SU929819A1 - Method of mine-type working of oil deposits - Google Patents

Description

(54) METHOD OF MINE DEVELOPMENT OF PEPTLET FILES The invention relates to the development of oil fields, namely to the method of thermo-mine oil production, and can be used in the oil industry. The most effective present invention can be used in the development of deposits with highly viscous oils and mobile (flowing) bitumens. At present, its time such deposits cannot be effectively developed in the usual way, in which the oil production is carried out by wells drilled with the surface of the earth, oil recovery is low. There is a known method of thermal oil production, in which vertical and inclined injection and production wells are drilled from the drilling chambers located above the oil-bearing formation. Through injection wells, coolant is supplied to the reservoir, which displaces oil to the bottom of production wells. From the downhole of production wells, oil is lifted into the drilling chambers by an air-lift method 1. The disadvantage of the method is the low efficiency of the process of thermo-mining oil production due to the low coverage of the formation by the process of displacement. There is also known a method of mining the oil reservoir, which consists in displacing oil from the reservoir by cyclically introducing steam into the reservoir through injection wells and cyclically withdrawing oil from production wells 2. The disadvantage of this method is low oil recovery due to incomplete coverage of the repression during breakthrough steam in production wells. The purpose of the invention is to increase the oil recovery of the reservoir, due to the increase in the coverage of its displacement when steam breaks into production wells. The goal is achieved in that the extraction of oil is dried up before the steam parameters (the degree of dryness and specific volume) in the production and injection wells are equalized. The essence of the method is as follows. Steam injection into the reservoir is accompanied by a gradual increase in the degree of dryness and the specific volume of steam in a porous medium. The change in the degree of dryness and specific volume of steam proceeds as follows. The degree of dryness of wet steam is the relative content of the vapor phase in a two-phase system consisting of saturated steam and an equilibrium liquid with it X Y2 Y -L Y2, where Y is the mass of the liquid phase; Y is the mass of the vapor phase. The specific volume of wet vapor is V (1-х) у1 + XV, where V ,, V is the specific volume of saturated steam and the fluid in equilibrium with it. The equilibrium state of a wet vapor is determined by two parameters, for which any pair of variables can be chosen: pressure P, temperature T, specific volume V, degree of dryness X, except pressure and temperature, which are not independent. At constant pressure P and temperature T, the vapor condenses gradually (the vapor phase decreases and the liquid phase V increases), i.e. the volume of the unit weight of the working fluid decreases. A gradual increase in the degree of dryness (X) and the specific volume of steam V occurs in comparison with the parameters X and V of steam, which were in a porous medium in an oil-bearing formation in the area of the production well B, the moment of steam penetration into the production well. At this moment, the steam parameters at the specified location are significantly reduced compared to the formation areas in the area of injection wells, since the process of oil displacement is accompanied by intense heat exchange at relatively low displacement rates. The maximum value of these parameters is reached when the state of steam in production wells turns out to be the same as in injection wells. Subsequent cessation of oil recovery or steam supply, leading to its condensation in a porous medium, will cause the greater increase in oil inflow to the steam condensation zone, the more important the steam parameters were before it starts to condense. The achievement of steam parameters in production wells that are equal to or close to those of injection wells becomes possible due to the fact that during thermal mining, oil-bearing formations are drilled by a dense grid of wells with distances between them of about 10-25 m. Moreover, It is possible to drill gently sloping and horizontal injection or production wells directly in the oil-bearing formation. The degree of opening of the reservoir significantly increased. Initially, steam displaces oil in the reservoir from highly permeable zones, channels, cavities and fractures. When steam condensates in the reservoir, additional pressure drops are created that promote the displacement of oil from the denser, less permeable portions of the oil reservoir or blocks. rocks in the indicated channels, caverns and cracks. In this case, the coolant due to the phase transition intensively gives off heat to the formation rock, lowering the viscosity, oil containing in it, or maintaining the fluidity of oil achieved during preliminary heating of the oil-bearing formation. Due to the pressure differential between injection and production wells, oil is forced out into production wells, and upon condensation of the next portions of steam, all new sections of the oil-bearing formation are forced out, which leads to an increase in oil recovery. The displacement process is especially effective when the parameters of the vapor state before the condensation are close to the initial ones. After steam breaks into production wells, oil production from them naturally decreases. Nevertheless, oil is extracted with steam with that condensate that has already been formed in the reservoir during oil displacement, i.e., the reservoir is purged, increasing the parameters of the output steam X and V. When purging, a certain amount of steam is lost However, since the distance between the injection and production wells during thermal development is small (10-20 m), the process of restoring the parameters of the X, V vapor state occurs very quickly (several minutes). In some cases, it is possible that the increase in the state parameters of the outgoing steam will be carried out without displacing the oil. In this case, the heat losses due to the situation noted above will be insignificant. The method is carried out as follows. A set of underground mines is created, which includes lifting and ventilating external shafts, near-shaft mines, drifts and working galleries. From these working galleries, drilling and production wells are drilled. Injection and production wells can be drilled from the same working galleries. The essence of the method does not change if steam injection and oil extraction will be carried out from various working galleries located at different levels. For example, when steam is injected from mine workings located above the operating gallery. The operating gallery is placed in the oil-bearing formation (usually in the middle or lower part of the formation) or below it. Through injection wells, steam is cyclically pumped into the oil-bearing formation to evenly distribute it throughout the production volume to the working gallery.

From production wells divided into groups, cyclic oil is taken into the working gallery. Oil is forced out of the reservoir by steam until steam breaks into production wells. Thereafter, the production wells are not closed, as in the known methods, but they carry out steam pumping in the reservoir, removing condensate from it, which is formed during oil displacement, and raising the state parameters of the outgoing steam, first of all, the degree of dryness of the steam and the specific volume.

When the steam parameters in the production wells are the same as in the injection wells, the production wells are closed.

Due to the loss of heat through the roof and the basement of the oil-bearing formation and the entrainment of heat with the produced fluid, the steam parameters change, the steam condenses. In the condensation zone, the pressure decreases, the volume is released and oil from the surrounding zones flows into the condensation zone. During steam condensation in large pores, as well as in cavities and fractures, additional local pressure drops create favorable conditions for the flow of oil from the shallow pores of the oil-bearing formation and its areas with impaired permeability.

Due to the fact that steam with preliminarily elevated parameters condenses, an intensive oil inflow from separate sections occurs, which increases the sweep coverage.

After complete steam condensation and pressure equalization in the reservoir, the next oil recovery cycle is carried out. The oil is transferred by the coolant flow to the production wells, primarily from high permeability zones, cavities and cracks, where it has come from areas of impaired permeability.

In subsequent oil extraction cycles, the steam lines (motions) of the steam expand, causing the displacement coverage to increase and the effect of steam pumping to increase. Oil from production wells enters the working galleries, from where it is supplied to the surface through a closed collection system, having previously separated it from 5 hot water, which is used for technological needs. The cycles of steam injection into the reservoir and the selection of them are not the same. Steam injection into the reservoir is longer. After creating an aggregate of underground mine workings, working galleries and

 drilling of injection and production wells, the method is carried out by implementing the following operations.

Through injection wells in the oil-bearing formation under pressure from 1 to 20 kgf / cm

5 pump the coolant at intervals of time from 10 to 30 days with stops of the same duration.

For this case, the steam injection time interval is 15 days, the stopping time is 15 days, and the discharge pressure is 3 kg / cm. All injection wells are divided into two groups, the injection of steam into each of which is carried out alternately with the above intervals for the injection of steam and the shutdown of injection wells.

5 A liquid (oil and water) is taken from production wells.

After flushing the steam into production wells, steam is pumped into the formation until the steam parameters (degree of dryness and specific volume) in the production wells become equal to or close to those of the injection wells, for which the control wells are installed in the production wells sampling, allowing the production wells to be closed upon reaching the specified parameters.

The cycles of injection into the reservoir of the coolant and oil recovery from various groups of production wells are repeated until the economically feasible development of reserves

0 oil from the developed area.

The cycle of oil extraction from production wells consists of the time of the well and the time it stops. The operation time of production wells already in the first cycle is determined by putting them into operation and

 stopping after equalization of steam parameters in production and injection wells.

To assess the effectiveness of the proposed method of thermo mine oil extraction

0 we will carry out its comparison with a known method. In both cases, pairs of identical parameters are injected; degree of dryness is 0.2; discharge pressure 3 kgf / cm. In the known method, production wells are shut off when the degree of steam dryness is 0.1 in the proposed method at 0.2.

According to the steam state diagram for 3 kgf / cm with a degree of dryness of 0.1 specific

steam volume is 0.06, with a degree of dryness of 0.2-0.12.

In both cases, with full condensation of 1 kg of steam, the volume occupied by the condensate is 0.001 m. With a degree of steam dryness of 0.2, the difference in specific volumes is 0.119 m / kg, with a degree of steam dryness equal to 0.059 m3 / kg.

The difference in specific volumes with a degree of dryness of 0.1 and 0.2 is 0.06. The displacement coverage rate in this case rises from 0.63 to 0.69. The displacement coefficient will be 0.70 and 0.71, respectively, and the oil output will be 0.63-0.7 0.44 and 0.71-0.69 0.49.

The calculation is presented in table 1.

Claims (2)

Thus, the application of the method in the described conditions gives an increase in oil recovery by 5%. The proposed method can be used for the extraction of mobile (flowing) bitumen. The steam consumption in the proposed method is higher, but higher and oil recovery is achieved. In the above example, it is shown that the application of the proposed method gives an increase in oil recovery by 5%. Consumption of steam is higher, but not by much. Calculations for the same period (5 years) show that the specific steam consumption, i.e., the amount of steam used to extract one ton of oil, is the same in both cases and amounts to 2.5 tons / ton. The method of the mine development of oil deposits, which consists in displacing oil from the reservoir by cyclically supplying steam into the reservoir through injection wells and cyclical extraction of oil from exploratory wells, characterized in that, in order to increase oil recovery by increasing the amount of oil displacing. in production wells, oil extraction is carried out before leveling the steam parameters (degree of dryness and specific volume) in production and injection wells. Sources of information taken into account in the examination 1. Mishakov V. N. and others. Experience in the application of thermal methods of mine development of high-viscosity oil fields. Petroleum business, No. 10, 1974, p. 31-35. 2. USSR author's certificate number 468529, cl. E 21 B 43/24, 13.03.72.