Research of Dynamic Reserves Estimation Methods for Complex Gas Wells in Low Permeability and Tight Gas Reservoir

As material basis of compiling and adjusting developing scheme, dynamic reserves are crucial for predicting well spacing density and stable production potential. Currently, for conventional gas wells with good physical properties and abundant pressure test data, the main evaluation methods of dynamic reserves are ranging from material balance equation to flowing material balance. However, complex gas wells in Ordos Basin such as type of inadequate pressure test data in low permeability reservoir, water production, downhole throttling in tight gas reservoir, these three types of wells cannot be easily applied to the current evaluation methods. Therefore, this paper presents rapid methods for estimating dynamic reserves in complicated situations which are based on analysis of gas wells percolation and production. The key points of new methods are evaluation of the formation pressure without shutting well, visual pressure drop and water influx, pseudo-pressure regularization rate under superposition time function respectively. Finally, with applying methods to track and evaluate the dynamic reserves of M gas field in Ordos Basin, results show that approaches are accurate and evaluation periods are greatly shortened. Besides, the procedures are simple which can be implemented in desktop application or spreadsheet with minimal computational effort.The new methods provide a direct reference for the deployment of gas infilling wells and gas wells refracturing, and further improve the utilization level of reserves.