RU2418943C1 - Procedure for development of oil deposit - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: procedure consists in drilling pressure and producing wells. Upon pumping plugging-back solution below water-oil contact oil is withdrawn above the level of oil-water contact through producers on tops of dome-shaped highs. Following treatment with chemical reagents working substance is pumped via pressure wells hydro-dynamically communicated with the given wells within the boundaries of the given payout bed. Below oil-water contact plugging-back solution in form of hydrophilic polymer is additionally pumped through the pressure wells and producers simultaneously. Working substance is pumped into the pressure wells above water-oil contact. Chemical reagents are pumped into producers above water-oil contact cyclically in form of gas or gaseous fluid. ^ EFFECT: decreased oil watering due to reduced volume of water ingress to bottomhole; raised yield of reservoir without additional exposure of producer above packer. ^ 4 dwg

Description

The invention relates to the oil and gas industry, to the field of development of oil fields confined to dome-shaped uplifts, and can be used in the final stage of field operation.

A known method of developing an oil reservoir (patent RU No. 2378502, IPC 8 E21B 43/20, published in Bulletin 1 of January 10, 2010), including drilling injection and producing wells, injection of a displacing agent and forced selection of reservoir products through wells with filter below the current position of the oil-water contact and the selection of oil from the bed interval of the formation by oil producing wells located in elevated sections of the structure, characterized in that oil producing wells in elevated sections of the structure are perforated in the bedside the interval of the formation and below the oil-water contact, the initial mode of operation involves the operation of the cover portion of the formation by these wells when injecting the displacing agent through the wells with a filter located below the current position of the oil-water contact, then, when pulling the water cone to the bedside interval of the formation, they switch to the second mode of operation, providing forced fluid withdrawal by oil producing wells from the interval of the reservoir below the oil-water contact with simultaneous injection and forced selection of the displacing agent through wells with a filter located below the current position of the oil-water contact, the second mode of operation is used until a stable oil content is established in the production of oil wells, then the initial mode of operation is returned, the two modes of operation are sequentially alternated, and periodically during use of the second mode mutually replace wells for injection and forced selection of the displacing agent.

The disadvantages of this method are:

- firstly, for the implementation of the method, perforation of production wells is required both in the near-bed interval of the formation and below the boundary of the oil-water contact (WOC), which entails additional material and financial costs;

- secondly, for effective development of the field, it is necessary to alternate the first and second modes of operation in a timely manner, non-compliance with which, for example, a time delay with a change in the operating mode, can lead to flooding of the produced products.

The closest in technical essence and the achieved result is a method of developing an oil field (patent RU No. 2330945, IPC 8 E21B 43/16, published in bul. 22 of 08/10/2008), including drilling injection and production wells, injection of a working agent through injection wells, oil production through production wells, the allocation of areas of domed uplifts exceeding the absolute elevations of the formation, characterized in that in the wells located on the tops of the domed uplifts, cutting off the packer, isolate the flooded hour open the reservoir with chemical reagents and / or grouting fluid, pushing with a buffer fluid, after which, to increase oil recovery, the part of the opened reservoir is further treated with chemical reagents above the packer, after additional processing of the reservoir, the reservoir is further opened above the packer, but below the roof of the reservoir then use these wells as production wells, the remaining wells that are connected hydrodynamically with these wells contact within this productive formation, transferred into injection, in which pump working agent.

The disadvantages of this method are:

- firstly, when implementing the method, it is necessary to perform an additional opening of the reservoir above the packer, which entails additional material and financial costs;

- secondly, residual oil withdrawal volumes are low, since residual oil withdrawal is not forced;

- thirdly, a constant flow of water from the zone below the border of the oil-water contact (WOC), i.e. from the flooded part of the reservoir.

The objective of the invention is to reduce the water cut of produced oil by reducing the volume of water flow to the bottom of the producing wells and to increase the volume of oil extraction by improving oil recovery without additional opening of the reservoir above the packer.

The problem is solved by a method of developing an oil field, including drilling injection and production wells, after pumping cement slurry below the oil-water contact, oil is produced above the level of water-oil contact through production wells located on the tops of dome-shaped elevations, and after processing with chemical reagents, the working agent is injected through injection wells associated hydrodynamically with producing wells within a given reservoir.

It is new that the grouting solution is injected below the oil-water contact in the form of a hydrophilic polymer additionally through injection wells simultaneously with the production wells, and the working agent is injected into the injection wells above the oil-water contact, and chemical agents are pumped into the production wells above the oil-water contact cyclically in in the form of gas or carbonated liquid.

The figure 1 shows a grid of injection and production wells in the field.

Figure 2 schematically shows a section of a dome-shaped elevation during the injection of cement slurry in the form of a hydrophilic polymer.

Figure 3 schematically shows a section through a dome-shaped elevation during water injection and oil recovery.

The figure 4 schematically shows the layout of the producing well.

The proposed method is as follows.

Drilling of wells 1, 2, 3, 4, 5 '... 5 ^{n is} performed (see Figs. 1 and 2) and opening of the reservoir 6 in each of these wells. After that, wells 1, 2, 3, 4, 5 '... 5 ⁿ are launched into production as production wells. During operation, reservoir 6 is gradually flooded, oil withdrawal volumes are reduced, and oil water cut from wells 1, 2, 3, 4, 5 '... 5 ⁿ is increased, and therefore the economic efficiency of developing this oil field is reduced.

Basically, wells 1 and 4 are flooded (see FIG. 2), located at the base of dome-shaped elevations below the absolute elevations of the productive formation 6, and wells 2 and 3, located at the tops of dome-shaped elevations 7, exceeding the absolute elevations of the reservoir 6, are partially flooded, only in the lower interval of opening, and in the upper interval of opening, that is, below the top of the dome-shaped elevations 7, there are areas of residual oil 8.

To reduce water cut and increase oil withdrawal volumes, as well as increase the economic efficiency of developing this oil field in wells 1, 2, 3, and 4 through their lower opening intervals below the oil-water contact (MIC) boundary, i.e. in the flooded part 9 of reservoir 6, in order to reduce fluid mobility in the aquifer, cement slurry is injected in the form of a hydrophilic polymer, for example a phase permeability modifier [WCA-1-hydrophilic copolymer DMDAAC (commercial name - supplier to the Russian Federation: Jiangsu international trade JI Jin Nao De, Ltd, China) - a cationic water-soluble monomer: Diallyl Dimethyl ammonium chloride or Diallyldimethylammonium chloride (chemical formula: C ₈ H ₁₆ NCl; molecular weight: 161.5)] and Staple body - acrylamide (TU-6-01-1049-92, manufactured by OptKhimSnab-Volga LLC, Kazan), which is able to bind and retain water in the reservoir, which does not impede the flow of oil and reduces the water cut to the bottom of wells 2 and 3, at the opening intervals of which there are zones of residual oil 7.

The modifier reduces the relative water permeability of the rock and does not lead to a change in the permeability of the rock for hydrocarbons, while it is not a physical block and delays or blocks the flow of water in the matrix of the reservoir 5, does not prevent the influx of oil. Its principle of operation is based on the fact that a highly hydrophilic elastic polymer chain of medium molecular weight lengthens upon contact with water and contracts upon contact with hydrocarbons (“accordion effect”).

Before injection into the well, a grout is prepared in the form of a hydrophilic polymer solution in the following ratio:

- hydrophilic copolymer DMDAAC - 65%; - acrylomide - 35%.

with the addition of 20-80 liters of the above solution per 1 m ^{3 of} water.

An additional example of a hydrophilic polymer can be a cement slurry based on DP9-8177 polyacrylamide according to TU 2458-010-70896713-2006 (manufacturer of OptKhimSnab-Volga LLC, Kazan), and chromium acetate (trivalent chromium salt is used as a crosslinker). ), alkali (NaOH), baking soda.

Also, other well-known solutions of hydrophilic polymers described in the patents (RF patent No. 2180039, IPC ЕВВ 43/22, publ. In bull. No. 6 of 02.27.2002; RF patent №2169258, IPC Е21В 43 / 22, published in bulletin No. 17 of 06/20/2001; RF patent No. 2382185, IPC ЕВВ 43/22, publ. In bulletin No. 5 of 02/20/2010).

The injection through wells 1, 2, 3, 4 of a hydrophilic polymer solution (see FIG. 2) and its injection into the flooded part 9 of the reservoir 6 with a buffer fluid is carried out in any known manner, for example, as described in patent (patent RU No. 2330945, IPC 8 ЕВВ 43/20, published in Bulletin No. 22 of 08/10/2008) along a pipe string using a squeeze plug (not shown in Figs. 1, 2, 3, and 4).

As a result, the lower opening intervals of wells 1, 2, 3, and 4, located below the BHC boundary, are insulated with a hydrophilic polymer solution.

Geophysical studies are carried out and it is determined that wells 1, 2, 3, 4 are hydraulically interconnected.

Therefore, wells 1, 4 are put into operation as injection wells, and the injection of a working agent, for example, wastewater, is carried out in the upper intervals into the zones of residual oil 8 of the reservoir 8 of the dome-shaped rise 7 above the level of the oil-water supply (see Fig. 3), since through the lower intervals openings below the level (WOC) in the flooded part 9 of the reservoir 6 is injected hydrophilic polymer solution.

Wells 2 and 3 are put into operation as producing wells, while oil is taken from the upper opening intervals located above the BHC boundary, i.e. zones of residual oil 8 of the reservoir 6, while the lower opening intervals of wells 2 and 3 remain isolated hydrophilic polymer solution.

If the water cut of the produced oil increases above the economically viable amount of operation, the source of the water cut is determined and the hydrophilic polymer solution is re-pumped and sold into this well, as described above.

In order to increase the oil recovery of productive formation 6 and the volumes of oil withdrawal to production wells 2 and 3, through chemical breakdown intervals above the oil-water contact, chemical agents are injected into the zones of residual oil 8 of productive formation 6, using gas or aerated liquid in any known manner . For example, deaf packers 10 are first lowered into production wells 2 and 3 (see FIG. 4), which are installed at the level of the oil-water contact (VOC) boundary, and then pipe pipes 11 are lowered with pumps 12, respectively, of any known design, so that the lower end the pipe string 11 was opposite the upper opening intervals of production wells 2 and 3.

Then, in the upper opening intervals of production wells 2 and 3 into the zones of residual oil 8 of the productive formation 6 above the BHC, for example, gas or carbonated liquid is injected through the annulus 13 between the pipe string 10 and well 2.

Having pumped into the zones of residual oil 8 of the productive formation 6 of producing wells 2 and 3 the estimated volume of gas or carbonated liquid, determined experimentally, their injection is stopped.

The selection of oil begins from the zones of residual oil 8 of the productive formation 6 of producing wells 2 and 3, is carried out using pumps 12 of any known design, which raise oil to the surface along the internal spaces 14 of the pipe columns 11.

Oil production from the zones of residual oil 8 of the productive formation 6 of production wells 2 and 3 is continued until the flow rate drops to an economically feasible value, after which the injection of gas or carbonated liquid into the zones of the residual oil 8 of the productive formation 6 of production wells 2 and 3 is resumed and the process is repeated as described above.

The proposed method for developing an oil field allows to reduce the water cut of produced oil by reducing the amount of water entering the bottom of producing wells due to the reliable isolation of the flooded part of the reservoir by hydrophilic polymer solutions, and the increase in oil recovery is achieved by improving oil recovery by cyclically injecting gas or carbonated liquid into the zone of residual oil of the reservoir without additional opening of the reservoir above packer, thereby reducing material and financial costs.

Claims (1)

A method of developing an oil field, including drilling injection and production wells, after pumping cement slurry below the oil-water contact, oil is produced above the level of water-oil contact through production wells located on the tops of dome-shaped elevations, after processing with chemical reagents, the working agent is injected through injection wells connected hydrodynamically with producing wells within a given reservoir, characterized in that tamp injection a solution of water below the oil-water contact in the form of a hydrophilic polymer is additionally produced through injection wells simultaneously with the production wells, and the working agent is injected into the injection wells above the oil-water contact, and the chemical agents are pumped into the production wells above the oil-water contact cyclically in the form of gas or carbonated liquid.

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