Development and Prospect of Drilling Fluid Technology for Deep Coal Gas Horizontal Wells In Ordos Basin
The 8#deep coal bed gas reservoir in Benxi Basin of Ordos Basin is an important replacement formation for increasing gas reserve and production in China.However,the development of deep coal bed/joint and micro-fractures,wide distribution of coal gangue,great heterogeneity,wall collapse and sticking accidents become the main technical problems restricting safe and efficient drilling of deep coal and gas wells.Based on the analysis of mineral composition,physical and chemical properties and microstructure of deep coal bed in Ordos Basin,the main controlling factors of coalbed methane horizontal well collapse are defined in this paper,a high efficient anti-sloughing drilling fluid technology suitable for deep coal-rock gas horizontal wells has been developed.Its API and HTHP filtrations are≤2 mL and 8 mL respectively,and its comprehensive plugging performance is more than 30%higher than that of conventional drilling fluid.Through the application of more than 40 deep coal bed gas horizontal wells in different regions of Ordos Basin,the problems of drilling fluid technology in deep coal-rock gas horizontal wells,such as high density,high cost,frequent wall collapse and completion difficulty,are systematically analyzed,the development of drilling fluid technology for high efficient development of deep CBM,such as the basic theoretical study of coal rock/coal gangue interface expansion and slippage law,optimization and upgrading of drilling fluid performance,reduction of complexities,cost reduction and efficiency enhancement,is prospected.
coal bed gasOrdos Basincoal ganguewellbore collapse
NETL
NSTL
万方数据
