RU2369724C1 - Method of oil deposit development - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention refers to oil industry and can be implemented at development of oil deposit. The essence of the invention is as follows: the method consists in pumping working agent via pressure wells, in withdrawing oil via producing wells and in boring additional producing wells into blind up- and/or stagnant holes. Drilling is carried out up to a producing bed, then a cased column is lowered and cementing of bottomhole space is performed; further the well is drilled with a bore bit of a smaller diametre up to the bottom of the bed with mineralised water used as a drilling agent, then the well is cemented and perforated or a slotted strainer is installed. Not later, than in 120 hours from the moment of perforation completion or lowering of the slotted strainer a flow string with an anchor shoe, a shutoff and a pusher of a ball of the shutoff is installed in the producer through a well head seal; well fluid is replaced by driving oil into the flow string at volume of well borehole; replaced well fluid is withdrawn via annular gate; and oil driving is completed with fresh water in volume equal to internal volume of the flow string from the well head to the shutoff. Change of well fluid with oil is performed at rate facilitating replacement of fluid with a piston; the process of change is controlled by pressure and consumption of pumped oil; also consumption of oil corresponds to less 6-8 l/sec at pressure at well head 6-7 MPa. An inserted sucker-rod pump is lowered on rods into the anchor shoe; simultaneously the ball of the shutoff is pressed by the pusher and the well is put into operation.

EFFECT: capability to perform outbreak measures at well, maintaining of collector properties of bed and increased yield of oil from deposit.

1 ex, 3 dwg

Description

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

A known method of constructing a well of a multilayer oil field, involving drilling a well to the design depth, lowering the production casing and cementing it. After opening the first oil reservoir by drilling, the well is fixed. Further, the drilling of the well continues with a bit of smaller diameter, revealing the remaining productive formations with subsequent cementing of the drilled part of the well. The last tubing shank pipes extending opposite the first oil reservoir are selected from easily drilled material, for example fiberglass. In this case, before the cementing of the well, a disconnector is installed opposite the producing formation, which is lowered into the well as a casing string, followed by cementing of the separated part of the well beneath and above the disconnector (RF Patent No. 2161239, class E21B 33/13, published 2000.12.27).

The method ensures the conservation of the reservoir properties of the reservoir, however, the method does not provide blowout measures at the well.

Closest to the proposed invention is a method of developing a multilayer oil reservoir, including drilling a well to the bottom of the upper formation, conducting well research, lowering the casing and cementing the annulus, continuing to drill a smaller bit to the bottom of the lower formation, conducting well research, developing the lower formation installation of a cement bridge in the interval of the lower layer, perforation of the interval of the upper layer and development of the upper layer. According to the invention, the drilling of a well to the bottom of the upper formation is carried out using saline water as a drilling fluid with a transition to a clay mud at the end of the drilling. Drilling is continued with a smaller diameter bit to the bottom of the lower formation. This is accomplished using mineralized water as the drilling fluid, with the transition to clay mud at the end of drilling. After the development of the lower reservoir, reservoir pressure is reduced in the lower reservoir in the near-wellbore zone. Clay mortar is injected under the roof of the lower layer on mineralized water and fresh water is pumped under the roof of the lower layer (RF Patent No. 2323330, class E21B 43/14, published. 2008.04.27 - prototype).

The known method does not provide blowout measures at the well.

The proposed invention solves the problem of providing blowout control measures at the well, preserving reservoir properties of the formation and increasing oil recovery of the reservoir.

The problem is solved in that in the method of developing an oil reservoir, which includes injecting a working agent through injection wells and taking oil through production wells, drilling additional production wells to a producing formation, lowering the casing string and cementing the annulus, continuing to drill a smaller diameter bit to the bottom of the formation , cementing and perforating or installing a slotted filter, according to the invention, the drilling of additional production wells is carried out in dead ends and / or stagnant zones, no later than 120 hours from the moment of completion of the perforation or descent of the slit filter in the production well, a tubing string with an anchor shoe, a shut-off valve and a ball valve pusher are installed through the wellhead seal, the well fluid is replaced by selling oil into the tubing string pipes in the borehole volume, the displaced borehole fluid is taken through the annular valve, the sale of oil with fresh water is completed in an amount equal to the internal volume of the tubing string x pipes from the mouth to the shutoff valve, the replacement of the borehole fluid with oil is carried out at a speed that provides piston displacement of the fluid, the replacement process is controlled by the pressure and flow rate of the pumped oil, while the oil flow rate is less than 8 l / s with a pressure at the mouth of 6-7 MPa, the plug-in sucker-rod pump is lowered onto the rods into the anchor shoe and at the same time the ball of the shutoff valve is pressed through the pusher and the well is put into operation.

The features of the invention are:

1. injection of a working agent through injection wells;

2. the selection of oil through production wells;

3. drilling additional production wells to the reservoir;

4. casing descent;

5. cementing annular space;

6. continued drilling of the well with a smaller diameter bit to the bottom of the formation using saline water as a drilling fluid;

7. cementing and perforation or installation of a slit filter;

8. drilling of additional production wells into dead-end and / or stagnant zones;

9. no later than 120 hours after the completion of the perforation or descent of the slit filter in the production well through the wellhead seal, installation of a tubing string with an anchor shoe, a shut-off valve and a pusher of a shut-off valve ball;

10. replacement of the borehole fluid by selling oil into the tubing string in the volume of the wellbore;

11. the selection of the displaced well fluid through the annular valve;

12. completion of the sale of oil by fresh water in an amount equal to the internal volume of the tubing string from the mouth to the shutoff valve;

13. replacement of the well fluid with oil at a speed that provides piston displacement of the fluid;

14. control of the replacement process by pressure and flow rate of the pumped oil;

15. oil consumption less than 8 l / s. at a pressure at the mouth of 6 - 7 MPa;

16. descent on the rods of the plug-in sucker-rod pump into the anchor shoe and simultaneous squeezing of the shut-off valve ball through the pusher;

17. launching a well into operation.

Signs 1-7 are common with the prototype, signs 8-17 are the salient features of the invention.

SUMMARY OF THE INVENTION

During the development of the oil reservoir, non-drained and dead-end zones remain in which the initial oil saturation was preserved. Production wells are drilled into these zones and oil is taken. However, at the opening of such zones, the bottomhole zone of the well is clogged, which leads to a decrease in permeability and to underdevelopment of the reserves of the reservoir. The proposed method solves the problem of increasing oil recovery deposits. The problem is solved as follows.

When developing an oil deposit, the working agent is pumped through injection wells and oil is taken through production wells. Drilling a production well to the top of the formation, lowering the casing and cementing the annulus, continuing to drill a smaller bit to the bottom of the formation, cementing and perforating or installing a slotted filter are carried out into non-drained and dead-end zones. Not later than 120 hours from the moment of completion of the perforation or descent of the slit filter in the production well, a tubing string with an anchor shoe, a shut-off valve, and a pusher of a shut-off valve ball is installed in the well through the wellhead seal. This period is due to the increasing time of mudding of the bottomhole zone after opening the reservoir. After 120 hours, the well loses the permeability of the bottomhole zone by half or even more. To preserve the permeability of the bottom-hole zone of the well, the well fluid is replaced by selling oil into the string of tubing in the volume of the wellbore. In this case, the oil pressure overcomes the spring resistance of the shutoff valve. The displaced borehole fluid is taken through an annular valve. Complete the sale of oil with fresh water in an amount equal to the internal volume of the tubing string from the mouth to the shutoff valve. Thus, oil is placed in the well in the space between the casing and the tubing string, and the tubing string to the anchor shoe is filled with fresh water. The bottom hole is under a layer of oil, in such conditions, the process of mudding of the bottom hole zone of the well is suspended. The replacement of well fluid with oil is carried out at a speed that ensures piston displacement of the fluid, which ensures replacement and lack of mixing of fluids. The replacement process is controlled by the pressure and flow rate of the pumped oil. Oil consumption is less than 8 l / s at the mouth pressure of 6-7 MPa. The plug-in sucker rod pump is lowered onto the rods into the anchor shoe and at the same time the ball of the shut-off valve is pressed through the pusher, providing the bottom hole message with the space of the tubing string, and the well is put into operation.

When using sucker-rod pumps in wells drilled with a lightweight mud or in a depression, well killing with weighted fluids is not allowed due to the negative effect of the fluids on the reservoir properties of the formation. Therefore, the descent of the tubing string and pump must be carried out without jamming, which leads to fountain manifestations. The proposed method and the equipment used eliminates gushing during the descent of the tubing string.

The layout diagram of the equipment used is presented in figures 1, 2 and 3.

In the production well 1, through the wellhead stuffing box 2, a tubing string 3 with an anchor shoe 4 and a shutoff valve 5, a plug-in pump 6, a rod 7 and a rod string 8 are installed. For direct flushing, the well reinforcement is equipped with a valve 9. For receiving fluid from the barrel when flushing, there is an annular valve 10. The shut-off valve 5 includes a ball 11, a spring 12 and an inverted seat 13.

Figure 2 shows the position of the shut-off valve 5 in the closed position. Figure 3 presents the position of the shut-off valve 5 in the open state after the descent of the pump 6.

Not later than 120 hours after completion of the perforation or descent of the slit filter, the well fluid is replaced by selling oil into the tubing string 3 in the volume of the wellbore 1. At the same time, the spring resistance 12 of the shutoff valve 5 is overcome by the oil pressure. The displaced well fluid is drawn through the annular valve 10. Complete the sale of oil with fresh water in an amount equal to the internal volume of the tubing string 3 from the wellhead 1 to the shutoff valve 5.

After the cessation of the sale, the ball 11 under the action of the spring 12 overlaps the bore of the inverted seat 13, which ensures that there is no gushing of liquid from the bottom of the well 1. The insert pump 6 is lowered onto the rod string 8 into the anchor shoe 4 and at the same time, the ball 11 is pressed through the pusher 14, providing communication of the bottom hole with the space of the tubing string 3. Connect the rod string to the rocking machine (not shown) and start the pump 6 in operation.

At the next underground repair of the well when the pump 6 is disengaged from the anchor shoe 4, the ball 11 overlaps the passage section of the inverted seat 13. In this position, the pump 6 is lifted without killing the well 1.

Concrete example

An oil reservoir is developed with the following characteristics: depth 1100 m, reservoir pressure 10 MPa, reservoir temperature 24 ° C, porosity 0.12, permeability 0.002 μm ² , oil saturation 0.8, direction of natural fracturing 310 °, oil viscosity 28 MPa · s, oil density 920 kg / m ³ , carbonate reservoir fractured-pore-cavernous. The working agent is pumped through injection wells, oil is taken through production wells. Non-drained and dead-end zones are identified on the deposits, which are undisturbed sections of the reservoir due to the presence on the earth's surface of the territory where it is impossible to install a derrick for directional drilling or sections of the reservoir where production or injection wells are liquidated for technical reasons. With a 215.9 mm drill bit, a production well is drilled in the dead end zone to the reservoir at a depth of 1100 m, the casing is lowered and the annulus is cemented. Drilling is continued with a bit with a smaller diameter of 114 mm to the bottom of the formation at a depth of 1250 m. A slotted filter is installed in the interval of the productive formation. 12 hours after the completion of the descent of the slit filter in the production well, a column of tubing with an anchor shoe, a shut-off valve and a pusher of a shut-off valve ball is installed through the wellhead seal. The well is filled with the drilling fluid. Replace the well fluid by selling oil into the tubing string in the borehole volume equal to 21 m ³ . At the same time, the spring pressure of the shutoff valve is overcome by the oil pressure. The displaced borehole fluid is taken through an annular valve. Complete the sale of oil with fresh water in a volume of 2.7 m ³ equal to the internal volume of the tubing string from the mouth to the shutoff valve. Replacing the well fluid with oil is carried out at a rate of less than 7 l / s, providing piston displacement of the fluid. The replacement process is controlled by the pressure and flow rate of the pumped oil. Oil consumption is less than 7 l / s at a mouth pressure of 7 MPa. The plug-in sucker rod pump is lowered onto the rods into the anchor shoe and at the same time the ball of the shut-off valve is pressed through the pusher, providing the bottom hole message with the space of the tubing string, and the well is put into operation.

As a result, it is possible to select oil from the dead-end and stagnant zones of the reservoir and increase oil recovery by 1.5%.

The application of the proposed method will improve oil recovery deposits.

Claims (1)

A method of developing an oil reservoir, including pumping a working agent through injection wells and extracting oil through production wells, drilling additional production wells to a producing formation, lowering the casing and cementing the annulus, continuing to drill a smaller diameter bit to the bottom of the formation, cementing and perforating or installing slotted filter, characterized in that the drilling of additional production wells is carried out in the dead-end and / or stagnant zones no later than 120 hours from the moment To complete the perforation or descent of the slit filter, a tubing string with an anchor shoe, a shut-off valve and a ball valve-pusher pusher is installed in the production well through the wellhead seal, and the well fluid is replaced by selling oil into the tubing string in the volume of the wellbore, the displaced borehole fluid is taken through the annular valve, the sale of oil with fresh water is completed in an amount equal to the internal volume of the tubing string from the mouth to the valve from projection, the replacement of the borehole fluid with oil is carried out at a speed that ensures piston displacement of the fluid, the replacement process is controlled by the pressure and flow rate of the pumped oil, while the oil flow rate is less than 6-8 l / s at a pressure on the wellhead of 6-7 MPa, lowered on rods the plug-in sucker-rod pump is used to squeeze the ball of the shutoff valve through the pusher through the pusher and start the well into operation.

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