SU1726737A1 - Bottomhole zone treatment method - Google Patents

Abstract

The invention relates to oil and gas production and can be used to increase the permeability of the bottomhole zone with the aid of an electrical current. The purpose of the invention is to intensify the flow of hydrocarbons into the well by cleaning the bottom-hole zone from the filtrate of the washing liquid and solid particles. Cyclic exposure is carried out by a constant electric current together with a pulsating different-polarity electric current, and the current strength and time of the action are the same for both the cycle of the action of a constant and pulsating alternating current and are respectively 1-30 A, and 6-8 hours, at the same time, the frequency of the pulsating alternating current is in the range of 1–20 G. Table 1.

Description

The invention relates to oil and gas production and can be used to increase the permeability of the bottomhole zone with the aid of an electrical current.

There is a method of processing bottom-hole zone, including the impact on the filter zone of the well with electric current. The method was applied to increase the water yield and injectivity of hydrogeological wells, as well as in the mining of mineral resources using the in-situ leaching method. According to the method, the electric current is cyclically performed, wherein the exposure time is set to no more than a value depending on a number of factors, in particular, the well radius, the distance between the electrodes, the porosity of the medium, etc., and the time between electrical exposure cycles. current set not less than the value, also depending on the number of yes

factors, in particular the heat capacity and density of the liquid medium, etc.

However, despite the increase in the pore space section, the clay and mud filtrate remain in place. They can be tolerated only in limited cases when the intra-layer pressure exceeds the pressure of the liquid column in the well by an amount exceeding the adhesion force of the clay particles to the walls of the capillary and the force of the tension surface of the filtrate in the pore space.

There is also known a method for processing the bottomhole zone, according to which a pulsating unidirectional or direct current is applied between two electrodes, of which at least one is located in the well. The duration of exposure in this method ranges from several days to several months.

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The disadvantage of this method is that when using a unidirectional potential difference, the movement of oil occurs only in one direction. The capillaries on which the oil is moving have a narrowing. In the case when solid particles move together with the liquid, which occurs almost continuously, they gradually stay in places where the capillaries constrict, as a result of which the rock permeability decreases and the flow rate decreases.

The purpose of the invention is to intensify the flow of hydrocarbons into the well by cleaning the bottom-hole zone from the filtrate of the washing liquid and solid particles.

The goal is achieved by the fact that in the method of processing the well bottom zone, which includes a cyclical effect on the bottomhole zone with a direct electric current, the cyclic effect is carried out together with a pulsating alternating electric current, and the current strength and time are the same both the same and the pulsating different-current currents and are respectively 1-30 A and from 6-8 hours, while the frequency of the pulsating alternating current is in the range of 1-20 Hz.

The table shows the results of the work.

Work was carried out on approbation of the method for processing the well bottom zone, which includes a cyclic effect on the bottom zone by an electric current.

The cyclic action was carried out in combination of a constant current and a pulsating different current of different frequencies and also a different force. The time of impact of both constant and pulsating currents is different and ranged from 1 to 30 hours. The work was carried out during the exploration of the Zernogradskoye gas field. The gas inflow from the sandstone bed was intensified from a depth of 450–470 m. The initial gas flow rate was 1000 m3 / day. The well is cased along the entire depth of a casing with a diameter of 114 mm, cemented to the mouth. An electric exploration station (generator group) ERS-67 was used as a current source. The casing strings of the Mg 525 borehole and well No. 804, located at a distance of 1000 m, served as grounding piers. With a current of up to 2 A and an exposure time of 1 h, the flow rate did not increase at all. When the pulsating and constant currents were combined with the effect of both currents up to 8 hours with a force of 15A, there was a slight increase in flow rate. Moreover, an absolutely insignificant increase in the flow rate was observed when exposed to only one pulsating different polarity or one constant current. With a current of 25-30 A and an exposure time of up to 8 hours, the cyclic effect of a pulsating differently polarized and constant currents increases the flow rate of the well during 3 cycles. With further processing of the well bottom zone, the stabilization of the flow rate within 2000 m in 1 day was noted. At frequencies up to 5 Hz, the increase in production rate is insignificant, the maximum production rate is obtained at frequencies of 10–20 Hz. The current frequency used depends on the type of collectors, their porosity and permeability.

As testing has shown, by passing an electric current in capillary systems located in the reservoir, electrolyte transfer occurs and, as a result, a pressure differential is created at different ends of the capillary (electroosmosis phenomenon). Due to this phenomenon, by passing a different polarized pulsating current, a vibration effect is generated on the mud filtrate and solid particles. The fine particles of the solid phase of the clay solution are detached from the walls of the capillary, and their swinging occurs (the Vanthus principle). This creates conditions for easier removal of particles with the electrolyte and increases the cross-sectional area of the capillaries. By passing direct current, unidirectional transfer of electrolyte occurs along with solid or dispersed particles detached from the walls of the capillary or constriction sites. In addition, when exposed to an electric current, the tangential deformation of the outer surface of the electric double layer on the surface of solid particles occurs, thus disturbing the equilibrium of the electric forces in the reservoir, and this contributes to the disintegration of the zone of formation closure.

The number of cycles from pulsating and direct current depends on the depth of the invaded zone and the physical properties of the formation. These cycles of exposure are maintained until growth in the production rate of the product from the well ceases. The type of product, oil or gas, is not significant, since the impact is not on the hydrocarbons, but on the fluids and solids that fill the bottomhole zone.

Claims (1)

Invention Formula The method of wellbore zone treatment, which includes cyclic impact on the bottomhole zone with a constant electric current, characterized in that, in order to stimulate the flow of hydrocarbons into the well by cleaning the wellbore zone from the filtrate of washing liquid and solid particles. 0 the impact of a constant electric current is carried out together with a pulsating bipolar electric current, and the current strength and time of exposure are the same for both the cycle of the impact of a constant and pulsating alternating current and are respectively 1-30 A and from 6-8 h, with In this case, the frequency of the pulsating pitch current is in the range of 1-20 Hz.