RU2537709C1 - Procedure for elimination of behind-casing flows - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas production industry, namely to well-workover operations. The procedure for elimination of behind-the-casing flows includes, before running in of the casing string, performance of geophysical investigations with identification of intervals for potential behind-the-casing flows, equipment of the casing string with pipe expandable up to 24% by outside sealing components, which are placed opposite the intervals of potential flows upon running in of the casing string. When behind-the-casing flows occur and affect inner surface of the expandable pipes equipped with sealing components, they expand the above pipes within the whole range of flows thus sealing borehole annulus and preventing fluid cross-flow from one stratum to another. In order to improve quality expanded pipes are used with sealing components swellable under action of stratum fluids.

EFFECT: suggested procedure allows elimination of behind-the-casing flows in proper way with maintenance of the casing integrity, reduction of material costs and speed-up of the well-workover process.

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Description

The invention relates to the oil and gas industry, and in particular to methods for overhaul wells.

A known method of sealing annular flows carried out by a device for sealing annular flows (patent RU No. 2287664, IPC ЕВВ 33/13, published on November 20, 2006, bull. No. 32), comprising a housing with wedge sections, dies interacting with them and hydraulic the drive that drives them, the hydraulic drive is multi-stage, the wedge sections are made along the entire transverse perimeter of the housing and form a truncated pyramid, in the initial state, the side surfaces of the dies are in close proximity, and aruzhnymi surfaces form a cylindrical face of the prism.

The disadvantages of this method:

- limited scope, since the casing is able to expand without breaking no more than 6%, after which the probability of its destruction increases significantly;

- when using a device with smooth dies, a significant axial hydraulic drive force is necessary, which can lead to an emergency in the well, and when using dies with protrusions, there is a high probability of casing collapse at the place of influence of the dies protrusions, since high pressure on a small area can “pierce” "Casing, as a perforator;

- in order to obtain continuous expansion in a large interval, it is necessary to carry out hundreds of cycles of local expansion, which will lead to an increase in repair time and, as a result, high material costs.

The closest in technical essence is the method of elimination of annular flows (patent RU No. 1813873, IPC ЕВВ 33/13, published on 05/07/93, bull. No. 17), including sealing of the channels of the flows, with the aim of simplifying the technology of work casing in the interval of overflows or in separate sections, expand beyond the limits of elastic deformations.

The disadvantages of this method:

- limited scope, since the casing is able to expand without breaking no more than 6%, after which the probability of its destruction increases significantly;

- the hydraulic anchor does not create an annular expansion around the entire perimeter of the pipe, which leads to low sealing efficiency of annular flows;

- the creation of very high pressures (100 MPa) requires the use of special pipes, machines, equipment and tools, which is associated with a significant increase in the cost of the process.

The technical objectives of the proposed method are to increase the reliability of eliminating overflows while maintaining the integrity of the casing due to the use of special expandable pipes in its composition, as well as reducing material costs through the use of standard tools and equipment and accelerating the process of well repair.

Technical problems are solved by the method of elimination of annular flows, including the expansion of the casing after cementing in whole or in separate sections in the interval of flows beyond the limits of elastic deformation.

New is that before the casing is run, geological surveys are carried out with the determination of the intervals of possible overflows, the casing is supplied with pipes expandable to 24% with external sealing elements located after the casing is lowered opposite the intervals of possible overflows, when annular flows occur, acting on the inner surface of the expandable pipes equipped with sealing elements expand them in the entire flow interval, sealing the annular space, thereby completely w except fluid flow from the formation into the formation.

Also new is the use of expandable pipes with external sealing elements that swell under the action of formation fluid.

Figure 1 shows the descent of the casing, equipped with expandable pipes, into the well with flow from formation to formation; figure 2 - expansion of expandable casing pipes by a flare tool to eliminate overflows.

The method is carried out in the following sequence.

Based on the geological material and information on the presence of casing flows in neighboring wells, the intervals of possible casing flows are introduced into the well construction project, including casing string 1 (Fig. 1) expandable to 24% pipe 2, equipped with sealing elements 3, located opposite possible flows 4. Lower the casing 1 with expandable pipes 2 provided with sealing elements 3, while the expandable pipes 2 are connected to each other by thread 5 or by welding 6. Cementing wells and od in operation produce a known manner.

When occurrence of annular flows 4, acting on the inner surface of expandable pipes 2, equipped with sealing elements 3, expand them in the entire interval of the flow 4, sealing annular space 7 (figure 2) to eliminate the gaps 8 between the casing 1 and the cement ring 9 and between cement ring 9 and the wall of the well 10, thereby completely eliminating the flow of fluid 4 from the reservoir 11 into the reservoir 12. Due to the fact that the expandable pipes are made of steel, allowing their expansion to 24%, the existing gaps between the column 1 and cement ring 9 and also between the cement ring 9 and the wall of the well 10 is completely eliminated without possible destruction of the casing 1. To improve quality using expandable pipe sealing elements 3, swelling under the influence of formation fluids.

The proposed method allows to qualitatively eliminate annular overflows while maintaining the integrity of the casing string, as well as reduce material costs and accelerate the process of well repair.

Claims (2)

1. A method of eliminating annular cross-flows, including the expansion of the casing string after cementing in whole or in separate sections in the cross-flow interval beyond the limits of elastic deformation, characterized in that before lowering the casing string, geophysical studies are carried out with the determination of the intervals of possible casing cross-flows, the string is supplied with pipes expandable to 24% with external sealing elements located after lowering the casing opposite to the intervals of possible overflows, in the event of annular flows, acting on the inner surface of expandable pipes equipped with sealing elements, expand them in the entire interval of the flow, sealing annular space, thereby completely eliminating the flow of fluid from the formation into the formation. 2. The method of eliminating annular flows according to claim 1, characterized in that they use expandable pipes with external sealing elements that swell under the action of the formation fluid.

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