A production casing joint suitable for use in horizontal well fracturing and applications

Abstract

The application discloses a production casing joint for horizontal well fracturing and application, which comprises first and second male connecting pipes with first and second outer threads and a female connecting cylinder connecting the two male connecting pipes, the female connecting cylinder is provided with first and second inner threads matched with the two outer threads; the outer wall of the pipe body of the end of the first and second male connecting pipes is respectively provided with first and second taper surfaces, the inner diameter of the pipe body at the corresponding end is smaller than the inner diameter of the main body section of the pipe body; the inner wall of the cylinder body between the two inner threads is provided with a protruding part protruding into the inner cavity, the end faces on the two sides of the protruding part form the pressing surfaces of the end of the two male connecting pipes, the inner wall of the cylinder body between the protruding part and the two inner threads is respectively provided with third and fourth taper surfaces matched with the first and second taper surfaces; each thread has a negative load angle; the tooth top of the corresponding inner and outer threads is in interference fit, and the tooth side is in clearance fit; relative to the end position of the two male connecting pipes, the farther the two outer threads are from the end position, the larger the outer diameter of the pipe body is; relative to the protruding part, the farther the two inner threads are from the protruding part, the larger the inner diameter of the pipe body is.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum pipe engineering, in particular to a production casing joint for horizontal well fracturing. BACKGROUND

[0002] With the development of unconventional oil and gas exploitation technology, shale oil and gas, tight oil and gas are increasingly exploited. The pipe material technology required for such unconventional oil and gas exploitation is high, and needs to withstand special processes such as horizontal running, high displacement hydraulic fracturing, etc. When the casing is subjected to compression, torsion, high internal pressure and other complex loads, it is prone to deformation or leakage. Therefore, developing a production casing joint for horizontal well fracturing to ensure the structural and sealing integrity of the casing has become an important basis for such unconventional oil and gas exploitation.

[0003] The gas-tight premium thread joint of ordinary carbon steel generally refers to a joint composed of a threaded metal sealing surface and a torque shoulder, etc. to meet the sealing performance of the joint. Similar technologies are disclosed in patents CN99240437.1, CN99240438.X, CN01253367.X, CN02209453.9, CN02257690.8, CN200420059633.1, CN200720096474.6, CN200720027706.2, CN200720027707.7, CN200720199432.5, CN200920154275.5, CN201020013334.X, CN200920277215.2, CN201020254008.8, CN00249827.8, CN201020506375.2, CN201120037927.4, CN97115288.8, CN1386953, CN102011557A and CN102071881A. The designs of these patents are mainly to meet the gas sealing through structural design, and cannot meet the actual needs of high torsion resistance, high internal pressure and high compression working conditions. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the above-mentioned deficiencies of the prior art and provide a production casing joint for horizontal well fracturing that can meet the requirements of unconventional oil and gas exploitation.

[0005] The technical problem to be solved can be solved by the following technical solutions.

[0006] A production casing joint for horizontal well fracturing, characterized in that it comprises:

[0007] A first male connecting pipe with a first connecting external thread, a second male connecting pipe with a second connecting external thread, and a female connecting cylinder for connecting the first and second male connecting pipes, the female connecting cylinder having a first connecting internal thread and a second connecting internal thread matched with the first and second connecting external threads;

[0008] A first taper surface is arranged on the outer wall of the pipe body at the end position of the first male connecting pipe, and the inner diameter of the pipe body near the end of the first male connecting pipe is smaller than that of the main body section of the first male connecting pipe; a second taper surface is arranged on the outer wall of the pipe body at the end position of the second male connecting pipe, and the inner diameter of the pipe body near the end of the second male connecting pipe is smaller than that of the main body section of the second male connecting pipe;

[0009] A convex part is arranged on the inner wall of the cylinder body between the first and second connecting internal threads, and the convex part protrudes into the inner cavity of the cylinder body, the end faces on both sides of the convex part form the pressing surfaces of the ends of the first and second male connecting pipes, respectively, a third taper surface matched with the first taper surface is arranged on the inner wall of the cylinder body between the convex part and the first connecting internal thread, and a fourth taper surface matched with the second taper surface is arranged on the inner wall of the cylinder body between the convex part and the second connecting internal thread;

[0010] The negative bearing angle is adopted for each connecting external thread and connecting internal thread; the top of the thread of the first connecting external thread and the first connecting internal thread is in interference fit, and the side of the thread is in clearance fit; the top of the thread of the second connecting external thread and the second connecting internal thread is in interference fit, and the side of the thread is in clearance fit.

[0011] The farther the first connecting external thread is from the end of the first male connecting pipe, the larger the outer diameter of the pipe body is; the farther the second connecting external thread is from the end of the second male connecting pipe, the larger the outer diameter of the pipe body is; the farther the first and second connecting internal threads are from the convex part, the larger the inner diameter of the pipe body is.

[0012] As a further improvement of the technical solution, the negative bearing angle α of each connecting external thread and connecting internal thread is ≤-3°.

[0013] As a further improvement of the technical solution, the transverse clearance δ1 of the thread profile of the first connecting external thread and the first connecting internal thread is (0, 0.06mm); the transverse clearance δ2 of the thread profile of the second connecting external thread and the second connecting internal thread is (0, 0.06mm).

[0014] As a further improvement of the technical solution, the thread taper β1 of the first connecting external thread and the first connecting internal thread is between 1 / 20 and 1 / 30; the thread taper β2 of the second connecting external thread and the second connecting internal thread is between 1 / 20 and 1 / 30.

[0015] Also as a further improvement of the technical solution, the inner diameter of the pipe body near the end of the first male connecting pipe is Ds1, the nominal inner diameter of the sleeve of the first male connecting pipe is Di1, Di1-Ds1=(1.5, 3) mm; the inner diameter of the pipe body near the end of the second male connecting pipe is Ds2, the nominal inner diameter of the sleeve of the second male connecting pipe is Di2, Di2-Ds2=(1.5, 3) mm.

[0016] Preferably, the interference of the male and female threads is between 0.25 mm and 0.65 mm.

[0017] Further, the inner diameter of the end of the first male connecting pipe or the second male connecting pipe, which does not include a tapered portion, is narrowed to form a nose end, and the outer diameter of the nose end is Dp3=D-t; wherein D is the diameter (outer diameter) of the sleeve, and t is the thickness consumed by the small taper thread, t=1.6-2.2 mm.

[0018] Preferably, the end face of the first male connecting pipe is perpendicular to the axis, the end face of the second male connecting pipe is perpendicular to the axis, the two side end faces of the protrusion are perpendicular to the axis, the taper of the first taper is the same as that of the third taper, and the taper of the second taper is the same as that of the fourth taper.

[0019] Preferably, the thread pitch of the male and female threads is 4TPI (6.35 mm / t).

[0020] Another technical problem to be solved by the present application is to provide an application of the aforementioned sleeve joint in the fracturing of a horizontal well for shale oil and gas or tight oil and gas.

[0021] Still another technical problem to be solved by the present application is to provide an application of the aforementioned sleeve joint as a production casing joint for oil drilling with an outer diameter of 100-200 mm.

[0022] The production casing structure for horizontal well fracturing using the technical solution has the following beneficial effects:

[0023] 1. The bonding does not occur during the three times of releasing the buckle of the casing;

[0024] 2. The tensile, internal pressure and external extrusion performance of the joint are not lower than those of the pipe body itself;

[0025] 3. The sealing capacity of the joint is the same as the internal pressure of the pipe body, and the bending of the joint can reach 20° / 30 m;

[0026] 4. The torsional resistance of the joint is increased by one time or more than that of the conventional API BTC. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The figure is a schematic diagram of the production casing joint structure for horizontal well fracturing.

[0028] Figure 2 Structure diagram of the male end of the casing joint of the present application;

[0029] Figure 3 Structure diagram of the female end of the casing joint of the present application;

[0030] Figure 4 Structure diagram of the male end of the casing joint of the present application; Figure 2 Another form of marking diagram;

[0031] Figure 5 Structure diagram of the female end of the casing joint of the present application; DETAILED DESCRIPTION

[0032] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0033] The present application provides a production casing joint for oil drilling with an outer diameter specification in the range of Φ100mm to Φ200mm (i.e. the outer diameter of the male end P mentioned in the text covers from Φ100mm to Φ200mm), which is suitable for shale oil and gas, tight oil and gas and other horizontal well and fracturing working conditions.

[0034] Referring to Figures 1 to 5 , the joint is composed of a male end (P) and a female end (B). The male end joint is composed of a thread P1 and a shoulder P3, and the female end joint is composed of a thread B1 and a shoulder B3. By screwing the male and female end threads P1 and B1, the shoulders P3 and B3 are butted, meeting the requirements of high torsion resistance and subsequent high internal pressure fracturing technology during the process of lowering the horizontal casing.

[0035] The structure of the male end P is composed of a thread P1 with a negative load angle, a metal sealing surface P2 and a torque shoulder P3. The structure of the female end is composed of a thread B1 with a negative load angle, a metal sealing surface B2 and a shoulder B3.

[0036] The thread of the present application has the characteristics of sealing and torsion resistance. To achieve this feature, the thread is designed as follows:

[0037] 1. The male and female threads are designed to be isometric;

[0038] 2. The male and female threads adopt a negative load angle α≤-3°;

[0039] 3. The male and female thread tooth profile transverse gap δ: (0, 0.06mm);

[0040] 4. The male and female thread taper β is between 1 / 20 and 1 / 30;

[0041] 5. The male and female thread pitch is 4TPI (6.34mm / t);

[0042] The purpose is to improve the overall torsional and liquid sealing (high internal pressure fracturing) performance.

[0043] Further, the male nose end is composed of a vertical torque shoulder P3 and a sealing surface P2, as shown in Figure 4 The torque shoulder surface length is between 5-15mm, and the end is a vertical angle. In particular, the torque shoulder inner diameter is as small as possible. In order to meet the higher torsional capacity, the torque shoulder inner diameter is generally controlled by the neck-in to meet Di-Ds=(1.5, 3)mm, where Ds refers to the torque shoulder P3 inner diameter, and Di refers to the nominal inner diameter of the casing. By increasing the torque shoulder thickness, the overall torsional capacity is improved. In particular, by necking-in to increase the nose end torsional shoulder thickness, the vertical angle structure shoulder also improves the torsional capacity.

[0044] The tapered metal sealing structure adopted by the nose end can ensure that the sealing surface has a certain airtight sealing effect after the torque shoulder contact, ensuring a certain gas and liquid sealing capacity under the premise of joint torsion resistance.

[0045] By reducing the thread taper (for example, β2 is controlled between 1 / 20-1 / 30), the nose end outer diameter can be increased, thereby achieving the purpose of increasing the thickness and torsional capacity. The nose end outer diameter Dp3=D-t. Here, the nose end thickness can refer to the position P3 in Figure 2 , which refers to the end thickness of the end head with a smaller inner diameter but excluding the tapered section, which directly affects the torsional capacity of the casing; D is the casing diameter (outer diameter); t is the small taper thread thickness consumption, t=1.6-2.2mm, which can be as small as possible to increase the P3 thickness and the joint torsional capacity.

[0046] Referring to Figure 5 , the structure of the female end B is composed of a negative bearing angle thread B1, a sealing surface B2, and a torque shoulder B3.

[0047] Since unconventional oil and gas exploitation such as shale oil and gas, tight oil and gas generally needs to use horizontal well design, the casing is usually placed to the design position by using large torque during drilling and mining. The joint of the present application improves the torsional capacity of the overall joint by high interference connection of the threads, with a thread interference of 0.25-0.65mm, increasing the thread portion consumption torque during screwing, and improving the overall torsional capacity; the thread adopted in the technical scheme has a small thread gap and a smaller taper than the conventional oil casing joint thread 1:16, and the equal height thread design can improve the overall joint torsional capacity; the thread top of the male and female ends adopts interference fit, and the thread side adopts gap fit (i.e. horizontal gap δ).

[0048] The following will be further described through specific examples.

[0049] Example:

[0050] Taking the 139.7m*12.7mm 125ksi production casing commonly used in shale gas as an example, the following table 1 is related parameters and performances.

[0051] Table 1:

[0052]

[0053] The production casing joint for horizontal well fracturing provided by the application can provide higher casing torsional and internal pressure resistance, and is suitable for unconventional oil and gas, such as shale oil and gas, dense oil and gas production casing environment.

Claims

1. A production casing joint suitable for horizontal well fracturing, characterized in that, include: A first male connecting pipe having a first external connecting thread, a second male connecting pipe having a second external connecting thread, and a female connecting sleeve for connecting the first and second male connecting pipes, the female connecting sleeve having a first internal connecting thread and a second internal connecting thread that mate with the first and second external connecting threads; The outer wall of the first male connector has a first conical surface, and the inner diameter of the first male connector near the end is smaller than the inner diameter of the main body section of the first male connector; the outer wall of the second male connector has a second conical surface, and the inner diameter of the second male connector near the end is smaller than the inner diameter of the main body section of the second male connector. The inner wall of the female connecting cylinder between the first and second internal connecting threads is provided with a protrusion that protrudes into the inner cavity of the cylinder. The end faces on both sides of the protrusion form the pressing surfaces of the first and second male connecting pipe ends, respectively. A third conical surface that mates with the first conical surface is provided on the inner wall of the cylinder between the protrusion and the first internal connecting thread. A fourth conical surface that mates with the second conical surface is provided on the inner wall of the cylinder between the protrusion and the second internal connecting thread. Wherein, each of the connecting external threads and connecting internal threads adopts a negative load-bearing angle; the tooth tips of the first connecting external thread and the first connecting internal thread are interference fit, and the tooth flanks are clearance fit; the tooth tips of the second connecting external thread and the second connecting internal thread are interference fit, and the tooth flanks are clearance fit. Relative to the end of the first male connector, the farther the first external thread is from the end, the larger the outer diameter of the pipe body; relative to the end of the second male connector, the farther the second external thread is from the end, the larger the outer diameter of the pipe body; relative to the protrusion, the farther the first and second internal threads are from the protrusion, the larger the inner diameter of the pipe body.

2. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, The negative load angle α used for each connecting external thread and connecting internal thread is ≤-3°.

3. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, The transverse clearance δ1 between the first connecting external thread and the first connecting internal thread is (0, 0.06 mm); the transverse clearance δ2 between the second connecting external thread and the second connecting internal thread is (0, 0.06 mm).

4. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, The thread taper β1 of the first connecting external thread and the first connecting internal thread is between 1 / 20 and 1 / 30; the thread taper β2 of the second connecting external thread and the second connecting internal thread is between 1 / 20 and 1 / 30.

5. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, Let Ds1 be the inner diameter of the first male connector near its end, and Di1 be the nominal inner diameter of the sleeve of the first male connector. Di1-Ds1 = (1.5, 3) mm. Let Ds2 be the inner diameter of the second male connector near its end, and Di2 be the nominal inner diameter of the sleeve of the second male connector. Di2-Ds2 = (1.5, 3) mm.

6. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, The interference fit between male and female threads is between 0.25mm and 0.65mm.

7. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, The narrowed inner diameter portion of the first or second male connecting pipe end, excluding the tapered section, is designated as the nose end, with an outer diameter Dp3 = Dt; where D is the pipe diameter and t is the thickness of the small taper thread consumption, t = 1.6~2.2mm.

8. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, The end face of the first male connector is perpendicular to the axis, and the end face of the second male connector is perpendicular to the axis; the two end faces of the protrusion are perpendicular to the axis; the first and third conical surfaces have the same taper; the second and fourth conical surfaces have the same taper.

9. The production casing joint for horizontal well fracturing according to claim 1, characterized in that, The pitch of the male and female threads is 4TPI (6.35mm / t).

10. The application of the casing joint according to any one of claims 1-9 in the fracturing of horizontal wells in shale oil and gas or tight oil and gas.

11. The casing fitting according to any one of claims 1-9 is used as a casing fitting for oil drilling production with an outer diameter between 100 mm and 200 mm.

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