RU2810375C1 - Casing drilling device with retrievable drilling assembly - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: drilling of oil and gas wells with simultaneous isolation of areas of shedding and collapse when drilling with a casing string. A device for drilling on a casing with a retrievable drilling assembly includes a casing string made of casing pipes connected to each other by couplings, with a connecting device at the end, and a retrievable drilling assembly containing a downhole motor and a bit and connected to the connecting device by an adapter. The connecting device body on the outer surface in the lower part is equipped with grooves with blades with PDC cutters mounted rigidly in the grooves in such a way that the end part of the blades is located below the end part of the connecting device body with the possibility of drilling a wellbore with a diameter sufficient for running the sleeve casing. The inner surface of the blades is made to match the internal lead-in chamfer of the connecting device body. The adapter of the connecting device is equipped with flushing holes, and the blades are made unified for connecting devices for drilling different standard sizes of casing strings.

EFFECT: proposed device for drilling on a casing string with a retrievable drilling assembly is easy to manufacture due to the unification of the blades for different standard sizes of casing strings, is reliable in operation, and eliminates the abandonment of rock-cutting tools at the bottom of the well.

1 cl, 2 dwg

Description

The invention relates to the oil and gas industry, namely to drilling oil and gas wells with simultaneous isolation of areas of shedding and collapse when drilling with a casing string.

A device is known for simultaneous drilling and securing zones of sloughs and collapses when drilling a well (patent RU No. 2753428, IPC E21B 7/20, published 08/16/2021, Bulletin No. 23), including a drilling and casing string, a rock-destroying element. The rock-cutting element is made in the form of a drillable bit, screwed to the lower end of the casing on a persistent conical thread and equipped with a seat for the ball. In the upper part of the casing there is a hermetically sealed sub with keys inserted into mating grooves made at the upper end of the casing. The sub is equipped at the bottom with a bit with a hole for passing the ball, and at the top with a groove inserted into the narrowing of the casing string, while the taper angle of the chamfer of the sub groove is designed to provide additional expansion when exiting through the narrowing of the casing string, in addition, the sub is equipped with a thread on top for connection with the drill string . On the outside, the narrowing of the casing is equipped with an elastic element with an outer diameter equal to the diameter of the casing, while the diameter of the casing is 10-15% less than the diameter of the bit being drilled.

The disadvantages of the device are:

- a high probability of jamming of the sub with the bit when exiting the upper end of the casing, since at the same time the elastic element is compressed and, as a result, the axial force increases significantly;

- large time and material costs when drilling the drill head, since during drilling it rotates and moves along the bottom;

- the bit used for drilling usually becomes unsuitable for further drilling of the wellbore, which leads to additional trips to replace it;

- high time and material costs due to the long assembly time of the device, since the pipes are assembled by welding;

- low mechanical speed, since only rotary drilling is used, it is not possible to use a downhole motor.

The closest in technical essence to the claimed one is a device for drilling on a casing string (patent RU No. 2792480, IPC E21B 7/20, published March 22, 2023, Bulletin No. 9), including a casing string, a drill bit, a sub installed at the top of the casing and threaded at the top for connection to the drill pipe. The casing string is made of casing pipes connected to each other by couplings, and the bit being drilled is screwed to a downhole motor and is made in the form of a drillable drilling head with a multifaceted hole with a non-drillable sub inserted into the multifaceted hole of the drilling head, fixed to the drilling head with a shear element that is destroyed during extraction sub when the drill head rests on the end of the connecting device. The upper sub is made with a diameter equal to the diameter of the casing coupling, and is equipped with a centralizer with a diameter 1.5-2% less than the internal diameter of the casing pipes, made of polymer material.

The disadvantages of the device are:

- large time and material costs when drilling the drill head, since for drilling it is necessary to assemble the drill collar for the weight of the assembly, and when drilling, the drill head rotates and moves along the bottom;

- the bit used for drilling usually becomes unsuitable for further drilling of the wellbore, which leads to additional trips to replace it;

- the drill head may fall due to premature destruction of the shear element during sticking and tightening, as a consequence of removing the assembly with lifting the casing pipes and replacing them.

The technical challenge is to create a device for drilling on a casing with a retrievable drilling assembly, easy to manufacture due to the unification of blades for different standard sizes of casing, reliable in operation, allowing to eliminate the abandonment of rock-cutting tools at the bottom of the well.

The technical problem is solved by a device for drilling on a casing with a retrievable drilling assembly, including a casing string made of casing pipes connected to each other by couplings, with a connecting device at the end, and a retrievable drilling assembly containing a downhole motor and a bit and connected to the connecting device by an adapter.

What is new is that the body of the connecting device on the outer surface in the lower part is equipped with grooves with blades with PDC cutters mounted rigidly in the grooves in such a way that the end part of the blades is located below the end part of the body of the connecting device with the possibility of drilling a wellbore with a diameter sufficient for lowering the coupling casing string, the inner surface of the blades is made to match the internal lead-in chamfer of the connecting device body, while the adapter is made with flushing holes for cooling the PDC cutters on the blades and removal of cuttings, and 4 blades are made unified for connecting devices for drilling different sizes of casing strings.

In fig. Figure 1 shows the device with a partial axial longitudinal section.

In fig. Figure 2 shows section A-A.

A device for drilling on a casing with a retrievable drilling assembly, including a casing string made of casing pipes 1 (Fig. 1) connected to each other by couplings (not shown in Fig. 1, 2), connecting device 2 (Fig. 1), downhole motor 3 and a bit 4. The housing 5 of the connecting device 2 on the outer surface in the lower part is equipped with grooves 6 with blades 7 (Fig. 1 and Fig. 2) rigidly installed (for example, by welding) in the grooves with PDC cutters so that the end part 8 (Fig.1) of the blades 7 is located below the end part of the housing 5 of the connecting device 2 with the possibility of drilling a wellbore with a diameter sufficient for running the sleeve casing. The inner surface 9 of the blades 7 is made to match the internal lead-in chamfer 10 of the housing 5 of the connecting device 2. The adapter 11 of the connecting device 2 is equipped with flushing holes 12, and the blades 7 are made unified for connecting devices for drilling different sizes of casing strings.

The device works as follows.

A device for drilling on a casing string, consisting of an arrangement located below - a screw downhole motor 3 (Fig. 1) and a bit 4, is lowered on a casing string 1 in the previously drilled direction to the bottom. Then the assembly is raised higher by one meter, the drilling pump is turned on and the downhole screw motor 3 is started. With a smooth downward feed, they reach the bottom and begin simultaneous drilling with expansion. Drilling of the main wellbore is carried out with a bit 4 due to the transmission of torque from a screw downhole motor 3. To expand the well, it is necessary to rotate the casing either by an upper power drive or by a rotor.

The blades 7 with PDC cutters installed in the grooves 6 of the housing 5 of the connecting device 2 perform the function of an expander. Since the expansion diameter is larger than the diameter of the casing couplings 1, this allows the casing to be lowered into the well without hindrance. For sufficient cooling of the PDC cutters on the blades 7 and removal of slurry, the adapter 11 of the connecting device 2 is equipped with flushing holes 12. The inner surface 9 of the blades 7 is made to match the internal lead-in chamfer 10 of the body 5 of the connecting device 2, for reliable fastening of the blades 7. In addition, the blades 7 are made unified for connecting devices 2 for drilling with different standard sizes of casing strings. For example, blades with a thickness of 14 mm are suitable for drilling under 146, 168, 178, 245 mm casing strings, since the diameter of the wellbore is 28 mm larger than the diameter of the couplings of these columns.

In this way, simultaneous drilling with expansion and lowering of the casing into the well occurs. Upon completion of drilling, a known extraction device is lowered into the casing string 1, connected to an assembly located below the connecting device 2, and the assembly is raised to the wellhead, and the casing is cemented. Thanks to this, large time and material costs are eliminated when drilling out the drill head.

The proposed device for drilling on a casing string with a retrievable drilling assembly is easy to manufacture due to the unification of the blades for different standard sizes of casing strings, is reliable in operation, and eliminates the abandonment of rock-cutting tools at the bottom of the well.

Claims (1)

A device for drilling on a casing with a retrievable drilling assembly, including a casing string made of casing pipes interconnected by couplings, with a connecting device at the end, and a retrievable drilling assembly containing a downhole motor and a bit and connected to the connecting device by an adapter, characterized in that the casing of the connecting device on the outer surface in the lower part is equipped with grooves with blades with PDC cutters mounted rigidly in the grooves in such a way that the end part of the blades is located below the end part of the connecting device body with the possibility of drilling a wellbore with a diameter sufficient for running the sleeve casing, the inner surface of the blades made to match the internal lead-in chamfer of the connecting device body, while the adapter is made with flushing holes for cooling the PDC cutters on the blades and removal of cuttings, and the blades are made unified for connecting devices for drilling different sizes of casing strings.