RU2263770C1 - Downhole equipment - Google Patents

Abstract

FIELD: oil industry, particularly for well operation.

SUBSTANCE: downhole equipment comprises casing pipe, cement bridge and liner screwed on casing pipe through sub with left-handed thread. Downhole equipment also has annular hydraulic packer adapted to provide stepped cementing and installed on the liner, grouting layer arranged under the packer and anticorrosion liquid located in casing annulus above annular hydraulic packer.

EFFECT: increased diameter of new inclined well bore and, as a result, increased oil recovery, possibility to remove casing pipe out of well and drilling new inclined bore from point located above annular hydraulic packer, wherein inclined bore diameter is equal to initial well diameter.

1 ex, 3 dwg

Description

The invention relates to the oil industry and may find application in the operation of the well.

Known well equipment, including a casing string, cement stone in the annulus and a tubing string [Techniques for substantiating the choice of designs of the faces of oil producing wells (RD 39-2-771-82)].

Known equipment allows you to select oil from the reservoir, however, for drilling a new deviated wellbore, the equipment requires significant refinement.

Closest to the invention in technical essence is the equipment of the well, including casing, cement stone in the annulus, cement bridge and the tubing string (RF Patent No. 2209941, publ. 2003.08.10 - prototype).

Known equipment allows you to select oil from the reservoir and drill a new deviated wellbore. However, the diameter of the new deviated wellbore is smaller than the diameter of the main wellbore. As a result, the flow rate of the well is reduced.

The proposed invention solves the problem of increasing the diameter of the new deviated wellbore and, as a result, increasing the flow rate.

The problem is solved in that the well equipment, including the casing and cement bridge, according to the invention, comprises a liner screwed onto the casing through a left-hand threaded sub, an annular hydraulic packer for step and lip cementing on the liner, a wellhead sealant and a cement layer under the annular hydraulic packer.

The features of the invention are:

1) casing;

2) cement bridge;

3) shank;

4) sub with left-hand thread;

5) annular hydraulic packer for step and cuff cementing;

6) the grouting layer under the annular hydraulic packer.

Signs 1 and 2 are common with the prototype, signs 3-6 are the essential distinguishing features of the invention.

SUMMARY OF THE INVENTION

When developing an oil reservoir, a situation often arises when it is possible to select oil from a part of the reservoir that is limited by the well influence zone. At the same time, the neighboring section of the reservoir at a relatively small distance from the well of about 30-150 m remains undeveloped. The reason for this phenomenon may be the rise of watering cones, the heterogeneity of the reservoir, the direction of formation fluids established in the formation, etc. To develop the adjacent section of the reservoir it is advisable to drill an additional new inclined or horizontal wellbore from the existing well to the neighboring section.

In addition, drilling an additional new inclined or horizontal wellbore is advisable when developing a multilayer oil reservoir during the selection of oil from a new reservoir at a new depth.

Existing well equipment provides for the kick-in of an additional new inclined or horizontal wellbore from an existing well casing. To pass the drilling equipment in the existing casing, it is necessary to use equipment of a smaller diameter. A new borehole of a smaller diameter is obtained, due to which the well loses productivity. The proposed invention solves the problem of maintaining when drilling the diameter of a new inclined or horizontal wellbore, equal to the diameter of the main wellbore, and, as a result, increase the flow rate of the well.

To solve the set tasks, well equipment is used, including a casing string, a liner screwed onto the casing through a left-hand threaded sub, a PDM type hydraulic packer (two-stage sleeve packer) on the liner, a grouting layer under the annular hydraulic packer and wellhead sealant.

Figure 1 presents the proposed equipment during the operation of the well. In the well 1 with wellhead sealant 2, a casing 3 with a liner 4 is installed, screwed by means of a sub 5 with left-hand thread and secured with an annular hydraulic packer 6, under which the cement layer 7 is placed.

Figure 2 presents the proposed equipment during the elimination of the main wellbore 1. Shown is a cement bridge 8 installed in the lower part of the well 1 above the liner 4 and annular hydraulic packer 6.

Figure 3 presents the proposed equipment when drilling a new inclined or horizontal shaft 9 on the same or another layer.

The equipment operates as follows.

An annular hydraulic packer 6 is installed on the liner 4. A liner 4 and a casing 3 are connected with the left-hand thread through an adapter 5. The assembled structure is lowered into the well 1 and the wellhead sealant 2 is installed. The grout is injected, the grout is formed 7 and the excess grout is washed over annular hydraulic packer, fill annular space above annular hydraulic packer with anticorrosive fluid, close flushing holes in annular hydraulic th packer. The use of an annular hydraulic packer allows for stepwise and cuff cementing of the well. At the end of the cement hardening, the quality of cementing is determined, a cement cup is drilled and the well is deepened to the design depth. After conducting geophysical surveys, measures are taken to develop the well and to prepare for oil production, and provide pumping equipment. Lead the selection of oil. After depletion of reserves of the reservoir in the near-wellbore zone, well 1 is stopped. Pumping equipment is removed. Cementing of productive intervals is carried out, the production casing is turned on the left sub and lifted to the surface. A cement bridge is installed above the annular hydraulic packer. In this position, it becomes possible to drill at the initial diameter of well 1 and use drilling equipment of the same diameter as for the initial drilling of well 1. Organize a new artificial face 15-30 meters above the remaining "head" of the production string and drill a new inclined or horizontal wellbore 9 of well 1 into an undeveloped section of the formation. The same casing 3 is lowered, also equipped with a liner 4, a sub 5. Further well equipment is carried out, as with the main shaft equipment. Oil is taken from the undeveloped section of the reservoir before it is developed.

It is possible to transfer the oil extraction site in this way from one well repeatedly until the reserves are completely depleted in the reservoir.

Concrete example

An oil well 1 is drilled on a deposit site with a depth of 970 m and a diameter of 215.9 mm. Well 1 is supplied with casing 3 with a diameter of 146 mm with a mouth seal 2 and with a shank 4 with a diameter of 146 mm 150 m long, screwed from below onto the casing 3 through a sub 5 with left-hand thread, and an annular hydraulic packer. An annular hydraulic packer 6 is installed 150 m above the reservoir. The grouting layer 7 is installed. The annular space is plugged in the interval of the reservoir to the washing holes in the annular hydraulic packer. The annular space above the annular hydraulic packer is filled with an anticorrosive fluid (for example, degassed Devonian oil, or mud, or industrial water with the addition of a corrosion inhibitor). A casing of tubing with a diameter of 76 mm, a casing string and a sucker rod pump are lowered into the well 1. Oil is taken through well 1. After depletion of reserves of the reservoir and watering the produced products to 99.7%, well 1 is stopped. Pumping equipment is removed. Carry out cementing of the productive interval. The casing is turned out of the sub 5 and released. Released casing 3 is lifted from well 1 and a cement bridge is installed in the range of 830-780 m. A new artificial face is organized at a depth of 815 m. From this depth, a new inclined wellbore with a diameter of 215.9 mm is drilled into an undeveloped section of the formation 75 m apart. from the main wellbore 1. The same casing 3 is lowered, also equipped with a liner 4 installed by means of a sub 5 and an annular hydraulic packer 6. Further equipment of the well 1 is carried out as the equipment of the main wellbore. Oil is taken from the undeveloped section of the reservoir to a water cut of produced products of 99.7%. After this operation, repeat and transfer the new wellbore to a new section located diametrically opposite to the previous one.

As a result of the application of the proposed equipment, the problem of increasing the diameter of a new deviated wellbore is solved, and, as a result, the flow rate of the well increases. The increase in flow rate is about 20-50% compared with the flow rate of a well drilled using known equipment.

The application of the proposed method will increase the flow rate of the well and the oil recovery coefficient.

Claims (1)

Well equipment, including casing and cement bridge, characterized in that it contains a liner screwed onto the casing through a left-hand threaded sub, an annular hydraulic packer for step cementing mounted on the liner, a grouting layer under the packer and anticorrosive fluid in the annulus above annular hydraulic packer, while the equipment provides the ability to extract the casing from the well and drilling above the annular hydraulic packer n new inclined wellbore of the same diameter as the initial diameter of the well.

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