The Well Trajectory Optimization Method For Efficient Development Of Linxing Multi-coal Area

China is a country with rich resource.Unconventional oil and gas resources are abundant and widely distributed,but its mining degree is far less than conventional oil and gas resources.Due to the non-renewability of oil and gas resources,conventional oil and gas resources will be one less.Therefore,the development of unconventional oil and gas is of great significance.Located in the eastern margin of the Ordos Basin,the Linxing area of Shanxi Province has a number of coal-bearing strata with a depth of more than 1500m.The multi-branch horizontal well is used for mining experiments.It is the main area for unconventional oil and gas resources such as coalbed methane.This paper summarizes the engineering desserts by statistical analysis of the complex accidents that occurred during the drilling process in Linxing area.According to the logging data,the rock mechanics parameters of the area are interpreted and the three-pressure profile is predicted.Combined with the indoor physical model experiment and numerical simulation of the multi-lateral wellbore in the coal seam,the multi-lateral wellbore trajectory in Linxing area is optimized.The main research contents and results are as follows:(1)Statistical analysis of complex accidents occurred in 24 wells drilled in Linxing area.It is found that there are leaky layers in the surface layer of the area;the problem of stuck drills mainly occurs in the Shanxi Formation..(2)Explain the rock mechanics parameters of the area through logging data and predict the three pressure profiles.The collapse pressure of the upper strata in Linxing area is basically less than 1.0g/cm~3,the pore pressure is basically 1.0g/cm~3,the fracture pressure is much larger than the pore pressure,and the safety density window is larger;the collapse pressure suddenly increases in the stone box group,the mud The lower limit of the density window increases and the window decreases.(3)Carry out the experiment of the physical model of the wellbore in the coal seam multi-lateral well.The large-scale true triaxial experimental system was used to conduct the wellbore instability experiment of coal rock outcrops,and the influence of branch number,branch orientation and branch length of coal seam multi-lateral wells on crack morphology and pumping curve was analyzed.(4)The numerical simulation method is used to optimize the well trajectory of multi-branch wells in Linxing area.Combining the rock mechanics parameters and indoor physical model experiments in this area,the numerical simulation method is used to establish the function of productivity evaluation.The number of branches,branch orientation and branch length of multi-lateral wells are optimized to realize more Linxing area and three-dimensional development of coal seam reservoirs.