RU2352765C1 - Method of insulating water production in watered oil reservoirs - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: here is disclosed method of water production insulating in watered oil reservoirs; said method consists in preparing processing reagent out of polyacrylamide, chromium acetate and water and in pumping it into reservoir; during preparation of processing reagent dry mixture is preliminary made containing, wt %: polyacrylamide 60-75; "РИТИН-10" 5-15; chromium acetate 5-10; bentonite clay 10-15; glycerin 0.3-1.0; said reagent pumping is performed in form of suspension of produced dry mixture in water with concentration 0.2-0.7 wt %.

EFFECT: increased processibility of preparing composition to pumping in field conditions, simplification of process, reduction of labour intensiveness and increased accuracy of components dosing in mixture; eased transporting and storage of reagent on site.

3 tbl

Description

The invention relates to the oil industry, in particular to methods for isolating water inflow in injection and production wells.

Chemical and other methods of isolating water inflow are known, based on the grouting effect of gels or on the insulating effect of sediments resulting from the cyclic injection of sediment-forming reagents. It should be noted that the injection of reagents into the reservoir is carried out in the form of aqueous solutions.

So, according to A.S. USSR 1747680 (1992) conducted a cyclic injection of aqueous solutions of calcium chloride and soda ash in a ratio of 1: 1. With the penetration of solutions into the formation and their mixing with each other, the formed precipitate of calcium carbonate impeded the movement of water flows.

A number of technologies are known for conducting insulating works using gelling compositions based on polyacrylamide (PAA).

So, in accordance with the patent of the Russian Federation 2159328 (2000), in order to isolate the highly permeable intervals of the formation, sequential injection of aqueous solutions of polyacrylamide with the addition of bentonite clay was carried out. The barrier was formed due to clay swelling in the formation.

Also known patent of the Russian Federation 2110676, (1998), according to which prepared solutions of the polymer and the bound polymer with high water retention at a certain ratio of components.

The disadvantage of the above technical solutions is the complex technology for preparing the composition for injection and its lack of effectiveness.

A known method of limiting water inflow by sequential injection of solutions of PAA and hydrochloric acid (A.S. USSR 1731943, 1992). The disadvantage of this method is the separate injection of components, which leads to incomplete mixing in the formation zone.

As a prototype of the invention, RF patent 2272891 can be considered, according to which PAA and chromium acetate solutions are mixed as a crosslinker. Additionally, a gel control additive is injected into the formation. The disadvantage of this method is the complicated preparation of the composition for injection, uneven mixing, insufficient processability.

The practical result of the invention is to increase the manufacturability of the process of preparing the composition for injection in the field, simplifying the technology, reducing the complexity and increasing the accuracy of the dosage of the components in the mixture, as well as facilitating the transportation and storage of the reagent in the field.

The problem is solved in that in a method of isolating water inflow of water-flooded oil reservoirs, comprising preparing a processing reagent from polyacrylamide, chromium acetate and water and pumping it into the reservoir, according to the invention, in preparing the processing reagent, a dry mixture containing polyacrylamide, chromium acetate and additionally bentonite is preliminarily obtained clay, RITIN-10 and glycerin in the following ratio of components, wt.%:

Polyacrylamide 60-75 RITIN-10 5-15 Chromium acetate 5-10 Bentonite clay 10-15 Glycerol 0.3-1.0

and the injection of the specified reagent is carried out in the form of a suspension in water of the obtained dry mixture with a concentration of 0.2-0.7 wt.%.

At the same time, bentonite clay and glycerin act in a new purpose - not only as fillers, but also as stabilizers of the dry mixture, preventing chemical interaction between the components and the formation of dust.

The RITIN-10 reagent is a mixture of a cross-linked polyamide of carboxymethyl cellulose, manufactured according to TU 2216-001-13303015-03.

Since the selection of compositions and the production of the reagent is carried out in the factory, errors in the dosage of the components are minimal.

Filtration tests were carried out on a bulk model of a formation element, consisting of a 1.54 cm ² steel pipe with a cross section of 15 cm long. Washed finely dispersed quartz sand was used as the core material. Previously, before each test, the initial permeability was determined, for which water was filtered before reaching a stable mode. The injection volume was 0.2 pore volume.

Tables 1 and 2 show the main technological parameters of the compositions presented - component concentrations, gelation time at 25 and 70 ° C, residual resistance factor and gel characteristic.

As follows from table 1, the optimal compositions are examples 3, 4-6. At the same time, the resistance factor during filtration tests is characterized by a high value and the gelation time at 25 and 70 ° C differs by 40-50 times. The obtained indicators indicate the operational suitability of the proposed technology.

Examples 1, 8 or 9 and 2 correspond to non-optimal boundary compositions.

Table 1 The composition and properties of the reagent dry structure-forming polymer composition (SSPK),% wt. in dry mix No pp PAA AC.X RITIN-10 B. gl. Glitz. Resistance factor Time gel Reagent quality one 54 6 19.5 twenty 0.5 - - No gel 2 78 7 - fifteen - - 150 Moving gel 3 70 6 10 13.5 0.5 350 60 Dense hanging tongue gel, free-flowing, dust-free four 75 5,6 9 10 0.4 350 70 Medium gel, free flowing, dust free, medium crosslinking 5 68.5 7 12 eleven 1,5 300 70 Medium gel, glycerol overdose 6 70 7.5 10 12 0.5 350 60 Thick gel, dry mix, loose, stable during storage, does not dust 7 70 5.5 fourteen 10 0.5 300 70 Mobile gel, dry mix, stable during storage 8 76 3 7 13 one - - No gel 9 75 6 10 8.7 0.3 - - The dry mixture is dusting

table 2 Gelling ability of the reagent SSPK No pp SSPK concentration Gelling time, hour Gel description At 25 ° C At 70 ° C one 0.2 70 1,5 Liquid gel 2 0.5 54 1,0 Optimal Tongue Gel 3 0.7 40 0.9 Durable, non-flowing

In dry form, the composition is a greenish free-flowing powder. Packed and stored in sealed paper bags in a place protected from moisture.

In field conditions, the reagent is injected into the reservoir in the form of a suspension with water at ratios that provide a concentration of the reagent in water of 0.2-0.7 wt.%. When developing a well treatment project, it should be borne in mind that the gelation time depends on the reagent concentration and temperature (Table 2).

For the injection of slurry, a set of equipment is used for strapping well reinforcement, and a mobile unit UDR-32 and a pump unit of the CA-320 type.

Examples of field treatments for wells.

Preparation of dry structure-forming polymer composition (CSPK).

70 wt.% Polyacrylamide and 10 wt.% RITIN-10 reagent are poured into the mixing hopper. While stirring the polymer material, 0.5 wt.% Glycerol is poured and stirred for one hour. Then, with stirring, 6% by weight of chromium acetate is poured and stirred for one hour. 13.5 wt.% Bentonite clay is added to the resulting mixture and stirred for another hour. The resulting reagent is dosed and packaged in sealed plastic bags.

Experimental treatment of wells with a reagent was carried out at the Vat-Yeganskoye field in an area with an oil saturated layer thickness of 5 m, porosity of 24%, permeability of 244 mD and injectivity of 400-500 m ³ / day. The injection volume was 350-450 m ³ in a cyclic mode at a reagent concentration in water of 0.5 wt.%.

As can be seen from table 3, example 1, with an injection volume of 340 m ^{3 the} pressure after treatment increased by more than 3 times, and the injectivity decreased by almost 1.5 times. A similar dependence was observed in other wells. So, with an injection volume of 429 m ³ (Example 2), the pressure increased from 40 to 88 atm, and the injection rate decreased by 25%.

Table 3 Well treatment results Npp Options Before processing After processing one Injection volume - 340 m ³ Pressure, atm
Pickup, m ³ / day fifteen
443 55
332 2 Injection volume - 429 m ³ Pressure, atm
Pickup, m ³ / day 40
480 88
368 3 Injection volume - 420 m ³ Pressure, atm
Pickup, m ³ / day 0
454 92
346 four Injection volume - 462 m ³ Pressure, atm
Pickup, m / day 55
467 81
182

Similar positive results were obtained at other wells of the Vat-Yeganskoye field (see examples 3 and 4 of Table 3).

In addition to the above, a well was treated at the Tevlin field (Western Siberia). In the section with a porosity of 0.19 with an injectivity of 350 mD, 639 m ^{3 was} injected, while the pressure in the well increased from 0 to 80 atm, and the injectivity dropped from 421 to 402 m ³ / day.

Thus, the test results of the proposed method indicate effective blocking of reservoirs and isolation of water inflow, which will allow for additional oil production.

Claims (1)

A method of isolating water inflow of water-flooded oil reservoirs, comprising preparing a processing reagent from polyacrylamide, chromium acetate and water and pumping it into a formation, characterized in that when preparing the processing reagent, a dry mixture containing polyacrylamide, chromium acetate and additionally bentonite clay, RITIN-10 is preliminarily obtained and glycerin in the following ratio of components, wt.%:
Polyacrylamide 60-75 RITIN-10 5-15 Chromium acetate 5-10 Bentonite clay 10-15 Glycerol 0.3-1.0
and the injection of the specified reagent is carried out in the form of a suspension in water of the obtained dry mixture with a concentration of 0.2-0.7 wt.%.