WO1998059014A1

WO1998059014A1 - Filtrate reducing additive and well fluid

Info

Publication number: WO1998059014A1
Application number: PCT/FR1998/001312
Authority: WO
Inventors: Annie Audibert-Hayet; Jean-François Argillier; Lionel Rousseau
Original assignee: Institut Francais Du Petrole
Priority date: 1997-06-24
Filing date: 1998-06-23
Publication date: 1998-12-30
Also published as: EP0927236A1; NO990844L; FR2764900A1; NO990844D0; CA2263952A1; FR2764900B1

Abstract

The invention concerns a water-based additive for well fluid, comprising an acrylamide and branched styrene sulphonate copolymer. It also concerns a water-based fluid comprising an acrylamide and branched styrene sulphonate copolymer. The additive is useful for controlling the filtering of a well fluid through the wall. The invention is advantageously applicable to drilling and/or completion of oil wells having a temperature higher than 120 °C.

Description

FILTRATE REDUCING ADDITIVE AND WELL FLUID

Wells drilled in the basement to a deep depth or having a

high bottom temperature requires stable drilling fluids and

having satisfactory properties vis-à-vis the background environment,

including temperature. The products of the present invention

have satisfactory filtration and viscosity properties up to

temperatures around 200 ° C. They can therefore be advantageously used

in conventional or low well fluid formulations

solid contents, or even for formulations weighed down using

mineral products or soluble salts.

The known products which are generally offered for the most

high temperatures generally contain AMPS type functions,

for example described in document US-A-5510436. Works

have shown that from a certain temperature and at the

after a certain aging time, these AMPS functions hydrolyze

with the temperature then making the product very sensitive to degradation molecular by decarboxylation (We can refer to the publication SPE-

28953- Oil Field Chemistry International Meeting; San Antonio, Feb. 1995).

The products of the present invention are stabilized by the introduction of

styrene sulfonate functions which are very stable with respect to temperature.

Thus, the present invention relates to a copolymer of acrylamide and

styrene sulfonate containing at least 30% of styrene sulfonate functions. The

molecular mass can be between 100,000 and 10 ⁷ , and preferably

between 500,000 and 5 10 ⁶ -

The copolymer is a branched product with a branching product.

The branching agent can be incorporated during the polymerization, it

these are then covalent agents, or after the post-branching polymerization.

The covalent agents can be unsaturated monomers

diethylenic (e.g. diacrylate esters, such as diacrylates of

polyethylene glycols PEG) or polyethylene, such as for example N, N '

methylenebisacrylamide (MBA), or an acrylic branching agent

known, or more generally a structure of the diallylamine or allylether type.

Post-branching agents can be metal salts

versatile, formaldehyde, glyoxal.

The present invention will be better understood and its advantages

will appear more clearly on reading the description of the following tests.

The copolymers (SI, S3a, S3b, S3c, S3d) tested in the tests below

have the following general formula structure:

The polymers used (referenced in the SI series) in these tests

Comparatives with one of the products according to the invention (S3a, S3b, S3c, S3d) are:

- unbranched acrylamide / styrene sulfonate copolymers having a

molar ratio of about 50/50 and which are in the form of solutions

aqueous containing 10 to 25% of active ingredients.

- acrylamide derivatives (acrylamide / acrylate copolymer) produced

by the company SNF Floerger- France,

- sulfonated derivatives (AMPS / vinylamide / acramide, for example,

the Hostadrill manufactured by the company HOESCHT),

- cellulose derivatives (CMC) produced for example by the company

Aqualon or Lamberti (Italy).

The S 3 series differs from the SI series by their branched structure.

In the four product structures (S3a, S3b, S3c, S3d), there are two

copolymers with long, little branched chains and two others with short chains of

more significant ramification. The branching agent used here is N, N'-Methylene bis

acrylamide (MBA) of general structure (CH2 = CHCONH) 2CH2. Agent

transfer used in synergy with the branching agent to increase branching

is sodium hypophosphite (NaH2Pθ2).

Notes: The molecular weight of samples S3c and S3d is

difficult to measure due to the branching of these polymers even for

high LiN03 concentrations (up to 1 M). It is however possible

to estimate that the molecular mass of these samples is between 2 and

4x1 θ6 g / mole.

Test 1: Study of the temperature stability of the copolymers

unbranched and branched acrylamide / styrene sulfonate SI, S3a, S3b, S3c and

S3d, and comparison with an AMPS / vinylamide / acrylamide terpolymer

(Hostadrill produced by the company Hoescht) and a poorly hydrolyzed polyacrylamide

classic (2% acrylate functions, produced by SNF Floerger):

The test conditions are:

Temperature of 180 ° C and aging from 24 hours to 72 hours in

an HP / HT test cell with a back pressure of 10 bar.

Solutions: Preparation and aging in deionized water between

3000 and 10000 ppm of polymer. Deaeration by nitrogen stripping of

solutions up to oxygen levels between 5 ppb. and 50 ppb. [η] is the intrinsic viscosity of the polymer obtained from the measurements

relative viscosity at different concentrations and extrapolated to concentration

nothing. [η] / [η ^j Q corresponds to the change in intrinsic viscosity after

temperature aging.

Characterizations: Carried out in KC1 5 g / 1 after addition of the salts.

Remarks: We note that the polyacrylamide is completely degraded at

100 ° C. There is a loss of viscosity (only 25% of the initial viscosity remains) and

hydrolysis of the acrylamide functions (there are 90% of carboxylate functions). The sulfonated functions of the HOSTADRILL hydrolyze from 150 ° C short

term and the polymer loses 50% of its viscosity. In comparison,

branched acrylamide / styrene sulfonate copolymers retain their functions

sulfonated even after aging at 180 ° C. In addition, branched products

according to the invention are less sensitive to hydrolysis.

Test 2: Comparison of the Efficiency of the Styrene Copolymers

Sulfonate / Acrylamide branched with SI and filtrate reducers used

for high temperatures, for clay-based fluids:

Conditions: API standard, ambient temperature (25 ° C).

Basic FB formulation: GREEN BOND clay 30 g / 1, Xanthane 2 g / 1,

NaCl 10 g / 1 - d = 1.03

* the cake of the formulation containing HOSTADRILL is fluid and is more like a gel structure than a cake proper.

The plastic viscosity and the viscosity of the filtrate are expressed in

centipoise (cP), the threshold value, or yield value (YV), is expressed in

pounds / 100 square feet, filtrate 30 'in milliliter (ml) and cake thicknesses

in millimeter (mm).

The IDVIS brand Xanthane and the low viscosity CMC used are

marketed by the company DOWELL-IDF. Remarks: The filtration properties at 25 ° C of the formulation

containing the branched acrylamide / styrene sulfonate copolymer are similar to

those of CMC low viscosity and HOSTADRILL, at values of

lower plastic viscosity.

Test 3: Influence of temperature:

Conditions: Standard API, in an HP / HT test cell with a

50 bar pressure and 15 bar back pressure.

Basic FB formulation: GREEN BOND clay 30 g / 1, Xanthane 2 g / 1,

NaCl 10 g / 1 - d = 1.03.

Remarks: At 160 ° C, the formulation containing the HOSTADRILL

exhibits a loss of its filtration properties since the filtrate, very

viscous, indicates product degradation despite a threshold value (YV)

high. Comparatively, the copolymer-based formulations

branched acrylamide / styrene sulfonate give smaller filtrates,

even when the concentration is decreased within the formulation, and with

lower threshold values and filtrate viscosities close to the

solvent. At 180 ° C., the brown filtrate and the complete gelation, after

cooling, the formulation containing HOSTADRILL, confirms the

results obtained at 160 ° C. This was not observed with the formulations

containing the branched acrylamide / styrene sulfonate copolymers but a

consistency of the filtrates 30 'whatever the temperature and the drop in

permeability of cakes from 120 ° C. Note the degradation of the CMC

low viscosity at 160 ° C in this type of formulation.

Test 4: Comparison of the effectiveness of the copolymers

acrylamide / styrene sulfonate branched in temperature with a homopolymer

styrene sulfonate:

Conditions: Standard API, in an HP / HT test cell with a

50 bar pressure and 15 bar back pressure.

Basic FB formulation: GREEN BOND clay 30 g / 1, Xanthane 2 g / 1,

NaCl 10 g / 1 - d = 1.03.

Notes: The use of an acrylamide / styrene sulfonate copolymer

branched reduces the filtered volume and the thickness of the filter cake.

Comparatively, a sulfonated homopolymer gives less good results

than the copolymers presented here.

Test 5: Influence of temperature aging (160 ° C)

Conditions: In an HP / HT test cell with a pressure of 50 bar

and a back pressure of 15 bar, but after aging for 16 hours at a

temperature of 160 ° C.

Basic FB formulation: GREEN BOND clay 30 g / 1, Xanthane 2 g / 1,

NaCl 10 g / 1 - d = 1.03.

VA: apparent viscosity

NAo: initial apparent viscosity Remarks: The branching of the acrylamide / styrene copolymers

sulfonate allows better temperature resistance of the formulations, and

maintain perfectly acceptable filtration properties.

Test 6:

Comparison of the dynamic efficiency of a formulation based on

Branched Styrene Sulfonate / Acrylamide copolymer with formulations

commercial used for high temperatures:

m MMH, marketed by IDF-DOWELL,

m THERMADRILL marketed by BAROÏD;

Conditions: Rotational speed 1000 RPM, dP = 35 bar, temperature

ambient (25 ° C). The dynamic filtration methodology was applied

as described in the document by Y. LI et al., Revue IFP, vol 52, no2,

March-April 1997.

Basic FB formulation: GREEN BOND clay 30 g / 1, Xanthane 2 g / 1,

NaCl 10 g / 1 - d = 1.03.

The plastic viscosity is expressed in centipoise (cP), the threshold value,

or yield value (YV) is expressed in pounds / 100 square feet, the filtrate 30 'in milliliter (ml), the slope in cm / minute and the total organic concentration of

filtrates (C.O.T) is expressed in ppm of carbon.

Remarks: In dynamic filtration, the formulation containing the

branched acrylamide / styrene sulfonate copolymers have the best

filtration properties and contribute to the decrease in the permeability of

cakes resulting in lower carbon concentrations in the filtrates,

compared to commercial formulations.

Test 7: Comparison of the Efficiency of Styrene Copolymers

Sulfonate / Acrylamide branched with filtrate reducers used for

high temperatures, for fluids based on calcite and filler clay, at

limit damage to formations.

Conditions: API standard, ambient temperature (25 ° C).

Basic FBI formulation:

Xanthan 4 g / 1, HYMOD PRIMA (or HMP) 28 .5 g / 1, NaCl 20 g / 1,

KC1 20 g / 1, IDCARB75 360 g / 1 - NaOH 2M for pH = 9.5 - d = 1.20.

The plastic viscosity is expressed in centipoise (cP), the threshold value,

or yield value (YV), Gel 0 and Gel 10 are expressed in pounds / 100 feet

square, the filtrate 30 'in milliliter (ml), the cake thicknesses in millimeter (mm)

and the total organic concentration of the filtrates (C.O.T) is expressed in ppm

of carbon.

HYMOD PRIMA, or HMP, is a filler clay marketed

by DOWELL-IDF, as well as IDCARB75 calcite, the

particle size varies from 0.1 to 10 μm.

Notes: formulations containing HOSTADRILL or

acrylamide / styrene sulfonate copolymers have filtration properties

comparable under these conditions, but for plastic viscosities less

important for the latter. We will note a carbon concentration

increasing, from 700 to 1000 ppm, throughout the filtration for the formulation

based on low viscosity CMC, not observed with formulations containing

branched acrylamide / styrene sulfonate copolymers.

Test 8:

Influence of temperature (110 ° C):

Conditions: Standard API, in an HP / HT test cell with a

50 bar pressure and 15 bar back pressure. Basic FBI formulation:

Xanthan 4 g / 1, Hymod Prima (HMP) 28 .5 g / 1, NaCl 20 g / 1, KC1 20 g / 1,

IDCARB75 360 g / 1 - 2M NaOH for pH = 9.5 - d = 1.20.

Remarks: At 110 ° C and in this type of formulation, HOSTADRILL

loses its filtration properties (increase in filtrate 30 'and thickness

cake) unlike the formulations containing the copolymers

branched acrylamide / styrene sulfonate. The large cake thickness observed

for the formulation containing the low viscosity CMC confirms a

degradation of the product and loss of its properties, which has not been observed

for formulations containing acrylamide / styrene sulfonate copolymers

branched.

Claims

1) Additive for well fluid, characterized in that it comprises a

copolymer of acrylamide and styrene sulfonate consisting of

minus 30% of styrene sulfonate functions and in that said

copolymer is branched using a branching agent.

2) Additive according to claim 1, wherein the branching agent

is chosen from the following group:

• diethylenically or polyethylenically unsaturated monomers,

• polyvalent metal salts, formaldehyde, glyoxal.

3) Additive according to claim 2, wherein said branching product

is N, N'-Methylene bis acrylamide.

4) Additive according to one of the preceding claims, in which the

acrylamide / styrene sulfonate molar ratio is about 50/50.

5) Additive according to one of the preceding claims, in which the

molecular weight of said branched copolymer is between

500000 and 5 10 ⁶ , and preferably between 2 10 ⁶ and 4 10 ⁶ g / mole. 6) Water-based well fluid, characterized in that it comprises a

additive according to one of claims 1 to 5.

7) Application of the additive according to one of claims 1 to 5, for

controlling the filtration of a well fluid in the wall of said well.

8) Application according to claim 7, for wells whose

temperature is above 120 ° C.