Optimization of Dynamic Reserves Evaluation Methods for Low Permeability Gas Reservoirs in Zizhou Gas Field of Ordos Basin

Dynamic geological reserves refered to some of the geologic reserves being percolated and flowed in the gas reservoirs.The evaluation on dynamic reserves was an important basis for the adjustment at the late stage of gas field development.Changqing Gas Field was characterized by low permeability and strong heterogeneity with slow shut-in pressure recovery,together with the factors of gas recovery with water drainage,production boosting was in the high gas consumption period in winter,overall shut-in pressure was not achieved,by which the difficulties lacking of the formation pressure testing data and frequent change of the working system were caused when dynamic reserves were evaluated by regular methods.To solve the problems,based on the pressure drop method and the full use of performance data,the RTA(Rate Transient Analysis) method,FMB(Flow Material Balance) method and pressure drop rate method are developed,and these methods are realized by the visual basic language.Furthermore,all these methods are applied to calculate dynamic reserves of the gas wells and optimized in the Zizhou Gas Field in Ordos Basin and are optimized.They provide evidence for gas well production and working system establishment and development well pattern deployment and adjustment.