CN-120197548-B - Submarine pipeline high-risk hydrate generation area identification method

CN120197548BCN 120197548 BCN120197548 BCN 120197548BCN-120197548-B

Abstract

The invention discloses a submarine pipeline high-risk hydrate generation area identification method, which is characterized in that three-dimensional multiphase flow simulation is carried out on a submarine pipeline to obtain flow parameters along a line, hydrate generation conditions are judged by combining hydrate generation temperature, hydrate generation pressure and hydrate generation rate when the pipeline flows, hydrate generation risk evaluation matrixes I and II are constructed, and a submarine pipeline high-risk hydrate generation area is identified, so that an effective means is provided for guaranteeing the safe operation of the submarine pipeline.

Inventors

WU XUELING
LIAO KEXI
QIN MIN
HE GUOXI
HE TENGJIAO

Assignees

西南石油大学

Dates

Publication Date: 20260508
Application Date: 20250307

Claims (7)

1. The method for identifying the high-risk hydrate generation area of the submarine pipeline is characterized by comprising the following steps of: s1, establishing a full-size model of a submarine pipeline, performing multiphase flow simulation, calculating flow parameters along the pipeline, and performing data acquisition; S2, combining multiphase flow simulation parameters and data to determine a hydrate generation model in the pipeline; s3, determining the hydrate generation temperature and pressure under the condition of pipeline flow by researching a hydrate generation model; S4, calculating the liquid holdup of the pipeline and judging the generation condition of hydrate in the pipeline; S5, establishing a hydrate generation risk evaluation matrix I and a hydrate generation risk evaluation matrix II based on the calculation results of the difference DeltaT between the hydrate generation temperature and the pipeline flow temperature and the difference DeltaP between the pipeline flow pressure and the hydrate generation pressure; S6, under the condition that the liquid holdup of the pipeline is more than 0, determining a critical temperature T l by taking a slope 1 as a critical point according to the variation trend of a hydrate phase equilibrium curve without any hydrate inhibitor; s7, comparing the flow temperature T m of the pipeline with the critical temperature T l , and determining a hydrate generation risk evaluation matrix; And S8, determining a high-risk hydrate generation area of the submarine pipeline through a hydrate generation risk evaluation matrix.
2. The method for identifying a high risk hydrate formation region of a submarine pipeline according to claim 1, wherein the calculation formula of the hydrate formation model in the submarine pipeline is as follows: in the formula, Pressure, pa; Is a gas constant, J/(mol.K); temperature, K; Is the molar volume, m 3 /mol; is the energy parameter of the state equation, pa.m 6 /mol 2 ; Is the volume parameter of a state equation, m 3 /mol; and m 3 /mol is a volume correction parameter of a state equation.
3. The method for identifying a high risk hydrate formation region of a submarine pipeline according to claim 1, wherein the pipeline hydrate formation condition is judged by the following steps: 201, judging that hydrate is not generated in the pipeline when the liquid holdup is less than 0; 202, judging that hydrate possibly forms in the pipeline when the liquid holdup is > 0.
4. A submarine pipeline high-risk hydrate formation region identification method according to claim 1, wherein the hydrate formation risk evaluation matrix I is established by the following steps: 301, when DeltaP <0bara, if DeltaT <0 ℃, hydrate formation risk grade is "None"; 302, when DeltaP <0bara, if DeltaT is less than or equal to 0 ℃ and less than or equal to 3 ℃, deltaT is less than or equal to 3 ℃ and less than or equal to 5 ℃ or DeltaT is more than 5 ℃, the hydrate generation risk grade is 'Low'; 303, when 0bara < DELTAP is less than or equal to 0.5bara, if DELTA T is less than 0 ℃,0 ℃ < -DELTA T is less than or equal to 3 ℃,3 ℃ < -DELTA T is less than or equal to 5 ℃, and the hydrate generation risk level is 'Low'; 304, when the delta P is less than or equal to 0.5bara and less than or equal to 1.5bara, if delta T is less than 0 ℃, delta T is less than or equal to 3 ℃ and delta T is less than or equal to 5 ℃, the hydrate generation risk grade is 'Low'; 305 hydrate formation risk level is "Medium" if DeltaT >5 ℃ when DeltaP is 0.5bara < 1.5 bara; 306, when DeltaP >1.5bara, if DeltaT <0 ℃, deltaT < 3 ℃ and DeltaT < 3 ℃ are less than or equal to 5 ℃, the hydrate generation risk grade is 'Medium'; 307 hydrate formation risk level is "High" if DeltaP >1.5bara, deltaT >5 ℃.
5. A submarine pipeline high-risk hydrate formation region identification method according to claim 1, wherein the hydrate formation risk evaluation matrix II is established by the following steps: 401 hydrate formation risk rating of "None" if DeltaP <0bara, deltaT <0 ℃; 402, when DeltaP <0bara, if DeltaT is less than or equal to 0 ℃ and less than or equal to 3 ℃, deltaT is less than or equal to 3 ℃ and less than or equal to 5 ℃ or DeltaT is more than 5 ℃, the hydrate generation risk is 'Low'; 403, when 0bara < DELTAP is less than or equal to 38bara, if DELTA T is less than 0 ℃,0 ℃ < DELTAT is less than or equal to 3 ℃,3 ℃ < DELTAT is less than or equal to 5 ℃, DELTA T is more than 5 ℃, and the hydrate generation risk grades are all 'Low'; 404, when 38bara < DELTAP is less than or equal to 63bara, if DELTA T is less than 0 ℃, DELTA T is less than or equal to 3 ℃ and DELTA T is less than or equal to 5 ℃, the hydrate generation risk grade is 'Low'; 405, when 38bara < [ delta ] P is less than or equal to 63bara, if DeltaT is more than 5 ℃, the hydrate generation risk grade is 'Medium'; 406, when DeltaP is more than 63bara, if DeltaT is less than 0 ℃, deltaT is less than or equal to 3 ℃ and DeltaT is less than or equal to 5 ℃, the hydrate generation risk grade is 'Medium'; 407, when DeltaP >63bara, the hydrate formation risk level is "High" if DeltaT >5 ℃.
6. The method for identifying a high risk hydrate formation region of a submarine pipeline according to claim 1, wherein the determining a hydrate formation risk evaluation matrix in step S7 is performed by: 501, selecting a hydrate generation risk evaluation matrix I when T m ＜T l is performed; 502, selecting a hydrate generation risk evaluation matrix II when T m ＞T l is carried out.
7. The method for identifying a High risk hydrate formation region of a submarine pipeline according to claim 1, wherein the High risk hydrate formation region of the submarine pipeline is determined to be "High" by calculation of a hydrate formation risk evaluation matrix in step S8.

Description

Submarine pipeline high-risk hydrate generation area identification method Technical Field The invention relates to a submarine pipeline high-risk hydrate generation region identification method, and relates to identification of a hydrate generation risk region in a submarine pipeline. Background In the field of ocean oil and gas resource development, a submarine pipeline is used as a key infrastructure for oil and gas transportation, and safe and stable operation is crucial. However, hydrate formation has been one of the major challenges affecting the proper operation of subsea pipelines. With the continuous global growth of energy demand, marine oil and gas resources are also gradually exploited. Hydrates are ice-like crystalline compounds formed from natural gas and water under certain temperature and pressure conditions. Once hydrate is generated in a large amount in a submarine pipeline, the pipeline is extremely easy to be blocked, fluid flow is blocked, pressure is abnormally increased, and even serious accidents such as pipeline rupture and the like can be caused, so that serious potential safety hazards are caused for exploitation and transportation of ocean oil gas. Currently, there are a number of difficulties in identifying areas of risk of hydrate formation in subsea pipelines. On one hand, the submarine environment is complex and changeable, and the mechanism of hydrate generation is not completely clear due to the interaction of factors such as temperature, pressure, fluid composition, flow rate and the like, so that the generation position and the generation condition of the hydrate are difficult to accurately judge. The geological conditions and the sea water properties of different sea areas are obviously different, and the complexity of identification is further increased. On the other hand, the existing identification techniques and methods still have limitations. Some traditional detection means, such as a method based on temperature and pressure monitoring, can only provide macroscopic environmental parameters, and cannot accurately determine a specific area generated by the hydrate, while detection technologies based on principles of acoustics, optics and the like can detect the hydrate to a certain extent, but are interfered by a submarine complex environment, and the detection precision and reliability are required to be improved. In addition, along with the continuous expansion of the scale of the submarine oil and gas pipeline, how to efficiently and comprehensively identify the risk area of the submarine pipeline is also a problem to be solved currently. The existing method is low in efficiency when processing large-scale data and complex pipeline systems, and is difficult to meet the requirements of actual engineering. The invention establishes a submarine pipeline high-risk hydrate generation region identification method by means of numerical simulation, and has important practical significance for guaranteeing safe and stable development of ocean oil and gas resources. Disclosure of Invention The invention provides a submarine pipeline high-risk hydrate generation area identification method for identifying a submarine pipeline hydrate generation risk area and reducing pipeline blockage and cracking accidents caused by hydrate generation. In order to achieve the purpose, the invention is realized by adopting the following technical scheme: s1, establishing a full-size model of a submarine pipeline, performing multiphase flow simulation, calculating flow parameters along the pipeline, and performing data acquisition; S2, combining multiphase flow simulation parameters and data to determine a hydrate generation model in the pipeline; s3, determining the hydrate generation temperature and pressure under the condition of pipeline flow by researching a hydrate generation model; S4, calculating the liquid holdup of the pipeline and judging the generation condition of hydrate in the pipeline; S5, establishing a hydrate generation risk evaluation matrix I and a hydrate generation risk evaluation matrix II based on the calculation results of the difference DeltaT between the hydrate generation temperature and the pipeline flow temperature and the difference DeltaP between the pipeline flow pressure and the hydrate generation pressure; S6, under the condition that the liquid holdup of the pipeline is more than 0, determining a critical temperature T l by taking a slope 1 as a critical point according to the variation trend of a hydrate phase equilibrium curve without any hydrate inhibitor; s7, comparing the flow temperature T m of the pipeline with the critical temperature T l, and determining a hydrate generation risk evaluation matrix; And S8, determining a high-risk hydrate generation area of the submarine pipeline through a hydrate generation risk evaluation matrix. Further, the calculation formula of the hydrate generation model in the pipeline comprises the following steps: Wherein