The Research Of Radial Well Technique In Coal-bed Methane

The new type of radial well technique is developed on the basis of vertical well,mainly including the casing opening,the vertical turning and the hydraulic jet forming technology.Considering the low yield and short lifetime when using vertical wells in the development of coal-bed methane,we would like to learn from the oil field which put radical technology into use and have a lot of successful experience in the application of radial well.We hope that radial horizontal drilling technology can play a major role for the production in CBM and promote the development efficiency.In this paper,the author analysis the strength and drill ability of coal in Shanxi province by the physical and mechanical properties experiment,especially the determination of the compressive strength of coal.Choosing abrasive water jet to open a window when using the radial drilling through analysis the advantages and disadvantages of three methods in casing opening such as casing window,vertical turning and hydraulic jet.Also,the parameters which have a great influence on the diameter and depth of casing opening were optimized by establishing BP neural network model.In order to minimum the thrust when the drill pipe has to turn 90°,compared the size of curvature changes in different conditions,and recommended to design the arc of steering trajectory,furthermore,optimized the trajectory parameters.Through the analysis of water jet coal breaking mechanism,calculated the pressure loss of radial wells in the whole circulatory system,and using the fuzzy analytic hierarchy model to evaluate the parameters that influence the effect of water jet.In the end,by using 1831,OP-40 and ethanolamine to compound a new method which have pulp drilling fluid,it turns out that the drilling fluid have good properties especially in the suspension of coal powder.