Potential-tapping technology and its application in old CBM wells in Hancheng block of Ordos basin

Comprehensive analysis of geological, fracturing and dynamic drainage data of coalbed methane wells in Hancheng block was made to determine the causes of low productivity. It concludes that poor reservoir property, low gas content and gas saturation due to faults, incompleteness of development well patterns, insufficient pressure drop due to leakage recharge, difficulty in fracturing due to local development of tectonic coal, and seepage channel blockage due to coal powder are the main causes. Through technical research, a series of techniques of potential tapping were proposed, including indirect fracturing, water plugging, acid fracturing, optimization of workover technology, and increasing drainage intensity. Field test results in Hancheng show that these techniques have significant effect on improving gas production of CBM wells, and can be used to guide coalbed methane development in Hancheng and other blocks with similar geological conditions.