RU2386799C1 - Development method of oil field in heterogeneous collectors - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: method includes drilling of producing and injection wells, pumping of displacement agent through injection wells, withdrawal of production through producing wells, definition of boundaries of substitute areas of collectors and withdrawal of stratum product from dead spaces nearby zone of collectors replacement. There are defined areas of band discontinuity of collectors, it is implemented drilling of additional producing wells nearby areas of band discontinuity of collectors replacement from the side of injecting wells.

EFFECT: increasing of oil recovery, increasing of oil extraction ensured by involvement into development of dead areas of oil, located nearby areas of band discontinuity of collectors displacement from the side of injection point.

2 ex, 2 cl, 2 dwg

Description

The invention relates to the oil industry and may find application in the development of an oil field in heterogeneous reservoirs.

A known method of developing a heterogeneous oil field (patent RU No. 2101475, IPC E21B 43/20, publ. 10.01.1998), including drilling injection and producing vertical and horizontal wells, water flooding and recovery of oil to the surface, refinement of the geological structure according to the results drilling and modeling and drilling additional horizontal boreholes or horizontal boreholes from old wells.

The disadvantage of this method is the incomplete coverage of formations by water flooding due to the impossibility of extracting oil located along the boundaries of reservoir replacement zones.

The closest technical solution to the proposed invention is a method of developing a heterogeneous oil field (patent RU No. 2259474, IPC E21B 43/20, publ. 08/27/2005), providing for the injection and production wells drilling, water flooding and oil recovery to the surface, clarification the geological structure according to the results of drilling and modeling and drilling additional wells with a horizontal wellbore or horizontal wells from old wells, determining the location of the boundaries of reservoir replacement zones, the amount of fixed oil is carefully calculated, concentrated near the reservoir replacement zones, then horizontal wells are drilled from old wells located near the boundaries of reservoir replacement zones and / or new wells with a horizontal wellbore in this zone, and horizontal wells are drilled in the direction perpendicular to the boundary of the replacement zone .

The known method does not allow to introduce into the development of stagnant oil zones located near the zones of rupture of the zones of substitution of reservoirs, characterized by a lower value of the final coefficient of oil recovery.

An object of the invention is to increase oil recovery, increase oil recovery due to the involvement in the development of stagnant zones of oil located near the zones of rupture of zones of replacement of reservoirs from the side of injection wells.

The technical problem is solved by a method of developing an oil field in heterogeneous reservoirs, including drilling production and injection wells, pumping a displacing agent through injection wells, selecting products through production wells, determining the boundaries of reservoir replacement zones and selecting reservoir products from stagnant zones near the reservoir replacement zone.

What is new is that they determine the zones of rupture of the zones of replacement of the reservoirs, drill additional production wells near the zones of rupture of the zones of replacement of the reservoirs from the side of the injection wells.

It is also new that additional injection wells are drilled with horizontal sections in the direction of fracture zones of reservoir replacement zones.

SUMMARY OF THE INVENTION

The development of an oil field in heterogeneous reservoirs is characterized by a low level of oil recovery and incomplete involvement of oil reserves.

The proposed method is aimed at maximizing involvement in the development of oil reserves in heterogeneous reservoirs and increasing oil recovery.

The method is as follows.

Figure 1 presents a diagram of a portion of a heterogeneous oil field, where:

1 - vertical injection wells; 2 - vertical production wells; 3 - additional producing vertical well; 4 - reservoir replacement zones; 5 - reservoir stagnant zones; 6 - a zone of a gap of a zone of replacement of collectors.

Figure 2 presents a diagram of the site of a heterogeneous oil field, where:

1 - vertical injection wells; 2 - vertical production wells; 3 - additional producing horizontal well; 4 - reservoir replacement zones; 5 - stagnant zones of the collector; 6 - a zone of a gap of a zone of replacement of collectors.

The field is drilled along the design grid of wells and equiped. Water is pumped into injection wells 1 and production is taken through production wells 2. During the operation of the field, oil and water production are measured. Refine the geological structure and oil reserves using reservoir parameters. The boundaries of the reservoir replacement zones are specified 4. The fracture zone 6 of the reservoir replacement zones is determined 4. The amount of stationary oil in the stagnant zones 5 concentrated near the reservoir replacement zones 4 is determined, comparing the reserves calculated by the volumetric method using the displacement characteristics.

New additional producing wells 3 (1-3 wells, and the higher the expected production rate, the more wells) are placed near the fracture zones 6 of the replacement zones of the reservoirs 4 from the injection wells 1, thereby creating a rarefaction of formation energy.

Drilling additional wells 3 allows you to clarify the boundaries of substitution zones 4 and oil reserves near them. The commissioning of these wells allows the use of additional oil reserves not previously involved in the development.

In the process, due to the formation of an additional pressure gradient in the stagnant zones 5, the motion of the previously immovable oil to the producing wells 2 and the redistribution of the filtration flows occur.

In cases where large oil reserves are concentrated in stagnant zones, additional production wells are drilled with horizontal sections in the direction of the fracture zones 6 of the reservoir replacement zones 4.

Case Study 1

The site of the field is drilled according to the design grid of wells and equiped (figure 1). Water is pumped into injection wells 1 and production is taken through production wells 2. Oil and water production and injection are measured. Lithological maps are built and oil reserves are calculated, recoverable reserves are determined by the displacement characteristics. Geological reserves amount to 2072 thousand tons, recoverable reserves - 1033.9 thousand tons. Significant zones (about 30%) in the field are not occupied by collectors. 586 thousand tons were mined. The water content of the extracted products reached 50%. By modeling the area, the areas of the smallest pressure gradients and the location of the boundaries of the reservoir replacement zones are determined, fracture zones 6 of the reservoir replacement zones are determined 4. It was determined that stagnation zones 5 formed near the fracture zones of 6 reservoir replacement zones 4 from the injection wells 1. An additional vertical producing well 3 and put into operation. Recoverable reserves are determined using displacement characteristics. As a result, recoverable reserves increased by 20% and amounted to 1240.68 thousand tons. Additional oil production from the event amounted to 206.78 thousand tons.

Case Study 2

In the same section of the field, modeling determines the areas of least pressure gradients and the location of the boundaries of reservoir replacement zones, determines the fracture zones of 6 reservoir replacement zones 4. It was determined that stagnation zones 5 were formed near the fracture zones of 6 reservoir replacement zones 4 from the injection wells 1 (Fig. 2). In this section, an additional production well 3 is drilled with a horizontal section in the direction of the fracture zone and put into operation. Recoverable reserves are determined using displacement characteristics. Additional oil reserves accounted for more than 20% of the recoverable due to the introduction of new horizontal production wells.

As a result of drilling horizontal wells, the recoverable reserves increased by 30%, which is 10% higher than when drilling vertical wells, and amounted to 1344 thousand tons. Additional oil production from the event amounted to 310.17 thousand tons. The coverage coefficient of the formation increased from 0.6 to 0.7 units. in comparison with analogues. That is, during the operation with additional horizontal production wells, the growth percentage when using this method is on average 10% higher than when operating with additional vertical production wells.

After conducting geological studies, production costs for the construction of additional horizontal and vertical wells are compared, the economic value of additional oil produced using an additional horizontal well instead of an additional vertical well (at the market price of oil), cost savings are calculated.

Based on profitability, the need to build an additional vertical or additional horizontal production well is selected.

The application of the proposed method is cost-effective and does not require additional material costs, since, unlike the prototype, it does not require the introduction of a large number of additional production wells with horizontal sections (1-3 wells), it will also allow to increase oil recovery and introduce additional oil reserves in the field in zones of rupture of zones of replacement of reservoirs.

Claims (2)

1. A method of developing an oil field in heterogeneous reservoirs, including drilling production and injection wells, pumping a displacing agent through injection wells, taking products through production wells, determining the boundaries of reservoir replacement zones and selecting reservoir products from stagnant zones near the reservoir replacement zone, characterized in that they determine the zones of rupture of the zones of replacement of reservoirs, drill additional production wells near the zones of rupture of the zones of replacement of reservoirs by pressure wells. 2. The method according to claim 1, characterized in that the additional injection wells are drilled with horizontal sections in the direction of the fracture zones of the reservoir replacement zones.

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