RU2130116C1 - Method of developing oil deposits - Google Patents

Abstract

FIELD: oil producing industry. SUBSTANCE: method includes injection of agents into injection wells. Rows of injection and producing wells are subdivided into sections for organization of change of filtration flows. Rows of injection and producing wells are subdivided into sections so that all wells of one section of injection row operate with maximum volume of injection. All wells of neighboring sections of this row operate with minimum volume of injection. Corresponding to section of injection row with maximum volume of injection is section of producing well row with minimum withdrawal of fluid from well. During the next half-period of cycle, operating conditions of sections of injection and producing rows are changed for opposite. Then, deposit sections are divided by rows of injection wells into closed blocks. Provided in each block is circular or close to it displacement of vectors of filtration flows, first in one direction and then in other. EFFECT: higher oil production and formation oil recovery.

Description

 The invention relates to the oil industry, in particular, to methods for developing oil fields.

 The closest analogue of the invention is a method of developing oil fields, including drilling a field, injecting agents into injection wells and taking oil, water and gas from production wells, dividing the series of injection and production wells into groups for organizing the process of changing the direction of the filtration flows of injected agents and changing the direction filtration flows [1].

 A disadvantage of the known solution is the lack of effectiveness of the method due to the low degree of coverage of productive formations during oil displacement.

 The technical result of the invention is to increase oil production and oil recovery by increasing the coverage of productive formations in the displacement of oil by water, gas, compositions based on chemical products and other agents.

 The required technical result is achieved by the fact that according to the method of developing oil fields, including drilling a field, injecting agents into injection wells and taking oil, water and gas from production wells, dividing the series of injection and production wells into groups for organizing the process of changing the direction of filtering flows of injected agents and a change in the direction of the filtration flows, the rows of injection and production wells are divided into sections so that all the wells of one section of the pump of a number of wells operate with a maximum injection volume, all wells in neighboring sections of this series operate with a minimum injection volume, a section of the injection series with a maximum injection volume corresponds to a section of the production series with minimal fluid withdrawal from the well, in the next half-cycle of the cycle, the operating modes of the sections of the injection and production rows change to the opposite, after which the sections of the field are divided by rows of injection wells into closed blocks and in each of the blocks provide a circular or near something to him displacement vectors filtration flows first in one direction and then in another.

Currently, for each tonne of oil produced, 3 to 12 m ^{3 of} water is pumped. The average water flooding method in Russia provides oil recovery of about 39%. This means that if we take the displacement factor equal to 0.7, then about 40% of the mobile oil reserves are not covered by the water flooding process. The low degree of oil recovery from the reservoirs and large volumes of injected water are explained mainly by their increased heterogeneity and increased oil viscosity. In heterogeneous formations, low-permeable oil-saturated areas and interlayers during the development process are not covered or poorly covered by water flooding, which leads to a decrease in reservoir coverage by water flooding and final oil recovery. The layers are heterogeneous in thickness, permeability, initial oil saturation, dissection and sandiness, etc. The indicated heterogeneity in different directions on the process of oil displacement manifests itself in different ways. Even the oil displacement coefficient is a tensor value, that is, depending on the direction of oil displacement by water or gas.

 Therefore, increasing the coverage of reservoirs by water flooding by changing the direction of filtration flows in the reservoir is the most important direction for increasing the efficiency of oil field development.

 This is achieved due to the fact that a change in the direction of filtration flows is organized throughout the field as a whole or in its individual blocks (sections) throughout the entire development period of the field.

 The method is as follows.

 1. In-line well placement systems.

 The injection and producing rows are divided into sections, each of which includes from one to six or more wells. The injection pressure (volume) is changed over the sections of the injection row so that all the wells in one section work with the maximum injection volume, while all the wells in the neighboring sections of this series work with the minimum injection volume.

 At this time, the bottomhole pressures (flow rates) of the wells of the corresponding sections of the production row operate in modes opposite to the operating modes of the injection wells, i.e., the section of the injection row with the maximum liquid withdrawal from the well (minimum pressure drop between the reservoir and bottomhole pressures).

 In the next half-cycle of the cycle, the operating modes of the sections of the injection and mining rows are changed to the opposite.

 When implementing this method, the injection pressure (volume) in wells with a maximum operating mode can be either constant during the half-cycle or varying in a sinusoid. After that, sections of the field are disassembled by rows of injection wells into closed blocks, in each of the blocks circular or close to it movement of the vectors of the filtration flows is provided, first in one direction and then in the other.

 As a result of the implementation of the proposed method, a periodic change in the direction of the filtration flows is achieved, which minimizes oil loss by increasing the coverage of the formation by water flooding both in the section and in the area of impact. In addition, at the same time, a simultaneous approach of the displacement fronts from two sides to the contracting production row is achieved, and the same development time for areas with different reservoir properties is achieved and, in general, the development period is shortened.

 2. Areal well placement systems, focal waterflooding, selective impact.

 In this case, the approach is the same as in line systems, only production wells in opposite modes work in the cell through one, and injection wells in the row also through one.

 In irregular well placement systems, injection and production wells for different modes of water injection and oil production are established by appropriate calculations using physically meaningful mathematical three-dimensional three-phase reservoir models.

 3. Changing the direction of filtration flows in the reservoir by treating wells with technologies based on intensifying compositions.

 Currently, for all types of reservoirs and the properties of oils and produced water, there is a set of technologies based on surfactants, acids, alkalis, solvents and compositions based on them for the intensification of oil production from wells. In addition, there are physical technologies (electrical vibration, hydraulic fracturing, instant depression method and others). The production rates and injectivity of injection wells can increase from 1.1 to 2.0 or more times with their use. The time of manifestation of the effect varies from 0.6 to 1.0 years or more. This means that when applied to individual wells, the direction of the filtration flows in the areas of these wells will change for the same time. Targeted changes in the direction of filtration flows according to predetermined programs is a new technology for the development of oil fields.

The following effective options for changing the direction of filtration flows in the reservoir due to well treatments are possible:
Inline well placement systems. The following well treatment options are possible here to implement a change in the direction of the filtration flows in the formation.

 First option. Injection and production wells are processed through one in a row so that a change in direction of flows is organized in the plan. Subsequently, when the effect of changes in production rates and injectivity of injection wells ceases to be manifested, they proceed to the next version of the change in flow direction.

 The second option. Injection and production wells are treated in groups of two, three or more wells in a row. The effect of bottomhole treatment on producing wells is determined by the displacement characteristics (increase in oil production due to intensification and separately due to an increase in oil recovery, as well as volumes of reduced water production along with oil).

 Areal five-point, seven-point and nine-point systems. Here, the processing of production and injection wells is carried out through one in the system along the rows of production and injection wells.

 Focal and selective flooding. The treatment of injection and production wells is carried out after modeling the development system before processing a number of wells and after processing on physically meaningful three-dimensional mathematical models of sections.

 Closed rows of injection wells, sections of various shapes (quadrangular, triangular and others). Here, also, the rows of injection wells are divided into sections from one to 5 or more injection wells.

 4. We have a layer of two interlayers of phase permeability. When developing this layer using water flooding, a highly permeable interlayer is first produced, and then this interlayer will allow the bulk of the injected water to pass through itself, thereby dramatically reducing the efficiency of the process. In our case, they provide for the isolation of a high-flooded layer with gels, emulsions, polymer-based solutions, and others. Due to the isolation of the highly permeable interlayer and the change in the direction of the filtration flow through the section, all injected water begins to flow into the low permeable, still oil-bearing interlayer. This increases the proportion of oil in the fluid flow to the bottom of the well, which increases the efficiency of the process.

 5. Drilling to the main grid of additional production and injection wells is carried out in order to cut the change in the direction of the filtration flows in areas previously not covered by drainage of the main grid of wells. Before drilling the wells, it is necessary to conduct modeling of the development of the site with different development options in order to justify the optimal option for drilling additional wells.

 6. Conducting directed hydraulic fracturing. Studies using hydraulic tapping and injection of indicators into injection wells establish the direction of natural fracturing or maximum permeability. Then conduct directed hydraulic fracturing across the main direction of the permeability vector.

 7. The formed deposits. At a late stage of development, production of production wells becomes outside the scope of cost-effective oil production and water cut exceeds 95-97%. At this late stage of development, eventually every oil field will eventually be. It is recommended to stop the wells of the entire field (block, section, and others) in such a way that, due to the natural redistribution of pressure in the formation, a new oil deposit is formed in the near-side part of the formation. Well shutdown is made for a year, two or more. During this time, a natural manifestation of capillary gravitational and hydrodynamic forces (pressure gradients) will occur. In this case, water will be absorbed into low-permeability interlayers or zones. Gravitational forces contribute to the movement of oil droplets in the vertical direction, which contributes to the accumulation of mobile oil in the roof of the reservoir. Hydrodynamic forces contribute to the movement of oil from the marginal part of the reservoir to the central. In general, the combined effect of all three forces contributes to the formation of a new deposit in the formation roof over time. The time it takes for a new oil reservoir to form in the formation depends on the physical properties of the formation rock and the fluids and gases that increase them. Then, the formed deposit can be developed by known methods.

Sources of information
Application PS N 94020061, cl. E 21 B 43/20, 05.20.96.

Claims (1)

 A method of developing oil fields, including drilling a field, injecting agents into injection wells and extracting oil, water and gas from production wells, dividing the rows of injection and production wells into sections for organizing a process of changing the direction of the filtration flows of injected agents and changing the direction of the filtration flows, characterized in that the rows of injection and production wells are divided into sections so that all the wells of one section of the injection row work with the maximum volume pumping, all the wells of neighboring sections of this series operate with a minimum injection volume, the section of the injection series with the maximum injection volume corresponds to the section of the production series with the minimum withdrawal of fluid from the well, in the next half cycle of the operating mode of the sections of the injection and production rows are changed to the opposite, after which sections of the field are divided by rows of injection wells into closed blocks and in each of the blocks provide circular or close to it movement of the filter vectors flow flows first in one direction and then in another.