RU2264533C2 - Method for oil reservoir development in carbonate or terrigenous formation with developed macrocracks - Google Patents

Abstract

FIELD: oil production industry, particularly enhanced recovery methods for obtaining hydrocarbons.

SUBSTANCE: method involves drilling production and injection wells and maintaining formation pressure; performing seismic works to determine volumetric routing of natural macrocrack system with lateral and depth routing; forming production and injection macrocracks of above system; drilling wells to corresponding macrocracks and forming producing well-macrocrack systems for oil production and injection well-macrocrack for formation flooding or production well-macrocrack for oil production and system including vertical and/or horizontal multibranch wells for formation flooding or injection well-macrocrack system for formation flooding and system including vertical and/or horizontal multibranch production wells for oil production or production well-macrocrack system, injection well-macrocrack system and system including vertical and/or horizontal multibranch production and injection wells.

EFFECT: increased efficiency, oil recovery and production well injectivity, as well as increased sweep efficiency and oil recovery ratio.

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Description

The invention relates to the field of oil and gas industry, namely, to increase the efficiency of development of oil deposits in a carbonate or terrigenous layer with developed macrocracking.

There is a method of developing oil deposits with a carbonate reservoir, including drilling production and injection wells and performing hydrochloric acid treatments in them in order to increase the productive characteristics of wells (see Amelin I.D. et al. Operation and technology for the development of oil and gas deposits. Publishing house Nedra, 1978, s.266-274).

The disadvantages of this method are as follows.

- As a rule, all productive oil-bearing strata are heterogeneous in reservoir properties. Carbonate reservoirs are also typically fractured. Therefore, the conduct of standard deviations, on the one hand, leads to an increase in the productive characteristics of the well. On the other hand, it strengthens the natural heterogeneity of the reservoir by reservoir properties. This is due to the fact that the acid injected into the formation penetrates the most permeable layer and / or crack. As a result of the reaction of the acid with the rock, the permeability of the corresponding layer and / or crack increases. A consequence of this is an increase in reservoir heterogeneity in terms of reservoir properties.

- A similar situation occurs from the side of the injection well during the completion of the RMS. As a result, the communication between the faces of the producing and injection wells is improved. This means that the water injected into the reservoir will not do the useful work of displacing oil to the bottom of the producing well. For the water will mainly circulate through the stimulated layer and / or crack.

- Operations of DIS are expensive, require a significant amount of various equipment. Transportation and operation of this equipment alone during the period of the DIS will have an undesirable impact on the environment.

Closest to the proposed method is the hydraulic fracturing of a carbonate or terrigenous layer (hydraulic fracturing), including the drilling of vertical and / or horizontal production and injection wells and hydraulic fracturing operations. Fracturing creates an increase in the filtration surface of the well. As a result, the production rate and injection rate of the injection well increase (see Amelin I.D. et al. Operation and technology for the development of oil and gas fields. Ed. Nedra, 1978, p. 274-281).

The disadvantages inherent in the considered method are the following.

- The direction of artificially created cracks in production and injection wells is practically uncontrollable. Therefore, the positive consequences in the form of an increase in the production flow rate and injectivity of the injection well can be offset by the negative consequences of the undesirable direction of hydraulic fractures. In the limit, for example, they can practically connect. Then, the waterflooding efficiency can drop sharply, which will lead to a decrease in the oil recovery factor (CIF), and hence the recoverable oil reserves.

- Fracturing operations are also expensive. They require a large and varied technique, reagents. Transport and the operation of all equipment involved in hydraulic fracturing likewise harm the environment.

The basis of the present invention is the creation of technology for the development of oil deposits in carbonate or terrigenous strata with developed macrocracking, which ensures an increase in the production rate of the production well and injectivity of the injection well, as well as an increase in the coverage rate by oil displacement by water and oil recovery factor with the simultaneous elimination of the disadvantages noted above.

This task is achieved by the fact that in the method of developing an oil deposit in a carbonate or terrigenous reservoir with developed macrocracks based on drilling production and injection wells and waterflooding of the reservoir, 3D seismic work is performed to identify volumetric tracing of the natural macrocracks and form “producing” ones and “injection” macrocracks, drill wells into the corresponding types of macrocracks and form the “producing well - macrocrack” system for oil recovery and the "injection well - macrocrack for flooding the formation, as well as the fact that:

- form the system "production well - macrocrack" for oil recovery, and water is pumped through vertical and / or horizontal, multilateral wells located between the specified production systems, as well as between the external oil-water contact and production systems;

- form the system "injection well - macrocrack" for waterflooding, and oil is extracted through vertical and / or horizontal, multilateral wells, located between the marked injection systems;

- form combined systems "production well - macrocrack", "injection well - macrocrack", vertical and / or horizontal, multi-sided production and injection wells, located relative to each other, based on the principle of achieving the highest coverage rate by oil displacement by water;

- the mentioned approaches are implemented in the case of the development of a gas condensate deposit based on a cycling process.

The method is as follows.

3D seismic work is carried out at the field. As a result of the interpretation of 3D seismic data, a system of macrocracks, their lateral and deep tracing are detected.

Based on the results of 3D seismic surveys, field geophysical and hydrodynamic studies of wells, as well as core analysis data, they create a 3D geological and then a 3D geological and hydrodynamic model of the oil reservoir under consideration. In this case, local refinement of the mesh region is carried out near the surface of each macrocrack. The 3D geological and hydrodynamic model of the formation is adapted to the data of hydrodynamic studies of the wells and the data of their experimental and industrial operation.

Using the created and adapted 3D geological and hydrodynamic model and the corresponding software package for solving 3D multiphase problems of the theory of filtration, multivariate computer experiments are performed. The purpose of these experiments is to maximize the coverage ratio, and hence the oil recovery factor, therefore, the amount of recoverable oil reserves. This goal is achieved on the basis of justification.

- those macrocracks that will play the role of producers in the "production well - macrocrack" system;

- those macrocracks that play the role of injection in the "injection well - macrocrack" system;

- the number, location of vertical, horizontal, multilateral wells and injection wells.

The selection of the best development option, as always, is based on subsequent technical and economic calculations. After that, the implementation of the best design option for development is carried out.

This means that the producing well is drilled into the corresponding macrocrack with the aim of creating a single system "production well - macrocrack". The success of this operation is facilitated by the presence of a decompression zone around the macrocrack. For greater reliability, a weakly expressed sinusoidal profile of the trunk is realized, which allows you to confidently cross the macrocrack plane and the decompression zone several times. Modern equipment and technology for drilling wells allow us to do this without any problems.

In a similar way, the system "injection well - macrocrack" is created. Wells of other types and related applications are also being drilled. The consequence is the creation of a designed development system.

It is easy to see that the proposed development method has the following advantages.

- There is no need for the costs of hydraulic fracturing and standard fracture.

- Natural macrocracks, due to the importance of the filtering surface, are able to provide oil production rates and the costs of injected water are several times larger than in traditional approaches.

- As a result, the required number of wells for the development of oil deposits is markedly reduced, the cost of drilling wells is reduced, the efficiency of oil resource development significantly increases.

- The use of natural macrocracks makes it possible to increase the recoverable oil reserves, because it is possible to switch from point-hole well effects to large-scale effects on the filtration processes in the reservoir.

Implementation example.

Almost all stages of consideration have passed. The project for developing the Prirazlomnoye oil field on the shelf of the Pechora Sea. The project for the development of this field with a carbonate reservoir provides for the drilling of horizontal production and injection wells, as well as the conduct of oil and gas production operations in them.

This means that standard deviations will increase the natural heterogeneity of the reservoir properties of the reservoir. Negative consequences follow from the point of view of premature watering of wells, reduction of recoverable oil reserves, etc. Wells being designed will carry out point impacts on the formation, which is usually characterized by a decrease in oil recovery factor and recoverable oil reserves, etc.

Based on 3D seismic studies at the field, a significant number of macrocracks have been identified. The corresponding map in the drawing shows their spatial location. In this case, individual macrocracks have a length of 5-6 km. For comparison, we note that the fracture size during hydraulic fracturing is not more than 200-300 meters.

The presented data on the Prirazlomnoye field indicate the feasibility of implementing the principles of developing an oil deposit with a carbonate reservoir and converting macrocracks from a negative factor into a positive factor in increasing recoverable oil reserves and reducing development costs. For it is possible to reduce the required number of wells for field development, to increase recoverable oil reserves, as well as to achieve or exceed the planned levels of oil production.

Thus, it seems that the proposed approach to the development of an oil deposit in a carbonate or terrigenous layer with developed macrocracking will increase the efficiency of the development of the considered and other relevant domestic oil fields and increase recoverable oil reserves. A similar conclusion is valid for gas condensate deposits developed with the implementation of the cycling process.

Claims (1)

A method of developing an oil deposit in a carbonate or terrigenous formation with developed macrocracking, including drilling production and injection wells and maintaining reservoir pressure, characterized in that seismic work is performed to detect volumetric tracing of the natural macrocrack system with their lateral and deep tracing, form “producing” "and" injection "macrocracks, drill wells into the corresponding types of macrocracks and form the production well - macrocrack system to extract I of oil and the "injection well - macrocrack" system for waterflooding or the "production well - macrocrack" system for oil recovery and a system of vertical and / or horizontal multilateral wells for waterflooding, or the "injection well - macrocrack" system for waterflooding vertical and / or horizontal multilateral wells for oil recovery, or the production well - macrocrack, injection well - macrocrack system and vertical and / or horizontal systems multi-hole production and injection wells.