CN104790931A - On-sea low-permeability reservoir thin interbed injection-recovery branched well control-increased method - Google Patents

Abstract

The invention relates to a method for increasing the control of injection-production branch wells in the development of thin interbeds in offshore low-permeability reservoirs; the composition of a single well at least includes a main wellbore, oil production branches, water injection branches and artificial fractures, the main wellbore and injection The water branch and the oil production branch are connected, and the oil production branch passes through at least one oil layer and communicates with the artificial fractures in the oil layer; this method can not only control more underground oil and gas resources through multiple oil production branches and artificial fractures on the oil production branches, but also Establish displacement pressure gradient through water injection branch, overcome start-up pressure difference and increase oil recovery effect, because the cost of drilling oil production branch and water injection branch is much less than the cost of drilling a single well, greatly reducing the operating cost of oil and gas resource control, thus The economical efficiency of offshore low-permeability reservoir development is improved; the method utilizes one injection-production branch well to control and develop more underground oil and gas resources, and is suitable for thin interbedded low-permeability reservoirs.

Description

A control method for injection-production branch wells in thin interbedded offshore low-permeability reservoirs

technical field

The invention relates to a method for increasing and controlling injection-production branch wells of thin interbeds in offshore low-permeability oil reservoirs.

Background technique

Since offshore oil and gas fields are located in a marine environment, production facilities and production wells need to be concentrated on offshore production platforms or wellhead platforms. Due to the constraints of platform construction and huge investment in drilling, offshore oil and gas fields can only be developed with a limited number of wells. The degree of recovery, rate of oil recovery and economy are limited to a certain extent.

When developing offshore low-permeability reservoirs, due to poor reservoir permeability, it is more difficult for oil and gas to flow underground, and there are fewer exploitable oil and gas resources within the control range of a well. Due to investment restrictions in offshore oil production facilities and drilling and completion operations However, it is impossible to effectively develop offshore low-permeability reservoirs by drilling multiple production wells and water injection wells in onshore low-permeability oilfields.

Therefore, it is more urgent to invent a method for controlling and developing more underground oil and gas resources by using one well in offshore low-permeability reservoirs.

Contents of the invention

The object of the present invention is to provide a method for increasing control of injection-production branch wells in thin interbeds of offshore low-permeability reservoirs, which uses the cooperation of oil production branches, water injection branches and artificial fractures in one well to increase the control degree of underground oil and gas.

In the method for increasing and controlling injection-production branch wells in offshore low-permeability reservoirs according to the present invention, the composition of a single well includes at least the main wellbore, oil production branches, water injection branches and artificial fractures, the main wellbore and water injection The oil production branch is connected with the oil production branch, and the oil production branch passes through at least one oil layer and communicates with the artificial fractures in the oil layer. The number and scale of artificial fractures are determined by the distance of the water injection branch, the reservoir conditions and the oil recovery intensity. Injection or layered water injection, the water injection volume is adjusted according to the distance of the artificial fractures of the oil production branches and the injection and production needs.

The oil production branches of the present invention are vertical wells, deviated wells or horizontal wells, the number and completion method of which are determined according to reservoir conditions and injection-production parameters, and the completion methods are casing perforation completion or gravel packing completion .

The water injection branch of the present invention is a vertical well or an inclined well, and the water injection mode is co-injection or layered water injection.

The number and scale of artificial fractures in the present invention are determined by reservoir conditions and injection-production parameters.

The present invention has remarkable functions of increasing control reserve, reducing cost and improving development effect in the development of thin inter-oil layers in offshore low-permeability reservoirs. The invention not only can control more underground oil and gas resources through multiple oil production branches and artificial fractures on the oil production branches, but also can increase the oil recovery effect by establishing displacement pressure gradient through water injection branches and overcoming the start-up pressure difference. Since the cost of drilling oil-production branches and water-injection branches is far less than the cost of drilling a single well, the operating cost of oil and gas resource control will be greatly reduced, thereby improving the economics of offshore low-permeability reservoir development. The method utilizes one injection-production branch well to control and develop more underground oil and gas resources, and is suitable for thin interbedded low-permeability reservoirs.

Description of drawings

Fig. 1 is a schematic diagram of the present invention.

Among them: 1 main wellbore, 2 oil production branch A, 3 oil production branch B, 4 oil production branch C, 5 water injection branch, 21 artificial fracture A, 31 artificial fracture B, 32 artificial fracture C, 41 artificial fracture D, 42 Artificial Fracture E, 43 Artificial Fracture F, 6 Reservoir, 7 Reservoir, 8 Reservoir.

Detailed ways

The purpose of the present invention can be achieved by adopting the following technical scheme. The method for increasing the control of injection-production branch wells in the development of thin interbeds in offshore low-permeability reservoirs consists of main wellbore 1, oil production branch A2, oil production branch B3, oil production branch C4, Water injection branch 5 is composed of artificial fractures A21, artificial fractures B31, artificial fractures C32, artificial fractures D41, artificial fractures E42, and artificial fractures F43. The oil production branches are connected, and the oil production branches pass through at least one oil layer and communicate with the artificial fractures. The scale of the artificial fractures depends on the distance from the water injection branch 5, the reservoir conditions and the oil recovery intensity. The water injection branches are combined or separated The water injection technology also adjusts the water injection volume according to the distance from the artificial fracture of the oil production branch and the injection and production needs.

The oil production branches of the present invention are vertical wells, inclined wells or horizontal wells, the number and well completion methods of which are determined by reservoir conditions, construction operation difficulty and injection-production parameters, without fixed restrictions.

The water injection branch of the present invention is a vertical well or an inclined well.

The number and scale of the artificial fractures in the present invention are determined according to reservoir conditions, construction operation difficulty and injection-production parameters, and there is no fixed limit.

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples.

Example 1:

The main wellbore is a vertical well with a vertical depth of 1300 meters (main wellbore 1 in the figure), using the same well injection and production technology, the thickness of the oil layer is 150 meters, and the thickness of a single layer is 50 meters (reservoir 6, reservoir 7, reservoir 8). The water injection branch extends the vertical well from the main wellbore (water injection branch 5 in the figure), with a well section length of 200 meters; the three oil production branches are inclined wells, with well sections of 100 meters, 200 meters and 300 meters in length, respectively passing through oil layers There are 1 layer, 2 layers, and 3 layers. The artificial fractures in the well section are 1, 2, and 3 respectively. The artificial fractures are perpendicular to the horizontal direction and parallel to the main wellbore. The half-length of the fractures is 50 meters; The water volume is 1,000 cubic meters, and the daily liquid production volume of the oil production branch is 800 cubic meters.

Claims (5)

1. a marine LOW PERMEABILITY RESERVOIR thin interbed exploitation note adopts multi-lateral well increasing control method, it is characterized in that: the composition of a bite individual well at least comprises main borehole, oil recovery branch, water filling branch and man-made fracture, main borehole is communicated with water filling branch, oil recovery branch, and oil recovery branch passes through at least 1 layer of oil reservoir and communicates with the man-made fracture in oil reservoir.

2. marine LOW PERMEABILITY RESERVOIR thin interbed exploitation note according to claim 1 is adopted multi-lateral well and is increased control method, it is characterized in that: the number of described man-made fracture and scale are determined by the Distance geometry reservoir conditions of water filling branch and oil production intensity.

3. marine LOW PERMEABILITY RESERVOIR thin interbed exploitation note according to claim 1 adopts multi-lateral well increasing control method, it is characterized in that: described water filling branch adopts and closes note or seperated layer water injection, and being noted to adopt by the Distance geometry of the man-made fracture of oil recovery branch needs conciliation water injection rate.

4. marine LOW PERMEABILITY RESERVOIR thin interbed exploitation note according to claim 1 adopts multi-lateral well increasing control method, it is characterized in that: described oil recovery branch is straight well, inclined shaft or horizontal well, its quantity and completion mode are adopted parameter by reservoir conditions, construction operation difficulty and note and are determined.

5. marine LOW PERMEABILITY RESERVOIR thin interbed exploitation note according to claim 1 adopts multi-lateral well increasing control method, it is characterized in that: described water filling branch is straight well or inclined shaft.