Study On Mechanical Properties Of Polyamide Cord Rubber

Low-permeability reservoirs have become an important area for exploration and development in China.Horizontal well completion fracture fracturing technology is an important stimulation measure for low-permeability reservoirs.The core of the expansion packer directly affects the effect of fracturing.At present,there are commonly used overlapping steel belt type and steel cord type rubber in China,but the residual deformation is large.When the pipe string is lifted up,the steel sheets and steel wires are easily stuck in the casing,causing underground accidents and affecting construction safety.Nylon cord rubber has the advantages of small residual deformation and difficult to clamp the pipe column.At the same time,it has problems of low pressure bearing performance and poor sealing performance,which greatly limits the cord expandable packer in low permeability tight reservoir.application.This paper is mainly aimed at the problem of low pressure bearing performance and poor sealing performance of nylon cord rubber in the development of low permeability oil and gas reservoirs.The mechanical properties of nylon cord rubber are studied,and the influence of factor analysis and optimization is improved to improve the nylon cord rubber.The performance of the work,the specific research content is as follows:(1)The basic material parameters of the rubber and cord in the nylon cord rubber were determined by tensile test and Gough-Tangorra theory,and the rubber and cord material failures were judged according to the third strength criterion and the maximum stress criterion,respectively.(2)Using the axisymmetric thin shell theory to es Tab.lish a two-dimensional theoretical model of nylon cord rubber cylinder,and study the stress distribution law of rubber and cord in nylon cord rubber cylinder under different sealing pressures.(3)Based on REFINE265 unit,the three-dimensional finite element analysis model of nylon cord rubber is es Tab.lished.The variation of stress and contact stress of nylon cord rubber under different sealing pressures is studied.The structural parameters are analyzed systematically for the pressure bearing performance and sealing performance of the rubber.The effect of combining genetic algorithms to optimize the structural parameters of the cartridge.The analysis results show that the optimal structural parameters of nylon cord rubber are 16° cord angle,6 cord layers and 1.6mm cord spacing.After optimization,the pressure performance of the rubber is increased by 25% and the sealing performance is improved by 66%.(4)Combining the indoor test,the performance test of the nylon cord rubber after optimization is completed.The test results show that the maximum setting pressure of the rubber is 70 MPa,the maximum working pressure difference is 50 MPa,and the residual deformation rate of the rubber is 3.2%,which is much lower than the residual deformation of6.4% of steel cord.It can effectively meet the on-site requirements of high-pressure and fine fracturing of low-permeability reservoirs.