1. The utility model provides a flexible nipple joint for alleviating oil gas well oil casing deformation, its characterized in that, include the bellows and connect in the constant diameter straight tube at bellows both ends, the both ends of bellows with the constant diameter straight tube communicates with each other and integrated into one piece, the distance between two liang of adjacent crests of bellows is more than or equal to the wall thickness of bellows.

2. The flexible sub for mitigating deformation of an oil and gas well casing of claim 1, wherein the wall thickness of the corrugated pipe is the same as the wall thickness of the straight pipe.

3. The flexible short section for relieving deformation of the oil casing of the oil-gas well as defined in claim 2, wherein the wall thickness of the corrugated pipe and the wall thickness of the equal-diameter straight pipe are both 5.21 mm-22.22 mm.

4. The flexible short section for relieving deformation of an oil casing of an oil and gas well according to claim 1, wherein a female thread section is arranged in the constant diameter straight pipe.

5. The flexible sub for mitigating deformation of an oil and gas well casing as claimed in claim 4, wherein the outside diameter of the wave crest of the corrugated pipe is equal to the outside diameter of the straight pipe with equal diameter.

6. The flexible short section for relieving deformation of an oil casing of an oil and gas well according to claim 1, wherein the constant diameter straight pipe is provided with a male thread section.

7. The flexible sub for mitigating deformation of an oil and gas well casing as claimed in claim 6, wherein the inside diameter of the wave crest of the corrugated pipe is equal to the inside diameter of the straight pipe with equal diameter.

8. The flexible sub for mitigating deformation of an oil and gas well casing of claim 1, wherein the bellows is a seamless steel tube.

Background

In the oil and gas industry, drilling is the process of opening a channel from the ground to a hydrocarbon reservoir and plays an important role in the process of exploration and development of hydrocarbon resources.

In recent years, a horizontal well technology is applied in a large scale, and with the application of a rotary steering drilling technology and a high build-up rate power motor, as shown in fig. 1, a point a (landing point) of a horizontal well borehole trajectory is closer to a vertical borehole projection point (namely, the point a' is moved forward to the point a, and the target front distance is smaller and smaller), so that the contact area between a reservoir stratum and a borehole is greatly increased. As can be seen from fig. 1, with the increase of the build rate, the bending degree of the pipe column in the well bore becomes larger, and due to the difference of geological structures, external forces with different actions are applied to the pipe column in the well bore by fault slip, reservoir lifting, temperature effect, reservoir transformation (such as perforation, fracturing or acidification, etc.), and the like, and the external forces with different actions may cause the pipe column to generate macroscopic deformation, thereby affecting the smoothness of the passage in the pipe column.

At present, more and more casing deformation and casing damage events occur at different stages of well completion and production, and the service life of a shaft and the recovery yield of oil and gas resources are seriously influenced. According to statistics, the deformation and serious damage of the casing pipe mostly occur near the point A.

Disclosure of Invention

The invention aims to provide a flexible short section for relieving deformation of an oil casing of an oil-gas well, which can effectively relieve the deformation of the oil casing of the oil-gas well and ensure the integrity and the service life of a shaft.

The above object of the present invention can be achieved by the following technical solutions:

the invention provides a flexible short section for relieving deformation of an oil casing of an oil-gas well, which comprises a corrugated pipe and equal-diameter straight pipes connected to two ends of the corrugated pipe, wherein two ends of the corrugated pipe are communicated with the equal-diameter straight pipes and are integrally formed, and the distance between every two adjacent wave crests of the corrugated pipe is greater than or equal to the wall thickness of the corrugated pipe.

In an embodiment of the present invention, a thickness of the corrugated tube is the same as a thickness of the equal-diameter straight tube.

In an embodiment of the present invention, the thickness of the corrugated tube and the thickness of the equal-diameter straight tube are both 5.21mm to 22.22 mm.

In an embodiment of the present invention, the constant diameter straight pipe is provided with a female thread section therein.

In an embodiment of the invention, the outside diameter of the wave crest of the corrugated tube is equal to the outside diameter of the straight tube of equal diameter.

In an embodiment of the invention, the straight pipe with the same diameter is provided with a male thread section.

In an embodiment of the invention, the inner diameter of the wave crest of the corrugated tube is equal to the inner diameter of the equal-diameter straight tube.

In an embodiment of the present invention, the corrugated tube is a seamless steel tube.

The flexible short section for relieving the deformation of the oil casing of the oil-gas well has the characteristics and advantages that: the flexible short section for relieving deformation of the oil casing of the oil-gas well has the advantages of simple structure, simple and convenient operation process and good universality, can effectively relieve deformation and damage of the oil casing in a shaft, and can ensure the integrity and the service life of the shaft.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a conventional horizontal well.

FIG. 2 is a cross-sectional view of a first embodiment of the flexible sub of the present invention for mitigating deformation of an oil casing of an oil or gas well.

FIG. 3 is a cross-sectional view of a second embodiment of the flexible sub of the present invention for mitigating deformation of an oil casing of an oil or gas well.

FIG. 4 is a schematic diagram of the flexible short section for relieving deformation of an oil casing of an oil-gas well in the borehole.

The reference numbers illustrate: 1. a bellows; 11. wave crest; 2. a straight pipe of equal diameter; 21. a female thread segment; 22. a male thread segment; h. a distance; a. wall thickness; b. wall thickness; D. an outer diameter; d', outer diameter; d. an inner diameter; d', inner diameter.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in figure 2, the invention provides a flexible short section for relieving deformation of an oil casing of an oil-gas well, which comprises a corrugated pipe 1 and equal-diameter straight pipes 2 connected to two ends of the corrugated pipe 1, wherein two ends of the corrugated pipe 1 are communicated with the equal-diameter straight pipes 2 and are integrally formed, and the distance h between every two adjacent wave crests 11 of the corrugated pipe 1 is greater than or equal to the wall thickness b of the corrugated pipe 1.

The flexible short section for relieving the deformation of the oil casing of the oil-gas well is particularly suitable for being applied to a vertical well or a directional well with a well body structure of a horizontal well or a complex geological structure, can be used as a member of a casing string or an oil pipe string in the well body, and is placed in the vicinity of a well section with the complex geological structure or a horizontal well landing point (namely, the point A in the figure 1) in the process of lowering an oil pipe or a casing. The flexible short section of the invention adopts the corrugated pipe 1 with the wavy structure, the corrugated pipe 1 can deform after being subjected to external force, the whole flexible short section has certain flexibility, and can adapt to larger deformation without influencing the size of the drift diameter. The flexible short section is used as a component of an oil pipe column or a casing string, and the flexibility and the deformability of the pipe column are improved.

Specifically, the flexible short section comprises a corrugated pipe 1 and equal-diameter straight pipes 2 connected to two ends of the corrugated pipe 1, the corrugated pipe 1 is a seamless steel pipe, the corrugated pipe 1 is wavy or wrinkled, and the wall thickness of each position of the corrugated pipe 1 is the same. The steel grade of the corrugated pipe 1 is consistent with the steel grade of the oil pipe or casing connected with the corrugated pipe.

In the invention, the design of the oil pipe column or the casing pipe column adopts a standard oil pipe or a standard casing pipe, the outer diameter D of the corrugated pipe 1 is less than or equal to the outer diameter of a coupling of the casing pipe (or the oil pipe), and the inner diameter D of the corrugated pipe 1 is more than or equal to the inner diameter of the body of the casing pipe (or the oil pipe). For non-standard tubing or casing, the outside and inside diameters of the bellows 1 are consistent with the corresponding non-standard tubing or casing. The wall thickness of the steel pipe of the corrugated pipe 1 is consistent with the wall thickness of the oil pipe or casing pipe connected with the corrugated pipe. And selecting the length of the corresponding flexible joint to adapt to specific working conditions according to the structural design of the well body.

In the embodiment of the present invention, the wall thickness b of the corrugated tube 1 is the same as the wall thickness a of the equal-diameter straight tube 2. Specifically, the wall thickness b of the corrugated pipe 1 and the wall thickness a of the equal-diameter straight pipe 2 are both 5.21mm to 22.22 mm.

In a possible embodiment of the present invention, as shown in fig. 2, the straight pipe 2 is provided with female thread segments 21; specifically, in this embodiment, the outer diameter D of the crests 11 of the corrugated tube 1 is equal to the outer diameter D' of the equal-diameter straight tube 2.

In another possible embodiment of the present invention, as shown in fig. 3, the constant diameter pipe 2 is provided with a male thread section 22. Specifically, in this embodiment, the inner diameter d of the wave crest 11 of the corrugated tube 1 is equal to the inner diameter d' of the equal-diameter straight tube 2.

In the invention, the flexible short section of the embodiment shown in fig. 2 can be connected with the flexible short section of the embodiment shown in fig. 3 through threads, and the flexible short section have certain sealing performance and connection strength after being connected.

The flexible short section can be directly in threaded connection with an oil pipe or a casing pipe, and has certain sealing performance and connection strength after connection. The female thread section 21 or the male thread section 22 of the flexible short section is an oil casing thread, and the corresponding flexible short section thread is selected according to the oil pipe or the casing thread connected with the flexible short section during operation.

The flexible short section for relieving deformation of the oil casing of the oil-gas well has the advantages of simple structure, simple and convenient operation process and good universality, can effectively relieve deformation and damage of the oil casing in a shaft, and can ensure the integrity and the service life of the shaft.

The operation process of the flexible short section comprises the following steps:

1. preparation before entering well

1.1, confirming that the size of the flexible short section is consistent with that of the connected oil pipe or casing pipe, and the connecting threads are the same;

1.2 detect the internal diameter of flexible nipple joint with the latus rectum rule, ensure that the internal diameter is unanimous with the design.

2. Procedure for entering well

2.1 according to the design of a pipe column, connecting flexible short sections at the designed length part of the oil pipe column or the casing string, wherein the connection length and the number are determined according to the design;

2.2 connecting the flexible short section with the corresponding oil casing according to the specified torque to ensure the sealing performance of the pipe column;

2.3, lowering all the pipe columns to a preset depth according to a casing (or oil pipe) lowering procedure;

2.4 pressing down the casing (or oil pipe) to finish other subsequent operations.

In the engineering application, flexible short sections with different structural sizes can be correspondingly designed according to different specifications of a casing and an oil pipe as follows:

the actual wellbore trajectory is typically tortuous as if the great wall were underground, and the corresponding tubing or casing run into the wellbore is tortuous. In a well section with large change of the curvature of the well bore, the geological structure is complex and is easy to generate fault slippage, stratum lifting or sinking, the bending stress and the shearing stress borne by an oil pipe or a casing pipe are large, and flexible short sections with certain length (or quantity) are arranged to adapt to the dislocation slippage of the well body.

For example: in a horizontal well with the measuring well depth of 5000m, a standard casing with the horizontal section length of 1500m and the end-opened well body structure design of 165.1mm and with the external diameter of 127mm, the wall thickness of 12.7mm, the steel grade of P110 and the thread of buttress thread is lowered in an open hole. The corresponding inner diameter of the casing is 101.6mm, the drift diameter is 98.42mm, and the outer diameter of the coupling is 141.30 mm. Because this horizontal well geological structure is complicated, pit shaft dog leg degree is great, and the possibility that later stage pit shaft takes place the stratum and slides is higher, has applied flexible nipple joint in this casing string design, and its specification is as follows: the outer diameter D of the flexible short section is 141mm, the inner diameter D of the flexible short section is 102mm, the wall thickness of the flexible short section is 12.7mm, and the steel grade of the flexible short section is P110. The flexible short section has a wave fold structure, so that the flexible short section can be better suitable for the change of a well track, and can be 'flexibly rigid' after being subjected to external forces such as bending, shearing, stretching and the like. Figure 4 shows a schematic representation of the flexible casing sub in position within the wellbore.

The above description is only a few embodiments of the present invention, and those skilled in the art can make various changes or modifications to the embodiments of the present invention according to the disclosure of the application document without departing from the spirit and scope of the present invention.