RU2391489C2 - Method of formation absorption zone isolation - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to oil-and-gas industry, particularly to methods of isolating zones of trouble and can be used in well drilling and repair. In compliance with proposed method of isolating formation absorption zone, sequentially pumped therein are suspension of water-based chemical gypsum with gypsum concentration in suspension making 1 to 50% to reduce relative injection capacity within 0.05 m³/h MPa -2.0 m³/h MPa and, then suspension of chemical gypsum mixed with formaldehyde resin and acidic solidifier with gypsum concentration of 0.01 - 65%. Note here that, prior to and after pumping suspension into formation, fluid sodium glass is forced therein with the following ratio: water-based chemical gypsum suspension - liquid sodim glass 1:0.1-2, while as chemical gypsum used are wastes of production of phosphoric acid - phosphogypsum, hydrofluoric acid - fluorogypsum, boric acid - borogypsum, magnesium - magnesium gypsum, cellulose - hydrolytic gypsum.

EFFECT: higher efficiency of formation absorption isolation, reduced time of work.

3 cl, 3 tbl

Description

The invention relates to the oil and gas industry, in particular to methods for isolating complication zones, and may find application in drilling and well repair processes.

There is a method of isolating waterlogged oil reservoirs by injecting an aqueous suspension of chemical gypsum and interacting with it to form gel products of an aqueous solution of a salt of polybasic acids with a monovalent cation (US Pat. No. 2224101, ЕВВ 43/22, publ. 20.10.2003, bull. No. 29). The disadvantage of this method is the low insulating ability of the resulting gel product due to its solubility in water.

There is also known a method of isolating the absorption zone of a formation by injecting a cement-based cement slurry into it, holding a certain time for setting this solution and injecting an oil-based emulsion solution (USSR author's certificate No. 927966, ЕВВ 33/13, publ. 05.15.82, bull. . No. 18). The disadvantage of this method is its low efficiency due to the fact that the oil-based emulsion solution after injection forms an insufficiently strong stone, which under significant pressure drops between the reservoir and the downhole space collapses, which in combination with the relatively low sedimentation stability of the well-known cement slurry leads to the resumption of filtration through the rocks of the isolation zone.

Closest to the invention is a method of isolating the formation absorption zone by pumping into it through tubing - tubing cement composition based on cement and water and after curing the cement composition based on a mixture of formaldehyde resin and an acid hardener with an injected acid solution of 5-10 % of the volume of the mixture of formaldehyde resin and acid hardener (US Pat. No. 2323325, ЕВВ 33/138, publ. May 27, 2008, bull. No. 15). The disadvantages of the method include its considerable duration due to the fact that the work according to the known method is carried out in two stages with additional temporary exposure to the hardening of cement and drilling a cement beaker. In addition, as shown by field work, after cementing, complete sealing of the violation zone is often not achieved, and the relative throttle response in it becomes, as a rule, minimal, which prevents further injection of other sealing compounds into the violation zone.

The aim of the invention is to increase the efficiency of isolation of the zone of absorption of the reservoir and reducing the time of work.

This goal is achieved by the fact that in the method of isolating the absorption zone of the formation by sequentially injecting grouting composition in it on a water and organic basis, a cement of gypsum chemical is used as grouting composition, the gypsum suspension of chemical water-based injection is carried out with a concentration of chemical gypsum in suspension 1- 50% until the relative injectivity of the absorption zone decreases within 0.05 m ³ / h MPa - 0.5 m ³ / h MPa, and then a suspension of chemical gypsum in a mixture of formaldehyde resin and acid is pumped hardener with a concentration of chemical gypsum in a suspension of 0.01-65%, and before and after pumping a suspension of gypsum chemical on a water-based basis, if necessary, sodium liquid glass is pumped in the ratio: suspension of gypsum chemical-based water-based liquid glass sodium 1: 0 , 1-2, and as a chemical gypsum, waste products are used to produce phosphoric acid (phosphogypsum), hydrofluoric acid (fluorogypsum), boric acid (borogypsum, magnesium (magnesia-gypsum), cellulose (hydrolysis gypsum).

The main material for the isolation of absorption zones is currently cement slurry based on water and cement. The main disadvantage of such a cement slurry is that the pore size of the formation is often smaller than the size of the cement particles. As a result of this, even after the injection of significant volumes of cement slurry, the permeability of the absorption zones, although sharply reduced, is kept to a minimum. To fix such absorption zones, organic-based grouting compositions are used. Moreover, the work according to the known method is carried out in two stages, which requires a lot of time for work and significant financial resources.

The essence of the invention consists in the isolation of absorption zones in one step due to the sequential injection into the isolation zone of a suspension of chemical gypsum. With a relative injectivity of the injectivity zone above 1.5 m ³ / h MPa, in order to increase the strength characteristics of the formed stone and save the sealing composition, the disturbance of the disturbance zone is reduced by injection of a structurant - an aqueous suspension of gypsum chemical, before and after injection of a suspension of gypsum chemical based on water into the violation zone, sodium liquid glass is pumped in accordance with GOST 13078-81 in the ratio: chemical gypsum suspension on a water basis - sodium liquid glass 1: 0.1-2 until the relative total injectivity in the range of 0.05 m ³ / h MPa - 0.5 m ³ / h MPa. Such a limit of relative injectivity is, as shown by field work, optimal for achieving sealing of the absorption zone and consumption of a suspension of gypsum chemical in a mixture of formaldehyde resin and an acid hardener. During the interaction of gypsum of chemical and liquid glass of sodium, a gel is instantly formed, which clogs highly permeable zones and reduces the injectivity of the formation absorption zone. With a relative injectivity of less than 1.5 m ³ / h MPa, a decrease in the injectivity of the formation absorption zone to the required interval is achieved by pumping an aqueous suspension of gypsum chemical without the addition of sodium liquid glass. In addition, chemical gypsum is a structure-forming material, which, when the suspension of chemical gypsum in a mixture of formaldehyde resin and acid hardener is further pumped, promotes the formation of a stone of higher strength than without preliminary injection of a structure-forming material. As laboratory studies have shown, the addition of chemical gypsum to a mixture of formaldehyde resin and an acid hardener increases the time of loss of fluidity of the cement composition.

In contrast to the method adopted by us for the prototype, isolation of the formation absorption zone is achieved in one step, because there is no time to wait for the hardening of cement and the drilling of a cement beaker. Due to this, a reduction in the time of work is achieved and, accordingly, savings in financial and material resources for the work.

As formaldehyde resins, acetonformaldehyde and phenol formaldehyde resins can be used, which are cured with an acid solution. Inorganic (sulfuric, hydrochloric) and organic (sulfonic acid, toluenesulfonic acid, paratoluenesulfonic acid) can be used as an acid hardener. Waste from the production of phosphoric acid (phosphogypsum), hydrofluoric acid (fluorogypsum), boric acid (borogypsum), magnesium (magnesia-gypsum), and cellulose (hydrolysis gypsum) is used as chemical gypsum according to TU 2182-002-00203683-95. liquid glass - sodium liquid glass in accordance with GOST 13078-81.

Laboratory studies were carried out to determine the optimal concentration of chemical gypsum in an aqueous suspension. The tests were carried out on bulk linear models, i.e. models in which the porous material was filled - quartz sand. Depending on the size of the grains, the desired permeability of the reservoir model was created. Sand was poured into the model, controlling the porosity and permeability of the reservoir model.

Reservoir model characteristics

total length cm 32 diameter cm 19 permeability, μm ² 7.3-10.5

According to the proposed method, an aqueous gypsum suspension was pumped into a flooded model simulating an absorption zone with the same initial relative permeability of 2 m ³ / h MPa until a permeability of 0.5 m ³ / h MPa was reached, then the time taken to reduce permeability was measured.

The results of the experiments are shown in table 1

Table 1 The concentration of chemical gypsum in an aqueous suspension,% Download time, min The initial relative permeability of the reservoir model, m ³ / h MPa The final relative permeability of the reservoir model, m ³ / h MPa 0.5 eleven 2.5 2.0 one 5 2.5 2.0 25 one 2.5 2.0 fifty one 2.5 2.0 55 one 2.5 2.0

Thus, it was found that the optimal concentration of chemical gypsum in an aqueous suspension is 1-50%, because with a smaller amount, the time for a decrease in relative injectivity increases, and with a larger amount, it does not decrease.

Laboratory studies were also conducted to determine the optimal concentration of chemical gypsum in a suspension of formaldehyde resin and an acid hardener. In this case, at first, the injectivity of the disturbance zone was reduced by injection of a structurant - an aqueous suspension of gypsum chemical to a relative injection rate of 2.0 m ³ / h MPa, and then a suspension of gypsum chemical in a mixture of formaldehyde resin and acid hardener was pumped. The tests were carried out similarly to the experiments of table 1.

The results of the experiments are shown in table.2

table 2 The concentration of chemical gypsum in a suspension of formaldehyde resin and acid hardener,% Volume of the injected suspension of gypsum chemical on an organic basis, ml The exposure time to cure, hour Breakthrough Pressure, MPa / m 0.005 16 48 27.9 0.01 16 48 28,4 5 16 48 28.6 fifteen 16 48 28.6 35 16 48 28.8 45 16 48 28.9 55 16 48 29.0 65 16 48 29.05 70 16 48 29.05

Thus, it was found that the optimal concentration of chemical gypsum in a suspension of formaldehyde resin and acid hardener is 0.01-65%, because with a smaller amount, the breakthrough pressure decreases, and with a larger amount, the breakdown pressure does not increase with an increase in the viscosity of the composition.

Laboratory studies were also conducted to determine the optimal ratio: sodium liquid glass - a suspension of water-based chemical gypsum. Table 3 shows the results of determining the breakthrough pressure and the optimal ratio. The concentration of the salt of polybasic acids with a monovalent cation in the experiments was 10.0%.

Table 3 Experience number Attitude: sodium liquid glass - suspension of water-based chemical gypsum The temperature of the experiments, ° C Breakthrough Pressure, MPa / m one 0.05: 1 twenty 5.7 2 0.1: 1 twenty 6.8 3 0.5: 1 twenty 7.6 four 1: 1 twenty 7.9 5 1.5: 1 twenty 8.1 6 2: 1 twenty 8.1 7 2.5: 1 twenty 8.1

Thus, it was found that the optimal ratio: sodium liquid glass - a suspension of water-based chemical gypsum is 0.1-2: 1, because with a smaller ratio, the breakthrough pressure decreases, and with a larger ratio, the breakthrough pressure does not increase. Similar results were obtained using other inventive waste chemical gypsum.

Tests were also carried out using the known method. When conducting a laboratory experiment using the known method, similarly to the experiments in Table 2, a grouting mixture based on water and cement was sequentially pumped into the flooded reservoir model, exposure was made on cement hardening (48 hours), and then the grouting composition based on a mixture of formaldehyde resin and acid hardener and left the model to hold for 48 hours. Then measured the breakthrough pressure of the reservoir model.

As a result of the experiments, it was found that the breakthrough pressure by the known method is 27.6 MPa / m, which is less than in the proposed method. In addition, isolation of the formation absorption zone by the proposed method is achieved in one step, because there is no time to wait for hardening.

The method in the field is as follows. Preliminary, a complex of field geophysical surveys is carried out in accordance with RD 39-1-1190-84 “Technology of field geophysical surveys during well overhaul” in order to identify the zone of production string disturbance. A cement bridge is installed below the disturbance zone. A calculated amount of a suspension of gypsum chemical is pumped to a decrease in the relative injectivity of the absorption zone within 0.05 m ³ / h MPa - 2.0 m ³ / h MPa, and then a suspension of gypsum chemical in a mixture of formaldehyde resin and an acid hardener is pumped. The well is left for the duration of the curing of the plugging mixture (48 hours), after which the packer is drilled from the cured plugging mixture and the wellbore is washed. After completion of the insulation work, the well is compressed and, based on the studies, the quality of the insulation is judged.

Thus, when applying the proposed method, an over-summarized (synergistic) effect is manifested, which consists in the fact that when using a suspension of gypsum chemical on a water and organic basis as a grouting composition and first pumping a suspension of gypsum chemical on a water basis to reduce the relative injectivity of the absorption zone in within the range of 0.05 m ³ / h MPa - 2.0 m ³ / h c MPa, and then the injection of a suspension of chemical gypsum in a mixture of formaldehyde resin and an acid hardener produces a stone with a higher In addition, the time for loss of fluidity of the grouting composition increases, and the isolation of the zone of absorption of the formation is achieved in one step, thereby reducing the time of work and, consequently, saving financial and material resources for the work. This allows us to conclude that the proposed solution meets the criterion of "inventive step".

The inventive method of isolation is not described in the literature, which allows us to conclude that the proposed solution meets the criterion of "novelty."

The set of essential features characterizing the essence of the invention can be repeatedly used in industry to obtain a technical and economic result, which consists in obtaining a higher and longer-lasting effect of isolating the absorption zone compared to the known methods when conducting work on repairing wells from water inflow and eliminating leakages in production columns and annular space, and reducing the time of work, which allows us to conclude that the image "Industrial applicability" criterion eniya.

Claims (3)

1. A method of isolating a formation absorption zone by sequentially injecting a cement-based grouting composition into it on a water and organic basis, characterized in that a chemical gypsum slurry is used as a grouting composition, a gypsum-based chemical gypsum suspension is injected with a concentration of chemical gypsum in a suspension of 1-50 % to reduce injectivity relative absorption zone within 0.05 - 2.0 m ³ / h MPa, and is then pumped into the gypsum slurry chemical mixture formaldehyde resin and an acid hardener having a concentration w ca chemical slurry 0,01-65%. 2. The method according to claim 1, characterized in that before and after the injection of a suspension of gypsum chemical on a water basis in the absorption zone is pumped liquid glass of sodium in the ratio: suspension of gypsum chemical on a water basis - liquid glass of sodium 1: 0.1-2. 3. The method according to claim 1, characterized in that the waste of production of phosphoric acid — phosphogypsum, hydrofluoric acid — fluorogypsum, boric acid — borogypsum, magnesium — magnesia — gypsum, cellulose — hydrolysis gypsum, is used as chemical gypsum.