WO1988004680A1

WO1988004680A1 - Method for stabilizing clayish formations

Info

Publication number: WO1988004680A1
Application number: PCT/FR1987/000502
Authority: WO
Inventors: Gilles Meunier; Jean-Pierre Zundel; Dominique Plee
Original assignee: Ceca S.A.
Priority date: 1986-12-17
Filing date: 1987-12-15
Publication date: 1988-06-30
Also published as: ES2005482A6; GR871916B; FR2608622A1; OA08750A; EP0298096A1; SU1755709A3

Abstract

Method for stabilizing clayish formations by injection into the formation of a cationic polymer. The latter is formed by quaternisation of the product obtained from the reaction of a polyamine with a copolymer formed of patterns derived from unsaturated alpha-beta-dicarboxylic acids and from at least one ethylenic unsaturated monomer.

Description

PROCESS FOR STABILIZING CLAY FORMATIONS

This invention relates to a method for stabilizing clay formations by injection into the formation of a cationic compound.

The underground reservoirs of fossil hydrocarbons often consist of clay rocks. During the drilling and operation of these reservoirs, the clay comes into contact with water foreign to the deposit. However, contact with water has a detrimental effect on the stability and permeability of clayey rocks.

On the one hand certain fine particles of clay move and block the capillaries of the reservoirs which precisely allow the exploitation of the deposit; on the other hand, certain qualities of clays, generally from the group of smectites, swell on contact with water.

Following the displacement and swelling of the clays, the reservoir loses its permeability and its stability. The production of hydrocarbons is disturbed and the mechanical characteristics of the rock can be lowered.

The phenomena cited occur in the immediate vicinity of the wall of the wells during drilling and completion operations. However, they also intervene deep in the reservoir during its exploitation by the techniques known as "improved recovery" involving the injection of an aqueous phase (injection of water, basic solutions, surfactant solutions, microemulsions or polymer solutions).

Numerous methods have already been proposed for maintaining the stability and permeability of clayey rocks in the presence of water.

US Patent 2,761,843 describes the use of quaternized polyalkyleneamines for the stabilization of clays.

US Patent 3,382,924 suggests the use of polymers or inorganic complexes. US Patent 4,366,074 relates to the use of homopolymers formed from a monomer containing a cationic site.

European patent 92,340 relates to the use of cationic polymers used in improved recovery operations.

We have now found a method of stabilizing clay formations by injection in the formation of a new class of cationic polymers, which are particularly effective.

The cationic polymer according to the invention is an ammonium salt, quaternary of the product of the reaction of a polyamine containing at least one unsubstituted amino group with a copolymer formed from units derived:

- one or more unsaturated alpha-beta-dicarboxylic compounds in the form of diacid or anhydride

- at least one ethylenically unsaturated monomer of general formula:

in which Z ₁ and Z _{2, which are} identical or different, represent

- hydrogen

- a saturated, unsaturated or aromatic C ₁ to C ₃₀ hydrocarbon radical

- a group - where R ₁ is a

C ₁ -C ₃ alkyl radical

- a group -OR ₂ where R ₂ is a C ₁ to C ₁₂ alkyl radical The copolymer contains 1 to 4 moles of units deriving from the ethylenically unsaturated monomer per unit deriving from the unsaturated alpha-beta-dicarboxylic compound and preferably 1 to 2 moles.

The unsaturated alpha-beta-dicarboxylic compounds used in the composition of the copolymer are more particularly maleic acid or anhydride or alkylmaleic acids, for example methylmaleic or citraconic acid.

The most suitable ethylenically unsaturated monomers are vinyl aromatic compounds such as vinyltoluene, styrene and alphamethylstyrene, olefins, such as ethylene, propylene, isobutene, butene, pentene, heptene, l octene, nonene, decene, dodecene, and vinyl ethers such as methylvinyl ether and isobutylvmyl ether.

The polyamines used must have a primary amine group, to allow the formation of a five-membered imide ring with the two neighboring carboxyl groups of the copolymer and at least one other tertiary amine group which can be quaternized.

The pclyamines used are of general formula

H ₂ N - Z - NR ₃ R ₄

where Z represents an alkylene or cycloalkylene radical. This radical can carry substituents, such as hydroxyl groups or preferably tertiary amines. R ₃ and R _{4, which are} identical or different, represent a hydrocarbyl radical, preferably C ₁ to C ₁₂ alkyl and preferably C ₁ to C ₄ alkyl.

As an example of these polyamines, mention may be made of dimetylaminoethylamine, diethylaminoethylamine, dimethylaminopropylamine, dimethylaminobutylamine, diethylaminopropylamine, diethylaminoamylamine, dipropylammopropylamine, methylpropylaminoaraylamine and propylbutylaminoethylamine. For the quaternization, an alkyl halide or a C ₁ to C ₁₂ and preferably C ₁ to C ₄ dialkyl sulfate is used; mention may be made of methyl bromide, iodide, chloride or sulphate or ethyl sulphate.

The preparation of the cationic compound according to the invention comprises three stages: the copolymerization, the reaction with the polyamine and finally the quaternization.

The copolymer can be prepared by conventional methods of radical polymerization. The preferred method is solution polymerization in the presence of a radical initiator. Among the radical initiators, peroxides or peroxydicarbonates are generally used.

The solvent must be compatible with the initiator used. Among these solvents, mention may be made of aromatic solvents, such as cumene, p-cymene, xylene, toluene, or else hydrocarbon cuts of aromatic nature. Ketones, such as for example methyl ethyl ketone are also suitable.

The copolymerization reaction is carried out by continuous or discontinuous addition of the radical initiator to the solution of the comonomers, at a temperature between about 30 and 300 ° C.

The copolymerization time depends on the nature of the monomers and initiators used. In general it is between 2 and 6 hours. The copolymer formed precipitates. Its number molecular mass is between 600 and 100,000 and preferably between 600 and 20,000 (measured by tonometry or GPC).

For the reaction with the polyamine, the polymer is redissolved in a solvent for the polymer and the polyamine used. Generally it is an aromatic solvent. The same solvent is usually used as for the copolymerization.

To the copolymer solution, the polyamine is added either all at once at the start of the reaction or gradually during the reaction. The proportion molar corresponds substantially to the proportion of alpha-beta-dicarboxylic compound involved in the preparation of the copolymer. This proportion can be for example from 0.9 to 1.1 mole of polyamine per alpha-beta-dicarboxylic compound.

The reaction temperature can vary widely, it is generally between 100 and 300 ° C and preferably between 100 and 200 ° C. At these temperatures the water of the reaction is continuously removed.

The duration of the reaction is generally between 1 and 10 hours, a duration of the order of 3 hours being generally sufficient.

The formation of the imide function is verified by IR spectroscopy, by the disappearance of the bands of the anhydride function at 1780 cm and 1855 cm ^-1 and the appearance of the bands of the imide function at 1700 cm ^-1 and 1770 cm ^-1.

The quaternization reaction can be carried out according to known methods. It is advisable to use the same solvents as above, so it is not necessary to isolate the imide from the copolymer prepared in the previous step. The quaternization takes place with a satisfactory speed even at room temperature, we are content to cool the previous solution before the introduction of the alkyl halide or dialkyl sulfate. At room temperature the reaction time can vary from a few minutes to a few hours depending on the ratio of the two constituents. In general, 0.5 to 1.5 moles of quaternization reagent are used per mole of polyamine. The quaternization is carried out with an efficiency of 30 to 100% and often from 50 to 100% depending on the operating conditions (measured by NMR).

The quaternized copolymer precipitates as it is formed. It is recovered by filtration.

To stabilize the clay formations, solutions of these cationic copolymers are injected into the formation. In general, this treatment takes place before the formation comes into contact with foreign water. However, it is possible to repeat the stabilization operation several times by injecting new solutions.

The solvents used are generally alcohols or mixtures of solvents based on alcohols. Advantageously, aqueous solutions are used.

The concentration of these solutions, as well as the volume and the flow rate of the injected liquid are determined according to the characteristics of the formation. The content of clays and fine minerals and the nature of these clays and minerals come into play.

In general, solutions are used whose concentration varies between 0.1 and 10% by weight and preferably between 0.5 and 5%.

The effectiveness of the copolymers in stabilizing clays is evaluated by comparison of the permeability of the rocks, before and after treatment with a solution of copolymer.

This parameter translates the reactivity of the fine fraction and the degree of reversibility of the phenomena to which it is subjected (essentially swelling and dispersion of the clays).

The following examples illustrate the invention without, however, limiting it. EXAMPLE 1

In 425 g of xylene are added 32.5 g of styrene, 32.5 g of maleic anhydride and 3.25 g of terdodecylmercaptan. The temperature of the reactor is raised to 80 ° C. and 3.25 g of benzoyl peroxide are added.

The reactor is maintained at a temperature of 80 ° C for 4 hours. The product is filtered and then dried.

The yield of polymer obtained is close to 100%. Number molecular mass measured by osmometry: 1320.

To 255 g of xylene are added 45 g of the copolymer of styrene and maleic anhydride previously obtained. In addition, 22.95 g of aminoimethyl amino propyiamine are incorporated. The temperature of the reactor is brought to 140 ° C. for 5 h. The reaction water due to the formation of the imide is eliminated.

Then 18.9 g of dimethyl sulfate are added and the reaction is allowed to proceed at room temperature. The quaternized polymer precipitates. It is filtered and then dried. Quaternization efficiency: 98%. EXAMPLE 2

Styrene (32.5 g) is replaced by methyl vinyl ether (33.5 g). The yield obtained is 95% for the maleic anhydride / methylvinyl ether copolymer. The molecular mass of this copolymer is 1100. Efficiency of quaternization: 95%. EXAMPLE 3

Styrene (32.5 g) is replaced by dodecylene (32.5 g). The yield obtained is 93% for the dodecylene / maleic anhydride copolymer. The molecular weight of this copolymer is 2000. The quaternization efficiency is equal to 90%. EXAMPLE 4

According to US Patent 4,366,074, the cationic polymer of formula is prepared:

EXAMPLE 5

The constant flow measurement of the pressure drop across a rock sample, before and after treatment with a copolymer solution, makes it possible to evaluate the modification of the permeability following the treatment.

The rock samples are crimped in a HASSLER cell, then drained alternately and in reverse with the reference water and the copolymer solution tested. Sequence of injections:

1 - the sample is soaked under vacuum with reference water. Measured permeability = K ° _R

2 - drainage with NaCl brine at 30g / 1 until the pressure stabilizes,

3 - drainage in the opposite direction with a copolymer solution in an amount limited to 5 times the volume of the pores,

4 - drainage with reference water identical to 1 until the pressure stabilizes. The measured permeability = K _E.

The effectiveness of the copolymers as stabilizers is expressed by the ratio of the two permeabilities = K _E / K ° _R

The reference water is permuted water. The copolymers are in aqueous solution. The fluids used are deaerated with nitrogen and filtered at 0.22 μm to avoid the incidence of corrosion and clogging phenomena on the course of the experiments. A bactericide allows, if necessary, to get rid of bacterial developments.

Tables 1 and 2 summarize the results of drainage tests with sandstone from the Vosges and sandstone from the Gulf of Guinea.

The comparison of the results obtained with a cationic homopolymer (comparative example 4) shows the superiority of our copolymers (examples 1 to 3). GRES DES VOSGES test results

It is a clayey sandstone with the following mineralogical composition: QUARTZ 69%

ORTHOSIS 15%

MICAS + CLAYS 16% Clays are for 1/3 of the chlorites and for 2/3 of the illites. All are diagenetically recent and therefore very sensitive to the phenomena studied.

GULF OF GUINEA

It is a clayey sandstone containing about 10% of fine particles (kaolmite + siderose + calcite)

Claims

CLAIMS 1- Method for stabilizing clay formations by injection in the formation of a solution of cationic polymer characterized in that the cationic polymer is a quaternary ammonium salt of the product of the reaction of a polyamine containing at least one amino group unsubstituted with a copolymer, formed from units derived:

- one or more unsaturated alpha-beta-dicarboxyic compounds in the form of the diacid or anhydride

- at least one ethylenically unsaturated monomer of general formula

in which Z ₁ and Z _{2, which are} identical or different, represent:

- hydrogen

- a saturated, unsaturated or aromatic C ₁ to C ₃₀ hydrocarbon radical

- a group

"

O where R, is a C ₁ to C ₃ alkyl radical

- a group -OR ₂ where R ₂ is a C ₁ to C ₁₂ alkyl radical. 2- A process according to claim 1 characterized in that the copolymer contains 1 to 4 units deriving from the ethylenically unsaturated monomer per unit deriving from the unsaturated alpha-beta-dicarboxylic compound. 3- A method according to claim 1 or 2 characterized in that the unsaturated alpha-beta-dicarboxylic compound is maleic or alkylmaleic acid or anhydride. 4- Method according to one of claims 1 to 3 characterized in that the ethylenically unsaturated monomer is a vinyl aromatic compound such as styrene, alphamethylstyrene or vinyltoluene. 5- A process according to claim 4 characterized in that the vinyl aromatic compound is styrene. 6- Method according to one of claims 1 to 3 characterized in that the ethylenically unsaturated monomer is an olefin such as ethylene, propylene, isobutene, butene, pentene, heptene, octene, nonene, decene and dodecene. 7- Method according to one of claims 1 to 3 characterized in that the ethylenically unsaturated monomer is a vinyl ether such as methylvinyl ether and isobutylvinyl ether. 8- Method according to one of claims 1 to 5 characterized in that the polyamine corresponds to the general formula:

H ₂ N - Z - NR ₃ R ₄ where Z represents a substituted or unsubstituted alkylene or cycloalkylene radical,

R ₃ and R _{4, which are} identical or different, represent a hydrocarbyl radical, preferably a C ₁ to

C ₁₂ and preferably in C ₁ to C ₄ . 9- A method according to claim 8 characterized in that the alkylene or cycloalkylene radical is substituted by hydroxyl groups, or preferably tertiary amines. 10- Method according to one of claims I to 9 characterized in that the polyamine is chosen from dimethylaminoethylamine, diethylaminoethylamine, dimethyluminopropylamine, dimethylaminobutylamine, diethylaminopropylamine, diethylaminoamylamine, dipropylaininopropylamine, methylpropylaminoamylamine and propylbutylaminoamine. 11- Method according to one of claims 1 to 1 characterized in that one carries out the quaternization ave an alkyl halide or a dialkyl sulfate in C ₁ to C ₁₂ and preferably in C ₁ to C ₄ , such as bromides, iodides, chlorides or methyl or ethyl sulfates. 12- Method according to one of claims 1 to 11 characterized in that the cationic polymer injected is in solution in an alcohol or a mixture of solvents based on alcohols. 13- Method according to one of claims 1 to 11 characterized in that the cationic polymer injected is in aqueous solution. 14- Method according to one of claims 1 to 13 characterized in that the concentration of solutions of the cationic polymers injected varies between 0.1 to 10% by weight and preferably between 0.5 and 5%.