Research On Optimal Design Of The Sucker-Rod Drainage System Use In CBM Well

In this paper,to solve the problem of short-checkperiodofpump caused by Rod and tube eccentric wear and corrosion and high cost of rod and tube,I make a research about mechanism of rod tube eccentric wear and Corrosion mechanism in CBM Well.Through the analysis the drainage rules and stress of tube and rod in CBM drainage well,I deduce the rod-tube combination optimization model,the optimization model of distribution position of centralizer and calculation model of neutral point.Meanwhile,I give the method of reasonable pump hanging depth and swabbing parameters that can ensure efficient production of CBM well.Apply dynamic pressure lubrication theory to design model of the inner guide centralizer.All above theory can provide theoretical guidance for the production of CBM in China in a large scale,high efficiency,stability,long and low cost.The main research contents of this paper are as follows:(1)Analysis of the water quality characteristics of water in CBM well and research about mechanism of rod tube eccentric wear and Corrosion mechanism,To provide basis for anti-corrosion and anti-abrasion technology of CBM well(2)Considering the inclination and "multilevel coupling effect" caused by coupling,Apply piecewise iterative method to establish a mechanical model of sucker rod and oil tube.Then according to the stress of sucker rod,establish the calculation model of neutral point that the neutral point in straight wells and inclined wells.(3)Analysis law of drainage in CBM well,combined with the field of liquid production to optimize the swabbing parameters.According to the relationship between the pump efficiency and the degree of sinking,calculate the reasonable depth of sinking and pump hanging depth.On the basis of equal strength criterion,combine with the stress of the rod and tube,to optimize the rod and tubeassembly.According to the three-dimensional wellbore trajectory and sucker rod deflection curve,to ensure the maximum deflection of rod are less than tubing confined space,optimize centralizer arrangement.(4)According to hydrodynamic lubrication theory,combined with the characteristics of sucker rod centralizer,complete model design of the inner flow centralizer,then applicationof FLUENT software to simulate of the internal flow field of the inner flow centralizer,and compared with conventional centralizer,performance evaluation of the new type of internal flow Performance evaluation of the new type of internal flow guiding stabilizer.Through the theoretical research of this paper,it can achieve the purpose of slowing down the eccentric wear of rod and pipe,improving the service life of the rod and tube,reducing the number of drainage system maintenance and reducing the cost.Field application shows that testwell work for 268 days without failure.And in the same period the other wells contrast,the wear of the rod and tube is obviously smaller,It can achieve the desired effect test.