RU2295029C1 - Method for processing face-adjacent zone of bed - Google Patents

Abstract

FIELD: oil industry, possible use during thermo-cyclic treatment of collector rock during processing of face-adjacent zone of bed.

SUBSTANCE: in accordance to method during processing of face-adjacent bed zone with sand collector, heating and cooling are performed cyclically. Heating is performed during 1,5-2,5 hours up to temperature of 80-90°C, cooling - during 0,5-0,75 hours up to temperature of 20-25°C. Number of cycles is set equal to 5-10.

EFFECT: increased efficiency of processing due to increased porosity and penetrability of productive bed collector.

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Description

The invention relates to the oil industry and may find application in thermocyclic impact on reservoir rocks during the treatment of the bottom-hole formation zone.

A known method of processing the bottom-hole zone of the formation, including injecting a treatment composition into the formation, lowering the heater into the well, installing it against the perforation interval and conducting thermal action on the formation. Thermal effects on the formation are carried out with alternating changes in the direction of movement of the composition from the well cavity to the formation and from formation to well. In each cycle, a fresh portion of the treatment composition is pumped into the formation. Before injection into the reservoir, each portion of the composition is kept for heating to the temperature of dissolution of pollutants (Application for invention of the Russian Federation No.2000117755, class E 21 B 43/24, publ. 2002.06.20).

The known method allows you to remove the clogging elements from the bottomhole zone, however, it does not affect the structure of the reservoir.

Closest to the proposed invention in technical essence is a method of processing a reservoir in the bottomhole zone of the well. In accordance with the method, a heating element is lowered into the bottomhole zone using the suspension means to heat the liquid above the boiling point of its components. In the bottomhole zone of the well, a bottomhole chamber is formed, the upper part of which is sealed with a packer above the placement of the heating element. After heating the liquid, it is cooled. The heating of the liquid and its cooling is carried out in the volume of the bottomhole chamber. Then the bottom-hole chamber is depressurized by removing the packer. Then remove the products of mudding from the bottomhole zone simultaneously with oil production (RF Patent No. 2172400, CL E 21 B 43/24, publ. 2001.08.20 - prototype).

Due to the application of the known method, the productivity of the wells is increased by intensifying oil inflows and increasing the oil recovery coefficient. However, the effectiveness of the method remains low due to the fact that the effect is aimed at pollution, but does not affect the structure of the reservoir of the reservoir.

The proposed invention solves the problem of increasing the impact efficiency by increasing the porosity and permeability of the reservoir of the reservoir.

The problem is solved in that in the method for processing the bottom-hole zone of the formation, including heating and cooling, according to the invention, heating and cooling the bottom-hole zone of the formation is carried out cyclically, while heating is carried out for 1.5-2.5 hours to a temperature of 80-90 ° C, cooling - for 0.5-0.75 hours to a temperature of 20-25 ° C, the number of cycles is set equal to 5-10.

The features of the invention are:

1) heating;

2) cooling;

3) cyclic heating and cooling of the bottomhole formation zone;

4) heating for 1.5-2.5 hours to a temperature of 80-90 ° C;

5) cooling for 0.5-0.75 hours to a temperature of 20-25 ° C;

6) the number of cycles is 5-10.

Signs 1, 2 are common with the prototype, signs 3-6 are the essential distinguishing features of the invention.

SUMMARY OF THE INVENTION

Existing methods for treating the bottom-hole formation zone affect pollution and do not affect the reservoir structure of the reservoir. Meanwhile, without an increase in porosity and permeability, it is difficult to obtain a qualitative improvement in the operation of the well. The proposed invention solves the problem of increasing the impact efficiency by increasing the porosity and permeability of the reservoir of the reservoir.

The problem is solved as follows.

The thermocyclic effect on reservoir rocks differs from other heat treatment schemes in that the heat flux in the well during heating does not remain constant, but changes according to a periodic law. With this treatment, damping temperature fluctuations occur in the near-wellbore zone of the formation at a certain distance from the borehole wall, affecting the reservoir and causing alternating temperature stresses in it. Under the influence of these stresses, additional cracks appear in the rock, and therefore, permeability increases.

With thermal fatigue of rocks, we can talk about the dominant influence on the process of occurrence and development of cracks precisely of microstructural stresses, which are manifested due to the heterogeneity of the thermal expansion of rock elements, grains of cementing material, and fluid saturating the rock.

The fluid in the crack, when it is heated and subsequently expanded, has a proppant effect on the end regions of the crack. The dissolution of surfactants in a liquid intensifies the process of thermocyclic fatigue. In this case, the wetting energy of the liquid passes into the energy of the proppant pressure of the tangential forces of the adsorption layer, which can reach a value of about 2-10 Pa or more.

The technology of processing the bottom-hole zone of the formation includes cyclic heating and cooling. Heating is carried out for 1.5-2.5 hours to a temperature of 80-90 ° C, and cooling - for 0.5-0.75 hours to a temperature of 20-25 ° C. The number of cycles is set equal to 5-10. This mode is especially well reproduced for a bottomhole formation zone with a sand reservoir.

Heating and cooling is carried out by pumping coolant and refrigerant into the bottom-hole formation zone. Heated water, steam, etc. are used as a heat carrier. As a refrigerant use water with a temperature of not more than 20 ° C.

Studies of changes in core permeability with a different number of heating and cooling cycles showed the promise of developing field thermocyclic technologies, and made it possible to develop basic criteria for selecting objects for thermocyclic impact on the bottomhole zone of the well.

Concrete example

The bottom-hole zone of the formation with a sand reservoir, opened by a well at a depth of 1700 m, is treated. Steam is injected into the bottom-hole zone for 2 hours until the bottom-hole zone is heated with a radius of 2 m to 90 ° C (calculated). After that, water is injected with a temperature of 5 ° C for 40 minutes until the bottom-hole zone is cooled to 25 ° C (calculated). The number of heating-cooling cycles is set equal to 6. As a result of further hydrodynamic studies, it was found that the porosity and permeability of the bottom-hole zone increased from 17 to 19% and from 100 to 120 mD, respectively. Conducted research on the treatment of the bottom-hole zone according to the prototype modes show the absence of changes in the permeability of the bottom-hole formation zone.

The application of the proposed method will improve the effectiveness of the impact by increasing the porosity and permeability of the reservoir of the reservoir.

Claims (1)

A method of treating the bottom-hole zone of the formation, including heating and cooling, characterized in that the heating and cooling of the bottom-hole zone of the formation is carried out cyclically, with heating being carried out for 1.5-2.5 hours to a temperature of 80-90 ° C., cooling for 0.5-0.75 hours to a temperature of 20-25 ° C, and the number of cycles is set equal to 5-10.