二阶导数识别井储效应的气井试井解释新方法

气井受井储效应影响严重，利用传统试井分析模型难以得到准确的解释结果。本文从试井理论入手，针对气井受井储效应严重，压恢试井曲线很难达到直线段的现象，分析实测曲线的偏离原因，从而对常规试井模型进行改进，并创新性的运用二阶导数法对试井曲线进行分析，明确井储效应影响下的压恢试井曲线具体变化情况。根据井储效应影响程度的大小划分了两类试井解释问题，结合二阶导数分别提出了气井试井解释新方法，进而运用有限差分等方法，根据实际数据，对压力恢复值随等效时间的变化、压力恢复值随等效时间的多阶导数变化情况进行拟合，从而得到两者耦合作用下的更准确的储层参数，达到指导区块合理开发的目的。

A new well test interpretation method for identifying well storage effect by second derivative

Gas wells are seriously affected by well storage effect,so it is difficult to obtain accurate interpretation results by traditional well testing analysis model.aiming at the phenomenon that the gas wells are seriously affected by the well storage effect,and pressure buildup test curve is difficult to reach the straight line,this article starts from the well testing theory,analyzes the cause of deviation of measured curve,so as to improve the conventional well test model.The well test curve is analyzed innovatively by second derivative methods,and the specific change of pressure buildup test curve under the influence of well storage effect is clarified.According to the influence degree of well storage effect,two types of well test interpretation problems are divided.Combined with the second derivative methods, new methods for well test interpretation of gas wells are proposed respectively .Then using the finite difference method, according to the actual data, the change of the pressure recovery value with the equivalent time and the change of the multi-order derivative of pressure recovery value with the equivalent time are fitted.The more accurate reservoir parameters under the coupling action of the two are obtained,so as to guide the rational development of the block.