Method for predicting oil well pipe special thread leakage rate
A special thread, leak rate technology, applied in special data processing applications, instruments, electrical digital data processing, etc., can solve the problem that the accuracy of leakage rate needs to be improved, the interaction of adjacent asperities is ignored, and it is difficult to microstructure the sealing surface of special threads. Elastic-plastic contact state and other problems, to achieve the effect of high reliability and rapid economic evaluation
Active Publication Date: 2020-10-02
CHONGQING UNIVERSITY OF SCIENCE AND TECHNOLOGY
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At the same time, there are a small number of special thread microscopic leakage prediction models that use spherical or conical surfaces to simulate the asperity contact on the sealing surface. Since the maximum average contact stress in the spherical asperity contact model is limited to 3 times the conventional hardness, and the e
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[0078] By measuring or consulting product parameters, we can get a special thread sealing surface roughness of 0.1μm, the maximum peak-to-valley distance of the sealing surface profile is 0.2μm, the elastic modulus of the pipe body end and the coupling end of the sealing contact pair are both 206000MPa, and the Poisson's ratio Both are 0.28 and the yield strength is 758.42MPa; by consulting the design parameters of the special threaded sealing structure, the average contact pressure of the sealing surface is 550MPa, the average diameter of the sealing surface is 171.1mm, and the length of the sealing surface is 20mm; it is obtained through the experimental parameters of the thread gas seal The gas pressure inside and outside the threaded sealing pipe is 70MPa and 0.101MPa respectively, and the dynamic viscosity of the sealing gas is 1.66×10 -6 MPa·s.
[0079] Step 1: Sampling and calculating the sample number sequence Z of the contour height distributed at equal intervals on the s...
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The invention discloses a circumferential leakage width and an average leakage height of a microcosmic leakage channel between special thread sealing surfaces based on elastic-plastic normal flattening contact simulation between a rigid plane and an axisymmetric sine micro-convex body distributed sealing surface. Therefore, the leakage rate of the special thread of the oil well pipe can be conveniently, quickly, quantitatively and reliably predicted. The method comprises the steps: obtaining a sealing surface contour height sample sequence based on random normal distribution sampling, and generating a contour curve; obtaining a sine simulation micro-convex body wavelength lambda and an amplitude delta of a sealing surface contour; generating an axisymmetric sine micro-convex body three-dimensional solid model by adopting finite element software; simulating elastic-plastic normal flattening contact between the rigid plane and the sealing surface where the axially symmetric sine micro-bulges are distributed, and obtaining the actual contact area Aep of a single micro-bulge under the action of the average contact pressure of the sealing surface; obtaining a circumferential total leakage width B in the cross section of the special thread leakage channel; obtaining the average height H of the cross section of the special thread leakage channel; and obtaining a special thread leakagerate Qv.
Description
Technical field [0001] The invention relates to the technical field of safe production of gas wells, in particular to a method for predicting the leakage rate of special threads of oil well pipes. Background technique [0002] The special thread of the oil well pipe is one of the key technologies for the safe production of gas wells under complex and severe working conditions. The leakage of the special thread will induce pressure in the annulus of the gas well, which will bring huge challenges to the integrity of the wellbore. Therefore, rapid and accurate evaluation of the air-tight performance of special threads is essential for designing sealing parameters, judging the leakage points of the pipe string, and controlling thread leakage. [0003] The existing evaluation methods for the gas seal performance of special threads mainly include experimental evaluation method and finite element method. The experimental evaluation method is the most direct and effective method to evalua...
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Login to View More IPC IPC(8): G06F30/23G06F113/14G06F119/14
CPCG06F30/23G06F2113/14G06F2119/14
Inventor 许红林杨斌龙学渊霍宏博徐家年苏堪华郭晓乐
Owner CHONGQING UNIVERSITY OF SCIENCE AND TECHNOLOGY