SU1710708A1 - Compound for oil field development control and its preparation method - Google Patents

Abstract

The invention relates to the oil and gas industry, in particular to k.2 composition for regulating the development of oil fields, including adjusting the injectivity profile of injection wells and / or isolating oil supply wells. The goal is to improve the rheological properties of the composition and to obtain a homogeneous kinetically stable dispersion of clay in an aqueous solution of polyacrylamide filtered through a porous medium. The composition contains the following components, wt.%; polyacrylamide 0.05-0.5, bentonite clay 1-8 and water the rest. The composition is prepared by dissolving powdered polyacrylamide in water dispersion of bentonite clay with a mass ratio of clay and a polymer of not more than 25. As a result of the implementation of the composition, the coverage ratio of the waterflood increases and improves the development of deposits with a sharp formation heterogeneity. 2 sec. F-ly, 1 tab. (LS

Description

The invention relates to the oil and gas industry, in particular, compositions for regulating the development of oil fields, including adjusting the injectivity profile of injection wells and (or) isolating the water influx of oil wells in order to improve oil recovery.

Known to regulate the development of deposits using an aqueous solution of polyacrylamide. However, this method is ineffective in fields with fissured or highly permeable rock (above 2 µm), since polyacrylamide molecules do not effectively resist the flow of water in such a porous medium even at high concentrations in solution (0.3-0.5%) .

The closest to the present invention is a composition containing 0.3-1.0% polyacrylamide, 0.001-0.03% chromic alum as a crosslinking agent, and water. However, this compound is not sufficiently effective at low polymer concentrations (less than 0.1%), and due to the active adsorption of the chromium cation on the rock at high polymer concentrations, leading to a decrease in the strength of the cross-linked polymer.

The purpose of the invention is to increase the efficiency of the composition by improving its rheological properties and obtaining

a homogeneous kinetically stable dispersion of clay in an aqueous solution of polyacrylamide filtered through a porous medium.

This goal is achieved by the fact that the composition for regulating mining, containing polycycrylamide, a crosslinking agent and water, contains the bptonite clay npii as a crosslinking agent, the following ratio of components, wt%;

Polyacrylamide 0.05-0.5

Bentonite clay 1-8

Water the rest.

At the same time, in order to obtain a homogeneous kinetically and extremely stable composition - dispersion of clay in an aqueous solution of polyacrylamide filtered through an aqueous medium, the method of preparation of the composition consists in introducing bentonite clay into the water with mechanical stirring, and then after its swelling polyacrylamide powder when the weight ratio of clay to polymer is not more than 25.

The following examples illustrate the effectiveness of the compositions prepared according to the known and proposed methods, when filtered through a homogeneous porous medium in comparison with the composition of the prototype.

PRI me R 1. The stability of the dispersion of clay in an aqueous solution of polyacrylamide, prepared by the proposed or known methods, evaluated by the following method.

800 ml of water is poured into a 1000 ml beaker, then with the stirring using a mechanical stirrer, the required amount of clay is gradually introduced. After adding the clay, the dispersion in water is stirred for 4 hours to swell the clay. After that, the clay dispersion in water is poured into 200 ml in 500 ml beakers with a mechanical stirrer and the required quantity of powdered polyacrylamide with a molecular weight of 16 million and a degree of hydrolysis of 15% (according to the proposed method) or 0.3% aqueous solution is introduced with stirring it (by a known method). After stirring for two hours, the condition of the prepared clay dispersions in the aqueous polymer solution is evaluated after 24 hours of storage at rest. Those clay dispersions that do not exfoliate during the day are considered stable.

The table shows the compositions and their stability. The data show that the clay dispersion in an aqueous solution of polyacrylamide prepared by the proposed method (using PAA powder) is stable at a weight ratio of clay to PAA Cgl / Spad) not more than 25 (compare compounds 1-4 with 7), since these compounds with a Cr / Spal ratio of 25 or less, prepared by a known method (using a solution of PAA) are unstable — stratified during storage (comparing composition 3 with compositions 5 and 6).

Thus, the proposed method for preparing a dispersion of bentonite clay in water, a pure solution of polyacrylamide differs significantly from the known method of preparing it.

Example 2. Prepared formulations are tested for the effectiveness of creating resistance to the movement of water in a porous medium in comparison with the composition of the prototype and control compositions (the dispersion of clay is unstable in an aqueous solution of polyacrylamide). Their effectiveness is evaluated by filtration and rheological properties in a porous medium by the following method.,

The reservoir model (core) with a length of 17.3 cm and a diameter of 2.5 cm, represented by quartz sand with water permeability in the average current of the model 61-99 µm, is saturated under vacuum with water with a total salt content of 0.034%. Then three core pore volumes of the studied composition are pumped into the core using a constant flow sensor, fixing the pressure at the inlet and at the midpoint of the model. From the pressure at the midpoint of the model, the drag factor is calculated from the composition of Rep. After daily storage of the composition in the core, seven pore volumes of water core with a total salt content of 0.034% are pumped and the residual water resistance factor Rcp is calculated from the pressure at the midpoint of the core.

Filtration and rheological properties of the composition is better than more Rep and

D ost

Ksr

The compositions and their filtration and rheological properties are shown in the table. Moreover, prototype formulations were prepared from the same polyacrylamide as the proposed formulations using chromium potassium alum (HCC) as a crosslinking agent.

Claims (1)

From the table it can be seen that the proposed compositions in their filtration and rheological properties are significantly superior to the prototype compositions (comparing composition 2 with 10 and 3 with 9 according to Rep). Moreover, these compositions showed these results when they were prepared by the proposed method, while the control compositions with the same polymer content, but prepared by a known method (introducing a solution of PAA into the aqueous dispersion of clay) were not filtered into the core and the pressure quickly grew at the core entrance due to the filtering of clay flocs at the end of the model, and water was filtered through the core (Rcp ° 1) (comparing composition 3 with 5 and 6). However, the compositions prepared according to the proposed method, but with a GHL / SPA over 25, were also not filtered through the core, as were the compositions prepared by a known method (comparing composition 3 with 6, 5 and 6). The table shows that the proposed formulations with clay content less than 1% and polyacrylamide less than 0.05% showed unsatisfactory rheological properties (comparing compounds 1 and 2). Therefore, for the lower limit of their content in the composition, the indicated values are taken. The upper limit of the polymer and clay content is taken at 0.5 and 8.0%, respectively, because above these values very viscous compositions are obtained, which cannot be pumped into the core. Thus, the claimed compositions prepared by the new method are much more effective than the known compositions. The technology of applying the compositions is simple and consists in pumping them into the reservoir before reducing the injectivity of the well by 2050%, pushing the composition from the wellbore into the reservoir with water, holding the reservoir for 16-24 hours and commissioning the well for oil wells or injecting water for injection wells. The application of the proposed formulations to control the development of oil fields and isolate the flow of water into the wells will lead to an increase in oil production (with a simultaneous decrease in water production). Compared with the composition of the prototype of the proposed composition will additionally produce 0.5-1.0 thousand tons of oil for each well-operation. Since the standard of reduced costs per ton of oil production increase due to measures to intensify oil production is 30 rubles, and the cost of conducting one well-operation is 3-4 thousand rubles, the economic effect from applying the composition as compared to -the prototype will be 12-26 thousand rubles. for each well operation. Claim 1. Composition for controlling the development of oil fields containing polyacrylamide, a crosslinking agent and water, characterized in that, in order to improve the rheological properties of the composition, it contains bentonite clay as a crosslinking agent in the following ratio of components,% by weight: Polyacrylamide 0 , 05-0.50 Bentonite clay, 1-8 Water Rest, 2, Method of preparing a composition for controlling the development of oil fields, characterized in that, in order to obtain a homogeneous, kinetically stable dispersion of gly In an aqueous solution of polyacrylamide, filtered through a porous medium, bentonite clay is introduced into water with mechanical stirring, and then powdered polyacrylamide with a mass ratio of clay to polymer not exceeding 25.