RU2448240C1 - Development method of oil deposits in carbonate reservoirs with water-oil zones - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: development method of oil deposits in carbonate reservoirs with water-oil zones involves drilling of vertical production and injection wells and wells with horizontal sections, intensification of oil production by pumping of chlorhydric acid, pumping of working agent to injection wells and oil extraction through production wells. Horizontal sections are performed in rows of vertical production wells. Acid is pumped in series to vertical wells in which horizontal section has been made, starting from the well which is the closest one to working face of horizontal section, with creation of hydrodynamic connection between vertical well to which the acid is pumped and horizontal section. When the time for the acid reaction elapses, reaction products are extracted from well shaft with horizontal section; then, some part of section is cut off so that hydrodynamic connection is formed between vertical well to which the acid has been pumped and the part of horizontal section, which is appropriate to it.

EFFECT: enlarging the coverage of oil deposit in carbonate reservoirs with water-oil zones, intensification of oil extraction, increasing oil removal coefficient with simultaneous cheapening of the process.

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Description

The invention relates to the oil industry and may find application in the development of oil deposits with carbonate reservoirs.

A known method of developing an oil reservoir (patent RU No. 2256069, IPC 8 E21B 43/16, published in Bulletin No. 19 dated July 10, 2005), including drilling vertical production and injection wells, taking oil through production wells and injecting a working agent through injection wells, low-permeability zones of the reservoir are detected, then lateral horizontal bores are drilled into low-permeability zones of the reservoir under reduced pressure in the well by erosion of the rock under high pressure fluid with the formation of thin and long channels. The erosion of the rock at the final stage is carried out with a solution of hydrochloric acid. The working agent is injected into low-permeability zones through horizontal lateral shafts with oil displacement into high-permeability zones at a well pressure of 5-10% lower than hydrostatic and through a cut out side window in the casing using a flexible pipe. Flushing fluid is supplied under a pressure of 15-20 MPa.

The disadvantage of this method is the low oil recovery due to the fact that a significant portion of the oil remains in the reservoir.

The closest in technical essence is a method of developing an oil reservoir with a carbonate reservoir (patent RU No. 2312212, IPC 8 E21B 43/27, published in bulletin No. 34 of 12/10/2007), including the injection of a working agent through injection wells, selection oil through production wells, drilling in wells of sidetracks and hydrochloric acid through sidetracks, while sidetracks in the form of radial holes are drilled and / or by a hydraulic monitoring method to a depth of 20 to 100 m from the calculation of 2-4 bore per meter of formation thickness I lower the ejector unit with the packer is pumped 10-15% strength hydrochloric acid solution in a volume of 1.5-3.0 m ^3, exposure process performed in response to mode bath for 2.5-3.5 hours, 4-6 carried multiple pulsed injection of hydrochloric acid solution into the reservoir in the cycle mode: 1-3 min — injection at a pressure of 1-4 MPa, holding for 4-6 minutes for reaction, completion of the injection in continuous mode, technological shutter speed for response for 2.5 -3.5 hours, carry out selection from the well up to 2.5 volumes of the injected solution of treatment with an ejector unit with reg tration parameters inflow from the formation, produce injection into the formation a second portion of 10-15% hydrochloric acid solution in a volume of 2.5-3.5 m ^3, which is carried out first in the pulsed mode 4-6 times: 4.6 minutes injection at pressure of 1-4 MPa, holding for 4-6 minutes for response, complete the injection in continuous mode, perform technological holding for 2.5-3.5 hours, carry out selection from the well with an ejector unit up to 2.5 volumes of the pumped treatment solution, pump in layer of the third portion of a 10-15% hydrochloric acid solution at the rate of 0.01-0.05 m ³ / m radial holes, first the injection is carried out in a pulsed mode 4-6 times in the cycle mode: 4-6 minutes injection at a pressure of 1-4 MPa, holding 4-6 minutes for reaction, complete the injection in a continuous mode at a pressure of 2-6 MPa carry out technological exposure for 2.5-3.5 hours, carry out a 4-6-fold pulsed injection of an acid solution with oil in a cycle mode: 1-3 minutes injection at a pressure of 1-4 MPa, exposure 4-6 minutes for reaction, spend extraction of reaction products and pollutants with an ejector unit or swabbing up to 2.5 injection volumes of the treatment solution with registration of the parameters of the inflow from the formation, groups of wells with radial opening of the formation in 5-, 7-point elements with an injection well in the center are combined, the working agent is injected in a cyclic mode into the central injection well, and oil is extracted through production wells . Further intensification of oil production - hydro-acid fracturing.

The disadvantages of this method are:

- firstly, it is a very labor-consuming and complicated technological process, since the acid is pumped in several portions in pulsed and continuous modes with different volumes of acid in several cycles, as well as with the subsequent 4-6-fold pulsed selling of the acid solution with oil;

- secondly, a small coverage of the reservoir with lateral shafts made in the form of radial holes by drilling and / or a hydro-monitor method to a depth of 20 to 100 m from the calculation of 2-4 shafts per meter of formation thickness, and, as a consequence, slight intensification of oil production and a small oil recovery factor (CIN).

The objective of the invention is to simplify and reduce the cost of the process of implementing the method, as well as increasing the coverage of oil deposits in carbonate reservoirs with oil-water zones by densifying the grid of wells by drilling wells with horizontal shafts through rows of vertical wells with the subsequent creation of hydrodynamic connections between them and, as a result, increase CIN.

The problem is solved by the method of developing oil deposits in carbonate reservoirs with oil-water zones, including the drilling of vertical production and injection wells and wells with horizontal sections, the intensification of oil production by the injection of hydrochloric acid, the injection of a working agent into injection wells, and the selection of oil through production wells.

What is new is that the horizontal sections are conducted along the rows of vertical production wells, the acid is pumped sequentially into the vertical wells along which the horizontal section is drawn, starting from the well closest to the bottom of the horizontal section, with the creation of a hydrodynamic connection between the vertical well into which the acid is pumped , and in the horizontal section, after the lapse of time for the acid reaction, reaction products are taken from the wellbore with a horizontal section, then cut off part of the horizontal section with the formation of a hydrodynamic connection between the vertical well into which the acid was pumped and the corresponding part of the horizontal section.

Figure 1 schematically shows the grid for the development of oil deposits in carbonate reservoirs with oil-water zones.

Figure 2 shows a section of a vertical row of wells with a well drilled through them with a horizontal section.

The method of developing oil deposits in carbonate reservoirs with oil-water zones includes drilling on a specific grid (see figure 1) of vertical producing 1; one';one''; 1 '''... 1 ⁿ and injection wells 2; 2 '; 2 ''; 2 '''... 2 ⁿ .

After this, an arrangement of the deposit is made and the development of the deposit is started, while the working agent is injected into the injection wells 2; 2 '; 2 ''; 2 '''... 2 ⁿ and oil extraction through vertical producing wells 1; one';one''; 1 '''... 1 ⁿ .

With the development of the reservoir, the volume of oil withdrawal decreases and the water cut of the produced products increases, and therefore oil production is intensified. Identify low-permeability zones of the reservoir and drill wells with horizontal sections 3; 3 '; ... 3 ⁿ in the rows of vertical production wells 1; one';one''; 1 '''... 1 ⁿ . For example, consider section AA (see FIG. 2) an oil reservoir in carbonate reservoirs with oil-water zones along rows of vertical wells, for example, a series consisting of three vertical production wells 1; one'; 1 '' through which a well with a horizontal section 3 is drilled. Next, an acid, for example hydrochloric acid (HCl) is injected sequentially into vertical production wells 1; one'; 1 '' along which a horizontal section 3 is drawn, starting from a vertical production well 1 '' closest to the bottom 4 of a horizontal section 3, with the creation of a hydrodynamic connection between the vertical well 1 '' into which acid is pumped and a horizontal section 3. over time, the reaction products are selected by any known method, for example, an ejector installation, from a wellbore with a horizontal section 3 through the mouth 5 of this well with a horizontal section 3.

Then, part of the horizontal section is cut off with the formation of a hydrodynamic connection between the vertical production well into which the acid was pumped and the corresponding part of the horizontal section, i.e. cut off 6 wells with a horizontal section 3 with the formation of a section 3 ₁ located before the bottom 4 of the well with a horizontal section 3. Thus, a hydrodynamic connection is created between section 3 ₁ of the wellbore with horizontal section 3 and vertical well 1 ''. Clipping 6 is performed by any known method, for example, by pouring cement mortar over a column of filling pipes (not shown in FIGS. 1 and 2) or by installing a blind packer plug (for example, as described in patent No. 2259466, IPC 8 E21B 33/12, published in Bulletin No. 27. 08.2005, in the horizontal section 3 (see figure 2). Similarly, from the bottom 6 to the side of the wellhead 4 of the well with the horizontal section 3, hydrodynamic communication between the vertical wells 1 ′ is carried out; 1 and the wellbore with a horizontal section 3 with the formation of successive from the bottom 4 of the horizontal section 3 of the corresponding cut-offs 6 '; 6 ''. Thus, hydrodynamic connections are formed: between a vertical well 1 'and a portion 3 ₂ in the wellbore with a horizontal portion 3; between the vertical well 1 and section 3 ₃ in the wellbore with the horizontal section 3. The above operations are performed with another row of vertical wells, for example, with a number of vertical wells 1 ″ ″; one''''; 1 ⁿ (see FIG. 1), through which a well was drilled with a horizontal section 3 ', and then with a number of vertical wells 1 ^{n + 1} , 1 ^{n + 2} ; 1 ^m , through which a well with a horizontal section of 3 ^{n was} drilled.

Further, the development of an oil deposit in carbonate reservoirs with oil-water zones is resumed, while the working agent is injected into injection wells 2; 2 '; 2 ''; 2 '''... 2 ⁿ and the selection of oil is carried out through wells with a horizontal section 3; 3 '; ... 3 ⁿ from producing wells 1; one';one'';one''';one''''; 1 ⁿ , 1 ^{n + 1} ; 1 ^{n + 2} ; 1 ^m , which are hydrodynamically connected with the corresponding cut off sections of the wellbore with the horizontal section 3; 3 '; ... 3 ⁿ .

The proposed method is simple and cheap to implement in comparison with the prototype, in addition, it allows you to increase the coverage of oil deposits in carbonate reservoirs with oil-water zones due to compaction of the grid of wells by drilling wells with horizontal shafts through rows of vertical wells with the subsequent creation of hydrodynamic connections between them, which leads to subsequent intensification of oil production and an increase in oil recovery ratio.

Claims (1)

A method for developing oil deposits in carbonate reservoirs with oil-water zones, comprising drilling vertical production and injection wells and wells with horizontal sections, intensifying oil production by injecting hydrochloric acid, pumping a working agent into injection wells and extracting oil through production wells, characterized in that the horizontal sections carried out in rows of vertical production wells, the acid is pumped sequentially into vertical wells, through which horizontal Astok, starting from the well closest to the bottom of the horizontal section, creating a hydrodynamic connection between the vertical well into which acid is pumped and the horizontal section, over time, the reaction products are taken from the wellbore with the horizontal section over the acid reaction, then part of the horizontal section is cut off section with the formation of a hydrodynamic connection between the vertical well into which the acid was pumped and the corresponding part of the horizontal section.

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