Method for balancing injection well water-intake capacity profile and restriction of water influx to production wells

FIELD: oil and gas industry.

SUBSTANCE: in method for balancing of injection well water-intake capacity profile and restriction of water influx to production wells, which involves pumping to the formation of gel-forming composition containing, wt %: sodium silicate 1-10, chrome acetate 0.5-2, water is the rest, pumping of the above composition to formation, technological pause, prior to pumping of the above composition to wells there pumped is fresh water; induction period of gel-forming composition at formation temperature is set so that it is equal to 6-10 hours, and technological pause is chosen so that its duration is equal to 24-36 hours.

EFFECT: improving the efficiency of oil displacement from formation due to water isolation of highly water-flooded formations in production wells either due to equalising the water-intake capacity profile of injection wells by partial or complete blocking of highly washed channels or interlayers for movement of injection water.

1 ex, 2 dwg

 

The invention relates to the oil industry and can find application for the limitation of the water in producing wells or to align the profile of the injection well.

Known "Method of regulation of the waterflood front oil reservoirs", involving the application of fringes of alkali metal silicate and a water-soluble polymer (U.S. Pat. EN 2146002, publ. 27.02.2000). The method produces a selection of oil through the production wells, injection working agent through the injection well, occasionally one injection well stop and stand to restore the pressure in the wellbore area to the reservoir, aqueous solutions of polymer and silicate of alkaline metal before download is mixed with water mineralization 15-180 g/l, the mixture is pumped rims, the transition from one rim to another exercise with increasing pressure injection of 0.5 MPa or more, while reducing the concentration of polymer (polyacrylamide or cellulose ether) and a silicate of an alkali metal.

The disadvantages of this method is the complexity of the regulation time of gel formation and the complexity of qualitative preparation of polymer solutions in the near-wellbore conditions.

Known for "the Way of the development of oil deposits, according to which the profile injectivity of injection wells proposed the Xia align by injection of an aqueous solution of sodium silicate together with zeolite rock, pre-treated acid (patent RU №2157451, publ. 10.10.2000). Injection solutions ceritadewasa breed carried out separately or sequentially, after the injection of spending restraint.

The disadvantages of this structure are the use of rims that contain suspended solid particles, which have a low penetrating power in the reservoir rock, the absence of components that regulate the gelation time and the low effectiveness of the composition in low salinity formation water.

Known "Method of enhanced oil recovery in fractured and porous reservoirs artificially created fractures after hydraulic fracturing - hydraulic fracturing" (U.S. Pat. RU # 2398102, publ. 27.08.2010), which includes the injection of an aqueous solution of polyacrylamide with a staple - chromium compound, using an additive bentonite bentonite and quartz sand, used bentonite bentonite modified and mixed with quartz sand, carry out first injection of an aqueous solution containing from 0.01 to 0.30 wt.% partially hydrolyzed polyacrylamide and 0.1 to 0.6 wt.% staple - chromium compounds, displacement water, then the injection of an aqueous solution of polyacrylamide with a viscosity of 10% of the greater viscosity of produced water, which is suspended 3-10 wt.% a mixture of modified bentonites is th bentonite and quartz sand with their initial ratio of 10:1 with a subsequent increase in the concentration of sand to the ratio 1:2.

The disadvantages of this method are the low controllability of time-linkage composition, the complexity of making quality structures in the near-wellbore conditions, the inability of highly effective destruction of cross-linked polyacrylamide molecules in situ.

The famous "Way of limitation of the water in the well", involving the injection of a composition containing hydrochloric acid (1-3%) and sodium silicate (1-15%) with a low pH (1.5 to 2) as of the first rim, with subsequent injection separately concentrated solution of sodium silicate to increase pH to 5-8 (U.S. Pat. RU # 2160832, publ. 20.12.2000).

The disadvantage of this method is uncontrolled gelation of the composition by blending it with formation waters, and not the formation of silica gel, as evidenced by the increase in the pH of the solution.

The well-known "Method of restricting the inflow of water into the production well, in which the plugging composition is used that contains a solution of sodium silicate, liquid, representing the solution of calcium salts and surfactants (U.S. Pat. RU # 2392419, publ. 20.06.2010). The method involves the separate injection of a solution of sodium silicate in podarennuyu water-saturated part of the reservoir, and a solution of calcium salts and surfactants in the productive part of the formation lying above the packer. RAS is the thief of calcium salts promotes nepremicnine solution of sodium silicate in paleobotany part of the layer or layers due to the formation of an impenetrable screen when the contact of calcium salts with sodium silicate.

The disadvantages of the method are the lack of hardener in the plugging composition that reduces the effectiveness of technology in formations with low salinity brine at high risk of confusion in the critical zone of the productive part of the reservoir due to cross-flows and uncontrolled promotion rim of calcium salts and surfactants, the lack of regulation time gelation cement composition in situ.

Known "Method of alignment of the profile of injection and limitations of water in mineral wells" (U.S. Pat. RU # 2382185, publ. 20.02.2010)adopted for prototipos involves the injection of gel-forming composition is a dispersion in water of polyacrylamide, chromium acetate, magnesium oxide and Guara, while the composition is forced into the formation to the extent that the full displacement of the variance of borehole water in the amount of tubing plus 0.5-1 m3, further produce technological pause on the gelation time duration of 2-3 days.

The disadvantages of this method are the relatively high viscosity of the resulting composition before crosslinking, low filterability composition in the rock formation and the formation of impervious cover in the well bottom hole, the complexity of making high-quality homogeneous composition in the well bore conditions, SL is a possibility the subsequent destruction of the composition in the reservoir, if necessary, the complexity of the regulation time of the crosslinking composition.

The technical result is to increase the efficiency of oil displacement from the reservoir by turning off water-saturated layers in producing wells or due to the alignment of the profile of injection wells by the partial or complete blocking vysokohromistyh channels (or layers) for the movement of the injection water.

The technical result is achieved in that in the method of alignment of the profile of injection wells and limitations of water in producing wells, including injection of gel-forming composition containing water and chromium acetate, the bursting of the composition into the formation, technological pause for complete gelation, the composition add sodium silicate in the following ratio, wt.%:

Sodium silicate1-10%
The chromium acetate0,5-2%
Waterthe rest,

when you do this before uploading the finished composition in wells pumped a slug of fresh water, the induction period gelling composition at reservoir temperature set equal to 6-10 hours, and t is geologicheskiy pause select duration of 24-36 hours.

When using sodium silicate (gelling agent) at a concentration of less than 1% wt. gel formation is achieved. Using concentrations higher than 10%, leads to the formation of extremely strong gels, and at the same time requires a significant increase in concentration of chromium acetate, which leads to a significant appreciation of the structure to limit water production. Experimentally obtained.

At concentrations of chromium acetate (hardener) less than 0.5% wt. unable to achieve gel formation. At concentrations above 2% gel formation occurs very quickly that it is not possible satisfactorily to upload it into the reservoir. Experimentally obtained.

In the calculated amount of fresh water under continuous stirring, chromium acetate (50-55% solution), achieving a uniform solution of chromium acetate in fresh water required concentration ranging from 0.5 to 2.0% wt. Then with continuous stirring in small portions enter the sodium silicate solution and stirring is continued for 3-5 minutes. In field conditions, the preparation can be carried out in a special container with a circular liquid circulation or directly in the tank cementing apparatus. It is not recommended preparation first of sodium silicate solution, and then diluted in n the m concentrated solution of chromium acetate, so when adding a concentrated solution of chromium acetate (50-55%) is the instantaneous formation of lumps of gel due to local contact of sodium silicate with a solution of chromium acetate, significantly higher than the desired concentration in the cooked part. This gel-forming composition loses uniformity, consistency due to the formation of highly viscous blobs of gel that prevents pumping the composition into the formation, and an effective concentration of chromium acetate in the composition is reduced, which contributes to the lengthening of the induction period and reduce the strength of the formed gel.

Pumping rims fresh water before injection of the composition to prevent premature formation of precipitation by reaction of sodium silicate with a saline formation waters.

The induction period specific gel-forming composition set with the reservoir temperature is equal to 6-10 hours. The induction period gelling composition should be high enough for the preparation of the composition through the wellbore, pumping it into the reservoir at a specified distance from the borehole bottom, but he should not have values exceeding 10 hours, as this will cause excessive increases in technological pause.

Injected into the reservoir gelling with the Tav is given primarily in high-permeability of the reservoir, where the filtration rate is higher. During the induction period the viscosity of the composition is low (1.2 to 10 MPa·s), which facilitates easy uploading it into the reservoir.

Figure 1 presents a graph of the dependence of induction period for the gel-forming compositions containing 4.2% of wt. sodium silicate. In figure 1, 2 curves 1-3 are based induction period compositions containing 4.2% of wt. of sodium silicate, brine temperature, where curve 1 - composition containing chromium acetate - 0,83% wt., curve 2 is 1.1 wt.%, curve 3 - 1,38% wt., curve 4 is a graph showing the change of the plastic strength of the gelling composition depending on reservoir temperature reservoir. For each individual reservoir temperature should be selected concentration of sodium silicate and chromium acetate so that the induction period obtained composition was 6-10 hours when sufficient plastic strength. Using similar graphs for other concentrations of sodium silicate, it is possible to find the desired solutions for the specific commercial objectives, the strength of the gel. Figure 2 presents the dependence of strength from the induction period is selected in the example 1 composition depending on the reservoir temperature.

After forcing the gel-forming composition into the reservoir well stop on technological pause prodolzhitelnost 36 hours. Technological pause is characterized by increase in the viscosity of the gelling composition and increase its plastic strength. While technological pause completes the process of gelation and the resulting gel clog highly permeable part of the reservoir and thereby contributes to the alignment pronitsaemostei heterogeneity and reduce water flow.

After technological pause well put in the work.

When applying the gel-forming composition in producing wells for water insulation requires prior determination of the inflow intervals using geophysical methods. When applying the composition for the alignment of the profile injectivity of injection wells to evaluate the effectiveness of the composition should be removing profiles injectivity of the wells before and after the downhole operations.

The method is as follows and includes the following basic operations:

1. Washed the wellbore by lowering the tubing to the bottom of a well.

2. Raise the tubing to the identified water shut-off interval.

3. Perform pressure testing of the well at a pressure not less than 1.2 times the expected maximum pressure in the injection process, the gel-forming composition.

4. Determine the injectivity of the well water at steady state.

5. Selection is given concentration of sodium silicate and chromium acetate.

6. In order to avoid premature gelation in a well bore zone pumped a slug of fresh water in the isolated interval of not less than 2 meters 1 meter perforated thickness.

7. Prepare the gel-forming composition based 2-10 m31 meter perforated thickness of the insulated frame.

8. Inject the gel-forming composition into the well at a cost not exceeding the measured acceleration of the well, when the tubing that is installed across the bottom perforations of the insulated frame.

9. Push the gel-forming composition into the reservoir. As the squeezing of the fluid can be used with fresh water or a liquid hydrocarbon-based.

10. Close the hole on technological pause for structural hardening of the gel-forming composition for a period of 24-36 hours.

When the injection of the gel-forming composition for alignment profiles injectivity of injection wells, it is recommended to use the composition, the values of the plastic strength of which does not exceed 1500 PA.

Example. You must pick a composition for water insulation layer at a temperature equal to 60°C. Based on data from figure 1, for these conditions to select gel-forming composition containing 4.2% of sodium silicate and 0,83% of chromium acetate. During this induction period will be about 360 minutes when the reservoir is the political strength of the formed gel, equal 1680 PA, which is sufficient for effective water shut-off water-producing interval. Given the low values of induction period of technological pause enough to take equal to 24 hours.

The pH of the proposed method, the gel-forming compositions are in the range of 10-11,5, which indicates their low corrosion activity. Gel-forming composition can be effectively destroyed in situ by using a 10-20% solution of sodium hydroxide.

The alignment profile injectivity of injection wells and limitations of water in producing wells, including injection of gel-forming composition containing water and chromium acetate, the bursting of the composition into the formation, technological pause, characterized in that the composition is added to the sodium silicate in the following ratio, wt.%:

Sodium silicate1-10
The chromium acetate0,5-2
WaterThe rest,

when you do this before uploading the finished composition in wells pumped a slug of fresh water, the induction period gelling composition at reservoir temperature condition is enableval equal 6-10 h, and technological pause select duration 24-36 hours



 

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3 cl, 2 tbl, 2 ex, 1 dwg

FIELD: oil and gas industry.

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12 cl, 2 tbl, 8 dwg

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EFFECT: improving bottom water insulation, providing the reduction of water content of wells during development of oil and gas deposits.

1 tbl

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