A seal for deep-sea compensator and a testing device and method for its sealing life

Abstract

The present invention relates to a seal for a deep-sea compensator and a test device and method for its sealing life, wherein the seal comprises: an annular sealing structure, which is sleeved in an annular gap formed by an outer working pipe string and an inner working pipe string, and the annular sealing structure comprises a first outer layer, a first filling layer, an intermediate layer, a second filling layer and a second outer layer which are arranged in sequence as one body, wherein the first outer layer, the intermediate layer and the second outer layer are all PEEK layers, and the first filling layer and the second filling layer are a multilayer structure formed by alternating distribution of at least one PTFE-based composite layer and at least one PTFE layer, and the axial cross-sections of the PTFE-based composite layer and the PTFE layer are in a herringbone shape; an annular straightening structure, wherein the two annular straightening structures are respectively sleeved on the outer wall of the inner working pipe string located at both ends of the annular sealing structure. When the seal is squeezed by the up and down floating of seawater, it can effectively buffer the axial sliding squeezing caused by the up and down floating of seawater.

Description

Technical Field

[0001] The invention relates to a seal for a deep-sea compensator and a test device and method for its sealing life, belonging to the technical field of marine oil and gas and natural gas hydrate exploration and development. Background Art

[0002] During the development of oil and gas in open waters, deepwater floating drilling platforms will float up and down due to the up and down floating caused by the waves during operation, which will cause the operating pipe string to float up and down and also generate lateral shear force. For this reason, a pipe string compensator for floating drilling platforms is developed, which has the functions of pipe string transmission torque and self-righting, and at the same time keeps the telescopic pipe string sealed for a long time without failure.

[0003] A floating drilling platform has a floating body submerged in the water and connected to the upper deck by columns. It is in a floating state during operation. When operating in deep water areas, floating drilling platforms need to rely on positioning equipment, generally an anchor positioning system. When the water depth exceeds 300 to 500 meters, a dynamic positioning system or a deepwater anchor positioning system is required. Since the lower part of the floating drilling platform is immersed in water, the amplitude of its roll and pitch is very small, but the vertical swing movement has a greater impact. Due to the floating operation characteristics of the floating drilling platform, its operating pipe string will be affected by the lateral shear force (smaller), but will also float up and down (more frequently). Therefore, during the testing operation of the floating platform, it is necessary to set a tool in the operating pipe string to compensate for the shrinkage of the pipe string. Summary of the invention

[0004] In response to the above-mentioned prominent problems, the present invention provides a seal for a deep-sea compensator and a testing device and method for its sealing life. The axial cross-section of the sealing structure of the seal adopts a herringbone design, which can greatly improve its sealing performance under high-pressure conditions. When the seal is squeezed by the up and down floating of seawater, it can effectively seal the pressure inside and outside the pipe column.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A first aspect of the present invention provides a seal for a deep-sea compensator, comprising:

[0007] An annular sealing structure is sleeved in an annular gap formed by an outer working pipe string and an inner working pipe string, the annular sealing structure comprises a first outer layer, a first filling layer, an intermediate layer, a second filling layer and a second outer layer which are sequentially arranged in an integral manner, wherein the first outer layer, the intermediate layer and the second outer layer are all PEEK layers, the first filling layer and the second filling layer are a multilayer structure formed by alternating distribution of at least one PTFE-based composite layer and at least one PTFE layer, and the axial cross-sections of the PTFE-based composite layer and the PTFE layer are herringbone-shaped, the tips of the PTFE-based composite layer and the PTFE layer in the first filling layer are toward the first outer layer, and the tips of the PTFE-based composite layer and the PTFE layer in the second filling layer are toward the second outer layer;

[0008] An annular straightening structure, wherein the two annular straightening structures are respectively sleeved on the outer wall of the inner working pipe string located at two ends of the annular sealing structure.

[0009] The seal for deep-sea compensator, preferably, the number average molecular weight of PEEK in the PEEK layer is 100,000-160,000, the tensile strength is 98 MPa, and the glass transition temperature is 150°C.

[0010] The deep-sea compensator seal preferably has a number average molecular weight of 1-1.5 million and a specific gravity of 2.17 g / cm 3 , the volume density is 814.16g / L.

[0011] The seal for deep-sea compensator, preferably, the PTFE-based composite layer is carbon fiber reinforced PTFE, the number average molecular weight is 1-1.5 million, the specific gravity is 2.089 g / cm 3 , the volume density is 708.8g / L.

[0012] A second aspect of the present invention provides a test device for the sealing life of a seal for a deep-sea compensator, comprising:

[0013] A test barrel, wherein a cooling and heat preservation system is arranged on the outer wall of the test barrel, a test fixture is arranged in the test barrel, an ice-water mixture is filled between the test fixture and the test barrel, the test fixture is a cylindrical structure including a top cover and a base, a slider which can slide along its axial direction is accommodated in the cavity of the test fixture, the annular sealing structure is sleeved on the outer wall of the slider, and the slider divides the cavity of the test fixture into an upper cavity and a lower cavity;

[0014] A hydraulic press, wherein the hydraulic press is provided with an A-end pressure regulator and a B-end pressure regulator, wherein the A-end pressure regulator is connected to the upper cavity via a No. 1 conduit penetrating the top cover, and the B-end pressure regulator is connected to the lower cavity via a No. 2 conduit penetrating the base;

[0015] A high-pressure pump is provided with a first liquid outlet and a second liquid outlet, wherein the first liquid outlet is connected to the upper cavity via a third conduit penetrating the top cover, and the second liquid outlet is connected to the lower cavity via a fourth conduit penetrating the base.

[0016] The testing device is preferably provided with a No. 1 high-pressure variable buckle and a No. 3 high-pressure stop valve on the No. 1 conduit, and a No. 2 high-pressure variable buckle and a No. 4 high-pressure stop valve on the No. 2 conduit.

[0017] The testing device is preferably provided with a No. 1 high-pressure stop valve and a No. 1 pressure gauge on the No. 3 conduit, and a No. 2 high-pressure stop valve and a No. 2 pressure gauge on the No. 4 conduit.

[0018] Preferably, the test barrel of the test device is also provided with a temperature sensor for monitoring the temperature in the test barrel at any time.

[0019] A third aspect of the present invention provides a method for testing the sealing life of a seal for a deep-sea compensator, comprising the following steps:

[0020] (a) placing the slider with the annular sealing structure in the test fixture, then placing the test fixture in the test barrel, and then adding an ice-water mixture into the test barrel;

[0021] (b) turning on the hydraulic press, setting the pressure of the A-end pressure regulator and the B-end pressure regulator respectively, and setting the number of times the slider slides up and down in the test fixture, so that the liquid in the hydraulic press enters the upper cavity and the lower cavity respectively through the No. 1 conduit and the No. 2 conduit, pushing the slider to slide up and down;

[0022] (c) When the slider slides up and down in the test fixture for a set number of times, close the No. 3 high-pressure stop valve and the No. 4 high-pressure stop valve, open the high-pressure pump and the No. 1 high-pressure stop valve and the No. 2 high-pressure stop valve, monitor the value changes of the No. 1 pressure gauge and the No. 2 pressure gauge, and judge the sealing performance of the annular sealing structure.

[0023] In the test method, preferably, the verification pressure in step (c) is higher than the reciprocating sliding pressure in step (b).

[0024] The present invention adopts the above technical solution, which has the following advantages:

[0025] 1. The seal of the present invention is composed of multiple polymer layers, wherein the PEEK layer with high hardness is used as the first outer layer, the middle layer and the second outer layer to form a skeleton structure to provide hardness support for the seal, and the first filling layer and the second filling layer are a multilayer structure in which PTFE layers and PTFE-based composite layers are alternately distributed, providing a soft zone buffer for the seal, which can play a real hard reciprocating sealing role; on the other hand, the axial cross section of the seal is designed to be a herringbone shape, which can greatly improve its sealing performance under high pressure. When the seal is squeezed by the up and down floating of seawater, it can effectively seal the pressure inside and outside the pipe column;

[0026] 2. The seal designed by the present invention is tested in a sealing life test device. After the seal reciprocates 10,000 times in the test device and is tested by a high-pressure pump (the test pressure is 70 MPa), it still has a good hard sealing effect, and the liquid in the test fixture will not leak. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the three-dimensional structure of the sealing structure in the present invention;

[0028] Figure 2 It is a schematic diagram of the cross-sectional structure of the sealing structure of the present invention installed between the inner and outer working pipe strings;

[0029] Figure 3 It is a schematic diagram of a partial three-dimensional structure of the sealing structure in the present invention;

[0030] Figure 4 is a cross-sectional view of a partial three-dimensional structure of the sealing structure of the present invention;

[0031] Figure 5 This is a verification flow chart for verifying the life of the sealing structure in the present invention;

[0032] The marks in the figure are as follows:

[0033] 1-annular sealing structure; 2-annular straightening structure; 3-external working string; 4-inner working string; 5-PEEK layer; 6-PTFE-based composite layer; 7-PTFE layer; 8-test barrel; 9-cooling and insulation system; 10-test fixture, 101-top cover, 102-base, 103-slider; 11-hydraulic pressure regulator, 111-A end pressure regulator, 112-B end pressure regulator, 113-No. 1 high pressure buckle, 114-No. 2 high pressure buckle, 11 5-No. 3 high-pressure stop valve, 116-No. 4 high-pressure stop valve, 117-A-end speed regulator, 118-B-end speed regulator, 119-No. 1 conduit, 120-No. 2 conduit; 12-High-pressure pump, 121-No. 1 liquid outlet, 122-No. 2 liquid outlet, 123-No. 1 high-pressure stop valve, 124-No. 2 high-pressure stop valve, 125-No. 1 pressure gauge, 126-No. 2 pressure gauge, 127-No. 3 conduit, 128-No. 4 conduit; 13-Temperature sensor. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the above components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0036] Example 1

[0037] like Figures 1 to 4 As shown, this embodiment provides a seal for a deep-sea compensator, comprising:

[0038] An annular sealing structure 1 is sleeved in an annular gap formed by an outer working pipe string 3 and an inner working pipe string 4, and the annular sealing structure 1 includes a first outer layer, a first filling layer, an intermediate layer, a second filling layer and a second outer layer which are arranged in sequence as a whole, wherein the first outer layer, the intermediate layer and the second outer layer are all PEEK layers 5, and the first filling layer and the second filling layer are a multilayer structure formed by alternating distribution of at least one PTFE-based composite layer 6 and at least one PTFE layer 7, and the axial cross-sections of the PTFE-based composite layer 6 and the PTFE layer 7 are herringbone-shaped, and the tips of the PTFE-based composite layer 6 and the PTFE layer 7 in the first filling layer are toward the first outer layer, and the tips of the PTFE-based composite layer 6 and the PTFE layer 7 in the second filling layer are toward the second outer layer;

[0039] The two annular straightening structures 2 are respectively sleeved on the outer wall of the inner working pipe string 4 located at both ends of the annular sealing structure 1.

[0040] In this embodiment, preferably, the annular straightening structure 2 is a PEEK annular ring, and the PEEK annular ring is cut and sleeved on the outer wall of the inner working pipe string 4 .

[0041] In this embodiment, preferably, the number average molecular weight of PEEK in the PEEK layer 5 is 100,000-160,000, the tensile strength is 98 MPa, the tensile fracture strain is 25%, and the tensile modulus is 3.7 GPa (the test standard is ISO527, and the test temperature is 23°C); the melting point is 343°C, and the glass transition temperature is 150°C (the test standard is ISO11357, DSC).

[0042] In this embodiment, preferably, the number average molecular weight of PTFE in the PTFE layer 7 is 1-1.5 million, and the specific gravity is 2.17 g / cm 3 , tensile strength (transverse) is 34.17 MPa, elongation at break (transverse) is 263.72%, bulk density is 814.16 g / L (test method is ASTM D4894), and Shore hardness is 62.5 Shore D (test method is ASTM D2240).

[0043] In this embodiment, preferably, the PTFE-based composite layer 6 is carbon fiber-reinforced PTFE with a number average molecular weight of 1-1.5 million and a specific gravity of 2.089 g / cm 3 , tensile strength (transverse) is 28.9MPa, elongation at break (transverse) is 171.31%, volume density is 708.8g / L (test method is ASTM D4894), Shore hardness is 70Shore D (test method is ASTM D2240), and the weight percentage of carbon fiber is 16%.

[0044] In this embodiment, by designing the axial cross section of the seal into a herringbone structure, when the seal is squeezed by the up and down floating of seawater, the internal and external pressures of the pipe column can be effectively sealed.

[0045] Example 2

[0046] like Figure 5 As shown, based on the deep-sea compensator seal provided in Example 1, the present invention further provides a test device for the sealing life of the deep-sea compensator seal, including:

[0047] A test barrel 8, a cooling and heat preservation system 9 is arranged on the outer wall of the test barrel 8, a test fixture 10 is arranged in the test barrel 8, an ice-water mixture is filled between the test fixture 10 and the test barrel 8, the test fixture 10 is a cylindrical structure including a top cover 101 and a base 102, a slider 103 which can slide along its axial direction is accommodated in the cavity of the test fixture 10, an annular sealing structure 1 is sleeved on the outer wall of the slider 103, and the slider 103 divides the cavity of the test fixture 10 into an upper cavity and a lower cavity;

[0048] The hydraulic press 11 is provided with an A-end pressure regulator 111 and a B-end pressure regulator 112. The A-end pressure regulator 111 is connected to the upper cavity via a No. 1 conduit 119 penetrating the top cover 101, and the B-end pressure regulator 112 is connected to the lower cavity via a No. 2 conduit 120 penetrating the base 102;

[0049] The high-pressure pump 12 is provided with a first liquid outlet 121 and a second liquid outlet 122 . The first liquid outlet 121 is connected to the upper cavity via a third conduit 127 penetrating the top cover 101 , and the second liquid outlet 122 is connected to the lower cavity via a fourth conduit 128 penetrating the base 102 .

[0050] In this embodiment, preferably, a No. 1 high-pressure variable buckle 113 and a No. 3 high-pressure stop valve 115 are provided on the No. 1 conduit 119 .

[0051] In this embodiment, preferably, a No. 2 high-pressure variable buckle 114 and a No. 4 high-pressure stop valve 116 are provided on the No. 2 conduit 120 .

[0052] In this embodiment, preferably, a No. 1 high-pressure stop valve 123 and a No. 1 pressure gauge 125 are provided on the No. 3 conduit 127 .

[0053] In this embodiment, preferably, a No. 2 high-pressure stop valve 124 and a No. 2 pressure gauge 126 are provided on the No. 4 conduit 128 .

[0054] In this embodiment, preferably, a temperature sensor is also provided in the test barrel 8 for monitoring the temperature in the test barrel 8 at any time.

[0055] Example 3

[0056] Based on the deep-sea compensator seal provided in Example 1 and the testing device provided in Example 2, the present invention also provides a method for testing the sealing life of the deep-sea compensator seal, such as Figure 5 As shown, the following steps are included:

[0057] (a) placing the slider 103 with the annular sealing structure 1 in the test fixture 10, then placing the test fixture 10 in the test barrel 8, and then adding the ice-water mixture into the test barrel 8;

[0058] (b) Turn on the hydraulic press 11, set the switching pressure of the A-end pressure regulator 111 and the B-end pressure regulator 112 respectively, and set the number of times the slider 103 slides up and down in the test fixture 10. The liquid in the hydraulic press 11 enters the upper cavity and the lower cavity through the No. 1 conduit 119 and the No. 2 conduit 120 respectively, pushing the slider 103 to slide up and down;

[0059] (c) When the slider 103 slides up and down in the test fixture 10 for a set number of times, close the No. 3 high-pressure stop valve 115 and the No. 4 high-pressure stop valve 116, open the high-pressure pump 12 and the No. 1 high-pressure stop valve 123 and the No. 2 high-pressure stop valve 124, monitor the value changes of the No. 1 pressure gauge 125 and the No. 2 pressure gauge 126, and judge the sealing performance of the annular sealing structure 1.

[0060] In this embodiment, preferably, the verification pressure in step (c) is higher than the reciprocating sliding pressure in step (b).

[0061] In this embodiment, preferably, in step (b), the pressure of the A-end pressure regulator 111 and the B-end pressure regulator 112 is set to 10 MPa. When the pressure in the upper cavity is greater than 10 MPa, the hydraulic pressure of the hydraulic press 11 is reversed, and the liquid begins to flow toward the lower cavity. When the pressure in the lower cavity is greater than 10 MPa, the hydraulic pressure of the hydraulic press 11 is reversed, and the liquid begins to flow toward the upper cavity. The slider 103 reciprocates up and down in the test fixture 10.

[0062] In this embodiment, preferably, in step (c), open the No. 3 high-pressure stop valve 115 and the No. 4 high-pressure stop valve 116, start the high-pressure pump 12, and when the pressure reaches 70MPa, stabilize the pressure for fifteen minutes, observe the No. 1 pressure gauge 125 in the upper cavity and the No. 2 pressure gauge 126 in the lower cavity, if there is no pressure drop on the No. 1 pressure gauge 125 and there is no pressure increase on the No. 2 pressure gauge 126, the sealing performance is reliable, and continue to perform the reciprocating test until the reciprocating reaches 10,000 times; when the pressure in the upper cavity is greater than 70MPa, manually perform the high-pressure reversal, and when the pressure in the lower cavity is greater than 70MPa, close the No. 3 high-pressure stop valve 115 and the No. 4 high-pressure stop valve 116.

[0063] In this embodiment, after the slider 103 reciprocates 10,000 times in the test fixture 10, its sealing performance is tested by the high-pressure pump 12 and is still good without leakage.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A test device for the sealing life of a seal for a deep-sea compensator, characterized in that: include: An annular sealing structure (1) is sleeved in an annular gap formed by an outer working pipe string (3) and an inner working pipe string (4), the annular sealing structure (1) comprising a first outer layer, a first filling layer, an intermediate layer, a second filling layer and a second outer layer which are arranged in sequence as one body, wherein the first outer layer, the intermediate layer and the second outer layer are all PEEK layers (5), the first filling layer and the second filling layer are a multilayer structure formed by alternating distribution of at least one PTFE-based composite layer (6) and at least one PTFE layer (7), and the axial cross-sections of the PTFE-based composite layer (6) and the PTFE layer (7) are in a herringbone shape, the tips of the PTFE-based composite layer (6) and the PTFE layer (7) in the first filling layer are directed toward the first outer layer, and the tips of the PTFE-based composite layer (6) and the PTFE layer (7) in the second filling layer are directed toward the second outer layer; an annular straightening structure (2), wherein two annular straightening structures (2) are respectively sleeved on the outer wall of the inner working pipe string (4) located at two ends of the annular sealing structure (1); Also includes: A test barrel (8), wherein a cooling and heat preservation system (9) is arranged on the outer wall of the test barrel (8), a test fixture (10) is arranged inside the test barrel (8), an ice-water mixture is filled between the test fixture (10) and the test barrel (8), the test fixture (10) is a cylindrical structure including a top cover (101) and a base (102), a slider (103) slidable along its axial direction is accommodated in the cavity of the test fixture (10), the annular sealing structure (1) is sleeved on the outer wall of the slider (103), and the slider (103) divides the cavity of the test fixture (10) into an upper cavity and a lower cavity; A hydraulic press (11), wherein the hydraulic press (11) is provided with an A-end pressure regulator (111) and a B-end pressure regulator (112), wherein the A-end pressure regulator (111) is connected to the upper cavity via a No. 1 conduit (119) penetrating the top cover (101), and the B-end pressure regulator (112) is connected to the lower cavity via a No. 2 conduit (120) penetrating the base (102); A high-pressure pump (12), the high-pressure pump (12) being provided with a first liquid outlet (121) and a second liquid outlet (122), the first liquid outlet (121) being connected to the upper cavity via a third conduit (127) penetrating the top cover (101), and the second liquid outlet (122) being connected to the lower cavity via a fourth conduit (128) penetrating the base (102); The number average molecular weight of PEEK in the PEEK layer (5) is 100,000-160,000, the tensile strength is 98 MPa, and the glass transition temperature is 150°C.

2. The testing device according to claim 1, characterized in that: The number average molecular weight of PTFE in the PTFE layer (7) is 1-1.5 million, and the specific gravity is 2.17 g / cm 3 , the volume density is 814.16g / L.

3. The testing device according to claim 1, characterized in that: The PTFE-based composite layer (6) is carbon fiber-reinforced PTFE, with a number average molecular weight of 1-1.5 million and a specific gravity of 2.089 g / cm 3 The volume density is 708.8g / L, of which the weight percentage of carbon fiber is 16%.

4. The testing device according to claim 1, characterized in that: The No. 1 conduit (119) is provided with a No. 1 high-pressure variable buckle (113) and a No. 3 high-pressure stop valve (115), and the No. 2 conduit (120) is provided with a No. 2 high-pressure variable buckle (114) and a No. 4 high-pressure stop valve (116).

5. The testing device according to claim 4, characterized in that: The No. 3 conduit (127) is provided with a No. 1 high-pressure stop valve (123) and a No. 1 pressure gauge (125), and the No. 4 conduit (128) is provided with a No. 2 high-pressure stop valve (124) and a No. 2 pressure gauge (126).

6. A test device and method for testing the sealing life of a seal for a deep-sea compensator as claimed in claim 5, characterized in that: The test method includes the following steps: (a) placing the slider (103) having the annular sealing structure (1) in the ring into the test fixture (10), then placing the test fixture (10) in the test barrel (8), and then adding an ice-water mixture into the test barrel (8); (b) turning on the hydraulic press (11), setting the pressure of the A-end pressure regulator (111) and the B-end pressure regulator (112), and setting the number of times the slider (103) slides up and down in the test fixture (10), so that the liquid in the hydraulic press (11) enters the upper cavity and the lower cavity through the first conduit (119) and the second conduit (120), respectively, and pushes the slider (103) to slide up and down; (c) When the slider (103) slides up and down in the test fixture (10) for a set number of times, the No. 3 high-pressure stop valve (115) and the No. 4 high-pressure stop valve (116) are closed, the high-pressure pump (12) and the No. 1 high-pressure stop valve (123) and the No. 2 high-pressure stop valve (124) are opened, and the value changes of the No. 1 pressure gauge (125) and the No. 2 pressure gauge (126) are monitored to determine the sealing performance of the annular sealing structure (1).

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