RU2133824C1 - Method for treating oil bed - Google Patents

Abstract

FIELD: oil production industry. SUBSTANCE: method is intended for treating oil beds with purpose of isolating water-washed high-permeable intervals. According to method, successively injected into oil bed is water solution of salt. Used in function of water solution of salt is mineralized water fringe. Also injected is water clayey system. Used in function of water clayey system is clayey dispersive system which contains clay in approximate amount of 3 mass%, and 60% vat still residue from production of synthetic glycerine or ethylene glycol which is produced by hydration of ethylene oxide, polyglycol is the balance. Injected additionally after clayey system is fringe of reagent which intensifies swelling of clay relative to its swelling in clayey dispersive system in volume which is 15-30 times larger than volume of fringe of clayey dispersive system. Application of aforesaid method makes oil bed treatment more favorable. EFFECT: higher efficiency. 1 tbl, 1 ex

Description

 The invention relates to the oil industry, in particular to methods for processing oil reservoirs to isolate water-washed high permeability intervals.

 A known method of processing an oil reservoir by alternately injecting a solution of polyacrylamide and clay dispersion [1]. The method is not effective enough, because it does not allow isolating sections of the formation that are relatively remote from the bottomhole zone.

 A known method of processing an oil reservoir using solutions of polycationites and clay dispersion [2]. The method also does not allow isolating sections of the formation that are relatively remote from the bottomhole zone.

 A known method of processing an oil reservoir [3] by sequential injection of 1-30% aqueous solution of aluminum, calcium, magnesium salts; then 0.001-0.1% aqueous polymer solution - polyacrylamide, CMC and a suspension of dispersed mineral particles - clay suspension; each of the rims is pressed through with a buffer liquid - water with a cycle of 2-5 times and the subsequent injection of a displacing agent - water.

 The disadvantages of the prototype [3] are the impossibility of isolating sections of the formation relatively remote from the bottomhole zone, as well as the use of expensive water-soluble polymers as a flocculant — a stabilizer of a clay disperse system.

 Solved by the invention, the problem and the expected technical result are to increase the efficiency of the method of treating an oil reservoir with a clay disperse system by isolating sections of the reservoir that are relatively remote from the bottomhole zone when the process is cheaper. Accordingly, the coverage of the formation by exposure and oil production will increase and the water cut of the product will decrease.

The problem is solved in that in the method of treating an oil reservoir by sequentially injecting an aqueous salt solution and an aqueous clay system, a rim of mineralized water is pumped as an aqueous salt solution, and a clay disperse system containing clay of the order of 3 wt.% Is pumped as an aqueous clay system and 60% vat residue of the production of synthetic glycerin "Polyglycerin" or ethylene glycol obtained by hydration of ethylene oxide, "Polyglycol" - the rest and additionally pumped after clay with Stem rim reagent that increases swelling clay relative to its swelling clay in the dispersion, in a volume of 15-30 times the volume of the clay dispersion rim
VAT residue production of synthetic glycerin - "Polyglycerin" is a by-product of the production of synthetic glycerin. General reagent formula
CH ₂ OHCHOHCH ₂ O (CH ₂ CHOHCH ₂ O) _n H,
where n = 1-3.

 Polyglycerin is non-combustible, non-explosive, non-toxic and does not form toxic compounds in the air. It is produced by the Sterlitamak software "Caustic" (TU 6-01-0203314-92-89). It is a dark brown liquid with a pH of 12-14 and mass fraction,%: of the main substance - not less than 45, sodium chloride - not more than 15, water - not more than 40. Polyglycerol is known to be used, for example, to reduce the adsorption of nonionic surfactants used to increase oil recovery [4].

The bottom residue of the production of ethylene glycol obtained by hydration of ethylene oxide is a mixture of glycols (di-, tri-, tetraethylene glycol, etc.) with a density of at least 1075 kg / m ³ (TU 38 30 214-88). It is used as an additive to boiler fuel and coolants called Polyglycol.

 Improving the efficiency of the method of treating an oil reservoir by isolating more remote sections of the reservoir compared to the prototype is achieved by experimentally establishing by the authors the facts of suppressing the process of clay particles swelling in concentrated Polyglycerin and Polyglycol solutions and, conversely, strengthening the clay particles swelling process in highly diluted Polyglycerol and Polyglycol solutions and some reagents.

 In the table. Figure 1 presents the results of experiments on the study of the swelling processes of a 3% dispersed system of bentonite clay in different media.

 As can be seen from the table. 1, the coefficient of clay swelling in concentrated solutions of oligomers of polyhydric alcohols is minimal, which ensures an increase in the depth of penetration of the insulating agent into the formation, and the coefficient of clay swelling in solutions of some reagents (items 8–11 of Table 1) is maximum, which ensures subsequent swelling clay and reliable insulation of highly permeable intervals, already more remote from the bottomhole zone.

Aminoacetic acid 0.5%, monoethanolamine 0.5%, acid tar neutralized with NH ₄ OH or NaOH, 0.5% are approved for use in the oil industry, which were established by the authors as reagents that increase clay swelling relative to its swelling in a disperse system.

 The method is carried out by the following sequence of operations.

 1. Injection of rims of mineralized water.

 2. Injection of the clay disperse system rims.

 3. Injection of a rim of a reagent that increases the swelling of clay relative to its swelling in a clay disperse system, in a volume 15-30 times larger than the volume of a rim of a clay disperse system.

An example of a specific implementation of the method. Polyglycerol and clay powder are delivered to an injection well with an injection rate of 360 m ³ / day at 150 atm of field X, represented by a productive Devon formation with an average formation thickness of 6.5 m and an open surface of 0.20.

After the injection of a small (50-100 m ³ ) rim of mineralized water, 60 m ^{3 of} approximately 3% clay dispersion in 60% polyglycerol are pumped.

Then, 1800 m ^{3 of a} 0.5% solution of monoethanolamine is injected, which increases the swelling of clay.

As a result of the formation treatment, the injectivity of the well was 270 m ³ / day at 150 atm, and the additional oil production was 2100 tons.

 Thus, the proposed method of processing an oil reservoir is effective and industrially applicable without expensive water-soluble polymers.

Sources of information
1. Gazizov A.Sh. Enhanced oil recovery by restricting the movement of water with chemicals // Oil industry, - 1992. - N 1. - p. 20.

 2. RF patent N 2061855, E 21 B 43/22, publ. BI N 16, 1996.

 3. RF patent N 2039225, E 21 B 43/22, 33/138, publ. BI N 19, 1995

 4. Ignatyev V.E., Silishchev N.N., Nigmatullina R.F. and others. Improving the technology of application of nonionic surfactants // Oil industry. - 1992. - N 6 - p. 49.

Claims (1)

 A method of treating an oil reservoir by sequentially injecting an aqueous salt solution and an aqueous clay system, characterized in that a rim of mineralized water is pumped as an aqueous salt solution, and a clay disperse system containing clay of the order of 3 wt. % and 60% bottoms of the production of synthetic glycerin Polyglycerin or ethylene glycol obtained by hydration of ethylene oxide, Polyglycol - the rest and additionally, after the clay system, a rim of the reagent that increases the swelling of the clay relative to its swelling in the clay disperse system is pumped in, 15 to 30 times the volume of the clay disperse system rims.

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