RU2796156C1 - Casing drilling method with retrievable bottomhole assembly (rba) - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to the field of drilling oil and gas wells, and in particular to methods for preventing the destruction and collapse of the walls of the well when drilling intervals with unstable rocks. The method of casing drilling with a retrievable bottomhole assembly (RBA) includes identification of unstable rock zones and drilling a wellbore on a drill string with telemetry and a downhole drilling motor (DDM) bit until the top of unstable rocks. Then the assembly with the telemetry system and the DDM bit is removed. The well is drilled to the design bottomhole on a drill string with a casing tail. The casing tail consists of standard casing pipes, equipped with an auto-hook hanger on top, connecting the casing tail to the drill string, transmitting axial load and torque for drilling. After that, the drill string is uncoupled from the casing tail by dropping the ball from the wellhead into the saddle with increasing pressure in the tail and shearing the pin. Drilling is carried out using an RBA consisting of a retractable bit, a DDM and a telemetry system installed at the bottom of the tail using a connection unit. After drilling to the design bottomhole and extraction of the RBA for cementing, a suspension device is lowered, equipped with an automatic hitch assembly. The hitch assembly includes a conical groove of the saddle and a bushing. The saddle is spring-supported down relative to the body of the automatic releaser with limited downward movement until it stops against the shear element. The bushing is installed outside the body of the auto-releaser and is spring-supported downwards with the ability to move down to the locking ring and cover the hole of the auto-releaser with installed balls with the possibility of engaging the drill string lowered for cementing behind the inner groove of the hanger by moving the bush up and pushing the balls into the inner groove of the conical hanger saddle groove when landing the body of the auto-releaser on the end face of the suspension device.

EFFECT: increased speed of drilling a well on a casing string, control and monitoring of the trajectory during drilling on a casing string and extraction of the RBA upon reaching the design bottomhole.

1 cl, 6 dwg

Description

The invention relates to the field of drilling oil and gas wells, and in particular to methods for preventing the destruction and collapse of the walls of the well when drilling intervals with unstable rocks.

A known method for simultaneously opening and fixing unstable rocks during well drilling (patent RU No. 2437997, IPC E21V 7/20, publ. 27.12.2011, Bull. No. 36) includes drilling a wellbore with a bit connected to a casing in the well with the subsequent extraction of the bit. A well section with unstable and destroyed rocks from the main shaft is drilled at a certain pressure of the consumable fluid with a sliding bit connected to the casing string in the form of a multi-beam expandable pipe, the length exceeding the length of this section, lowered on the drill string. The inner diameter of this section is made larger than the diameter of the main borehole by at least the thickness of the walls of the casing string, after drilling the section, an excess pressure is created in the casing string that exceeds a certain pressure and is sufficient to completely straighten the corrugations of the casing string with its fixation relative to the walls of the well and with subsequent disconnection and extraction drill strings to the surface. A sizing tool is lowered to finally straighten the casing string to a diameter equal to the diameter of the main wellbore. The sizing tool is equipped with a catcher at the lower end to capture, detach and retrieve the bit when interacting with it.

The disadvantages of the method:

- high probability of an emergency due to a sharp increase in pressure above the critical one, which will lead to premature expansion of profile pipes and jamming of the device in the well;

- low speed of drilling by rotary method in comparison with drilling with the use of a screw downhole motor (SDM);

- with this method, it is impossible to control the trajectory and control the trajectory during drilling, as a result, failure to reach the design bottomhole, which leads to time and material costs for re-drilling the well section;

- during simultaneous drilling and expansion due to pulsations in the flow rate of the flushing fluid of the pump, it is not guaranteed that the bit will move into the working position and, as a result, the inability to expand the profile pipes, as a result, the creation of an emergency due to failure of the assemblies.

The closest in technical essence and the achieved result is the method of drilling a sidetrack with unstable rocks (patent RU No. 2785164, IPC E21B 7/04, publ. 05.12.2022, Bull. No. 34), including the definition of zones of unstable rocks, cutting out a window in the production string, drilling a sidetrack to the design bottom, fastening the sidetrack with a pipe string, increasing hydraulic pressure in the drill pipe string, unhooking and removing the landing device. From the window, drilling is carried out on a drill string with telemetry and a drill bit with a screw downhole motor with a set angle and a subsequent stabilization zone of the wellbore to the top of unstable rocks. Then the assembly with the telesystem and the bit with the screw downhole motor is removed and the well is drilled to the design bottomhole using a rotary method on a drill string with a casing liner consisting of standard casing pipes. Casing pipes are equipped from below with a bit with PDC cutters, a centralizer to maintain a stable direction during drilling and a valve with a stop ring, and from above - a suspension device. The casing liner is connected to the drill string with a suspension device that transmits axial load and torque for drilling. Squeezing plugs of the suspension device are used when cementing the liner after drilling to the design bottom hole and flushing the wellbore. The drill string is unhooked from the casing liner by dropping the ball from the wellhead into the saddle with increasing pressure in the liner and shearing the pin, while the length of the casing liner is equal to the sum of the length of the lateral wellbore to the bottom and section L of the liner for sealing in production. Then, according to the data of geophysical surveys, the liner is perforated in the interval of the productive formation and the well is put into operation.

The disadvantages of the method are:

- low speed of drilling by rotary method in comparison with drilling with the use of PDM;

- with this method, it is impossible to control the trajectory and control the trajectory while drilling the last section of the well on the casing liner, as a result, not reaching the design bottomhole, which leads to time and material costs for re-drilling the well section;

- the likelihood of an emergency due to clogging of the drilling holes of the bit when cementing through them, as a result, the hardening of cement in the liner and additional material costs for drilling cement.

The technical objective of the invention is to create a method for drilling in a casing string with a recoverable BHA, consisting of a retractable bit, a PDM and a telesystem that provides an increase in the speed of drilling a well in a casing string, control and monitoring of the trajectory during drilling in a casing string, and retrieval of the BHA upon reaching the design bottom hole.

The technical problem is solved by a method of drilling on a casing string with a recoverable bottom hole assembly, including determining zones of unstable rocks, drilling a wellbore on a drill string with telemetry and a PDM bit to the top of unstable rocks, then the assembly with a telesystem and a PDM bit is removed, after which the well is drilled to the target bottomhole on a drill string with a casing liner, consisting of standard casing pipes, equipped with a hanging device from above with an automatic uncoupler, connecting the casing liner to the drill string, transmitting axial load and torque for drilling, after which the drill string is unhooked from the casing liner by dropping the ball from the mouth into the saddle with an increase in pressure in the shank and a pin shear.

What is new is that drilling is carried out using a BHA, consisting of a retractable bit, a PDM and a telesystem installed from the bottom of the liner using a connection unit, while after drilling to the design bottom hole and extracting the BHA for cementing, a suspension device is lowered, equipped with an automatic hook assembly, including an annular conical groove of the seat, spring-loaded down relative to the auto-trapper body with limited movement down until it stops in the shear element, and a bushing installed outside the auto-trapper body, spring-loaded down, with the possibility of moving down to the locking ring and blocking the holes of the auto-trapper with installed balls, with the possibility of engaging the drill string lowered for cementing behind the inner groove of the hanger by moving the sleeve up and pushing the balls into the inner groove of the hanger by the conical groove of the saddle when the body of the automatic releaser is seated on the end of the hanger.

In FIG. 1 shows an arrangement for drilling a liner in a section of a well with unstable formations.

In FIG. 2 shows the liner after the drill string has been cut and the BHA has been run in to retrieve it.

In FIG. 3 shows a suspension device equipped with an automatic hitch assembly.

In FIG. 4 shows the hanger already mated to the liner for the cementing operation.

In FIG. 5 shows the liner after pumping the cement slurry and pushing it with plugs.

In FIG. 6 shows the liner after the cementing operation and uncoupling of the transport string from it.

The method is carried out in the following sequence.

The wellbore is drilled on a drill string with telemetry and a bit with a PDM to the top of unstable rocks (not shown in Figs. 1-6). Then the drill string with the telemetry and the PDM bit is retrieved from the well.

Next, the assembly is lowered into the well, consisting of a sliding bit 1 (Fig. 1), a PDM 2 and a telesystem 3 installed below the liner 4, consisting of casing pipes. The assembly located below the liner 4 is connected to it using a connection unit 5 of a known design (for example, patent RU No. 201342 "Connecting assembly of a drilling tool with a casing string"), and from above the liner is connected to the drill string by a suspension device 6. This arrangement drills the wellbore wells to the design bottom hole.

Then a ball 7 is thrown into the drill string from the wellhead, which reaches the saddle 8 of the suspension device 6, by increasing the pressure, the pins 9 are sheared and the drill string is separated from the liner 4.

After that, a fishing tool 10 is lowered into the well on the drill string (for example, patent RU No. 201342) (Fig. 2), which reaches the connection node 5, disconnects the BHA, fixes it on the fishing tool 10 and after that the BHA is removed at the wellhead . Only the liner and the lower part of the hanger 6 remain in the well.

The next operation is the descent into the well on a drill string of a hanging device equipped with an automatic hook assembly and a hanging squeezing plug 11 (Fig. 3). The device has an annular conical groove 12 of the seat 13, spring-loaded by a spring 14 down relative to the body of the suspension device, with limited movement down until it stops in the shear element 15. The suspension device also has a sleeve 16 installed outside the body and spring-loaded down to the retaining ring 17, and blocking the holes 18 with balls 19. When the suspension device enters the lower part of the suspension device 6 (Fig. 4), the sleeve 16 moves up relative to the body, the saddle 13 moves down and at the same time squeezes the balls 19 out of the annular conical groove 12 of the seat 13. The balls 19 go into the inner groove 20 (Fig. 4) of the suspension device 6, and from the inside the balls 19 are fixed by the saddle 13, which has moved down to the stop in the shear element 15. Thus, the suspension device with the shank 4 is fixed.

Next, the operation of cementing the liner 4 is started. A cementing head is installed (not shown in Figs. 1-6), the estimated volume of cement is pumped using a known technology, then the top displacement plug 21 is started. Then the upper displacement plug 21 reaches the hanging displacement plug 11, is fixed in it, and with an increase in hydraulic pressure, the fixing pins of the hanging squeezing plug 11 are sheared and cement is squeezed from the liner 4 into the annulus. Next, the hanging displacement plug 11 is seated with a retaining ring 22 (Fig. 5) into the annular groove in the holder of the joint 5 (Fig. 5) and we get the “stop” pressure. After that, we increase the hydraulic pressure to open the flush windows 23 located in the suspension device 6. The pressure drop means that the windows 23 have opened. Then the cementing head is unscrewed, the ball 24 is thrown into the drill string. The ball sits in the saddle 13, cuts off the pins 15, and the balls 19 at the same time release the upper part of the suspension device, together with the drill string, from the liner. Then the column is lifted and excess cement is washed out, and the liner 4 is left for the cement hardening operation (Fig. 6).

The proposed method of casing drilling with a retrievable BHA makes it possible to increase the speed of drilling a well in a casing string, to control and control the trajectory during drilling in a casing string, and to extract the BHA upon reaching the design bottom hole.

Claims (1)

A method for drilling on a casing string with a retrievable bottomhole assembly (BHA), including determining zones of unstable rocks, drilling a wellbore on a drill string with telemetry and a bit with a screw downhole motor (PDM) to the top of unstable rocks, then assembling with a telesystem and a bit with The PDM is retrieved, after which the well is drilled to the design bottomhole on a drill string with a casing liner consisting of standard casing pipes equipped on top with a hanging device with an automatic release connecting the casing liner to the drill string, transmitting axial load and torque for drilling, after which a release is made of the drill string from the casing liner by dropping the ball from the wellhead into the saddle with increasing pressure in the liner and shearing the pin, characterized in that drilling is carried out using a BHA consisting of an expanding bit, a PDM and a telesystem installed from the bottom of the liner using a connection unit, with In this case, after drilling to the target bottom hole and retrieving the BHA for cementing, a suspension device is lowered, equipped with an automatic hitch assembly, including an annular conical groove of the seat, spring-loaded down relative to the auto-trapper body with limited downward movement until it stops against the shear element, and a bushing installed outside the auto-trapper body and spring-loaded down with the possibility of moving down to the locking ring and blocking the holes of the auto-releaser with installed balls with the possibility of engaging the drill string, which is lowered for cementing behind the inner groove of the hanger by moving the bushing up and pushing the balls into the inner groove of the hanger by the conical groove of the seat when landing the body of the auto-releaser on the end suspension device.

Images