RU2374425C1 - Method of productive stratum treatment with water shut-off agent - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: invention related to oil-and-gas production, particularly to methods of water shut-of execution, and can be used for regulation of filtration streams inside oil stratum during production and well-workout operations. The method includes sequential pumping of hydrochloric acid, fresh water buffer, acrylic polymer solution, fresh water buffer and over flushing mineralised water, keeping well at rest during gelling. Into hydrochloric acid silica-alumina added, chemicals used with the following component ratio, wt %: Silica-alumina 4-12, Hydrochloric acid 8-12. Water is the rest. "Givpan" used as acrylic polymer, which consists of fully hydrolysed polyacrilycnitrited material, chemicals used with the following component ratio, wt %: "Givpan" with content of 6-20% hydrolysed polyacrilycnitrited material 20-100. Water is the rest. Between acid and "givpan" solutions fresh water buffer pumped in with volume which allow to mix "givpan" with other components in bottomhole zone, then water shut-off supplied into stratum.

EFFECT: water shut-off effectiveness increase.

2 cl, 2 tbl, 3 ex

Description

The invention relates to the oil industry, in particular to methods for carrying out waterproofing works, and can be used to control filtration flows in oil reservoirs during the development process and during overhaul of wells.

A known method for the selective isolation of the influx of formation water into oil wells, including the injection of water-soluble polymers of acrylic series [Kleschenko II, Grigoryev A.V., Telkov A.P. Insulation work during completion and operation of wells. - M .: Nedra, 1998, 267 p. (p.31)]. The mechanism of isolating the influx of formation water is based on the interaction of water-soluble polymers of acrylic series with salts of formation water or the adsorption of polymers on water-saturated rock. Therefore, this method is applicable only for the isolation of highly mineralized stratal waters of calcium chloride type.

There is a method of isolating produced water in wells, including the sequential injection of fresh water, hydrolyzed polyacrylonitrile (hypane) into the aquifer of the formation, fresh water again and forcing them into the formation with mineralized water with a density of 1.18 g / cm ³ [Yumadilov A.Yu., Isolation formation water. - M: Nedra, 1976, 111 s, (S.59)].

The disadvantage of this method is the low insulation efficiency due to the extrusion of a water-soluble polymer from the formation. The reason for extruding polymer from the formation is the mutual repulsion of negatively charged rock surfaces and the anionic groups of the hypane macromolecule.

A known method of developing a heterogeneous oil reservoir, including sequentially alternating injection into the flooded reservoir of an aqueous solution of partially hydrolyzed polyacrylamide and clay slurry and subsequent injection of a displacing agent [Instructions for the use of polyacrylamide with clay slurry in flooded wells to increase oil production and limit the flow of water. RD 39-5765678-213-87P, 1987]. The disadvantage of this method is its low efficiency due to the rapid erosion of the insulating material due to insufficient adhesion to the rock and the destruction of polyacrylamide.

There is a method of regulating the permeability of a heterogeneous terrigenous layer [RF patent 2128281, MKI E21B 43/22. Publ. 03/27/1999], which includes a two-stage injection of a gel-forming acid solution into the formation, pumping it into the formation with water and stopping for the duration of gelation. Its disadvantage is lack of effectiveness. In addition, in the presence of carbonates, this composition forms a weak, loose and permeable gel, which does not allow its use in carbonate formations and in formations with carbonate cementitious material.

The closest technical solution to the proposed invention, i.e. the prototype is a method of isolating water inflow in an oil well [RF Patent No. 2186941, MKI E21B 33/138, E21B 43/32, publ. 08/10/2002], including treating the formation with a 1: 1 diluted solution of hydrochloric acid and a diluted solution of hypane, subsequent injection of hypane as an insulating material and forcing it into the aquifer of the formation with mineralized formation water.

The disadvantage of this method is the low efficiency of water isolation, due to the insufficient strength of the obtained gels, which leads to a reduction in the time of the effect of reducing water inflow, insufficient reduction in the permeability of the rock.

The technical task of the present invention is to increase the efficiency of water insulation both in terms of the decrease in water inflow and the duration of this decrease, as well as the application of a method of treating productive formations containing carbonates or purely carbonate formations with a water-insulating composition.

This goal is achieved by the fact that in the method of treating a productive formation with a water-insulating composition, comprising sequentially injecting a solution of hydrochloric acid, a buffer from fresh water, a solution of acrylic polymer, a buffer from fresh water and pumping mineralized water into the formation with keeping the well at rest for the duration of gelation, into the solution hydrochloric acid add aluminosilicate component, chemical reagents are taken in the following ratio of components, wt.%:

Aluminosilicate component 4-12 Hydrochloric acid 8-12 Water rest

As an acrylic polymer, an acrylic polymer givpan, consisting of a fully hydrolyzed polyacrylonitrile raw material, is used, the chemical reagents are taken in the following ratio of components, wt.%:

Givpan with a content of 6-20% hydrolyzed polyacrylonitrile feed 20-100 Water rest

Between acid and givpan solutions, a buffer of fresh water is pumped in such a volume that the givpan solution is mixed with the remaining components in the bottomhole formation zone, then the water-insulating composition is forced into the formation.

If it is necessary to pump a large volume of the water-insulating composition, the givpan polymer solution is divided into two or more parts, then after the composition of hydrochloric acid and the aluminosilicate component are pumped, the first fresh water buffer, the first part of the givpan polymer solution, the second fresh water buffer are sequentially pumped mineralized water, the third fresh water buffer, the second part of the givpan polymer solution, the fourth fresh water buffer, the mineralized water and then all parts of the givpan polymer solution are pumped into a similar sequence with alternating buffers from fresh water and mineralized water, then the fluid is pushed into the reservoir.

As an aluminosilicate component, aluminosilicate-containing industrial wastes are used, for example, a zeolite component for the production of synthetic detergents, or self-scattering slag, or blast furnace slag, or ferrochrome self-scattering slag, or Portland cement slag, which makes it possible to create a gel in the reservoir [RF Patent Application No. 96610000/03 " Gel-forming composition ”/ BI No. 9 of 03/27/98. Patents of the Russian Federation No. 2178059, ЕВВ 33/13, Е21В 33/138. Gel-forming composition. Publ. 01/10/2002. No. 2188313, ЕВВ 43/22, ЕВВ 33/138. Gel-forming composition. Publ. 08/27/2002. No. 2188314, ЕВВ 43/22, ЕВВ 33/138. Gel-forming composition. Publ. 08/27/2002. No. 2211914, Е21 Е21В 33/138. Gel-forming composition. Publ. 09/10/2003], which in addition to the acid effect of the solution on the rock (according to the prototype) increases the degree and quality of water insulation as an additional waterproofing ingredient. As an acrylic reagent, the givpan reagent is used, which is an alkaline solution of fully hydrolyzed polyacrylonitrile raw materials with a pH of 12-14 manufactured by Dubitel OJSC according to TU 2216-001-04698227-99, with a content of 6-20% hydrolyzed polyacrylonitrile fiber [Production Method acrylic reagent givpan. RF patent No. 2169754, MKI C09K 7/02, publ. 06/27/2001]. After injection of the givpan solution, a calcium chloride solution can be pumped to further strengthen the gel from givpan.

To provide high-quality waterproofing, the sequence and volumes of injection and the place for mixing the reagents are set so that the mixing of the acid solution with the addition of the aluminosilicate component and the water solution of givpan occurs in the bottomhole formation zone. Thus, in the present invention, new ingredients and a sequence of actions are used, which gives reason to assert that the proposed solution meets the criterion of "novelty."

To reduce the water cut of the selective isolation of formations, to control the permeability of waterlogged interlayers, it is known to use gel-forming and sediment-forming compositions [for example, RF patents Nos. 2163965, 2219328, MKI E21B 33/138]. However, the known methods have a number of significant drawbacks, the main of which is the creation of insufficiently dense and short-lived gels. This leads to incomplete waterproofing and insufficient waterproofing.

In the scientific, technical and patent literature, information on the use of the Givpan acrylic polymer reagent with completely hydrolyzed polyacrylonitrile feedstock in its composition in the preparation of gelling water-insulating compositions was not previously provided, it was previously used for additives in drilling fluids. Previously, to obtain water-insulating compositions, oxides, alkalis, acids were used in various combinations, and the concentrations of ingredients, hypane and givpan with partially hydrolyzed polyacrylonitrile raw materials were changed. Partially hydrolyzed polyacrylonitrile feedstock during reaction with salts of alkali polyvalent metals creates insufficiently branched polymer structures and, as a result, the resulting gel (precipitate) has insufficient water-insulating properties. As a result of the interaction of more branched macromolecules of a fully hydrolyzed polymer directly in the bottomhole formation zone with alkali metal cations in an acid solution with the addition of aluminosilicates, a voluminous gel-like precipitate is formed, the polymerization of which accelerates in the presence of hydrochloric acid. The use of the givpan polymer reagent containing fully hydrolyzed polyacrylonitrile feedstock, compared with givpan containing partially hydrolyzed polyacrylonitrile feedstock, enhances the gelation and hardening of the resulting compositions due to the fact that the fully hydrolyzed polyacrylonitrile fiber, which is the basis of interaction with hydrochloric acid, aluminum and calcium chlorides obtained in the reaction of the zeolite component for the production of si synthetic detergents with hydrochloric acid, which, due to the amphoteric properties of polyvalent cations, are able to form a spatial gel, hardened over time, forms a dense precipitate and accelerates gelation in general to strengthen the precipitate. Following the givpan polymer reagent, a solution of calcium chloride can be added.

Thus, the foregoing indicates the conformity of the claimed invention to the criterion of "inventive step".

Example 1

To prepare composition No. 5, Table 1, the following is done: per 100 ml of a solution of a zeolite component for the production of synthetic detergents with hydrochloric acid, 7 g of a zeolite component for the production of synthetic detergents, 10 g of hydrochloric acid (in terms of 100 g of dry matter) are taken and 83 ml of water. The zeolite component for the production of synthetic detergents and hydrochloric acid were manually mixed for 1 minute and then mixed with water. The resulting mixture (solution 1) was mixed manually or on a magnetic stirrer for 25 minutes. To prepare 30 ml of givpan solution with the desired concentration, 7.6 ml of 20% givpan and 22.4 ml of water are taken. A mixture of givpan and water (solution 2) was mixed manually or on a magnetic stirrer for 10 minutes. Then solutions 1 and 2 were mixed with stirring manually for 5 minutes. Samples in which viscosity was determined using a capillary viscometer were periodically taken from the prepared composition. A kinematic viscosity of 25 mm ² / s was adopted as a gelation criterion.

In this example, the gelation time at a temperature of 20 ° C was 18 hours.

When determining the gelation rate at a higher temperature (75 ° С), the obtained sample was thermostated.

To prepare the water-insulating composition, we used a zeolite component for the production of synthetic detergents, which contains silicon, aluminum, and potassium oxides and is produced according to TU 381011366-94 and TU 2163-003-05766557-97, hydrochloric acid inhibited according to TU 2122042-00203306-98, polymer Givpan, manufactured by Dubitel OJSC according to TU 2216-001-04698227-99 (with a content of 6-20% hydrolyzed polyacrylonitrile fiber) and calcium chloride (GOST 4568-95).

The prepared compositions of the waterproofing compositions are shown in tables 1 and 2. Here are the indicators of the prototype. Based on the data presented in the tables, we can conclude that the claimed method of treatment with a water-insulating composition containing a zeolite component for the production of synthetic detergents, hydrochloric acid, water and givpan reagent has a high gelation rate and high strength of the gel formed. The best indicators for the rate of gelation are given in experiments 5-10.

Example 2. In the industrial implementation of the invention, obtaining a water-insulating composition and treatment of the reservoir is carried out as follows (for example, composition No. 9, see table 1, 2).

In the capacity of the cementing unit, 925 l of water is poured and into the water, with constant stirring by circular circulation, 285 kg of dry calcium chloride are added; mixing is carried out until the complete dissolution of calcium chloride (can be used ready-made 20% solution of calcium chloride, brought from the base). The finished 20% solution of calcium chloride is pumped into a separate container. Then, 1780 liters of water are poured into the capacity of the cementing unit and 1170 liters of 23% hydrochloric acid are added to the water. 180 kg of the zeolite component for the production of synthetic detergents are poured into the hopper of a cement mixing machine. The cementing unit and cement mixing machine are tied and the first part of the water-insulating composition is closed on the prepared hydrochloric acid solution using a zeolite component for the production of synthetic detergents. The resulting composition is pumped into the measured capacity of the cementing unit and is mixed by circular circulation for at least 25 minutes. Simultaneously with the preparation of the composition of the zeolite component for the production of synthetic detergents with hydrochloric acid, 260 l of a 20% givpan solution are pumped into the measured containers of the second cementing unit, 740 l of technical (fresh) water is added to it and at least 20 are mixed by circular circulation minutes. Next, the composition of the zeolite component for the production of synthetic detergents with hydrochloric acid is pumped through the tubing or drill pipe into the well, immediately after the first part, a buffer of 500 l of technical (fresh) water is pumped (such a volume of buffer in this particular case allows mixing solutions bottom-hole zone of the formation), then a 6% solution of givpan is pumped, a buffer of 500 l of technical (fresh) water (such a volume of buffer in this particular case allows mixing e of solutions in the bottom-hole zone of the formation), 1 m ^{3 of a} 20% solution of calcium chloride and all liquids are pressed into the formation, then the water-insulating composition is left for structuring and gel strengthening in the pores of the formation.

If it is necessary to pump large volumes of water-insulating composition, all solutions can be divided into 2 or more parts and pumped into the well in the indicated sequence.

Table 1. The start time of the gelation of the waterproofing composition Experience number Structure The presence of carbonates,
wt.% Gelation time, h The ratio of the ingredients of the gel-forming composition, wt.% givpan
wt.% Zeolite component for the production of synthetic detergents Hydrochloric acid Water at t ° С twenty 75 prototype 9 9 82 - - 62 5,0 prototype 9 9 82 - 10 6.0 1.7 one 6 9 85 2 10 2.9 0.25 2 6 9 85 6 10 2.7 0.2 3 6 9 85 10 10 2.5 0.16 four 6 9 85 twenty 10 2.1 0.12 5 7 10 83 6 10 3.8 0.6 6 7 10 83 10 10 3.2 0.5 7 7 10 83 twenty 10 2.8 0.4 8 8 10 82 four 10 2.5 0.3 9 8 10 82 6 10 2.2 0.25 10 8 10 82 10 10 2.0 0.2 eleven 9 9 82 6 - 51 3,5 12 9 9 82 6 10 4.0 1.3

Table 2. The decrease in the permeability of a sample of a porous medium (core) after treatment with a water-insulating composition. Experience number Structure The permeability of carbonate-containing core, μm ² The multiplicity of reduction k _n / k _to , times The ratio of the ingredients of the gel-forming composition, wt.% givpan
wt.% Zeolite component for the production of synthetic detergents Hydrochloric acid Water Initial k _n Ultimate k _to prototype 9 9 82 - 0.236 0,112 2.1 one 6 9 85 2 0.357 0.018 19.8 2 6 9 85 6 0.413 0.011 37.5 3 6 9 85 10 0.195 0.003 65.0 four 6 9 85 twenty 0.363 0.009 40.3 5 7 10 83 6 0.168 0.006 28.0 6 7 10 83 10 0.292 0.012 24.3 7 7 10 83 twenty 0,309 0.014 22.1 8 8 10 82 four 0.318 0.005 63.6 9 8 10 82 6 0.401 0.008 50.1 10 8 10 82 10 0.267 0.004 66.7 eleven 9 9 82 6 0.251 0.007 35.9 12 9 9 82 6 0.387 0.010 38.7

Example 3. Composition No. 9, see table 1, 2. In the capacity of the cementing unit, 925 l of water is poured and into the water, with constant stirring by circular circulation, 285 kg of dry calcium chloride are added; mixing lead to complete dissolution of calcium chloride. The finished 20% solution of calcium chloride is pumped into a separate container. 3560 liters of water are poured into the capacity of the cementing unit and 2340 liters of 23% hydrochloric acid are added to the water. 360 kg of the zeolite component for the production of synthetic detergents is poured into the hopper of a cement mixing machine. The cementing unit and cement mixing machine are tied up and the first part of the water-insulating composition is closed on the prepared hydrochloric acid solution using a zeolite component for the production of synthetic detergents. The resulting composition is pumped into the measured capacity of the cementing unit and is mixed by circular circulation for at least 25 minutes. Simultaneously with the preparation of the composition of the zeolite component for the production of synthetic detergents with hydrochloric acid, 520 l of a 20% givpan solution are pumped into the measured containers of the second cementing unit, 1480 l of technical (fresh) water is added to it and at least 20 are mixed by circular circulation minutes. Then ^1/2 _{of the} obtained volume of the composition of the zeolite component for the production of synthetic detergents with hydrochloric acid is pumped into the well through tubing or drill pipe, immediately after the first part, a buffer of 500 l of technical (fresh) water is pumped (such a volume of buffer in this particular case allows for mixing of solutions in the bottomhole formation zone), then pumped _^1/2 volume of 6% "givpana" solution, 500 l of buffer technical (fresh) water (such buffer volume in this case may be ae allows mixing solutions in the bottom-hole zone of the formation), 1 m ^{3 of a} 20% solution of calcium chloride, a buffer of 500 l of technical (fresh) water (this volume of buffer in this particular case allows mixing of the solutions in the bottom-hole zone of the formation); then the remaining _^half resulting volume of the composition of the zeolitic component for the production of detergents with hydrochloric acid, a buffer of 500 l technical (fresh) water (such buffer volume in a given case allows mixing of solutions in the bottomhole formation zone), the remaining _^1/2 volume of a 6% "givpana" solution, 500 l of buffer technical (fresh) water (such buffer volume in a given case allows mixing of solutions in the bottomhole formation zone), 1 m ³ of 20% calcium chloride solution and all forced into the formation fluid, more water shutoff composition is left to its structure and hardening of the gel in the pores of the formation.

Thus, the examples of implementation of the invention show its compliance with the criterion of "industrial applicability".

Claims (2)

1. A method of treating a productive formation with a water-insulating composition, comprising sequentially injecting a solution of hydrochloric acid, a buffer from fresh water, a solution of acrylic polymer, a buffer from fresh water and pumping mineralized water into the formation with holding the well at rest for the duration of gelation, characterized in that it is into the solution hydrochloric acid add aluminosilicate component, chemical reagents are taken in the following ratio of components, wt.%:
Aluminosilicate component 4-12 Hydrochloric acid 8-12 Water Rest
as an acrylic polymer, an acrylic polymer "givpan" is used, consisting of a completely hydrolyzed polyacrylonitrile raw material, chemical reagents are taken in the following ratio of components, wt.%:
"Givpan" with a content of 6-20% hydrolyzed polyacrylonitrile feed 20-100 Water Rest
between the acid and givpan solutions, a buffer of fresh water of such a volume is pumped that the givpan solution with the other components is mixed in the bottomhole formation zone, then the water-insulating composition is pushed into the formation. 2. A method of treating a productive formation with a water-insulating composition according to claim 1, characterized in that the givpan polymer solution is divided into two or more parts, then after the composition of hydrochloric acid and the aluminosilicate component are injected into the well, the first fresh water buffer is sequentially pumped, the first part of the solution givpan polymer, second fresh water buffer, calcium chloride solution with 20% concentration, third fresh water buffer, second part of givpan polymer solution, fourth fresh water buffer, calcium chloride solution I with a 20% concentration and then all parts of the givpan polymer are pumped in a similar sequence with alternating buffers from fresh water and a solution of calcium chloride, then the liquids are pushed into the reservoir.