RU2808789C1 - Emergency connection and cementing device for casing string - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: construction and repair of wells when unfastening casing strings in wells with offset ends of the fracture vertically and horizontally. The device is designed to connect a loose string along a thread and contains a sub with internal and external trapezoidal threads, designed to fit into the coupling of the lower part of the casing pipe and with the possibility of installing it on the nipple part of the upper casing pipe, with a check valve installed inside the sub made of lightweight material being drilled and with an internal metric thread through which the sub is connected to the cementing agent. The means for cementing is made in the form of a cementing cone, having a counter external metric thread and made of easily drillable material, at least 2 m long. The cementing cone has a central channel and at least four radial circulation channels.

EFFECT: reliability and tightness of the alignment of the loosened parts of the casing string with cementing is ensured in the shortest possible time, and the emergency situation is completely eliminated.

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Description

The invention relates to the oil and gas industry, namely to the construction and repair of wells by centering for repair and alignment of casing strings in wells during cementing with displacement of the ends of the fracture vertically. Provides the creation of a device for repairing casing ruptures with a significant displacement of the ends of the rupture horizontally and vertically.

A device for repairing casing strings in wells is known, including a means for cementing (a cementing plug with elastic cuffs), a sealing plug rigidly connected to the lower part of the cementing plug, and a means for centering in the form of a centering cone in the lower part of the body (author's certificate No. 1768759, IPC E 21 B 33/13).

This device for repairing ruptures of casing strings in wells does not allow repairing casing strings with a rupture of 0.5 m or more or with a significant displacement of the bottom of the upper part of the column and the top of the lower part, and also does not allow high-quality repairs with a minor rupture of 10-15 cm, in the absence of smooth surfaces of the ends of the bottom of the upper part of the column and the top of the lower part of the column.

The closest is a device for repairing casing ruptures by centering and cementing (patent RU No. 2166062, MPK E21B 29/00, 33/13, publ. 04/27/2001), including a guide tip (cementing cone), centralizers made of drillable aluminum alloy D16T, placed on pipe sections, a coupling body for cementing, including shear pins, channels for cementing and bushings with the ability to move in the axial direction of a crown reinforced with a hard alloy, with an internal annular projection, a support ring and a receiving pipe, a ball, perforation holes. The device additionally contains a means for drilling cement stone and centralizer blades, made in the form of a drill bit reinforced with a hard alloy, and connected to the receiving pipe, and a means for centering is made in the form of centering elements made of an easily drilled alloy, mounted on pipe sections, and connected to means for cementing, made in the form of a coupling, in the body of which side flushing channels are made and the coupling is placed with the ability to move with a sleeve secured in the coupling body with shear pins. The coupling body in the upper part is equipped with a support ring, through which it is secured to the inside of the receiving pipe.

The disadvantages of the above device are:

- impossibility of connecting columns fastened along the threaded part;

- the presence of a section between the pipes consisting only of cement, there is no integrity of the metal in the casing string bracing interval, which can lead to leaks in case of unsuccessful cementing.

The technical problem is to create a device for repairing braced casing strings with a vertical displacement of the bracing ends, allowing for the connection of the displaced threaded ends of the casing string, cementing the annular interval above the bracing interval, as well as a hermetically sealed connection of the new section of the casing string with the part of the casing string located in the well immediately after cementing.

The stated technical problem is solved by a device for emergency connection and cementing of a loose casing string, including a means for cementing.

What is new is that it is designed to connect a loose string along a thread and contains a sub with internal and external trapezoidal threads, designed to fit into the coupling of the lower part of the casing pipe and with the possibility of installing it on the nipple part of the upper casing pipe, with the sub with a check valve made of easily drillable material and with an internal metric thread, through which the sub is connected to a means for cementing, made in the form of a cementing cone, having a mating external metric thread and made of easily drillable material, a length of

at least 2 m, while the cementing cone has a central channel and at least four radial circulation channels.

Figure 1 shows the device before docking.

Figure 2 shows the device at the time of cementing.

A device for emergency connection and cementing of a braced casing string (hereinafter referred to as the device) lowered on the casing pipe (not shown in Fig. 1, 2) includes a cementing cone 1 (Fig. 1), which is made of an easily drillable material, for example duralumin. The device additionally contains a sub 2 with a check valve 3 installed inside the sub, made of an easily drillable material, for example, duralumin, as well as with an internal trapezoidal thread 4 and an external trapezoidal thread 5, made in accordance with GOST 632-80, and an internal metric thread 6 (Fig. 2), through which the sub 2 is connected to the cementing cone 1, which has a mating external metric thread (not shown in Fig. 1, 2). The cementing cone 1 (Fig. 1) is made at least 2 m long, while in the cementing cone 1 there is a central through channel 7 and at least four radial circulation channels 8.

The device works as follows:

In case of emergency unfastening of the casing into two parts, the upper part (not shown in Fig. 1, 2) of the casing is removed to the wellhead. The condition of the thread of the nipple part of the last pipe removed at the mouth of the upper part of the casing is assessed. Provided that the threaded connection is intact, a decision is made to connect with the lower part 9 (Fig. 2) of the casing string remaining in the well, lower the upper part of the casing string and connect them by twisting. To do this, an emergency connection and cementing device for the unfastened casing is installed on the nipple part of the lower casing pipe of the newly assembled upper part of the casing string. This arrangement is lowered into the well until the sub 2 (Fig. 2) is seated in the coupling 10 of the lower part 9 of the casing remaining in the well. In this case, the cementing cone 1 enters the lower part 9 of the casing until the external thread 5 (Fig. 1) of the sub 2 is seated in the coupling 10 (Fig. 2), while on the surface, using the weight indicator, the unloading of the upper part of the casing is determined by the weight drop by 1.5-2 t.

Next, the upper part of the casing together with the device is raised to a height of no more than 1.5 m, and the annulus is cemented above the casing joining interval by pumping cement mortar through the central through 7 (Fig. 1) and radial circulation channels 8 of the cementing cone 1 of the device. The calculated amount (taking into account leaving the cement slurry inside the lowered upper part of the casing to a height of no more than 10 m from the joining interval) of cement slurry is forced with drilling fluid or water into the casing string. After cementing stops, check valve 3 closes, preventing the arbitrary flow of cement slurry back into the casing. Due to the entry of the cementing cone 1 into the coupling 10 (Fig. 2), both parts of the casing are centered relative to each other. After cementing is completed, the upper part of the casing is again unloaded onto the coupling 10 to a value not exceeding 2 tons, and the upper part of the casing is rotated to the right until the maximum permitted torque is obtained for the existing threaded connection, monitoring the latter on wellhead instruments.

The cemented casing is left while waiting for the cement slurry to harden (hereinafter referred to as CMC). At the end of the OZT time, a bit is lowered into the casing on drill pipes, check valve 3 (Fig. 1) and cementing cone 1 with the remaining cement slurry are drilled until the bit moves freely in the joining interval, then the drill string is removed along with the bit to the surface.

Thus, the proposed device for emergency connection and cementing of a braced casing string makes it possible to reliably and hermetically join the braced parts of the casing string and cement the annulus above the bracing interval to the wellhead in the shortest possible time, completely eliminating the emergency situation associated with bracing the casing along the thread and its fall parts to the bottom during the cementing process.

Claims (1)

A device for emergency connection and cementing of a braced casing string, including a means for cementing, characterized in that it is designed to connect the braced casing string via a thread and contains a sub with internal and external trapezoidal threads, configured to fit into the coupling of the lower part of the casing pipe and with the possibility of its installation on the nipple part of the upper casing pipe, with a check valve installed inside the sub made of easily drillable material and with an internal metric thread, through which the sub is connected to a cementing tool made in the form of a cementing cone, having a matching external metric thread and made of lightweight of drilled material, at least 2 m long, with a central channel and at least four radial circulation channels made in the cementing cone.