Key Technology for Drilling the Long Horizontal Section of No. 8 Coalbed Methane Wells in Jia Nan Area

The Jiaxian area of the Ordos Basin, a place enriched with the deep coalbed methane resources, is characterized by well-developed fractures and cleats, complex structure and stress field, low mechanical, easy collapse and leakage, and interbedded shales. The risk of wellbore instability during the long horizontal section construction is high, and it is difficult to ensure the safe running of casing and the quality of cementing, which may lead to well abandonment. This paper starts with the research on the mineral composition, microstructure and rock mechanical properties of 8# coal rock. Through the research on key technologies such as wellbore stability analysis, reasonable selection of drilling fluid systems and cementing techniques, a drilling technology for deep coalbed methane horizontal wells in the Jia’nan block has been formed. The application results of more than 10 wells on site show good effects, providing technical support for the effective development of deep coalbed methane in this basin in the future. It also has certain reference value for the exploration and development of other deep coalbed methane blocks in China.