RU2760110C1 - Collar for stage cementing of casing string in a well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry, in particular to the field of construction of oil and gas wells, namely to devices for staged cementing of the casing in two stages. The collar for staged cementing of the casing in the well includes a hollow body with an internal shoulder and connecting threads at the ends. A sub is attached to the upper thread, the cementing holes are closed with destructible elements, the sealing rings are installed above the cementing holes. The locking flap is installed inside the body above the cementing holes and is equipped with a lock in the form of a split spring ring. The drillable landing seat is installed inside the locking flap, secured by a shear pin to the ring installed at the junction between the body and its sub. The body is made thickened, with longitudinal grooves made on its outer surface. The cementing holes are made between the longitudinal slots and are equipped with spring-loaded valves that open from the inner side of the body. The valve seat body is installed hermetically and on the outside is provided with a support platform for the valve spring with holes for the passage of the cement slurry. The destructible elements covering the cementing holes are made in the form of shear nozzles installed on the inner side of the body. Shear-off nozzles are closed with a stopper and rigidly fixed to the valve seat body or made integral with the valve seat body. In the upper part of the locking flap, an internal groove is made, which forms a ledge with the possibility of placing a drillable landing saddle with a counter protrusion under the ledge of the locking valve.

EFFECT: increased reliability by ensuring high tightness of the closure of the cementing holes on both sides - a flap and a valve.

1 cl, 6 dwg

Description

The proposal relates to the oil and gas industry, in particular to the field of construction of oil and gas wells, namely, devices for staged cementing of the casing in two stages.

Known coupling for staged cementing of casing strings (patent RU No. 2074311, IPC E21B 33/14, publ. 27.02.97), containing a housing with a stop and cementing holes, plugged plugs equipped with O-rings. Inside the casing, above the cementing holes, a shut-off valve is installed in the form of a cage with a diameter equal to the inner diameter of the casing string and is equipped with a ball lock, as well as a landing seat made of easily drilled material, fixed to the valve with a hairpin.

The disadvantages of the known coupling are the complexity of the design and not manufacturability, as well as its insufficient reliability during the operation of the well.

The closest to the proposed one is a sleeve for staged cementing of the casing (patent RU No. 179007, IPC E21B 33/14, publ. 04.24.2018), containing a body with cementing holes, plugged plugs fixed with bursting screws, with an internal annular ledge, made below from the cementing holes, connecting threads at the ends, to the upper end of which a sub is attached, a sleeve-shaped locking gate installed inside the body above the cementing holes, a drillable seat installed inside the locking gate, fixed with a shear pin to the ring installed at the junction between the sub and the body, keeping them from falling, while the locking flap is equipped with a retainer made in the form of a spring split ring installed in a groove made from its outer side with the possibility of fixing in a counter groove of the body, while the upper end of the saddle body is made with external to ring protrusion resting on the upper end of the locking flap.

The disadvantage of the known coupling is that during repair work in the well, it is necessary to install a cement bridge, when drilling out of which the fixed damper can fail and cease to perform its function. At the same time, the cavity of the cementing hole remains unprotected, although it is filled with cement stone, which rapidly collapses under the influence of alternating loads, causing the fluid to enter from the annulus. This leads to casing corrosion as well as water cut in the well production.

The technical objectives are to increase the reliability and operability of the sleeve for staged cementing of the casing string by ensuring high tightness of closing the cementing holes of the device and its durability during well operation, increasing the turnaround time of the well and reducing material costs for its operation, simplifying the assembly and reducing the metal consumption of the sleeve.

Technical problems are solved by a coupling for staged cementing of a casing in a well, including a hollow body with an internal shoulder and with connecting threads at the ends, to the upper thread of which a sub is attached, cementing holes closed with destructible elements, sealing rings installed above the cementing holes, a locking flap, installed inside the body above the cementing holes and equipped with a retainer in the form of a split spring ring, a drillable landing seat installed inside the locking flap, fixed with a shear pin to the ring installed at the junction between the body and its sub.

The novelty is that the body is made thicker, on the outer surface of which longitudinal grooves are made, while the cementing holes are made between the longitudinal grooves and are equipped with spring-loaded valves that open from the inner side of the body, the valve seat body is installed hermetically and is provided with a support platform on the outer side for valve spring with made holes for the passage of cement slurry, the destructible elements closing the cementing holes are made in the form of cut-off nozzles installed on the inner side of the body, while the cut-off nozzles are closed with a plug and rigidly fixed to the valve seat body or are made integral with the valve seat body, in the upper part of the locking The damper has an internal groove that forms a ledge with the possibility of placing a drillable landing saddle with a counter ledge under the ledge of the locking damper.

FIG. 1 shows a sleeve for staged cementing of a casing in a well in a partial longitudinal section.

FIG. 2 depicts a collar for staged cementing of a casing in a well after completion of cementing.

FIG. 3 depicts a valve assembly mounted in a casing bore with a spring loaded valve.

FIG. 4 shows the valve assembly in operating position.

FIG. 5 shows the upper part of the damper in the initial position.

FIG. 6 section C-C of FIG. 2.

The sleeve for staged cementing (MSC) of the casing (not shown in Figs. 1-6) in the well contains a hollow body 1 (see Fig. 1) with an internal ledge 2 in the lower part and with connecting threads 3 and 4 at the ends, to the upper thread 3 of which the sub 5 is connected, and the cementing holes 6.

The body 1 of the clutch is made thickened. Longitudinal grooves 7 are made on the outer surface of the thickened body 1 (see Fig. 6), while the cementing holes 6 (see Fig. 1) are made between the longitudinal grooves and are equipped with spring-loaded valves 8 (hereinafter referred to as the valve), working to open from the inner side of the body 1. As spring-loaded valves 8 can be used, for example, spring-loaded ball or poppet valves. The execution of longitudinal grooves 7 (see Fig. 6) on the body 1 (see Fig. 1) of the coupling ensures the preservation of the cement slurry throughput in the annular gap between the coupling and the column (due to the thickening of the body), and also reduces its metal consumption. In this case, the body of the seat 9 (see Fig. 3) of the valve 8 is installed hermetically and from the outside it is equipped with a support platform 10 for the spring 11 of the valve 8 with holes 12 for the passage of the cement slurry.

The cementing holes 6 are closed with destructible elements (see Figs. 1 and 3), made in the form of cut-off nozzles 13 (hereinafter referred to as cut-off nozzles) installed inside the body 1. Shear-off nozzles 13 are closed with a plug 14 and rigidly fixed to the seat body 9 of the valve 8 or are made in one piece with the body of the seat 9 of the valve 8. In this case, the cut-off cups 13 are equipped with a protective casing 15 (see Fig. 3).

MSC also contains a locking flap 16 (see Fig. 1, 2 and 5) installed inside the housing 1 above the cementing holes 6 (see Fig. 1), made in the form of a sleeve, secured with a shear pin 17 (see Fig. 5) to the ring 18 installed at the junction between the sub 5 and the body 1. In the upper part of the valve 16, an internal groove is made (shown in Fig. 5 conditionally), forming a ledge 19 (see Fig. 5) in which the drillable seat 20 is concentrically installed (hereinafter referred to as the saddle) with a counter ledge 21 under the ledge 19 of the damper 16.

To eliminate the piston effect of the locking flap 16 when it is in the operating position, i.e. after closing the cementing holes 6 (see Figs. 1 and 2), it is equipped with a retainer made in the form of a spring split ring 22 installed in a groove 23 made on the outside of the locking flap 16 with the possibility of fixing in a counter groove 24 of the body 1. For preventing rotation when drilling out the cement plug (not shown in Figs. 1-6) after the completion of cementing work, the saddle 20 (see Figs. 1, 5) is made with an inner conical surface 25 (see Fig. 5) under the cone of the cementing plug.

MSC also contains O-rings 26, 27 and 28 (see Fig. 1 and 2), which ensure the tightness of the contact zones of the locking flap 16 with the body 1, the O-ring 29 - through the threaded connection of the body 1 with the sub 5, and the seat body 9 is sealed with body 1 by O-ring 30 (see Fig. 3 and 4).

The coupling for staged cementing of the casing in the well works as follows.

After assembly, the coupling (see Fig. 1) is subjected to hydraulic tests. If it withstands the test for tightness by the verification pressure, the cavity of the seat 9 of the valve 8 is filled with a viscous-plastic substance 31 (see Fig. 3), packed and sent to the finished product warehouse. Assembled, it is delivered and lowered into the well as part of the casing.

Then the first stage of the well is cemented by injecting the estimated volume of cement slurry.

Following the last portion of the first stage cement slurry, the first cement plug is launched into the well, which is pushed through by the squeezing fluid until it lands on the stop ring (not shown in Figs. 1-6) installed at the lower end of the casing, which is recorded by a pressure gauge at the wellhead a sharp increase in pressure. But, without waiting for it to sit on the stop ring, which is determined by calculation, an intermediate plug with a shearing element is launched, which, reaching the shear nozzle 13 (see Fig. 1, 2), cuts it off, at which the first cementing plug sits on the stop ring. In the opened cementing hole 6, the flushing fluid presses the valve 8 under pressure and, squeezing the viscous-plastic mass through the holes 12, enters the annulus, and then the excess cement slurry located above the cementing hole 6 is washed out.

Then proceed to cementing the second stage. Through the cementing hole 6 and holes 12, the calculated volume of cement slurry is pumped in, required for cementing the second stage column. Under the pressure of the cement slurry, the spring-loaded valve 8 is squeezed out (see Fig. 4) and the slurry through the hole 12 enters the annulus.

At the stage of completion of the injection, the next cementing plug is launched and pushed through until it lands on the seat 20 (see Figs. 1, 2).

Further, the pressure is increased to the calculated value, at which the shear pins 17 are cut off, which is noted at the wellhead by a sharp drop in pressure. In this case, the landing seat 20, the associated shut-off flap 16, together with the cementing plug, is directed down to the stop of the lower end of the shut-off flap 16 on the ledge 2 of the body 1. This moment is also recorded at the wellhead by a pressure gauge by a sharp increase in pressure. This means that the cementing holes 6 are closed by the locking flap 16. After which the spring-loaded valve 8 returns to its original position (see Fig. 1). The reliability of fixing the closing flap 16 is ensured by the spring split ring 22, which expands in the groove 24, and the tightness of the flap contact zones is ensured by the O-rings 26, 27 and 28.

Then, inside the string, the pressure is released, and after waiting for the cement to solidify (WOC) of the cement slurry, the landing saddle 20 together with the cement plug are drilled out, opening the MSC passage channel and access to the wellbore for subsequent operation.

The proposed sleeve for staged cementing of the casing in the well has increased performance and reliability due to the high tightness of the closure of the cementing holes on both sides - by a gate and a valve, thereby preventing access to the well of corrosive formation fluid from the annulus. And this, in turn, will prevent pipe corrosion, as well as watering of the well production. Ultimately, the use of a coupling in oil fields will lead to a reduction in repair and insulation work and a decrease in the associated time and material costs. The offered coupling is simple in design, easy to manufacture and assemble, has low metal consumption.

Claims (1)

A collar for staged cementing of a casing in a well, including a hollow casing with an internal shoulder and with connecting threads at the ends, to the upper thread of which a sub is attached, cementing holes closed with destructible elements, sealing rings installed above the cementing holes, a shut-off valve installed inside the casing above the cementing holes and equipped with a retainer in the form of a split spring ring, a drillable landing seat installed inside the locking flap, fixed with a shear pin to the ring installed at the junction between the body and its sub, characterized in that the body is made thickened, on the outer surface of which longitudinal grooves are made, while the cementing holes are made between the longitudinal grooves and are equipped with spring-loaded valves that open from the inner side of the body, the valve seat body is installed hermetically and on the outside is provided with a support platform for the valve spring with made holes for the passage of cement slurry, the destructible elements closing the cementing holes are made in the form of cut-off nozzles installed on the inner side of the body, while the cut-off nozzles are closed with a plug and rigidly fixed to the valve seat body or are made integral with the valve seat body, in the upper part of the locking The damper has an internal groove that forms a ledge with the possibility of placing a drillable landing saddle with a counter ledge under the ledge of the locking damper.

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