. M nm l s 9 trn bin ng. M Bch H cch t lin im gn nht

l 100 km v cch thnh ph Vng tu l 120 km v hng ng Nam.

Hnh 2: S v tr m Bch H trn thm lc a pha Nam


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1.2.2 c im kh hu.

Kh hu ca m Bch H mang tnh cht nhit i gi ma v chu nh hng

ca bin, c chia ra hai ma r rt l ma ma v ma kh.

Ma ma ko di t thng 6 n thng 10. Giai on ny c gi ma ng

Nam hot ng mnh, tri nng, nhit trung bnh t 260C-320C. Lng ma

ma ny t 260mm/thng n 270mm/thng. m khng kh trung bnh t 87-

89%. y cng l thi k hot ng ca bo bin, cc cn bo c t 7-10 cn/nm,

khi vn tc ca gi t ti 20-40m/s c lc ti 60m/s. Trong cc cn bo bin

mnh chiu cao ca sng c th t ti 10m.

Ma kh vo t thng 11 n thng 04 sang nm. Vo ma ny ch yu l gi

ma ng Bc vi sc gi cp 5 cp 6. Vo thng 12 c gi cp 7 - cp 8 khi

sng bin ln cao ti 8m. Nhit ma ny trung bnh t 22 - 27oC. Lng ma

ma ny rt nh trung bnh khng qu 1mm/thng. m khng kh tng i

thp ch t 65 - 68% v chu s nh hng ca bin.

Ma chuyn tip vo thng 4-5. Ma ny gi bt u chuyn hng gi ng

Nam. m khng kh ca ma ny tng ng k, n t ti 85%.

1.2.3. Ch hi vn

Ch sng khu vc ny mang tnh cht sng gi r rt. Gia ma ng, hng

sng ng Bc chim u th gn tuyt i vi cao sng t gi tr cao nht trong c

nm. Thng 1 nm 1984, cao ca sng t cc i ti 8m khu vc vm Trung Tm

m Bch H. Ma ng hng sng u th ng Bc, Bc ng Bc v ng ng

Bc. Ma h, hng sng chnh l Ty Nam, hng Ty v ng Nam cng xut hin

vi tn xut tng i cao.

Dng chy oc hnh thnh di tc ng ca gi ma vng bin ng. Hng

v tc dng chy xc nh c bng hng gi v sc gi.

1.2.4. c im a cht

1.2.4.1 a tng

Theo trnh t nghin cu bt u bng cc phng php o a chn trn mt, ch

yu l o a chn, sau n cc phng php o a vt l trong l khoan v phn


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tch cc mu t thu c, ngi ta xc nh r rng thnh h ca m Bch H.

l cc trm tch thuc cc h T, Neogen, Paleogen ph trn mng kt tinh Jura

Kreta c tui tuyt i t 97 n 108,4 triu nm. T trn xung di ct a tng tng

hp ca m Bch H c m t nh sau:

a) Trm tch Neogen v T

Trm tch Pliocen Pleistocen (ip Bin ng).

ip ny c thnh to ch yu t ct v ct dm, gn kt km, thnh phn

chnh l thch anh, glaukonite v cc tn tch thc vt. T 20 25% mt ct l cc va

kp montmorillonite, i khi gp nhng va st mng. t ny thnh to trong iu

kin bin nng, mui trung bnh v chu nh hng ca cc dng chy, ngun vt

liu chnh l cc magma axit. B dy ip dao ng t 612 654 m.

Di ip Bin ng l cc trm tch ca thng Miocen thuc h Neogen. Thng

ny c chia lm ba ph thng.

Ph thng Miocen trn (ip ng Nai).

t ip ny ch yu l ct dm v ct vi mi trn t trung bnh n tt.

Thnh phn thch anh chim t 20 90%, cn li l felspat v cc thnh phn khc nh

magma, phin ct v sBt kt hu nh khng c nhng cng gp nhng va st v

st dy n 20 m v nhng va cui mng. Chiu dy ip ny tng dn t gia (538 m)

ra hai cnh (619 m)

Ph tng Miocen gia (ip Cn Sn).

Phn ln t ca ip ny c to t ct, ct dm v bt kt. Phn cn li l cc

va st, st vi mng v vi. y l nhng t lc nguyn dng b ri mu xm

vng v xm xanh, kch thc ht t 0,1 10 mm, thnh phn l thch anh (hn 80%),

feldspat v cc phun tro c mu loang l, b ri mm do, thnh phn chnh l

monmoriolonit. B dy ip t 810 950 m.

Ph tng Miocen di (ip Bch H)

t ip ny nm bt chnh hp gc, thnh to Oligocen trn, gm ch yu nhng

tp st dy v nhng va ct, bt mng nm xen k nhau. St c mu ti nu loang l

xm, thng l mm v phn lp.

b) Trm tch h Paleogen

Thnh to ca thng Oligocen thuc h Paleogen c chia lm hai ph thng:


13

Ph thng Oligocen trn (ip Tr Tn)

Cc trm tch ny bao trm ton b din tch m. Phn trn l cc tp st mu en

rt dy (ti 260 m). Phn di l ct kt, st kt v bi kt nm xen k. ip ny cha

nm tng du cng nghip: 1, 2, 3, 4, 5. S phn chia c th thc hin su hn ti hng

lot cc ging khoan trong ip Tr Tn c chia lm ba ph ip: di, gia v

trn. y c gp s thay i hng mnh, trong thi k hnh thnh trm tch c th

c hot ng ni la phn trung tm v cui pha bc ca va hin ti, do c gp cc

phun tro trong mt s ging khoan. Ngoi ra cn c gp cc trm tch than st kt

mu en, xm ti n nu b nn p, khi v c mt trt.

Ph thng Oligocen di (ip Tr C)

Thnh to ny c ti vm bc v ra nam ca m. Gm ch yu l st kt (60 70%

mt ct), c t mu en n xm ti v nu, b nn p mnh, gin mnh vn v sc cnh

c mt trt, dng khi hoc phn lp. c thnh to trong iu kin bin nng, ven

b hoc sng h. y gp nm tng du cng nghip 6, 7, 8, 9, 10.

Cc tp c s (v phong ha)

y l nn c s cho cc tp Oligocen di pht trin trn b mt mng. N c

thnh to trong iu kin lc a bi s ph hy c hc ca a hnh. ny nm trc

tip trn mng do s ti trm tch ca mnh vn ca mng c kch thc khc nhau.

Thnh phn gm: cui ct kt ht th, i khi gp phun tro. Chiu dy ip Tr C

v cc tp c s thay i t 0 412 m v 0 174 m.


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c) mng kt tinh t trc Kainozoi

y l cc thnh to granate nhng khng ng nht m c s khc nhau v thnh

phn thch hc, ha hc v v tui. C th gi thit rng c hai thi k to granite:

vm Bc vo k Jura, vm Nam v vm Trung tm vo k Kreta. Din tch ca batholit

granite c th ti hng nghn km2 v b dy thng khng qu 3 km. mng bt u

t su 3888 4700 m. y l by cha du khi in hnh v c trin vng cao. Hin

ny tng mng l tng khai thc quan trng m Bch H. Du t phun t mng vi

lu lng ln l mt hin tng c o, trn th gii ch gp mt s ni nh Bombay

(n ), Angel (Lybia) v mt vi ni khc. Ging khoan su vo tng mng m Bch

H cha tm thy ranh gii du nc. gii thch cho s hin din ca du trong mng

kt tinh ngi ta tin hnh nghin cu v a ra kt lun s hnh thnh khng gian rng

cha du trong mng m Bch H l do tc ng ng thi ca nhiu yu t a

cht khc nhau.


15

Hnh 3: Mt ct a tng tng hp m Bch H


16

1.2.4.2. c im cha du kh

Trong phm vi bn trng Cu Long pht hin c nhiu m du v kh, trong

m Bch H l m ln, cc m cn li nh v trung bnh. i tng cha du kh

ca khu vc l Mng hang hc-nt n tui Trc Kainozoi v trm tch ph trn

Mng. Cc m ca bn trng Cu Long ch yu cha du, ch c mt s m nh ring

l (S T Trng, ng Bc Rng ) cha kh condensat.

Ti m Bch H du c pht hin trong lc nguyn tui Mioxen di, Oligoxen

trn, Oligoxen di v Mng hang hc-nt n. Trong , thn du dng khi c

sn phm cao tp trung trong Mng hang hc nt n. Trong trm tch lc nguyn cc

thn du cu trc phc tp v c sn phm khc nhau. Chng c phn loi theo

cc dng vm vi mn chn thch hc, a tng v kin to. Ranh gii du nc trong

cc thn du trm tch nm ngang, trong Mng khng xc nh.

1.2.5. Tr lng du kh

Ph

c

h

a

tn

g

Cp

TL

Tr lng du (ngn m3) Tr lng du (ngn tn) Tr lng kh (triu m3)

P10 P50 P90 P10 P50 P90 P10 P50 P90

Mio

xen

d

i P1 48.534 40.174 32.803 41.883 34.669 28.308 4.432 3.669 2.996

P2 21.663 17.880 14.519 18.687 15.424 12.525 1.660 1.370 1.112

P3 8.628 7.120 5.800 7.418 6.122 4.987 605 499 406

Oli

goxen

tr

n P1 36.544 30.986 25.892 31.604 26.797 22.391 2.250 1.908 1.594

P2 13.748 11.776 9.974 11.760 10.074 8.532 768 658 557

P3 1.597 1.368 1.158 1.399 1.198 1.015 58 50 42

Oli

gox

en d

i

P1 93.218 75.124 59.393 77.215 62.227 49.200 16.190 13.038 10.30

0

P2 7.493 6.055 4.815 6.261 5.059 4.024 1.331 1.075 855

P3 726 587 466 598 483 384 174 140 111


17

M

ng

P1 615.751 563.11 513.951 511.643 467.897 427.041 90.392 82.668 75.440

P2 56.212 51.485 47.079 46.641 42.716 39.061 8.380 7.664 7.009

P3 62.426 56.509 51.066 51.877 46.958 42.433 8.454 7.652 6.921

C

ng

to

n

m

P1 794.047 709.40 632.039 662.345 591.590 526.941 113.265 101.28 90.33

P2 99.115 87.196 76.386 83.350 73.273 64.141 12.139 10.767 9.534

P3 73.376 65.584 58.490 61.292 54.761 48.818 9.291 8.341 7.481

2P 893.163 796.59 708.425 745.695 664.863 591.082 125.404 112.05 99.86

3P 966.539 862.18 766.915 806.987 719.624 639.900 134.695 120.39 107.34

M Bch H c a vo khai thc vo nm 1986 bng vic a thn du Mioxen

di vo khai thc th. thi im hin ti, cc i tng khai thc ca m Bch H

gm: vm Bc, Trung Tm v khu vc pha Nam Mioxen di, khu vc pha Bc, Trung

Tm, pha Nam v phn ng-Bc Oligocen trn, khu vc pha Bc, ng-Bc v phn

pha Ty Oligocen di, khi pha Bc, Trung Tm, pha Nam v khu vc ng-Bc

thn du Mng.

1.3. C IM A CHT TRM TCH TNG OLIGOCEN

Theo kt qu nghin cu a chn thch hc, a tng cho thy trm tch Oligocen

ca bn trng Cu Long c thnh to bi s lp y a hnh c, bao gm cc tp

trm tch lc nguyn sng h, m ly, trm tch ven bin, chng ph bt chnh hp ln

mng trc Cenozoic, khu vc trung tm ca bn trng c trm tch Oligocen c

ph bt chnh hp ln cc lot trm tch tui Eocen.

Trm tch Oligocen c chia thnh h tng Tr C Oligocen h v h tng Tr

Tn Oligocene thng.

1.3.1. Thi k Oligocen (to bn trm tch)

y l thi k tch gin v to thnh cc a ho, bn a ho dc theo cc t gy

v ta vo khi plutonic. Lp y cc a ho v bn a ho l cc vt liu trm tch lc

Bng 1: Tr lng du kh ca cc tng m Bch H


18

nguyn c vn chuyn t cc vng cao n, y l cui, sn v ct ht th a khong

v cc trm tch mn hn (bt v bt st).

Giai on ny c th chia lm hai ph giai on:

1.3.1.1 Giai on Oligocen sm:

Thi k ny b Cu Long c ngn cch vi bin bi i nng Cn Sn pha

ng v Natura pha Nam. V th cc trm tch hon ton c tng lc a.

Ngun cung cp ch yu v vt liu trm tch l cc khi granit v granodiorit b

phong ho. Cc thnh to ch yu l trm tch ht th deluvi, aluvi nh cui, si, ct kt,

bt kt ximng gn kt chng l cacbonat, st, zeolit giu mnh ni la. Xen k cc

lp ct kt l cc lp bt kt v st kt. Pha ng Nam ca b c ngn bi i nng

Cn Sn v pha Ty Nam bi ng bng Cu Long. Tng ng vi giai on ny l:

H tng Tr C

Trm tch h tng Tr C nm ph bt chnh hp trn h tng C Ci v c m

t ti ging khoan CL-1 thuc vng C Ci huyn Tr C tnh Tr Vinh. Ti y t

su 1082 2000m trm tch c trng bng s xen k gia ct kt, si kt xen nhng

lp bt st cha cui sn si. Cc cui sn c thnh phn thch hc khc nhau ch yu

l andezit v granit. Thnh phn st ca h tng ny ch yu l kalinit, illit, clorit.

Tp st ny ph trc tip trn mng v ng vai tr l tng chn tt mang tnh a phng

cho cc va cha du trong mng m Bch H.

Ct kt, bt kt thnh phn a khong thuc loi acko t ht nh n th, i khi ht

rt th hoc ct cha cui v sn ht vn c mi trn, chn lc trung bnh, km

bn gc cnh n bn trn, thnh phn fenspat thch anh v mnh . Ct kt nhn chung

rt rn chc do c gn kt chc bi mt lng ln ximng, cacbonat, thch anh, zeolit

i khi anhidrit l kt qu ca qu trnh bin i th sinh mnh t katagenes mun ti

giai on bin cht sm lm gim rng v thm nguyn sinh. Trm tch ca h

tng ny c hnh thnh trong mi trng trm tch khc nhau t deluvi, l tch, bi

tch sng, knh rch n m h, vng vnh.

Trong h tng Tr C c chiu di t 100 500m cc vm nng, cn cc bn

trng a ho c t ti 1000m. l tp rt t phn d, lin tc km bin kh ln,


19

tn s thp, khng c quy lut. Chng thng ph bt chnh hp trc tip trn cc

mng.

1.3.1.2 Giai on Oligocen mun

Cc thnh to thi k ny in hnh l delta, prodelta bao gm cc trm tch thuc

tng aluvial fan, fluvial xen k cc trm tch m h, vng vnh. Cng v cui giai

on Oligocen mun cc trm tch lowerdelta pht trin ch yu cc tp ht mn dy,

giu vt cht hu c m sau ny chng tr thnh cc tng sinh v chn du kh trong b

Cu Long. Cc doi ct aluvial fan v fuvial tr thnh cc by cha du kh m ngy

nay c pht hin ti khu vc m Bch H u c cc tp st dy bao ph m ta

c th bt gp qua cc ging khoan thm d v khai thc du kh.

Vo cui Oligocen, cc a ho trong b Cu Long c lp y v lin kt vi nhau

tr thnh mt m h ln. Nu nh Oligocen sm - mun b gn nh hon ton khp

kn th n giai on cui ca Oligocen mun b tr thnh mt h ln, c ca lin thng

vi Bin ng qua mt knh hp pha ng bc to nn hin tng khi triu ln nc

bin trn vo h, khi nc rt th nc trong h chy ra bin. iu ny c chng minh

qua cc mu thu c t nhng ging khoan phn cui ca mt ct a tng Oligocen

mun.

H tng Tr Tn

H tng Tr Tn ln u tin c m t u tin ti ging khoan 15 AO 1X trn

cu to Tr Tn t su 2535m 3038m. Ti y trm tch ch yu l ct kt ht nh

n trung mu xm trng, ximng cacbonat chuyn dn ln trn nhiu lp bt v st kt

mu nu v en c xen cc lp mng than, c ch pht hin thy glauconit. bin i

giai on katagenes mun. ng cong carota c in tr rt cao phn di v thp

phn trn. Trn lt ct trm tch vng Tr Tn c s xen k gia st kt (chim ti 40-

70% mt ct) v bt kt, ct kt v nhiu ni khu vc xut hin lp phun tro ni

la c thnh phn khc nhau. Trm tch Tr Tn nhn chung b tc ng bi qu trnh

bin i th sinh khng ging nhau t giai on katagenes sm n katagenes mun vi

rng 5-15% v thm


20

Trm tch ca h tng ny c b dy quan st theo ging khoan thay i t 400m

800m, cn cc ni trng c th t n 1500m theo ti liu a chn pha di l nhng

vng phn x gm nh trng, bin thp tn s trung bnh n cao, cn pha trn

phn x lin tc tt, tn s trung bnh, bin kh cao, phn lp tt. H tng Tr C

nm trong phm vi SH10 (y ) nhiu ni l SH12 v SH8 (mi) cn h tng Tr Tn

nm trong phm vi SH11 v SH10.

1.3.2. Trin vng du kh

1.3.2.1. c im tng sinh Oligocen

sinh tng Oligcen ca b Cu Long phn b ch yu l cc tp st.

Tng st ca Oligocen trn (E32) b dy 100m ven ra v dy ti 1200m phn

trung tm b. y l tng rt phong ph vt cht hu c, thuc loi rt tt:

TOC dao ng t 3,5% n 6,1% Wt, i ni ti 11-12% cc ch tiu S1 v S2 cng

c gi tr rt cao.

S1 t 4 12 Kg HC/ t

v S2 t 26,7 21 Kg HC/t. .

HI c th t ti 479 Kg/t .TOC.

cc vng su gi tr ny c th rt cao nh cc mu ca ging khoan CNX-1X.

Tng Oligocen di + Eocen thuc loi tt v rt tt vi tng bt st c b dy t

0m n 600m phn trng su ca b.

TOC =0,47% - 2,5%Wt.

S1 = 0,4 2,5 Kg HC/t.

S2 = 3,6 8,0 Kg HC/t.

HI ch cn 163,6 Kg HC/ t. .TOC

Tng ny lng hydrocacbon trong m c gim so vi tng trn l do sinh du

v gii phng phn ln hydrocacbon vo cha. Nhn chung tim nng ca vt cht

hu c trong trm tch Oligocen l rt ln, Kerogen thng gp trong trm tch Oligocen

thuc loi cao, phn nh c hot ng ca vi khun to nc ngt cng nh nc l v


21

bin. i vi tng m Oligocen trn loi vt cht hu c ch yu loi II th yu l

loi I. Ch tiu Pr/Ph ph bin 1,6-2,3 phn nh tch t trong mi trng ca sng vng

nc l, bin nng v mt s t m h.

Qua nghin cu ta nhn thy cc tng m Oligocen mi t mc trng thnh v

trng thnh mun, cng l ngun cung cp ch yu HC cho cc by cha ca b Cu

Long. V vy cc ch tiu Tmax v Ro c gi tr cao trong Kerogen vi Tmax > 435C

v Ro > 0,6=0,8%. i sinh du mnh ca tng Oligocen trn bao gm ch yu phn

trung tm c din tch 193Km2.

1.3.2.2. c im tng cha Oligocen

cha du kh trong b Cu Long bao gm cc : granitoid nt n hang hc ca

mng kt tinh, phun tro dng va hoc ai mch v ct kt c cu trc l hng gia

ht i khi c nt n. Trong , i vi h tng Oligocen cha ch yu l ct kt vi

thnh phn fenspat rt a dng: octocla, plagiocla axit, plagiocla trung tnh, thch anh

n tinh v rt ph bin cc mnh phun tro.

Ct kt tng Oligocen di l acko-litic, i ch nm xen vi cc tp ni la dy,

ng vi h tng Tr C c ngun gc nn qut bi tch sng ngi nm trn mng kt

tinh phn cao ca mng v c sn st tin chu th (prodelta) v m h phn su

ca b.

Ct ht th cha cui, sn n trung bnh c mu xm, xm nu vi chn lc km

vi ximng gn kt l kaolinit, clorit v carbonat kiu lp y v tip xc. rng ct

kt Oligocen di c th t ti 18%, trung bnh 12-16%, thm 1-250 mD. phn

gia v phn trn mt ct Oligocen di ct kt c cht lng tt hn. Theo chiu su

tnh thm, cha ca c tnh cht gim di 3800m do b thch anh v clorit ho mnh

nn rng 14-15%, tr mt s trng hp m ng Rng v S T Trng rng vn

c bo tn tt 15-16%, rng gim theo chiu su l do qu trnh to (diagenes)

p ln mnh.

Ct kt Oligocen trn ht mn xen lp mng vi st, bt, bt kt, i ch vi cc tp

ni la, pht hin rng trn din tch ca b. Ct kt ch yu l arkos, arkos litic,

vt liu trm tch ngun cung cp lin quan ti cc khi magma axit gn, tch t trong

mi trng m h ca sng, m ly, vng vnh thu triu trong iu kin kh vi nh

hng ca bin tng dn v pha ng Bc. Khong vt st thng gp nh trong


22

Oligocen di, ngoi tr zeolit, hm lng cacbonat trong xi mng cao. rng 12-

21%, trung bnh 14%, thm 2- 26mD.

1.3.2.3. c im tng chn Oligocen

Tp st Rotalit l mt tng chn khu vc rt tt vi hm lng st 90-95%, kin trc

phn tn vi c ht nh hn 0.001mm. Thnh phn khong st ch yu l monmoriolit,

y l tng chn tt cho c du v kh. Ngoi ra, cn c tng chn a phng kh tt:

Tng chn 1: nm trong phn st tp ca ip Bch H ( Miocene h) ph trc

tip ln cc va sn phm 22, 23, 24.

Tng chn 2: l phn nc ca ip Tr Tn ( Oligocene thng ). y l tng

chn a phng ln nht.

Tng chn 3: nm nc ip Tr C ( Oligocene h). y l tng Acgilit, hm

lng st 70 - 80%, khong vt ch yu l hydromica.

Vt liu trm tch lp y phn rng ca cc khe nt lp phong ha mng to

nn tng chn i phng trn b mt mng.


23

CHNG 2: C S L THUYT CHUNG V RNG

Thut ng rng ca c hiu l t s th tch cc l hng trong trn tng

th tch ca . rng c th c biu din bng phn n v hoc phn trm. Theo

xut x hay ngun gc to thnh cc l hng c chia ra thnh:

L hng nguyn sinh:

c thnh to trong qu trnh lng ng v hnh thnh . L hng nguyn sinh bao

gm l hng gia ht v cc thnh phn ht ca , gia cc lp, l hng xut hin sau

khi phn hu cc vt cht hu c, bt kh b mt i v.v. L hng nguyn sinh thng

c quan st thy trong ct, ct kt, cui kt v st.

L hng th sinh:

c thnh to trong qu trnh bin i th sinh nh kin to, ph hu ca nhit dch,

qu trnh bin cht ca v.v. Cc l hng th sinh bao gm cc l hng, nt n, hang

hc c thnh to trong qu trnh ho tan ho hc, tri ra, ph hu kin to v.v. L

hng th sinh thng quan st thy trong cacbonnat nh vi, lmit, phun

tro v mc ma. L hng nguyn sinh thng c phn b theo quy lut nht nh.

Ngc li l hng th sinh hu nh khng c phn b theo quy lut nht nh.

Cng thc chung:

= V/ V . 100 (1)

Trong l rng, thng tnh bng %

V : Tng th tch cc l hng trong mu

V: Th tch mu

Th tch ca mu V do th tch ca cc l hng V v th tch khung rn to

thnh: V = V + Vs hay V = V- Vs do cng thc (1) thnh :

= V- Vs/ V . 100 = ( 1- Vs/ V).100 (2)


24

Cc loi rng:

rng c phn ra cc loi sau:

1. rng chung l t s th tch ca tt c cc loi l hng trn th tch ca

2. rng h l t s th tch ca tt c cc loi l hng h, thng nhau trn th

tch ca .

3. rng kn l t s th tch ca tt c cc loi l hng kn, khng thng nhau

trn th tch ca .

Tng rng h v rng kn bng rng chung

4. rng hiu dng l t s th tch ca tt c cc loi l hng hiu dng c kh

nng cha v cho du v kh thm qua khi c chnh p nht nh trn th tch ca .

Phn bit rng hiu dng v rng hiu dng ng:

hd = (1-Swr ); hd = (1-Swr Sor )

Cc yu t nh hng ti rng h v rng hiu dng bao gm c im phn

b khong vt st, xi mng v h s bt ng nht ca ht. H s bt ng nht cng cao

th rng h, rng hiu dng cng nh cng nh s chnh lch gia rng h v

rng hiu dng cng ln.

rng thng c xc nh trn mu li trong phng th nghim v theo ti liu

a vt l ging khoan.


25

CHNG 3: CC PHNG PHP NGHIN CU

3.1 CC PHNG PHP CHUNG V PHNG X

Cc phng php phng x l cc phng php a vt l nghin cu ging khoan

da trn qu trnh phng x (phng x t nhin, phng x do b kch thch) xy ra cc

phn t ht nhn nguyn t c gi l phng php a vt l phng x hay carota

phng x.

Nhng ch c 2 phng php phng x sau y dng xc nh rng

Phng php Gamma Gamma hay cn gi l phng php mt (Density)

Phng php Neutron

3.1.1 Phng php Gamma Gamma (Density):

Phng php Gamma Gamma l phng php o mt khi ca thnh h t .

Mt khi l mt tng cng ca t bao gm khung t v cht lu chim

ch trong cc l rng.

3.1.1.1 Nguyn l:

Khi chiu x vo mi trng t xung quanh ging khoan bng mt chm tia

gamma c nng lng khc nhau v o cc tia gamma tn x do kt qu tng tc ca

chng vi mi trng gi l phng php gamma tn x hoc gamma - gamma, ngha

l chiu x bng tia gamma v o cc tia gamma sau khi mt bt nng lng b tn

x do tng tc vi vt cht trong mi trng

nghin cu.Khi cc tia gamma tng tc vi mi

trng t chng s gy ba hiu ng chnh

(Xem hnh 4):

* Hiu ng to cp: di tc ng ca

lng t (kvant) c nng lng rt ln (5-

10MeV) vi ht nhn nguyn t, kt qu lng

t mt i v trong trng in ht nhn cp

electron pozitron c to thnh.

* Hiu ng quang in: Din ra di s hp

th lng t t mt trong nhng electron ca ht nhn. Nng lng lng t to

Hnh 4: Cng c o gamma tn x


26

thnh nng lng ng electron, electron ny quay quanh ht nhn. Thng thng th

nh hng ca hiu ng quang in i vi vt cht rt nh.

* Hiu ng Compton: Khc vi hiu ng quang in lng t khng mt i m

ch mt mt phn nng lng cho mt trong nhng electron ca ht nhn v thay i

hng chuyn ng (tn x). Tn x Compton ch ph thuc vo mt electron ca

thnh h (hay s electron trn mt n v th tch), m gn nh l lin quan ti mt

khi. y l c s ca php o mt chun.

3.1.1.2 ng cong mt (bulk density log)

Thng thng trn bng carota, ng cong mt c biu din trn Track 2

v 3 trn mt thc o thay i t 1,95 2,95 g/cc. Mt tiu chun thay i t 2,0 -

2,7 g/cc khi rng thay i t 0 40 %. ng cong hiu chnh biu din trn

Track 3, thay i t -0,25 n 0,25. ng hiu chnh nhm xc nh tnh ng dng ca

ng mt ; n khng c ngha l cng vo hoc tr i gi tr b m cho thy tnh

chnh xc ca b , n ch ra mc tin cy ca gi tr mt t o c.

Hnh 5: Cc kiu va chm


27

Hnh 6: Mt v d v minh gii ct a tng v ng log density


28

Khi phn tch mt ng Density, u tin ta nn quan st gi tr trn ng b

, v ng cong ny l ng cong kim sot cht lng. Trong ging trn nhn gi

tr gn vi gi tr khng. Khi gp phi lp v st hoc b mt ging g gh th gi

tr hiu chnh s tng. Min l thp hn 0,15 g/cc hiu chnh l thch hp v

ng b c th tin tng. Nu trn 0,15 g/cc hiu chnh l khng thch hp v

ng b b li.

3.1.1.3. Phng php dng o gamma tn x mt

Mt trong nhng nhc im ca cc Zond o l trong cc tng thm (permeable

formation) tia gamma trc khi i n detector th phi i qua v bn khoan (mudcake)

vi gia tr mt (density) khc ng k so vi h tng

Hnh 7: s cng c o mt hai cm bin (dual detector density tool)


29

Chnh v th khc phc nhc im ny ngi ta dng Zond o c hai detector. Mt

gn, mt xa. Bin th ca phng php gamma tn x mt nh th gi l phng

php gamma tn x mt b kp (FDC Formation - Density Compensated)

Phng php gamma tn x mt b kp (FDC)

Detector gn ngun (short spacing detector) c chiu su nghin cu nh ch yu

o cc gamma tn x trong v st (mudcake) v phn nh mc nhn ca thnh ging

Hnh 8 biu din giao hi gia hai s im ca cc detector xa v gn tnh lng hiu

chnh nh hng ca v st (mudcake) ln gi tr o b (bulk density)

Nu ging khoan khng c v st khi mi gi tr mt ca cc va thnh ging

khoan c o bi hai Zond s l cc im giao hi ri tren ng thng MN gi l trc

Spine.

M

N

Hnh 8: th ng spine v Rib theo phng php FDC

Hnh 8: th ng spine va Rib theo phng php FDC


30

Nu ging khoan c v st(mudcake) th cc giao hi s khng nm trn ng MN

m nm lch sang tri hoc sang phi trn cc ng xng c (sn) gi l Rib.

Nm bn tri ng MN l trng hp dung dch nng

Nm bn phi ng MN l trng hp dung dch thng

Ty vo mt v dy va st m im giao hi trn ng Rib s cch ng

MN mt khong bao nhiu. T ngi ta c th xc nh c ga tr hiu chnh v

st l bng b

Trong thc t my tnh trn mt t s t ng ghi gi tr ca b v b cng vi chiu

su v sau s v hai ng cong b v b trn cng mt bng ghi

Ta c :

= +

Vi gi tr mt biu kin c o bi cm bin xa (long-spaced detector)

Minh gii v x l ti liu gamma gamma

Xut pht t mi quan h gia cng chm tia gamma o c vi mt ca cc

vt cht cu thnh t v cht lu cha trong chng ngi ta xy dng hm mt

o c bi my o gamma gamma nh sau:

x = f . + sh . Vsh + ma . (1- - Vsh)

trong x , f , sh v ma l mt o c, cht lu, st phn tn v khung tng

ng;

- rng, Vsh - hm lng st.

T cng thc trn rng ca c th c xc nh theo cng thc sau:

= (ma - x )/(ma - f ) - Vsh . (ma - sh )/(ma - f )

Cng thc cho php ta xc nh c rng ca va cha bng ti liu o c ca

phng php gamma mt .

ma , sh v f c ly theo phng th nghim tng ng vi tng loi khc nhau.

Mt ca mt s loi tiu biu:


31

Ct vi Dolomit Anhydrit

ma (g/cm3) 2.65 - 2.68 2.70 - 2.72 2.85 2.98

f =1 g/cm3 hoc 1,04 g/cm3 tu thuc vo khong ho ca nc va

3.1.1.4. Chiu su nghin cu v phn gii ca cc Zond o gamma

gamma:

Chiu su nghin cu ca cc thit b o gamma gamma ph thuc vo mt

khi ca t thnh ging khoan. Mt cng cao th chiu su nghin cu ca php

o cng gim. Trong cc thnh h c l rng v thm tt, chiu su nghin cu ca cc

thit b hin nay khng qu 10 inches (~25cm), ngha l trong vng i ngm thnh

ging.

Kh nng phn gii lt ct ca cc thit b o gamma tn x mt ph thuc vo

khong cch t ngun n detector. i vi cc Zond c mt detector khong cch ny

l 16 inch (0,4m), cn cc Zond c hai detector th khong cch gia cc detector l 10

inch (0,25m).

Mc dy mng khc nhau ca lp v st s nh hng n kt qu o. B mt

thnh ging khoan cng gy nh hng n kt qu o.

3.1.1.5. ng dng ca phng php Gamma Gamma:

Xc nh rng v gin tip xc nh mt hydrocacbon

Xc nh thch hc, thnh phn khong vt

nh gi hm lng vt cht hu c, pht hin va kh

Xc nh d thng p sut v rng khe nt

3.1.2 Phng php Neutron:

Phng php neutron l phng php ghi nhn lin tc s phn ng ca thnh h

t xung quanh thnh ging khoan i vi s bn ph ca cc ht neutron nhanh. S

phn ng ny lin quan vi ch s hydro (hydro index) ca va mt thng s xc

nh s phong ph hydro ca va.


32

3.1.2.1. Nguyn l chung:

Ht neutron l nhng ht khng tch in, khng b ion ha bi mi trng xung

quanh. Khi lng ca Neutron gn bng khi lng ca Proton (1,66.10-24 g), k hiu

01 n, khi lng bng 1 n v v in tch bng khng. Do khng tch in nn Neutron

khng b mt nng lng khi tng tc vi cc electron tch in v ht nhn, bi vy 01

n c kh nng m xuyn cao. Nng lng ca Neutron o MeV. Nng lng ca

Neutron biu hin vn tc chuyn ng V.

Theo nng lng ca Neutron, ngi ta chia lm 4 loi:

Neutron nhanh : 1 15 MeV

Neutron trung bnh : 10 eV 1 MeV

Neutron trn nhit: 0,1 10 eV

Neutron chm (nhit) : 0,025 eV

Khi cc ht Neutron tng tc vi cc ht nhn nguyn t th xy ra hin tng

tn x Neutron hoc b bt gi bi ht nhn. S tn x Neutron dn n cc ht Neutron

thay i hng chuyn ng. C hai loi tn x Neutron:

Tn x Neutron n hi: Khi Neutron c nng lng t vi MeV n 0.1eV.

Tn x khng n hi: Din ra i vi cc Neutron nhanh.

Hnh 7: Hnh trnh ca Neutron trong t Hnh 9: Hnh trnh ca Neutron trong t


33

Trong t khi cc ht Neutron tng tc vi vt cht cha nhiu nguyn t H2

th s lm chm cc ht Neutron. Nu trong t tn ti mt lng nh nc hay du

(cha nhiu H2), s chm cc ht Neutron ch yu xy ra nguyn t H2.

Khi nghin cu mt ct ging khoan bng phng php Neutron, ngi ta phng

vo t nhng ht Neutron nhanh v ghi bc x . Tia Neutron nhanh (khong 5 Mev)

lin tc c pht ra bi ngun Neutron v di chuyn theo nhiu hng vo thnh h

t . Khi di chuyn, chng tr nn chm hoc gim bt nng lng do va chm vi

cc ht nhn trn ng i. Khi nng lng gim ti mt mc rt thp (khong 0,025

ev) (hoc gi l nng lng nhit), chng c dng zigzag hoc khuych tn theo cc

hng cho n khi chng b hp th hoc b bt gi bi s hin din ca ht nhn cc

nguyn t, c bit l nguyn t nng nh Cl.

Ty theo cch ghi, ngi ta phn lm 3 phng php sau:

Phng php Neutron Gamma.

Phng php Neutron Neutron trn nhit.

Phng php Neutron Neutron nhit.

3.1.2.2 Phng php Neutron Gamma:

Nguyn l:

mc nng lng thp, neutron nhit d b mt s ht nhn trong mi trng bt gi.

Sau khi bt gi cc neutron, ht nhn ri vo trng thi kch thch v chng thng thot

khi trng thi kch thch ny bng cch pht x nng lng di dng mt lng t

gamma. Cc lng t ny cn c gi l gamma chim gi. S lng ht gamma thu

c t l vi mt ca .

Hnh 8 l s o theo phng php Neutron- gamma (hay l N-G tool)

Ngun S pht x ra cc neutron


34

Detector D m cc lng t gamma chim gi.

Mn ch (4) ngn cc tia gamma khng i thng t ngun n detector.

Tn hiu t Zond i theo cp ln mt t qua cc ngn iu ch tn hiu (2) sau

a ln b ghi (3).

Nhn xt:

Cng phng x gamma chim gi ph thuc vo hm lng nguyn t hydro

trong mi trng nghin cu.

Cc lu cht ny bo ho, lp kn trong l rng ca , do cng gamma

o c s c quan h cht ch vi l rng ca thnh h cha.

Hm lng hydro trong du v nc c coi l xp x bng nhau. Nhng trong

pha kh li t hn hn

Cng phng x gamma chim gi cn ph thuc vo khong cch t ngun

S n detector D hay l chiu di ca Zond o (Ln) v thng th Ln 0,4 m

Cng ca Gamma bc x Neutron ln hn nhiu so vi Gamma bc x I

v gamma t nhin (I).

ng cong Neutron Gamma:

Nhng phn t c kh nng bt gi Neutron ln nh Cl, Li, Co, Bor c nh hng

n kt qu ghi ca phng php Neutron Gamma.

Theo kh nng cha Hidro, t c th chia lm hai nhm:

Hnh 10: S phng php neutron-gamma


35

Nhm cao:

o St (c kh nng ngm nc ln v nhn phn ln cc khong vt c thnh

phn ho hc lin h vi H2O.

o Thch cao CaSO4.2H2O, tuy c rng thp nhng thnh phn ha hc lin

h vi H2O.

o Vi loi t cha du v nc.

Nhm thp: vi, Dolomit, cha nhiu thnh phn xi mng, anhydrite,

mui.

i vi t trm tch th gi tr ca Neutron Gamma ph thuc t st v lng

H2 v Cl cha trong l rng ca t .

n v ghi ca Neutron Gamma l V/V (%).

3.1.2.3 Phng php Neutron Neutron:

Phng php neutron neutron c thc hin theo nguyn tc bn ph mi trng

nghin cu xung quanh ging khoan bng mt lung cc neutron nhanh v o ghi

neutron c nng lng thp (E


36

Phng php ny o ghi neutron trng thi nhit. V trng thi nhit th cc

neutron t thay i nng lng v khuch tn lan ta trong mi trng cho n khi b bt

gi.

S nguyn l phng php ny cng gn gng vi phng php neutron gamma.

Nhng detector D l loi ng ch m neutron nhit m khng phi gamma chim gi

Hydro ng vai tr chnh trong qu trnh lm chm cc neutron nhanh. Chnh v th

s thay i mt cc neutron nhit theo khong cch t ngun S n detector D s th

hin s thay i hm lng hydro trong mi trng. tuy nhin mt neutron nhit

trong mi trng cn chu nh hng khong ha nc va hay thnh phn mui

khong trong

Cng ging nh phng php Neutron Gamma, i vi nhng va m thnh phn ho

hc c nhiu Hidro th phng php Neutron Neutron nhit biu hin thp. Tuy nhin

Neutron Neutron nhit rt nhy cm i vi Cl cho nn ng cong Neutron Neutron

nhit ph thuc rt nhiu vo khong ha nc va v dung dch ca ging khoan.

u im ca phng php neutron neutron trn nhit so vi phng php neutron

neutron nhit l:

Kt qu o t ph thuc vo cc nguyn t co tit din bt gi ln nh Clore hay

phng php ny khng nhy vi khong ha ca nc va v dng dch khoan

Kt qu o ch ph thuc vo hm lng hydro trong cc lp t thnh ging

khoan cho nn kh nng tnh rng cha c chnh xc cao hn

Nhc im:

Khong cch Ln-nep (t ngun S n detector) ngn hn so vi phng php neutron

neutron nhit mt neutron trn nhit ln c s m ln v gim sai s.

Tuy nhin chnh v th nn phng php Neutron Neutron trn nhit c bn knh

hot ng nh.

c. Cc my o dng trong phng php neutron

Cc cng ty dch v u c thit k ring my ging o cc phng php neutron.

Sau y l mt s kiu my o trong ging khoan ca cng ty schlumberger

GNT (Gamma ray/neutron tool) c mt detector o cc gamma chim gi. Php o dung

f n v API


37

SNP ( sidewall neutron porosity tool) o cc neutron trn nhit. Ngun v detector gn

trn tm m t vo thnh ging khoan. Thit b tnh da vo ng cong hiu chnh

(hnh 9) chuyn i trc tip t n v xung/giy ra n v rng vi.

CNT (compensated Neutron tool) dng loi my ging c hai detector loi tr s

nh hng ca ging khoan nh ng knh thay i hay lp mn khoan (mudcake).

Cc s m xung xa v gn c a ln my trn mt t v chuyn sang n v

rng cho cc nn xng khc nhau.

TDT (Thermal Decay time) dng my pht xung neutron chiu x vo mi trng t

cc neutron c nng lng cao (14MeV). Trng khong thi gian gia hai xung pht

tin hnh o neutron nhit v tnh thi gian sng trung bnh ca chng. Thi gian sng

trung bnh ca Neutron trong chn khng l 13 pht tuy nhin trong t ngn hn rt


38

nhiu. Chng cn ph thuc vo clore chng c tit din bt gi cao. Nhng ch c trong

nc va khng c trong du kh.

d) Minh gii v x l ti liu ntron nhit

Nh trn ta thy ch s o c ca phng php ntron nhit t l vi hm lng

hydro cha trong . Chnh v vy ch s o c ca phng php ntron nhit thng

c gi l hm lng hydro o c. i vi st hm lng hydro thng c gi tr

cao hn c bi xung quanh ht st, do din tch b mt ring rt ln, nn hm lng

nc lin kt kh cao. Ct kt cng rn chc, granite nguyn sinh, vi thng c

hm lng hydro thp. cng rn chc rng cng thp th hm lng hydro cng

thp. Xut pht t c tnh ng cong ntron ntron c th gp phn vo vic phn

chia cc lp t c thnh phn thch hc khc nhau hoc c rng khc nhau.

Hm lng hydro o c l tng hm lng hydro cha trong khung , trong khong

vt st v trong l hng ca . Chnh v vy hm lng hydro o c phn b theo

phng trnh sau:

Wx = Wf . + Wsh . Vsh + Wma . (1 Vsh )

Trong Wx, Wf , Wsh v Wma l hm lng hydro o c, cht lu, khong vt st v

khung tng ng;

v Vsh - rng v hm lng st cha trong va.

T cng thc trn ta c cng thc xc nh rng bng phng php ntron ntron

nh sau:

= (Wx - Wma )/(Wf Wma ) Vsh . (Wsh - Wma )/(Wf Wma )

Wma , Wsh , Wf c xc nh trong phng th nghim. i vi vi Wma = 0, i vi

ct kt Wma thng bng 0,01 hoc 0,015. Wf tu thuc vo hm lng mui ca nc

va. Tnh ton cho ta kt qu: i vi nc ngt Wf = 1, i vi nc va c khong

ho khng cao lm Wf = 0,991. Wsh = 0,35 0,40.

ng cong ntron nhit o trong ging chng ng cn phi c hiu chnh bi nh

hng ca ng chng v vnh xuyn xi mng. ng knh ging khoan khng chun

cng l yu t cn phi c hiu chnh bi nh hng ca iu kin ging ln gi tr

o.


39

3.1.2.4. Cc yu t nh hng ti kt qu o:

bn ca ngun

Khong cch gia ngun v my thu

B dy ng chng

B dy lp ximng

S hin din ca kh

Thi gian o ( time constant )

Thnh phn thch hc ca t

3.1.2.5. ng dng ca phng php neutron:

Phng php Neutron khi c kt hp vi cc phng php khc dng :

nh gi rng ca va

Xc nh ranh gii du kh

Xc nh thnh phn thch hc ca t .

3.2.1. Bn cht ca phng php:

t nm trong mi trng t nhin thc t l nhng vt n hi. Nu ta kch

thch mt lc bn ngoi vo n th trong mi trng s xut hin mt ng lc kch thch

ln cc ht v lm dch chuyn cc ht. Trong trng hp chung dn n s xut hin

bin dng. Qu trnh dao ng lan truyn theo trnh t ca s bin dng c gi l sng

n hi. Log siu m da vo s lan truyn ca sng c hc n hi trong mi trng

t . Chnh s lan truyn ca sng n hi s lm di chuyn cc phn t vt cht theo

hng song song hay vung gc vi hng lan truyn ca sng. B mt m trong mt

thi im no xut hin cc ht chuyn ng c gi l mt sng. C 2 loi sng

chnh l sng dc P v sng ngang S

Sng dc hay sng nn: Loi sng ny gy cho cc ht vt cht chuyn ri xung

quanh v tr cn bng theo phng song song vi phng truyn sng. Sng dc

P tn ti trong mi trng rn v lng


40

Sng ko hay sng ngang: lm cho cc im cht dao ng theo phng vung

gc vi phng truyn sng. Sng ngang S ch tn ti trong mi trng rn khng

tn ti trong mi trng lng

Nhn xt

Trong mi trng lin tc tc truyn sng dc ln hn tc truyn sng

ngang. Trong mi trng t t s tc truyn sng dc v sng ngang thay

i: Vp/Vs = 1,6 n 2.0

Trong mi trng t tn ti sng dc v sng ngang nhng trong mi trng

dung dch khoan th nng lng chuyn sang sng dc P

Sng ngang S lan truyn vi tc thp hn nhng nng lng ca sng ny ln

hn hng chc ln so vi nng lng ca sng dc

Hnh 12: Nguyn l truyn ca sng dc P trong mi trng t


41

Nh vy ta c th thy rng sng dc n sm hn , bin nh tt dn chm

trong khi sng ngang n chm hn bin cao hn nhng cng suy gim nhanh

hn

Sng dn ng hay cn gi l sng ng(Stoneley Wave) trong iu kin

ging khoan c dung dch(nc) trn thnh ging cn tn ti mt loi sng sinh

ra trn b mt tip xc gia dung dch khoan v t thnh ging khoan. S

lan truyn ca sng ny lm cho thnh ging khoan b bin dng. Tc truyn

ca sng ng rt thp

Sng phn x (h qu ca 2 loi sng trn): xut hin khi kh nng cn sng

ca mi trng ny ln hn mi trng kia. Khi sng lan truyn t mi trng

ny sang mi trng khc th sng s b i hng v i vn tc.

3.2. PHNG PHP SNG SIU M (SONIC LOG - DT):

Phng php siu m l phng php dng o thi gian truyn sng n hi

ca t dc theo thnh ging khoan nghin cu tnh cht vt l cng nh thch

hc ca t da trn tnh cht lan truyn ca sng siu m c tn s cao (> 20 Hz )

truyn qua cc lp t .

3.2.2. Thit b

Thit b u tin gm mt my pht v hai my thu c t trn mt u d

(sonde) vi khong cch theo tiu chun l 3 ft gia my pht v my thu gn, gia hai

my thu l 2 ft.

Hnh 13: Khc nhau gia sng dc v sng ngang theo thi gian n v bin


42

Hnh 14: M hnh nguyn l ca thit b siu m

Thit b Borehole Compensated Sonic c trnh by trong hnh 14. Thit b ny

gm mt dy hai my pht v nhiu my thu.

Hnh 15: M hnh thit b Borehole Compensated Sonic


43

3.2.3. Cc yu t nh hng n kt qu o:

Kh trong dung dch khoan : cc bt kh trong dung dch khoan s lm phn tn

v hp th nng lng ca sng siu m. Sng siu m s suy yu v s suy yu

tn hiu i khi lm my thu khng nhn c hoc nhn khng ng k gy nn

nhm ln n kt qu o.

ng knh ging khoan ln : trong cc ging khoan c ng knh ln,

khong thi gian sng dc hoc sng ngang i t my pht v bn thnh

h v bn my thu s ln hn khong thi gian sng dc truyn trc tip

t my pht v st my thu. Nu iu ny xy ra ngha l ta khng thu c

d liu o chnh xc.

Nhy chu k (Cycle skipping): C mt s trng hp do chn ngng o qu

thp hoc nng lng (bin ) sng ti chn t xa qu yu nn trigger nh du

o thi gian ch lm vic vi chu k th hai hoc th ba. V th t ko di thm

t nht mt chu k. Hin tng sng b hp th mnh trc khi ti chn t thu xa

c th do va bo ha kh c khi c du trong cacbonat, mng. Hin tng

ny c th gp do gp cc i nt n lm cho sng gim bin mnh

3.2.4. Loi tr nh hng ca ng knh ging khoan

Khi ng knh ging khoan thay i th ng biu t s thay i: ln hn hoc

nh hn gi tr thc. Hay khi trc ca Zond o v trc ging khng trng nhau (ging

nghing Zond thng ng v ngc li) u lm cho t ko di thm

khc phc nhc im trn nht l ng knh ging khoan st l, ngi ta dng

Zond o kp b chnh ng knh. V vic b tr cc bin t pht(transmitter) E1 v

E2, cc bin t thu(receiver) R1 v R2 trn Zond o ty thuc vo cch x l b ng

knh ging khoan ca tng cng ty. Mt trong nhng cch ph bin l t mt Zond pht

E1 pha trn v cc chn t R1, R2 t pha di; Zond o th 2 th t ngc li, E2

t pha di v R1, R2 t pha trn

3.2.5. n v o

Trong cng nghip ngi ta s dng n v o micro giy trn b (s/ft) o thi gian

truyn, l khong thi gian t tnh bng s sng n hi i c mt qung ng

l foot trong mi trng nghin cu. (1 s/m = 3,28084 s/ft)


44

3.2.6 Minh gii v x l ti liu

Thi gian truyn sng siu m trong 1 mt t xung quanh thnh ging khoan l tng

thi gian sng siu m truyn trong cht lu cha trong cc l hng gia ht, thi gian

sng siu m truyn trong cc ht st phn tn v thi gian sng siu m truyn trong

khung . Hm phn b thi khong c th hin trong phng trnh sau:

Tx = Tf . + Tsh . Vsh + Tma .(1 Vsh )

Trong Tx , Tf , Tsh v Tma l gi tr thi khong o c, trong cht lu, trong

khong vt st v trong khung ;

v Vsh l rng v hm lng st ca va.

Do tc truyn sng ca va cng nh nh hng ca ng knh ging khoan nn

ng cong T c p dng phn tch cc va st bi gi tr T kh cao, trong khi

i vi cc va ct c thm tt v bn dy, ng knh ging khoan n nh th

gi tr T n nh thp tu thuc vo rng ca va.

Trn c s phng trnh trn, rng ca va cha c th c xc nh theo cng

thc sau:

= (Tx - Tma )/ (Tf - Tma )/Cp Vsh . (Tsh - Tma )/ (Tf - Tma )

Cp l h s nn ca . rn chc Cp = 1, Cp c th bng 1,2; 1,4 tu thuc vo mc

b ri ca . Cc gi tr Tma , Tf , Tsh xc nh c trong phng th nghim. i

vi ct kt Tma thng bng 55-57 s/ft; Tf = 189 s/ft v Tsh = 60-170 s/ft

Trong trng hp ct sch rng ca c xc nh theo cng thc :

= (Tx - Tma )/ (Tf - Tma )/Cp

i vi granite rng c xc nh theo cng thc:

= (Tx - Tma )/ (Tf - Tma )


45

3.2.7. ng dng ca phng php siu m:

Phng php siu m dng :

Phn va sn phm

nh gi rng

Nghin cu tnh cht c l ca t

Lin kt ging khoan.


46

CHNG 4: KT QU TNH TON

4.1. Tnh ton rng hiu dng theo ng Density:

Mt khi (bulk density) l tng cc loi mt trong mt n v h tng

= f + ma (1- Vsh) + Vsh sh

Vi : mt khi cn tm

: mt trung bnh ca cht lng trong khng gian rng

: mt ca khung

T cng thc, ta tnh c rng ca :

= ( ma x ) / ( ma - f ) Vsh * ( ma - sh )/ ( ma f)

Gi tr mt ca mt s loi khung ph bin:

Rock type Matrix density (g/cm3)

Ct (ct kt) 2,65

vi (limestone) 2,71

Dolomite 2,87

Anhydrite 2,98

Vi nhng vng xm nhp (invaded zone) gi tr mt ca cht lu c tnh bng

cng thc sau:

= . + (1 ).

Vi: : mt ca nc lc (mud-filtrate density)

: bo ha ca nc lc (mud-filtrate saturation)

: Mt hydrocabon trong vng xm nhp(invaded zone)

Ch : vi vng ngm nc (water-bearing zone) th Sxo = 1 f = mf


47

logmat

hd sh sh

mat fluid

V

Vi ma = 2.71 (g/cm3), fluid = 1 (g/cm3) c cui log v log c c t log

tng v tr va, Vsh = 30%.

Xc nh c hd theo ng Density cho tng va.

4.2. Tnh ton rng bng phng php neutron

rng xc nh t ng Neutron (NPHI) :

= (W Wma)/( Wf Wma) - Vsh* ( Wsh- Wma)/(Wf-Wma)

Trong : , Wma v Wsh ch s hydro ca filtrate, khung v st tng ng;

rng; Vsh hm lng st.

rng va c xc nh bng phng php tnh ton kt hp c Neutron v Mt

trong trng hp s liu rng neutron v mt c mc tin cy:

rng tng ( rng ton phn) tnh cho va du l:

= +

2

rng tng ( rng ton phn) tnh cho va kh l:

rng hiu dng c tnh:

ef= T * (1 Vsh)

4.3. Tnh ton rng theo phng php sonic (DT)

= [ (t tma)/ ((t f tma)] /Cp Vsh .(tsh tma)/ (t f tma)

t : L thi gian truyn sng trong thnh h

tma : L thi gian truyn sng trong xng


48

tf : L thi gian truyn sng trong cht lu

Cp : l h s nn thnh h, i vi m Bch H ta ly bng 1,2

Tnh ton gi tr o kt qu minh gii gi tr rng (%) cho ging BH-129 m

Bch H tng Oligocene.( Ti liu minh gii nh km phn ph lc)

Hm lng st ca cc lp cha c tnh theo hm s sau:

Vsh = 0,7. (GR min1 GR min)/(GR max GR min)

Trong va sn phm nghin cu, ta thu c Vsh=0,34

Do s hn ch v ti liu nn nhm ch c th xc nh rng theo 2 phng php

gamma density v neutron

Tnh rng bng phng php gamma density:

= ( ma x ) / ( ma - f ) Vsh * ( ma - sh )/ ( ma f)

Vi ma = 2.65(g/cm3) , f =1,04 (g/cm3), sh = 2.62 (g/cm3)

Tnh rng bng phng php neutron:

= (W Wma)/( Wf Wma) - Vsh* ( Wsh- Wma)/(Wf-Wma)

Vi Wma =-0.01 , Wf=0,99 , Wsh=0.38

Bng tnh ton rng theo su bng 2 phng php

gamma density v neutron 4 tng sn phm ging khoan BH-129, m Bch H

Tng SP Depth(m) NPHI Porosity(%) RHOB Porosity(%)

I

(3485-3530)

3487 0.2658 14.32 2.4191 13.71

3488 0.3087 18.61 2.428 13.16

3489 0.2876 16.5 2.4431 12.22

3490 0.2806 15.8 2.4518 11.68

3503 0.3018 17.92 2.4031 14.7

3504 0.3254 20.28 2.4184 13.75

3505 0.2948 17.22 2.3929 15.34

3506 0.2814 15.88 2.4549 11.48

3529 0.286 16.34 2.4401 12.4

3530 0.2787 15.61 2.3888 15.59

3531 0.2849 16.23 2.3823 15.99


49

II

(3530-3630)

3536 0.3111 18.85 2.3441 18.37

3545 0.2656 14.3 2.3913 15.43

3553 0.2614 13.88 2.4193 13.7

3555 0.2816 15.9 2.3157 20.13

3567 0.2829 16.03 2.3105 20.45

3568 0.2961 17.35 2.3513 17.92

3569 0.2753 15.27 2.4315 12.94

3571 0.3073 18.47 2.4481 11.91

3572 0.2754 15.28 2.3959 15.15

3573 0.3221 19.95 2.3896 15.54

3574 0.2707 14.81 2.4205 13.62

3575 0.2871 16.45 2.4523 11.65

3576 0.2719 14.93 2.3789 16.2

3577 0.2813 15.87 2.3522 17.86

3578 0.2809 15.83 2.3769 16.33

3579 0.2878 16.52 2.3965 15.11

3580 0.2727 15.01 2.4156 13.93

3597 0.2262 10.36 2.4023 14.75

3598 0.2868 16.42 2.3809 16.08

3599 0.2597 13.71 2.3747 16.47

III

(3630-3712)

3629 0.2617 13.91 2.4592 11.22

3630 0.2395 11.69 2.4398 12.42

3631 0.2455 12.29 2.4803 9.91

3632 0.2263 10.37 2.3817 16.03

3640 0.2597 13.71 2.3531 17.81

3641 0.2493 12.67 2.3631 17.19

3642 0.2548 13.22 2.378 16.26

3643 0.2381 11.55 2.3886 15.6

3644 0.2432 12.06 2.3874 15.68

3645 0.2319 10.93 2.3885 15.61

3658 0.238 11.54 2.4187 13.73

3659 0.2451 12.25 2.3893 15.56

3660 0.2434 12.08 2.4763 10.16

3661 0.2434 12.08 2.3815 16.04

3662 0.2381 11.55 2.383 15.95

3677 0.2148 9.22 2.4681 10.66

3678 0.2327 11.01 2.4141 14.02

3688 0.2382 11.56 2.42 13.65

3689 0.2406 11.8 2.4219 13.53

3690 0.2321 10.95 2.4116 14.17

IV

3715 0.2993 17.67 2.4364 12.63

3717 0.2466 12.4 2.3555 17.66


50

(3712-3750) 3718 0.2626 14 2.3656 17.03

3719 0.2522 12.96 2.366 17.01

3720 0.2565 13.39 2.3622 17.24

0

5

10

15

20

25

0 5 10 15 20 25

RHOB-NPHI

RHOB-NPHI

rng tnh theo phng php neutron(%)

r

ng tn

h th

eo p

h

n

g ph

p gam

ma d

ensity(%

)

th 1: So snh kt qu rng 2 phng php gamma density v neutron


51

3450

3500

3550

3600

3650

3700

3750

0 5 10 15 20 25

gamma density

neutron

depth(m)

porosiry(%)

0

1

2

3

4

5

6

7

8

9

10

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94 97

Tn s rng theo NPHI

Tn s rng theo NPHI

th 2: Kt qu xc nh rng theo su bng 2 phng php

gamma density v neutron

th 3: Tn s phn b rng theo phng php neutron


52

Nhn xt:

Qua biu so snh nhn thy phng php xc nh rng gamma neutron( 13-

17%) cho gi tr rng khng chnh lch nhiu so phng php xc nh rng

gamma density ( khong 12-16%) ( hiu chnh nh hng ca khong vt st). Theo

, cc gi tr rng theo c phng php gamma neutron v phng php xc nh

rng gamma density cho kt qu v rng lun lun nm trn ng phn gic (

hiu chnh nh hng ca khong vt st), dao ng trong khong t 10%-20% v hon

ton ph hp vi kt qu thc nghim. V vy, c 2 phng php gamma density v

phng php neutron cho ra kt qu rng ph hp nht xc nh rng cc

tng va sn phm I v II, III v IV ca tng Oligocene, ging khoan BH-129, m Bch

H. nh gi s phn b ta s dng biu Tn sut rng nhng v s liu t,

ti liu a vt l c gii hn nn khng th nh gi c ht cc va sn phm tng

Oligocene. Chnh v vy gy kh khn cho vic v biu cng nh vic nh gi

c im phn b ca chng. Tuy nhin, vi nhng s liu c c v c th hin

trn biu Tn sut- bo ha trong cc hnh di y, ta cng d dng nhn thy

phng php xc nh rng gamma density cho kt qu rng tp trung ch yu

khong 15%, ph hp vi cc kt qu nghin cu khoa hc v rng Oligocene m

Bch H, m c th y l ging khoan BH-129. Mt ln na ta li thy, phng php

0

2

4

6

8

10

12

14

1 5 9 13172125293337414549535761656973778185899397

Tn s rng theo RHOB

Tn s rng theo RHOB

porosiry(%)

th 4: Tn s phn b rng theo phng php gamma density


53

gamma density v neutron u kh d trong vic tnh ton rng cc tng sn phm

Oligocene di m Bch H.


54

KT LUN V KIN NGH

Kt lun: Trn c s phn tch cc c im a cht v tnh ton rng ta i n

nhng kt lun sau:

1. Phng php neutron v gamma density dng xc nh rng m Bch H

u thch hp xc nh rng m ny,c th l ging khoan BH-129. C th s

dng ng thi 2 phng php tng tin cy cho vic nghin cu. Trong khi phng

php sonic do khng c s liu nn nhm cha th a ra kt lun cui cng.

2. Tng sn phm c rng nhn chung khong 15%.

3. Tnh ton rng du bng phng php gamma density v neutron c gi tr tng

i, ph thuc vo nhiu yu t a cht, khoa hc k thut,....Nn cn so snh, i chiu

vi nhiu phng php c tin cy khc.

4. Phng php gamma density v neutron tnh ton nhn chung 4 va sn phm cho

ra kt qu kh st nhau, tuy nhin vn c s khc bit tng phng php.

5. T nhng kt qu thu c, nhm sinh vin ngh dng t hp nhiu phng php

nh gamma density hay neutron xc nh rng du tui Oligocen m Bch H.


55

TI LIU THAM KHO

1. Nhm tc gi. a cht ti nguyn v du kh Vit Nam. Tng cng ty Du Kh

Vit Nam 2005

2. PGS.Ts Hong Vn Qu. Gio trnh a vt l ging khoan. 2005

3. Zaki Bassiouni. Theory, Measurement, and interpretation of well logs. Society of

Petroleum Engineers, Richarson, TX USA 1994

4. Lun n tt nghip: Nng cao hiu qu khai thc du kh tng Oligoxen h m

Bch H. Nguyn Lng Bng. i hc m a cht H Ni

5. Lun n tt nghip: c im thch hc vt l, cc m hnh vt l nh gi

rng nt n rng khi ca mng cha du bn trng Ca Long. Phan Vn

Cng. i hc m a cht H Ni.


56

PH LC

Ti liu minh gii ging khoan BH-129, m Bch H

(Cc v tr t mu vng l v tr nhm dng s liu minh gii)


57


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