Micro-pore structure characteristics and its influence on gas well performance of tight gas sand reservoir in Ordos Basin

Aim To study the micro-pore structure of tight gas sand reservoir,and its influence on gas well performances.Methods Experimental analysis and Comprehensive analysis are applied.Results Micro-pore structures of tight gas sand reservoir are divided into 4 categories,whose pore types and pore-throats distribution are different.Every pore-throat zone plays a different role,the water-blocking effect,pressure sensing effect,principal filtration rooms and well operating ways are the main factors for the gas well development.Bound water saturation of pore structure category Ⅳ is high,water-blocking effect of category Ⅱ and Ⅲ are serious,the main flow pore-throat radius of category Ⅰ and Ⅳ are big,and the pressure sensing effect of He 8 and Shan1 formation are strong.Conclusion To extending production period and increasing cumulative gas production,the methods,that no more than 10 MPa of producing pressure drop is advised for Shan 2 formation and about 5 MPa for He 8 and Shan1 formation,avoiding close/open well frequently and the correct techniques for gas recovery and water draining,are proposed.