RU2105139C1 - Method for development of oil deposit - Google Patents

Abstract

FIELD: oil production industry. SUBSTANCE: this can be used in development of oil deposits with large number of stopped wells. According to method, working agent is injected through injection wells, and oil is recovered through producing wells, and some wells are stopped. Selected in deposit is development section with producing and injection wells having hydrodynamic connection between each other. Separated in this section is zone of higher oil saturation, filtration flow is formed through zone of higher oil saturation by putting into operation earlier stopped producing wells located beyond zone of higher oil saturation over its perimeter and within its limits. In addition, introduced in operation are earlier stopped injection wells located behind zone of higher oil saturation. Initially, injection wells are put into operation, then earlier stopped producing wells are started to operate. EFFECT: high efficiency. 2 cl, 1 dwg, 4 tbl

Description

 The invention relates to the oil industry and can be used in the development of oil fields with a large stock of stopped wells.

 A known method for the development of oil deposits, including the injection of a working agent through injection wells and the selection of oil through production wells [1].

 However, in relation to deposits with high zonal and layer-by-layer heterogeneity, it does not allow for a high oil recovery coefficient due to the low coverage of the reservoir with drainage and premature flooding of production wells.

 Closest to the proposed invention in technical essence is a method of developing an oil reservoir, which includes injecting a working agent through injection wells, taking oil through production wells and shutting down part of the wells [2].

 The known method, adopted as a prototype, allows for greater completeness of extraction of reserves due to the regulation of the development process by stopping part of the wells. Putting wells into operation after a long downtime without taking into account the distribution of current oil saturation prevailing under the conditions noted above, as well as the lack of focus in the formation of a filtration stream with the aim of involving zones with high oil saturation of reservoirs in the process, limits the possibilities of the prototype. Oil recovery deposits remains at a low level.

 The aim of the invention is to increase oil recovery due to the involvement in the development of low-permeability oil-saturated zones.

 This goal is achieved by the fact that in the method of developing an oil reservoir, including pumping a working agent through injection wells, taking oil through production wells and shutting off part of the wells, according to the invention, a development area with production and injection wells having a hydrodynamic connection is allocated to the deposits, at the development site, a zone of increased oil saturation is distinguished, a filtration stream is formed through the zone of increased oil saturation by commissioning of stopped add vayuschih well beyond the area of increased oil saturation along its perimeter and within it. In addition, shutdown injection wells located in front of the high oil saturation zone are commissioned, with injection wells being commissioned first and then shutting down production wells.

 The essential features of the invention are.

 1. Injection of a working agent through injection wells.

 2. Oil extraction through production wells.

 3. Stop part of the wells.

 4. Allocation of a development site with active and stopped production and injection wells, hydrodynamically interconnected.

 5. The allocation in areas of zones of high and low oil saturation.

 6. Formation of a filtration stream through a zone of increased oil saturation.

 7. Putting into operation stopped production wells located beyond the zone of increased oil saturation along its perimeter and within it.

 8. Putting into operation shut down injection wells in front of the high oil saturation zone.

 9. Priority commissioning of shutdown injection wells in front of the high oil saturation zone and subsequent commissioning of shutdown production wells behind the zone and in the high oil saturation zone.

 Signs 1-3 are common with the prototype, signs 4-7 are the salient features of the invention, signs 8-9 are the private salient features of the invention.

 SUMMARY OF THE INVENTION

 Currently, many large oil fields are in the late stages of development and are characterized by a large number of shut-off, production and injection wells. The reasons for the stops are different. They are mainly due to technological and organizational-technical factors. The duration of stops is different and sometimes measured over the years. As a result of long shutdowns of production and injection wells, deformation of the zones of contraction of oil reserves and / or the formation of zones of increased oil saturation in places with poor drainage occur. To establish the localization places of these zones, it is necessary to conduct special geological and geophysical studies of wells or to simulate the history of the development of deposits. In addition, in order to ensure higher technological parameters of the oil production process, the factor of controlling the filtration flow and, mainly, the flow of the working agent, acquires significant significance in the above conditions. This refers to ensuring the direction of the flow and its orientation in such a way as to prevent uneven development of reserves and the blurring of zones of increased oil saturation that have developed in the process of oil extraction.

 The effectiveness of the method can be enhanced by combining the planned commissioning of previously stopped wells with changes in the operating modes of injection wells in such a way that, due to these factors, provide a more active direction of the filtration stream (working agent) through the zone of increased current oil saturation and intensify the development of reserves zones with their increased content.

 The difference between the prototype and the recommended method consists in the absence in the prototype of actions to form a filtration stream through the zone of increased oil saturation. This is expressed in a predetermined sequence of works on the commissioning of production and injection wells, causing the formation of a filtration flow through the zone of increased oil saturation.

 Examples of specific performance.

 The method has been tested on one of the fields in Western Siberia, on deposits with a length of 12 and a width of 6 km.

The production facility is represented by interbedded reservoir rocks (sandstones and siltstones) with impenetrable rocks. The reservoirs are morphologically represented by two species: thin alternating rocks with effective interlayer thicknesses of up to 3 m and monolithic strata localized in the upper part of the horizon (AB $\genfrac{}{}{0ex}{}{\text{3}}{\text{1}}$ )

The permeability of monoliths is usually higher and amounts to 200-300 μm ² • 10 ^-3 and sometimes more, and the permeability of thinly alternating collectors is lower (5 - 50 μm ² ). The deposit has been under development for 8 years.

- добывающие скважины простаивающие;

- нагнетательные скважины;

- нагнетательные скважины простаивающие;

- нагнетательные скважины с ограниченным объемом закачки;

- нагнетательные скважины с увеличенным объемом закачки;
0,5 - изолинии равной нефтенасыщенности.A section in the form of an independent development block (3.5 x 2.24 km) is allocated to the deposits in the upper monolith development zone, all the wells within which are interconnected hydrodynamically. The block contains 37 producing 20 injection wells, the location of which is shown in the drawing, which shows a section of the formation limited by rows of injection wells. Zones with oil saturation of more than 0.6 have been identified by isolines within the plot; from 0.5 to 0.6 and less than 0.5. For greater clarity, the following conventions are used:
⊙ - producing wells;

- production wells idle;

- injection wells;

- injection wells idle;

- injection wells with a limited injection volume;

- injection wells with increased injection volume;
0,5 - contour of equal oil saturation.

The development of the block is characterized by the following indicators: monthly production of liquid and oil, respectively, 38.7 and 11.6 thousand / t. Injection - 53.9 thousand / m ³ . The average production rate of the producing well is approximately 43 t / s. The injectivity of one injection well is an average of 120 m ³ / s. Water cut of mined products -70%. The corresponding figures for the options for implementing the recommended method and for known technology are shown in table 1.

 The essence of development options for known and recommended methods.

 The analogue. Development is carried out according to well-known technology. 30 producing and 15 injection wells are in operation. Development indicators are given in the second column of table 1.

 Examples 1 and 2 characterize the recommended method for the stages of implementation.

 So, for example 1, the directed formation of the filtration flow through the zone of increased oil saturation is characteristic due to the commissioning of part of previously abandoned production wells bordering and located in the zone of increased oil saturation.

 Example 2 is characterized by the greatest intensification of the filtration flow through the zone of increased oil saturation. It provides for the priority commissioning of previously stopped injection wells and the commissioning of part of previously stopped production wells.

 An example of a prototype is characterized by the fact that all previously stopped production wells were commissioned. Thus, 37 producing and 17 injection wells are in operation.

 Example 1. In the development block, 20 injection and 37 production wells were drilled. Eight years after the start of the development of the block, for technical and technological reasons, five injection wells and seven production wells were shut down (drawing).

 A development area was allocated to the deposits, within which the same production interval was perforated in production and injection wells. In this example, the considered development block is in the development zone of the upper monolith so that hydrodynamic connectivity should take place between all the wells of the block. Using the method of geological and field analysis and the results of hydrodynamic studies of wells, we additionally established the presence of hydrodynamic communication between the wells drilled in the block.

 A zone of increased oil saturation was identified at the development site. Its position is shown in the drawing. In the zone of increased oil saturation, 5 production wells are located (19, 20, 21, 24, and 32), including one well stopped (20). The number of producing wells located around the perimeter of the zone in front of and behind it, can be seen from the consideration of the scheme (Fig.). As you can see, four stopped wells are located directly behind the zone of increased oil saturation (13, 14, 9, 15). Of the 5 stopped injection wells, two are in front of the high oil saturation zone (50 and 52) and one after it (41). The other two wells 46 and 57 are located on transverse injection lines.

 The formation of the filtration flow of the working agent through the zone of increased oil saturation was carried out by putting into operation stopped production wells located in close proximity to the zone of increased oil saturation: 9, 13, 14, 15 and in the zone of increased oil saturation (well 20).

 The production rates of these wells are shown in table 2.

 Technological indicators of the development of the site under these conditions are shown in table 1, column 3.

 Due to the directional formation of the filtration flow with a smaller (relative to the prototype) number of wells put into operation, the best technological indicators of the development of the site are ensured: greater oil production (by 352 tons / month) and less water cut by 3%.

 Example 2. It differs from the considered example by the formation of a more intense flow in the direction of the zone of increased oil saturation.

 For this purpose, first of all, part of the previously stopped injection wells located in front of the high oil saturation zone was commissioned (50 and 52; table 3).

 In addition, the formation of the flow is reinforced by the fact of an increase in injection into some of the injection wells from among those located in front of the zone of increased oil saturation (49, 51; table 4).

 Then, previously stopped production wells were put into operation located on the border with and within the oil saturation zone (9, 13, 14, 15 and 20).

 Thus, in terms of the number of injection wells and volumes of water injection, the development options for the recommended method and for the prototype are the same. The difference is in the number of producing wells (two more wells in the prototype) and, mainly, in the sequence of work with the wells to put them into operation. In the prototype there was no directed formation of the filtration flow in the direction and through the zone of increased oil saturation.

 A comparison of technological development indicators according to the known (table 1, column 5) and recommended methods (table 1, column 4) shows that the recommended method provides greater current oil production and less water cut. The difference in monthly terms is 739 tons and 3.7%, respectively.

 The application of the proposed method allows to increase oil recovery.

 Sources of information taken into account when preparing the application.

 1. Krylov A.P. and others. Designing the development of oil fields. M., Gostoptehnadzor, 1962.

 Surguchev M.L. Secondary and tertiary methods of increasing oil recovery. M., Nedra, 1985, 76--78.

Claims (3)

 1. A method of developing an oil reservoir, including pumping a working agent through injection wells, taking oil through production wells and shutting off part of the wells, characterized in that a development section with production and injection wells having a hydrodynamic connection between them is isolated, and a development section is isolated zone of increased oil saturation, forming a filtration flow through the zone of increased oil saturation by putting into operation stopped production wells located beyond the high oil saturation along its perimeter and within it.  2. The method according to claim 1, characterized in that the shut down injection wells located in front of the high oil saturation zone are additionally commissioned.  3. The method according to claim 2, characterized in that when commissioning shut-in wells, shut-down injection wells located in front of the high oil saturation zone and then stopped producing wells in the high oil saturation zone and beyond the perimeter are first put into operation.

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