RU2105126C1 - Device for adjusting bottom-hole pressure in process of drilling - Google Patents

Abstract

FIELD: oil production industry; bore-hole drilling technology. SUBSTANCE: device has body with packing member, and installed inside this member is pipe which is hydraulically connected with above- and under-packing annular space. Packing member is made in the form of collar with reinforced ring. Internal space of it through non-return valve with calibrated hole is connected with internal space of drilling string. Device ensures local dynamic disconnection of annular space of drilling tool in adjusting bottom-hole pressure in process of drilling bore-hole at maintaining round circulation of liquid through drilling tool. EFFECT: higher efficiency. 3 dwg

Description

 The invention relates to well drilling and is intended for the mining industry.

 There are various designs of blowout control equipment [1].

 Their disadvantage is the high elevation of the base of the tower from the Earth’s surface during well construction, the complexity of installation and operation of all types of blowout control equipment, especially in winter.

 Known packer preventer for uncoupling the layers while drilling the well [2], adopted for the closest analogue.

 This preventer packer is designed to pack the well at a predetermined depth to prevent oil and gas occurrences and subsequent weighting of the drilling fluid over the developing formation.

 The disadvantage of the packer preventer for the separation of the layers are the structural and technological difficulties of manufacturing, as well as applications.

The packer preventer cannot be used to control the bottomhole pressure on the exposed formations during the drilling process, i.e. when deepening the well,
The proposed technical solution is aimed at dynamic local uncoupling of the annular space of the drilling tool, to control the bottomhole pressure during drilling while maintaining circular circulation through the drilling tool.

 This problem is solved in that in the device containing the housing with a packing element, a pipe is installed inside the housing hydraulically connecting the sub- and nadpakerny annular space, and the packing element is made in the form of a cuff with a reinforced frame and a shirt with a reinforced ring, the inner cavity of which is through a check valve with a calibrated hole connected to the in-tube space of the column.

 Comparison of the claimed technical solution with the closest analogue allowed us to establish compliance with its criterion of "novelty."

 There are various devices [1, 2] used to separate layers and prevent oil and gas occurrences during well drilling.

 However, their use for separating the layers is possible only without the movement of the drilling tool.

 In the proposed technical solution, the implementation of the inner tube in the device’s body will allow maintaining circular circulation and will not require stopping the process of deepening the well to prevent oil and gas manifestations.

 The presence of a calibrated hole in the non-return valve, acting as a pressure regulator, allows local sealing of the annular space of the drill string during tool build-up. The implementation of the packer element in the form of a cuff with a reinforced frame and a shirt with a reinforced ring is done in order to obtain a one-piece sealed unit and increase the strength of the packer element, as well as simplifying its manufacture.

 In addition, as a result of the difference between the bottomhole and reservoir pressures (positive differential pressure), penetration of solid particles of the drilling fluid into the pores of the reservoir or, when the drilling fluid penetrates the reservoir and comes into contact with the reservoir fluid, precipitates insoluble solid sediment in the pores of the reservoir. All of the above allows us to conclude that the claimed technical solution meets the criteria of the invention "inventive step".

 In FIG. 1 shows a device for controlling downhole pressure during drilling; in FIG. 2 shows an enlarged assembly of a packer element (assembly B); in FIG. 3 shows a check valve.

 A device for controlling downhole pressure during drilling consists of a housing 1 with holes 2 for installing check valves 3 assembled, a packer element 4, half couplings of the upper 5 and lower 6, an inner pipe 7 that serves as a circulation channel hydraulically connected to the upper and lower parts of the packer element 4, and through them with the annular space of the drilling tool, sleeve 8 and nipple 9 for connection with drill pipes, centralizer 10. Packing element 4 mounted on the housing, made in the form of cuffs 11 with reinforced Arkása 12 and jacket 13 with the reinforced ring 14.

 The non-return valve with a pressure regulator consists of a seat 15, a cover 16 with holes 17, a spring 18, a valve 19 with a calibrated central hole 20.

 Drilling a well using a device to control the bottomhole pressure during drilling is as follows.

A device for controlling downhole pressure during drilling is lowered into the well in a layout with a drilling tool. The lead pipe (square) is screwed up and circulation through the drilling tool is restored. After the restoration of circulation, the pressure rises, which ensures the actuation of valves 3 (Fig. 1) at a pressure of 2 to 3 MPa (20 to 30 kgf / cm ² ).

 When the drilling fluid is filled with the inner cavity of the packer element 4, the cuff 11, the packer element 4 are moved in the axial direction, and the shirt 13 in the radial direction, against the stop with the wall of the well or casing.

To ensure reliable guaranteed sealing of the annulus with a packer pressure element in the drill string, at least 6 MPa (60 kgf / cm ² ) is supported, which is technologically realized when drilling wells using downhole motors.

 When the pressure in the drill string reaches more than 6 MPa, there is a local disconnection of the annular space of the drilling tool in the process of deepening the well, and the drilling fluid in the well circulates through the inlet of the lower part of the packing element, the channel of the inner pipe and the outlet of the upper part of the packing element in the annulus.

 In order to preserve local sealing of the annular space of the drill string during the time of building up the tool or other estimated time so that the pressure does not immediately decrease to the hydrostatic column of the drilling fluid, due to the displacement of fluid from the packing element 4, a calibrated hole 20 is drilled in the check valve for a certain time emptying from the working fluid of the packing element 4.

 Before lifting the drilling tool from the well after the end of the drilling, a technological stop is made to relieve pressure in the packer element 4, as well as to increase the strength of the drilling fluid structure in the pore space of the open hole reservoir.

 If it is necessary to increase the pressure in the wellbore during tripping operations, it is sufficient to restore circulation through the drilling tool with a downhole motor.

 Depending on the technological requirements, the device for regulating the bottomhole pressure during the drilling process is installed in the drill string above the roof of the oil and gas reservoirs or in the casing string. The efficiency of the device is increased when the packer element of the device is located above the roof of the oil and gas developing layer when it is opened to its full thickness.

The proposed device for regulating bottom-hole pressure on the exposed formations during drilling provide:
- simplification of the installation of drilling equipment and well construction technology, which reduces the total cost of the well;
- reliable environmental protection with the simplicity of the technological process for preventing oil and gas manifestations in the process of opening them.

Claims (1)

 A device for controlling downhole pressure during drilling, comprising a housing with a packer element, the inner cavity of which is connected via a valve to the in-pipe space of the drill string, characterized in that a pipe is installed inside the body that hydraulically connects the under- and over-packer annulus, the packer element is made in the form cuffs with a reinforced frame and shirts with a reinforced ring, and the valve is made back and has a calibrated hole.

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