SU1755709A3 - Fluid for clay seams stabilization - Google Patents

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

The invention relates to the oil industry, in particular to the stabilization of clayey layers using solutions.

Underground deposits of natural hydrocarbons often include clay rocks. During the drilling and exploitation of these deposits, the clay comes into contact with water. However, contact with water adversely affects the stability and permeability of clay rocks,

On the one hand, some small particles of clay move and clog the capillaries of the field, which, however, allow the field to be exploited, and on the other hand, some clay, usually from the group of smectites, swell upon contact with water.

Owing to the displacement and swelling of the clay, the walls of the field lose their permeability and their stability. Hydrocarbon production is disturbed and the mechanical characteristics of the rock may be impaired.

These phenomena occur in close proximity to the borehole wall during the operation of drilling. But they are also observed at the depth of the field during its operation by the so-called method of improved recovery, associated with the injection of the aqueous phase (water injection, basic solutions, solutions of surfactants, microemulsions or polymer solutions)

The purpose of the invention is to preserve the permeability of the reservoir.

The goal is achieved by using as a salt of a cationic polymer a quaternary ammonium salt, obtained by reacting dimethylaminopropylamine with a copolymer of maleic acid anhydride and styrene or methyl vinyl ether or dodecylene with mol.m. mass of solution.

The preparation of the cationic compound according to the invention includes three stages:

(L

WITH

x | SL JV XI

O u

 WITH

copolymerization, reaction with polyanine and. finally, quaternization.

The copolymer can be obtained by classical methods of polymerization by radical means. The preferred method is solution polymerization in the presence of a radical initiator. Of the radical initiators, peroxides or peroxycarbonates are commonly used .l f, b

The solvent must be compatible with the initiator used. Of these solvents, you can specify aromatic solvents, such as cumene, p-cumene, xylene, toluene, or aromatic hydrocarbon fractions. Ketones such as, for example, methyl acetyl ketone are also suitable.

The copolymerization reaction is carried out by continuously or periodically adding a radical initiator to the comonomer solution at a temperature of 30 ° C.

-300 ° C.

The copolymerization time depends on the nature of the monomers and initiators used. It is usually 2 to 6 hours. The copolymer formed precipitates. His number average mol.m. 600 to 100,000, preferably 600 to 20,000 (measured by tonometry or gel permeation chromatography).

For the reaction with the polyamine, the polymer is again dissolved in the solvents used for the polymer and the polyamine. Usually it is an aromatic solvent. Usually use the same solvent as for the copolymerization.

The polyamine is added to the copolymer solution either at one time at the beginning of the reaction, or gradually during the reaction. The molar content corresponds to the amount of alpha-beta-dicarboxylic compound used during the preparation of the copolymer. This amount may be, for example, 0.9-1.1 mol of oliamine per alpha-beta-dicarboxyl compound.

The reaction temperature may vary within very wide limits, usually it is 100-800 ° C, preferably 100-200 ° C.

At these temperatures, the reaction water is continuously removed. .

The reaction time is 1 to 10 hours, and usually a duration of the order of 3 hours is sufficient.

The formation of the imide function is confirmed by IR spectroscopy by the disappearance of the bands of the anhydride function at 1780 and 1855 and the appearance of the bands of the imide function at 1700 and 1770.

The quaternization reaction can be carried out by known methods. It is recommended to use the solvents mentioned above, therefore there is no need

select the imide of the copolymer obtained in the previous step. Quaternization proceeds at a satisfactory rate even at room temperature, it is sufficient to cool the previous solution before the introduction of the alkyl halide or dialkyl sulfate. At room temperature, the reaction time can vary from several minutes to several hours, depending on the ratio of both components. 0.5 to 1.5 mol of quaternization agent per mole of polyamine is usually used. Quaternization is carried out with an efficiency of 30-100% (often 50 - 100%) depending on the working conditions (measured by NMR).

The quaternized copolymer precipitates as it forms. It is isolated by filtration.

To stabilize clay formations, cationic solutions are injected into them.

copolymers. Typically, this treatment is carried out before the formation comes in contact with extraneous water. However, it is possible to repeat the stabilization operation several times by injecting new

solutions.

The solvents used are usually alcohols or alcohol-based solvent mixtures. It is preferable to use aqueous solutions.

The concentration of these solutions, as well as the volume and flow rate of the injected fluid, is determined depending on the characteristics of the formation. The clay content of the rock and small minerals, as well as the nature of these clays and minerals are taken into account.

Solutions are usually used whose concentration varies from 0.1 to 10% by weight, preferably from 0.5 to 5%.

The effectiveness of the copolymers in the stabilization of clays is assessed by comparing the permeability of the rocks before and after the treatment with the copolymer solution.

This parameter expresses the reactivity of the fines fraction and the degree of reversibility of the processes occurring in the rock to which it undergoes (mainly swelling) and the dispersion of clays.

The following examples illustrate the invention, however, do not limit the scope of its protection.

Example 1. To 425 g of xylene, 32.5 g of styrene, 32.5 g of maleic anhydride and 3.25 g tert-dodecyl mercaptan are added. The temperature of the reactor is raised to 80 ° C and

3.25 g benzoyl peroxide is added. The reactor is maintained at 80 ° C for 4 hours. The product is filtered, then dried, i,

The yield of the obtained polymer is close to 100%. The number average mol.m., modified by osmometry, is 1320. To 255 g of xylene, 45 g of the obtained styrene-maleic anhydride copolymer is added. In addition, include 1BK95 g dimethylaminopropylamine. The temperature of the reactor is adjusted to 140 ° C and maintained at it for 5 hours. The reaction water resulting from the formation of imide is removed.

Then 18.9 g of sulfate d-sulfate are added and the reaction is continued at room temperature. The quaternized polymer precipitates. It is filtered, then dried. The efficiency of conversion is 98%.

Example 2: Styrene (32.5 g) is replaced with methyl vinyl ether (33.5 g). The yield obtained is 95% for the copolymer of maleic anhydride with methyl vinyl ether. Mol.m. this copolymer is 1100. The quaternization efficiency is 95%.

PRI me R 3. Styrene (32.5 g) is replaced by dodecylen (32.5 g). The yield obtained is 93% for a copolymer of dodecylenes with maleic anhydride. Mol.m. that copolymer 2000. The efficiency of quaternization is 90%.

PRI me R 4. According to U.S. Patent 4,366,074, a cationic polymer of the formula

0-CHfc-CH-CHfc-N - Me

CHi

 lle

Example 5. Measurement at a constant flow rate of pressure loss in a sample of rock before and after its treatment with a solution of copolymers makes it possible to assess the change in permeability due to treatment.

Rock samples are inserted into an SSLER HA-type chamber, then drained alternately, first in one and then in the opposite direction with standard water and pacteopoM of the test copolymer

Sequence of operations:

1. The sample is impregnated under vacuum with standard water. Permeability measured K ° R.

2. Drainage with NaCf brine at a concentration of 30 g / l until the pressure stabilizes.

3. Drainage in the opposite direction with a solution of a copolymer in an amount 5 times smaller than the volume of pores.

4. Drainage with standard water such as in item 1 until pressure stabilizes. KE permeability measured

The effectiveness of the copolymers as stabilizers is expressed by the ratio of two permeabilities - KE / K ° R, Standard water is running water. The copolymers are in aqueous solution. The liquids used are deaerated with nitrogen and filtered through a 0.22 / gt sieve in order to avoid the effects of corrosion and clogging of the pores during the experiments. If necessary, use a bactericide to eliminate the development of bacteria.

Tables 1 and 2 show the results of drainage experiments with the Vosges sandstone and the Gulf of Guinea sandstone.

Comparison of the results obtained with a cationic homopolymer (comparative example 4) shows the superiority of copolymers (examples 1–3) according to the invention.

Test results Sandstone Vosges. It is a clay sandstone, the mineralogical composition of which is as follows,%: quartz 69; orthoclase 15: mica + clay 16.

Clays 1/3 consist of chlorites and 2/3 of illites.

All breeds are diagenetically young and very sensitive to the studied phenomena.

Sandstone of the Gulf of Guinea. We are talking about clay sandstone containing about 10% of small particles (kaolinite + calcite + siderite).

Claims (1)

The invention of the solution for the stabilization of clay layers based on an aqueous solution of salt cationic polymer, characterized in that, in order to preserve the permeability of the formation, as the salt of the cationic polymer, it contains a quaternary ammonium salt obtained by the interaction dimethylaminopropylamine with a copolymer of maleic anhydride and styrene, or methyl vinyl ether, or dodecylenomethane mol. copolymer 1100 - 2000 in the amount of 0.5-5.0% by weight of the solution. Table 1 Table 2