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CHAPTER

4DRIL-N Fluid SystemsContents

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

DRIL-N fluid systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3BARADRIL-N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Formulation guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

Maintenance guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5COREDRIL-N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6Formulation guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7Maintenance guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

MAXDRIL-N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8Formulation guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9Maintenance guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

QUIKDRIL-N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11Formulation guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11Maintenance guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

SHEARDRIL-N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13Formulation guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13Maintenance guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

SOLUDRIL-N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15Formulation guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

Maintenance guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

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DRIL-N fluids

4-2

Overview

DRIL-N Fluids are designed to be essentially non-damaging to the producing formation, providesuperior hole cleaning, allow easy clean-up and becost effective.

These fluids address the wide range of problemsencountered in horizontal drilling, completion, andworkover operations. These systems are designed toprovide the lowest filtration rate possible in order tominimize or prevent formation damage.

Bridging off the production zone is a key topreventing formation damage. Bridging materialsthat are utilized in DRIL-N fluids include sizedcalcium carbonate an sized salt

When bridging production zones, the correct sizingof particles becomes important. The pore diameter ofthe formation must be known to effectively bridge.An industry rule of thumb for estimating an unknownpore diameter (microns) is to take the square root ofthe permeability in millidarcies. To effectively bridgeoff the production zone, 20-30% by weight of thebridging material should be one-third of the pore size

in microns.

Filtration tests on DRIL-N fluids are conducted usinga ceramic disc which simulates as close as possiblethe pore size of the formation. These tests can beutilized in the field to determine proper applicationof the DRIL-N fluids system.

Baroid has six unique systems, each designed to do aspecific job of addressing a specific set of conditionsand objectives. The following table gives a briefdescription of each system. A more detaileddescription is found in each system section.

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Baroid fluids handbook

Revised August 1, 1997 4-3

DRIL-N Fluid systems

System Description

BARADRIL-N Sized calcium carbonate system

COREDRIL-N All oil drilling and coring system

MAXDRIL-N Mixed metal silicate system

QUIKDRIL-N Clay and solids free, polymer system

SHEARDRIL-N Clay and solids free, modified polymer system

SOLUDRIL-N Sized salt system

Table 4-1: DRIL-N Fluid systems.This table describes DRIL-N fluid systems.

The following table lists the DRIL-N systems in this

chapter, providing a matrix that rates each system

according to its applicability for various drilling

situations. Systems are identified as:

Good

Better

Best

Systems shales zones angle drilling damage Clean -up

DRIL-N Fluid situations

Reactive Depleted Horizontal/High formation

Minimize

BARADRIL-N

COREDRIL-N

MAXDRIL-N

QUIKDRIL-N

SHEARDRIL-N

SOLUDRIL-N

Table 4-2: DRIL-N fluids versus drilling situations.This table rates DRIL-N fluids as

good, better or best under various drilling situations.

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DRIL-N fluids

4-4

BARADRIL-N Overview

The BARADRIL-N system provides acid solubledrilling, completion, and workover fluid

compositions. The BARADRIL-N system is

designed for non-damaging drilling when fluid loss

and formation stability are of primary concern.

Return permeabilities are excellent with the

BARADRIL-N system and the filtercake is easily

removed by treating with hydrochloric acid.

Formulation

Products are listed in order of addition.

Density range 8.5 - 14.5 lb/gal (1.02-1.74 sg)

Additive Function lb/bbl (kg/m )Typical concentrations,

3

N-VIS Viscosifier 0.25-1 (0.7-3)

N-VIS P PLUS Viscosifier/Filtration 1-5 (3-14)

control

N-DRIL HT Filtration control 2-10 (6-29)

PLUS

BARACARB Weighting/ Bridging As needed

5/25/50/150agent

BARABUF Alkalinity 0.1-3.0 (0.3-9)

Table 4-3: BARADRIL-N product guidelines.This table lists products and provides

typical product concentrations for formulating BARADRIL-N fluids.

Formulation guidelines

BARADRIL-N fluids may be formulated infreshwater , seawater , potassium chloride,sodium chloride, calcium chloride, sodiumbromide, or calcium bromide brines.

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Add all polymers slowly to prevent theformation of fish eyes.

Add BARACARB as needed for density andbridging requirements.

Add BARABUF for pH control

Base fluid BARADRIL-N fluid density, lb/gal (sg)

Freshwater 8.8-10.0 (1.05-1.20)

Seawater 9.0-10.0 (1.08-1.20)

Potassium chloride 9.0-12.0 (1.08-1.50)

Sodium chloride 9.0-12.5 (1.08-1.50)

Sodium bromide 12.0-14.5 (1.44-1.74)

Calcium bromide 12.0-16.0 (1.44-1.92)

Table 4-4: BARADRIL-N base fluid guidelines.This table lists base fluids and theirrecommended corresponding density ranges for formulating BARADRIL-N fluids.

% Caution: When selecting a saturated salt f luid beaware of it s crystall ization point.

Maintenance guidelines

Add BARABUF to maintain alkalinity in the 8 -

10 pH range.

BARACARB addition should be sizedaccording to the mean pore diameter size of theformation.

Note: "Rule of thumb" To effectively bridge off the

production zone, 20-30% by weight of the bridging

material (BARACARB) should be one-third of the

pore size in microns.

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DRIL-N fluids

4-6

COREDRIL-N Overview

COREDRIL- N fluids are 100% oil/synthetic drilling

fluids (diesel, mineral, ester or crude) that have been

developed to control the formation damage that could

be caused by conventional drilling operations. The

COREDRIL-N system contains an optimum

concentration of BARACARB designed to bridge

rock pores, thus providing low filtration rates -

minimizing fluid invasion into potential pay zones.

COREDRIL-N fluids use passive emulsifiers which

reduce the risk of creating emulsion blockage and

preserve the wettability characteristics of the

reservoir rocks.

Formulation



Additive Function lb/bbl (kg/m )Typical concentrations,

3

Oil/Synthetic Base fluid As needed

EZ-CORE Passive emulsifier 1-5 (3-14)Lime Alkalinity/Emulsification aid 1-3 (3-9)

BARABLOK or High temp filtration control 5-25 (14-71)

BARABLOK 400 or

DURATONE HT

N-VIS O Viscosifier/Suspension 6-15 (17-43)

BARACTIVE Polar additive 2-3% (2-3%)

BARACARB Weighting/ Bridging agent As needed

5/25/50/150

BARAPLUG Weighting/ Bridging agent As needed

20/50/6-300

Table 4-5: COREDRIL-N product guidelines.This table lists products and providestypical product concentrations for formulating COREDRIL-N fluids.

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Note: When using DURATONE HT for filtration

control, BARACTIVE must be used as an activator.


COREDRIL-N fluids may be formulated with

diesel, mineral oils, esters, and synthetics.

Provide sufficient mixing time and high shearing

action for proper yield

Lime addition provides alkalinity to aid inemulsification


Minimize invasion of water from formation

through proper control of hydrostatic pressure.

Do not contaminate fluid with water fromsurface equipment.



material (BARACARB or BARAPLUG) should be

one-third of the pore size in microns.

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DRIL-N fluids

4-8

MAXDRIL-N Overview

The MAXDRIL-N system is a mixed-metal silicate

system (MMS) designed for drilling, milling, andcompletion operations. MAXDRIL-N fluids provide

borehole stability and superior hole cleaning for

milling casing and drilling highly deviated/horizontal

sections. This fluid is especially effective when

drilling in unconsolidated, unstable, stressed or

faulted formations.

MAXDRIL-N fluids form a low permeability

filtercake that restricts solids and fluid invasions into

the formation, thus reducing damage to the

formation.

Formulation



Additive Function (kg/m )

Typical concentrations, lb/bbl3

Soda ash Hardness reducer 0.05-0.25 (0.15-0.7)

AQUAGEL Viscosifier 8-15 (23-43)

GOLD SEAL

Caustic soda Alkalinity As needed for pH 9.5-11.5

N-DRIL Fluid Control 2-6 (6-17)

N-VIS HI Viscosifier 0.075 lb per lb AQUAGEL (0.075kg per kg AQUAGEL )

BARACARB Weighting/Bridging As needed

5/25/50/150 agent

Table 4-6: MAXDRIL-N product guidelines. This table lists products and provides

typical product concentrations for formulating MAXDRIL-N fluids.

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%

%

Treat fresh water with soda ash to reduce

hardness below 60 mg/L to improve the yield

of AQUAGEL GOLD SEAL.

Prehydrate AQUAGEL GOLD SEAL for at

least one hour before adding caustic soda.

Caution: Do not add any chemicals (i .e., fluid

loss contr ol additi ves or thinners) that are not on

the formulation li st.

Note: For a seawater system, premix chemicals infreshwater and add the premix to salt water in thepits.


Add prehydrated AQUAGEL GOLD SEAL

and/or N-VIS HI, when necessary, to increaseviscosity.

Dilute with water when necessary to decreaseviscosity.

Avoid using more than 0.1 lb of N-VIS HI perlb (.1 kg/kg) of AQUAGEL GOLD SEAL.

Maintain pH between 9.5 and 11.5 with

caustic soda.

Caution: Any anionic product may cause adverse

def locculation or dispersion.


production zone, 20-30% by weight of the

bridging material (BARACARB) should be one-third of the pore size in microns.

Contamination

Clean tanks prior to addition of fluid or products.

When milling casing the old drilling fluid left

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DRIL-N fluids

4-10

behind casing may cause deflocculation or

thinning.

Keep calcium levels below 60 mg/L with soda ash.

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QUIKDRIL-N Overview

QUIKDRIL-N fluids are designed as water-based,

solids-free polymer drilling fluids .QUIKDRIL-Nfluids are especially beneficial in slimhole drilling

or coiled tubing operations when minimizing

circulation pressure is critical.

Formulation



Additive Function lb/bbl (kg/m )

Typical concentrations,3

N-VIS Viscosifier 1-2 (3-6)

N-DRIL HT PLUS Viscosifier/ Filtration 3-5 (9-14)

control

BARABUF Alkalinity 2-3 (6-9)

Table 4-7: QUIKDRIL-N product guidelines.This table lists products and provides

typical product concentrations for formulating QUIKDRIL-N fluids.

%

Formulation guidelines When mixing N-VIS and N-DRIL HT PLUS,

add slowly and agitate to insure proper

hydration of polymers.

Use brines to obtain the required density.

Refer to the brine density tables in the chapter

titled Completion fluids for density guidelines.

Caution: Do not use in calcium chlor ide brines

heavier than 11.0 lb/gal. Do not use in calcium

bromide or zinc bromide brines.

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DRIL-N fluids

4-12


Maintain the Brookfield viscometer between

45,000 and 60,000 cP using the 0.5 spindle.

N-VIS L may be substituted for N-VI S.

BARALUBE GOLD SEAL will aid in

reducing torque and circulating pressures.

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SHEARDRIL-N Overview

SHEARDRIL-N fluids are designed as a solids-free

modified polymer drilling fluid. SHEARDRIL-Nfluids provide maximum penetration rates while

minimizing formation damage.

Formulation






N-DRIL HI Viscosifier/ Filtration 1-3 (3-9)

control

N-DRIL LO Viscosifier/Filtration 1-3 (3-9)

control

Caustic soda Alkalinity 0.05-1 (0.15-3)


Table 4-8: SHEARDRIL-N product guidelines.This table lists products and provides

typical product concentrations for formulating SHEARDRIL-N fluids.

%


When mixing N-DRIL HI and N-DRIL LO, add

slowly and agitate to insure proper hydration of

polymers.

Use brines to obtain the required density. Refer

to the brine density tables in the chapter titled

Completion fluids for density guidelines.

Caution: Do not use bri nes containing zinc.

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DRIL-N fluids

4-14


In saltwater fluids use BARABUF to maintain

alkalinity.

In other systems maintain alkalinity with caustic

soda.

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SOLUDRIL-N Overview

SOLUDRIL- Nfluids are designed for drilling,

completion or workover operations in horizontal and

vertical wells. SOLUDRIL-N fluids utilize

BARAPLUG (sized salt) and a cross-linked polymer

to provide superior rheological and filtration control.

Formulation





Brine (saturated) Base fluid Saturate based on the brineused


N-VIS P PLUS Viscosifier/Filtration 3-5 (9-14)

control

N-DRIL HT PLUS Filtration control 5-10 (14-29)

BARAPLUG Weighting/Bridging As needed

6-300/20/40/50 agent


Table 4-9: SOLUDRIL-N product guidelines.This table lists products and provides

typical product concentrations for formulating SOLUDRIL-N fluids.


SOLUDRIL-N fluids may be formulated insaturated potassium chloride, sodium chloride,calcium chloride, or sodium bromide brines.

Add all polymers slowly to prevent theformation of fish eyes.

Add BARAPLUG as needed for density andbridging requirements.

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DRIL-N fluids

4-16

Add BARABUF to maintain alkalinity in the 8-10 pH range.

Base fluid SOLUDRIL-N fluid density, lb/gal (sg)

Potassium chloride 10.0-12.0 (1.20-1.44)

Sodium chloride 10.4-12.5 (1.25-1.50)

Calcium chloride 12.0-13.5 (1.44-1.62)

Sodium bromide 13.0-14.5 (1.56-1.74)

Table 4-10: SOLUDRIL-Nbase fluid guidelines. This table lists base fluids and theircorresponding density ranges for formulating SOLUDRIL-N fluids.

% Caution: When selecting a saturated salt f luid beaware of it s crystall ization point.Maintenance guidelines

Any fluid dilution should be made with thesaturated brine used for the base fluid.

BARAPLUG additions should be sizedaccording to the mean pore diameter of theformation.



material (BARAPLUG) should be one-third of the

pore size in microns.

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