RU2236558C1 - Method of well completion - Google Patents

Abstract

FIELD: oil and gas industry, particularly for completing oil and gas wells.

SUBSTANCE: method involves boring well over planned drilling depth; covering productive bed with sand; arranging cement bridge of 2-4 m height over sand layer; driving casing pipe up to reaching bed roof; cementing hole annuity of casing pipe up to well head; drilling cement bridge; washing out sand; deepening shank; cementing hole annuity around shank and punching shank within the thickness of productive bed.

EFFECT: retention of collecting properties of productive bed and reduced cost.

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Description

The invention relates to the oil industry and can be used when completing oil and gas wells.

There is a known method of completing a well opening an unstable reservoir, including opening the reservoir and creating a sump beneath it from under the casing of the well lowered to the top of the formation, creating a cylindrical cavity by expanding the open borehole under the cemented casing and placing filter material in this cavity. A cement-sand mixture is injected between the wall of the cavity and the slotted shank, after it has hardened, the cement-sand stone is crushed behind the shank slots against the highly permeable interval of the formation, creating a dense network of filtering cracks and microcracks in it. To improve the quality of cavity cementing during the injection of a cement-sand mixture, the slit section of the liner is lowered into the sump of the well, and after the mixture is placed in the cavity and above the cavity behind the liner, the liner is raised and its slot section is placed against the highly permeable interval of the formation. Moreover, the cement-sand mixture is injected taking into account the compensation of the volume of pipes extracted from the wells when the liner is lifted from the sump after the mixture is pumped (USSR author's certificate No. 1567761, class E 21 B 33/13, publ. 30.05.90).

The method improves the efficiency of fixing unstable rocks in the zone of occurrence of the reservoir at high speeds of water. The disadvantage of this method is the descent of the casing in the absence of parameters of the reservoir and possibly in the absence of the reservoir. In the presence of a productive formation, reservoir properties are deteriorated due to contact with the cement-sand mixture.

Closest to the invention in technical essence is a method of completing a well, including drilling from a conductor, lowering and cementing the annulus of the technical (casing) string, first opening the reservoir, lowering and cementing the annular space of the liner, lowering the level of fluid in the well and re-opening productive formation, while drilling from under the conductor and the descent of the technical column is carried out to the roof of the productive formation, and cementing its annulus well to the wellhead, as a result of which the technical string overlaps the high-pressure water-developing formations, the primary opening, cementing of the annular space of the liner and the secondary opening being carried out “at equilibrium” or at negative differential pressure (RF patent No. 2140521, class E 21 B 33/13 , publ. 1999 - prototype).

The method provides an increase in the quality of opening of productive deposits by reducing the amount of repression during technological operations to complete wells. The disadvantage of this method is to increase the intensity of the well. After the descent of the string and the deepening of the well, the absence of a productive formation is also possible under conditions when the costs of lowering and fixing the casing have already been made.

The proposed invention solves the problem of preserving the reservoir properties of the formation and saving costs.

The problem is solved in that in a method of completing a well, including drilling a well to a design depth, lowering the casing to the top of the reservoir and cementing the annulus of the casing to the wellhead, lowering the liner and cementing the annulus of the liner, according to the invention, fill the reservoir with sand after drilling and a cement bridge 2-4 m high is installed on top, after cementing the annulus of the casing, the cement bridge is drilled and the peso is washed And after cementing the annulus of the shank is perforated liner in the productive formation interval.

The features of the invention are:

1) drilling a well to a design depth;

2) the descent of the casing to the roof of the reservoir;

3) cementing the annulus of the casing to the wellhead;

4) the descent of the shank;

5) cementing the annulus of the shank;

6) after drilling, filling the reservoir with sand;

7) installation of a cement bridge from above;

8) the height of the cement bridge is 2-4 m;

9) after cementing the annulus of the casing, drilling a cement bridge;

10) leaching of sand;

11) after cementing the annular space of the liner, perforation of the liner in the interval of the reservoir.

Signs 1-5 are common with the prototype, signs 6-11 are the hallmarks of the invention

SUMMARY OF THE INVENTION

When completing the well, drill a well to the design depth, fill the reservoir with sand and install a cement bridge 2-4 m high on top, lower the casing to the cement bridge, cement the annulus of the casing to the wellhead, drill a cement bridge and wash the sand.

After filling the reservoir with sand and installing a cement bridge, the conditions for preparation of the wellbore by mounting are improved, the need for using a step cementing coupler or a two-stage sleeve cementing packer is eliminated.

If the strata are composed of stable rocks and saturated with the same fluids, then you can leave the wellbore open or lower the cementless liner-filter. This increases the area of filtration into the well.

If in the section several layers and layers are saturated with different-pressure fluids, the liner is lowered, the annular space of the liner is cemented and then a second opening is performed, for example, by perforation. In the absence of a reservoir, the casing is not lowered into the well. This reduces the cost of well construction. In the absence of cementing the annular space of the liner, contamination of the reservoir by cement is reduced. When using a cemented liner, repression on the formation during cementing and, consequently, cement contamination of the reservoir are significantly reduced. In this case, due to the diameter of the liner smaller than the diameter of the casing, the annular gap between the liner and the walls of the borehole increases, the volume of cement stone and, consequently, its durability increase.

An example of a specific implementation of the method

A well with a diameter of 215.9 mm is drilled to a design depth of 1840 m. Geophysical surveys are conducted. The roof of the upper productive layer is determined at a depth of 1802 m. The productive layers are filled with sand in the range of 1840-1794 m. A cement bridge is installed in the range of 1797-1794 m. Casing with a diameter of 168 mm is lowered to a depth of 1794 m and its annulus is cemented. A cement bridge is drilled with a 144 mm diameter chisel and sand is washed. A liner with a diameter of 144 mm is lowered and the annulus of the liner is cemented. The shank is perforated with a hydromechanical puncher and thereby a secondary opening is performed.

As a result, the productivity of the well was 25% higher than the productivity of neighboring wells in this section of the development of the oil reservoir, which indicates the preservation of reservoir properties of the reservoir. Cost savings during well construction amounted to 5%.

The application of the proposed method will save reservoir properties of the reservoir and save the cost of well construction.

Claims (1)

A method of completing a well, including drilling a well to the design depth, lowering the casing to the top of the reservoir and cementing the annulus of the casing to the wellhead, lowering the liner and cementing the annular space of the liner, characterized in that after drilling, fill the reservoir with sand and install a cement on top a bridge 2-4 m high, after cementing the annulus of the casing, drill a cement bridge and wash the sand, and after cementing the pipe space of the liner perforated the liner in the interval of the reservoir.