Study On Evaluation Method Of Recoverable Reserves In Changqing Gas Field

Natural gas reserve is the material base of gas field development. It plays a decisive role to gas field development scale and stable production period length. Reserve's accurate certainty directly affects gas field development plan reasonable implementation and the overall development effect. Along with gas field development further going, adopting many methods (especially dynamic method) to reexamine and revise reserves is an extremely important work. To gas reservoirs in different exploration and exploitation period, the different data will bring different understanding degree and reserve calculation method. Accurate single well or gas reservoir dynamic calculation and analysis of reserves, affect gas reservoir objective synthetic evaluation, gas well reasonable proration, working system establishment as well as gas field development well deployment and adjustment. It is the base to highly effectively and scientifically develop gas fields. It is also the prerequisite to realize gas fields' long-term high production and stable production.At present there are many dynamic reserves calculation methods, but the majority need more accurate gas reservoir physical property parameters, or request gas reservoir reserve recovery reaches a certain degree, or request gas wells carry on shut in examination, even request gas wells flow enter a pseudosteady state, etc,. For Changqing's low permeability gas reservoir or well, it is hard to achieve these requests. Changqing gaseous section dynamic reserve calculation is always at an exploration stage, not forming a calculation system in view of low permeability reservoir characteristics.Because of the strong anisotropism of reservoir stratum of carbonate rock in Jingbian gas field, interwellprediction of properties is difficult. Objective factors, such as gas well production with water withdrawal, hydrate block-removing, increasing the productivity in winter and so on, cause frequent changes of gas-well working system, so the discharge range of gas well is indefinable. In view of the above difficulties, the paper applies the gas pool production dynamic data fully, basing on conventional pressure drop evaluation method, through reorganization of pressure and flow, and transforming variable data into constant data, establishes a suit of Changqing characteristic calculating methods for gas-well control reserve of anisotropic carbonate rock, including instability analysis of production, material balance method, optimum fitting method, Influence function method, etc, of which the adaptability is clearly defined. These methods can be used to monitor and evaluate control reserve of gas wells of carbonate rock in Jingbian gas field, analyze the production status according to the pressure decline signature, optimize the gas-well working system, and define the current discharge range. So the paper can instruct infill wells deployment, and make further improvement on the reserves producing.