SU1745891A1 - Compound for tentative isolation of seams - Google Patents

Abstract

Summary of the invention: in a composition containing a hydrocarbon liquid and an additive, atactic polypropylene is used as an additive for polypropylene production, and as a hydrocarbon liquid is nefl, in the following ratio, wt.%: Atactic polypropylene 2-8; oil - the rest. A solvent based on aromatic hydrocarbons is used to dissolve the composition and restore the permeability of the formations. Table 1.

Description

The invention relates to the oil industry, in particular to the temporary isolation of the permeability of water and oil bearing formations for the repair of wells and underground equipment.

Structures based on structured fluids are used as drilling and tamper solutions for securing the well bottom zone, partially and completely isolating the water and oil permeability of subterranean formations in order to increase oil recovery and repair of wells, transporting dispersed material to the reservoir channels, formed by its hydraulic fracture.

Compositions are known for isolating the water permeability of formations in the bottomhole zone of receiving wells based on water-soluble polymers: polyacrylamide, polyacrylic acid,

polyvinylpyrrolidone, polysaccharides, polyvinyl alcohol, carboxymethylcellulose, polysulfonates and complex electrolytes.

However, the well-known salt and polymer aqueous solutions are not suitable for isolating the permeability of carbonate rock formations, as well as for isolating highly-watered formations. Carbonate rock formations absorb water from the cement slurry, while polymers and salts precipitate, which leads to salinization of the formations, wells and the rapid decommissioning of underground equipment. Compositions based on carbamide resins are suitable for long-term well killing after the production of oil deposits and for securing the rock while drilling wells.

Water-oil and water-hydrocarbon emulsions are known for limiting the water inflow into the well, which are recommended for their use in order to enhance oil recovery.

In the literature, there are no known universal formulations (grouting solutions) for

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VI SP 00 H)

complex isolation of water, gas and oil permeability of formations, especially strongly watered carbonate rock formations, sandstones, and effective reservoir oil permeability reagents are also not known after the need for isolation has ceased.

The closest to the proposed results achieved is a very complex highly filled dispersed composition based on hydrocarbon liquid, bentonite clay, bitumen (highly oxidized), barite in a weight ratio equal to 8.5: 0.05-0.25: 2-6: 4 -12: 40. respectively. The hydrocarbon fluid and bitumen give the composition a relationship with the oil reservoir, the barite (filler) acts as an extender, and the clay at the expense of viscosity keeps the particulate in suspension. The composition is close to the solid state. It can isolate the permeability of the formation by forming a heavy mechanical plug (tampon) in the well, which, depending on its mass, can hold the formation pressure.

The disadvantages of the known composition are multicomponent ™, the complexity of its preparation due to the mixing of a dispersed and heavy filler into it, the difficulty of pushing it into the well due to high viscosity, it can be pressed into the well only in a heated state, the difficulty of eliminating and removing mechanical plugs from the well after the termination of the need for it.

In winter, the composition is not suitable for injection into the well. Due to the high density of the composition (1.80-2.15 g / sig), it cannot be used in combination with aqueous buffer solutions, which are used to raise the wellbore column in order to reduce the cement slurry consumption. Consequently, the entire volume of the well needs to be filled with the composition, which makes it less economical.

The purpose of the invention is to increase the effectiveness of the composition for the temporary isolation of water, gas and oil permeability of the layers in a wide range of temperatures.

The goal is achieved by the fact that the composition on the basis of oil contains atactic polypropylene (aTP) - waste production of isotactic polypropylene in the following ratio of components, wt.%:

Atactic Polypropylene (APP) Oil

Composition as active reagent composition contains atactic polypropylene with an average molecular weight of 20–35 thousand. A positive effect of the composition is achieved when the aPP content is 2-8 wt.%. The introduction of more than 8% is inexpedient, since already at 8% 100% insulation is achieved. Atactic polypropylene is used to solve the problem.

(APP) - waste production of polypropylene (TU 6-05-1902-81), benzene, toluene (GOST 5789-78), hexane (TU 6-09-3375-78). oil Samotlor and Soviet-Sosninskoye fields. To improve the solubility and accelerate the dissolution of aPP in oil, it can be used as an 80% solution in hexane.

The effectiveness of the proposed composition based on an APP oil solution in insulating the permeability of a water-saturated reservoir is significantly higher than in insulating an oil-saturated reservoir because, when the composition interacts with water, the main effect of insulating permeability is enhanced by such side effects as surface tension and natural formation water-oil emulsion. The effect of isolating the permeability of a reservoir saturated with oil containing 12

wt.% water is slightly higher than when the formation is saturated with anhydrous oil.

The compositions were tested on a model of the Yu-1 reservoir of the Samotlor field, which is a cylindrical column-core holder.

For the experiment, the column was filled with natural sand with a particle size of 0.25-0.5 mm. After determining the natural oil permeability through

the column is filtered insulating and regenerating compositions. The permeability of the reservoir model is then determined (isolation efficiency) depending on the concentration and ratio of the injected

reagents according to the formula

Uh

100%

where T is the filtration time through the reservoir models of the proposed compositions;

That is the filtration time through the model of the oil reservoir of the Sovetsko-Sosninskoe oil field.

A reduction in the permeability of the formation after its isolation with the proposed compositions is achieved. The dependence of the change in permeability of the reservoir on the concentration is given in the table.

Compositions for temporarily isolating the permeability of the formations are prepared and applied as follows.

Example 1. In 99 g of oil, 1 gactactic polypropylene is dissolved with stirring at room temperature, and a fine phase is separated from the solution. The resulting composition is filtered through a core. The permeability of the formation permeability is 40%. Then toluene or a fraction of aromatic hydrocarbons in the amount of 0.3 parts by volume is pumped into the formation. from oil solution apt. The permeability of the formation is restored by 98%.

Example 2. In 98 g of oil, 2 g of APP is dissolved with stirring and at room temperature, while a fine precipitate is released from the solution. The resulting composition is filtered through a core. The permeability of the formation permeability is 56.6%. Then toluene or a fraction of aromatic hydrocarbons in the amount of 0.5 vol. hours from the oil solution apt. The permeability of the reservoir is restored by 99%.

Example 3. In 97 g of oil, 3 g of APP is dissolved with stirring and at room temperature, while a fine precipitate is released from the solution. The resulting composition is filtered through a core. The permeability of the formation permeability is 67.2%. Then toluene or a fraction of aromatic hydrocarbons in the amount of 0.7 parts by volume is pumped into the formation. from oil solution apt. The permeability of the formation is restored by 99.8%.

Example 4. In 95 g of oil, 5 g of APP is dissolved with stirring at room temperature, and fine precipitate is separated from the solution. The resulting composition is filtered through a core. The permeability of the formation permeability is 86.8%. Then, toluene or a fraction of aromatic hydrocarbons in the amount of 1.0 vol. from petroleum cement slurry aPP. The permeability of the formation is restored to 100%;

Example 5. In 93 g of oil, 7 g of aPP is dissolved with stirring at room temperature, and a fine precipitate is released from the solution. The resulting composition is filtered through a core. The permeability of the formation permeability is 99.2%. Then toluene or a fraction of aromatic hydrocarbons in the amount of 1.4 parts by volume is pumped into the formation. from petroleum cement slurry aPP. The permeability of the formation is restored by 99.9%.

Example In 92 g of oil, 8 gactactic polypropylene is dissolved under stirring at room temperature, and a fine precipitate is released from the solution. The resulting composition is filtered through a core. The permeability of the formation permeability is 100%. Then a toluene or a fraction of aromatic hydrocarbons in the amount of 1.5 vol / h is pumped into the formation, from the oil cement slurry of the aPP. The permeability of the formation is restored to 100%.

Example. In the well 2508 pumped 5 m3 of buffer salt solution. To prepare an insulating composition, 33 m3 (97.88%) of technical water are pumped into the container, 700 kg (2.12%) of polyacrylamide are added, the mixture is stirred for 3-4 hours until the polymer is completely swollen and dissolved. The resulting composition is pumped into the well through the tubing (NKT), then the composition is forced into the reservoir by injecting 30 m3 of saline solution through the annulus with an injection pressure of 30-50 atm. After the pump is turned off and the injection pressure is relieved, the overpressure in the well is 18 atm. The permeability of the formation is not insulated. After repeating the entire isolation cycle, the overpressure in the well decreases.

Example 8. A 5 m3 buffer saline solution is pumped into the well 1439. To prepare the insulating composition, 10 m (98%) of industrial water is pumped into the tank, 200 kg (2%) of carboxymethylcellulose (CMC) is added, the mixture is stirred for 2-3 hours until complete swelling and dissolution of the CMC. The resulting composition is pumped into the well through the tubing, then pushed into the reservoir by pumping 80 m of saline solution through the annulus with a discharge pressure of 30-50 atm. After the pump is turned off and the injection pressure is relieved, the overpressure in the well is 20 atm. The permeability of the formation is not insulated. After repeating the entire isolation cycle 2 times, the overpressure in the well does not decrease.

PRI me R 9. (known). Additional examples of experiments are given to prove the effectiveness of the compositions in isolating the permeability of a water-saturated reservoir and a reservoir saturated with oil-saturated (up to 12% water).

I'll try it on. In 98 g of oil, 2 g of APP is dissolved under stirring at room temperature, and a finely dispersed precipitate forms from the solution. Received by

the composition is filtered through water-saturated core. The permeability of the formation permeability is 63.8%. Then toluene is pumped into the formation in the amount of 0.5 vol. h from the oil composition. The permeability of the formation is restored by 97%.

Example 11. V95g oil is dissolved

5 g apt with stirring at room temperature, a finely dispersed precipitate falls out of solution. The resulting composition is filtered through water-saturated core. The permeability of the formation permeability is 95.7%. Then 1.0 toluene is pumped into the reservoir in volume. from oil composition. The permeability of the formation is restored by 98.5%.

PRI me R 12. In 94 g of oil is dissolved

6g APP with stirring and at room temperature, a fine precipitate falls out of solution. The resulting composition is filtered through water-saturated core. The permeability of the formation permeability is 100%. Then toluene is pumped into the formation in the amount of 1.4 vol. from grouting composition. The permeability of the formation is restored by 99.3%.

Example13. 95 g of oil dissolve 5 g of APP with stirring and at room temperature, a fine dispersible precipitate falls out of solution. The resulting composition is filtered through a core saturated with water-flooded oil (12% water). The permeability of the formation permeability is 91.2%. Then toluene is pumped into the formation in the amount of 1.0 ob.h. from oil composition. The permeability of the formation is restored to 99.0%.

Fraction of aromatic hydrocarbons - an artificially obtained mixture of benzene, toluene, xylene in any weight ratio because the use of benzene, toluene and xylene separately in the process of restoring the permeability of the formation gives similar results. Toluene (a mixture of aromatic hydrocarbons) is pumped over the formation at any isolation efficiency of the formation (40-100%). Under the influence of its own mass and self-diffusion, toluene moves along the front of the reservoir (as an eluent through the chromatographic column), a solution of oil sediment in its path in the pores of the reservoir and, thus, restoring the filtration (permeability) of the reservoir.

Example 14: In 95 g of oil, 5 g of aPd is dissolved with stirring and at room temperature, a thin precipitate is released from the solution. The resulting composition is filtered through oil-saturated core. The permeability of the formation permeability is 86.8%. Then benzene is pumped into the formation in the amount of 1.0 vol. from oil cement slurry aPP. The permeability of the reservoir is restored to 100%.

(as in the case of the use of toluene, see example 4).

Example 15: In 95 g of oil, 5 g of aPd is dissolved with stirring and at room temperature, a thin precipitate is released from the solution. The resulting composition is filtered through oil-saturated core. The permeability of the formation permeability is 86.8%. Then xylene is pumped into the formation in the amount of 1.0 ob.h. from oil

5 grouting solution apt. The permeability of the formation is recovered by 97.8%. Example 16. In 95 g of oil, 5 g of APP is dissolved under stirring at room temperature, a thin precipitate is released from the solution. The resulting composition is filtered through oil-saturated core. The permeability of the formation permeability is 86.8%. Then a benzene: toluene: xylene 1: 1: 1 mixture is pumped into the formation in the amount of 1.0 parts by volume. from oil cement slurry aPP. The permeability of the formation is restored by 99.3%.

The proposed composition based on a solution of APP in oil can be applied for

0 layers with a permeability of 0.01-1 μm2. The effect of the insulation on reverse filtration is up to 100% at pressures of up to 5.5-7.2 kg / cm2 and temperatures from -50 ° C to 80 ° C. As can be seen from the table and examples, the proposed composition for the temporary isolation and restoration of reservoir permeability in the bottomhole zone of oil producing wells with a chain of underground well workover and elimination

0 emergency situations effectively isolate the water and oil penetration of oil-saturated formations with a lower consumption of active reagent. The solvent based on aromatic hydrocarbons used in the temporary isolation process allows the formation permeability of the formation to be quickly and completely restored after the repair work. The proposed formulations can be applied in various geological and technical conditions of plugging in the bottomhole formation zone. The use of the proposed compositions in the jamming technology allows reducing the volume of cement slurry by raising the injection level in the well.

5 with the aid of a water column, since the aPP oil solution is lighter than water and does not mix with it, and also to reduce the simple technology and prevent environmental pollution due to the simplicity of preparation of the composition and ease of pumping it into

well. The use of a reservoir permeability reducing agent can reduce the time spent on technological work, preserve the injectivity of the well and, ultimately, increase oil production. The proposed formulations for temporarily isolating and restoring the permeability of the formations can be applied in a wide range of temperatures, from -70 to 80 ° C, which is important for work in Siberia and in the Far North.

Atactic polypropylene (aPP) itself is not dispersive. In appearance, it looks like a rubber. DGPs are manufactured in the form of blocks, ingots, or in the form of adhesive tapes. APP, when dissolved in oil, precipitates from it resinous, asphaltene, paraffinic substances in the form of fine particles with a size of 0.04–3.0 μm, which plug the formation and, thus, isolate its permeability. It is not excluded that the aPP itself can be precipitated in combination with oil compounds in the form of fine particles.

The proposed composition based on a solution of APP in oil can be applied to formations with a permeability of 0.01-1 μm2.

The effect of the insulation during inverse filtration is up to 100% at pressures up to 5.5-7.2 kgf / cm2 and temperatures (-50) - {80) ° C.

The use of other liquids (except for oil) is probably possible if they contain tar and asphaltenic substances. However, the proposed formulation is intended for use in field conditions where the oil is the most readily available liquid.

Claims (1)

Invention Formula A composition for temporarily isolating formations containing a hydrocarbon liquid and an additive, characterized in that, in order to increase the effectiveness of the composition in the temperature range from -70 to + 80 ° C and reduce the consumption of active reagent, it contains atactic polypropylene as an additive polypropylene, and as a hydrocarbon liquid-oil in the following ratio, wt.%: Atactic polypropylene 2-8 Oil Others