Study On Trajectory Control And Well Completion Technology For CBM Horizontally-intersected Well In Coal Mining Areas

CBM development in coal mining areas has great prospect and conforms to the development direction of Chinese security,economic and environmental protection,while the study on drilling and completion techniques of horizontally-intersected well is of important significance.Aiming at the intractable problem that the maximum utilization of the effective footage along seam during drilling and completion of horizontal well is unsatisfactory,the thesis starts with butted well for CBM development,takes the key drilling and completion techniques as research object,uses comprehensively theoretic analysis,digital simulation,experiment of lab model,field engineering application and other methods,obtained the following major research results:(1)Through optimal correction of the theoretic model of three original focal point circle and curvature compensation slop arc,the prediction of deflection capacity of single bend positive displacement motor and parameters of well trajectory was achieved;While a design method which could confirm the optimum landing point and target angle has been presented via minimizing the incremental displacement of the target,providing theory support for safe landing and trajectory control along coal seam.(2)With Visual Studio 2015 as development tool,C#as programming language,computer system software for prediction of borehole trajectory of CBM horizontal well was developed,the response characteristics based on geosteering LWD tracking gamma was combined to guide optimal safe landing target and extend in-seam directional drilling.(3)Through the theoretic analysis,digital simulation and lab compression test,?50.8mm conical slotted PE screen pipe with high compression resistance and big slotted density suitable for highly efficient CBM development was optimally designed,its structural parameters are:radius 8mm,phase angle 60°,orifice area ratio 5%.(4)A complete set of techniques for well completion and stimulation in horizontally-intersected wells,including screen pipe completion and sliding sleeve staged fracturing completion and hydraulic sand blasting perforation fracturing completion,has been formed via research aiming at the specific characteristics of coal measure strata in coal field.These techniques meet the different requirements of well completion in primary coal and fragmented coal and fine coal.Those research achievements have been verified due to successful application in horizontally-intersected wells WP02 and 2013ZX-SH-UM15 and 2014ZX-U-01 in the southern Qinshui Basin.The theory research achievements about trajectory control and well completion techniques have some reference value for further studies and application in related areas,can guide horizontal wells drilling.