金秋气田变系数一点法产能公式建立与应用

Establishment and application of productivity formula of variable coefficient one point method in Jinqiu gas field

金秋气田沙溪庙组气藏具有储层较薄、河道较窄且低渗致密特点,压裂气井受初期排液、地层压力下降快影响,常规一点法产能系数α值差异较大,其均值不能代表气田实际情况,单井早期产能快速评价难度大。针对金秋气田已完成的6口气井修正等时试井测试资料,采用变系数法确定了α值的校正公式及图版,确定了原始地层压力条件下α值为0.2,建立了金秋气田一点法产能公式,并比较了不同经验公式间产能计算结果的差异。结果表明,变系数的一点法产能公式计算误差更小、适用范围更广,对比投产前后的修正等时试井结果,误差仅为2.78%~4.27%。金秋气田的一点法产能公式为河道型致密砂岩气藏产能评价和合理配产提供了依据。

The Shaximiao Formation gas reservoir in Jinqiu gas field has the characteristics of thin reservoir,narrow channel and low permeability and tightness.The gas wells obtained by fracturing are affected by the initial drainage and the rapid drop of formation pressure.There is a big difference in the calculation of the productivity coefficientαvalue by the conventional one-point method,and its mean value cannot represent the actual situation of the gas field.It is difficult to quickly evaluate the early productivity of a single well,based on the corrected isochronous well test data of 6 gas wells,the variable coefficient method was used to determine theαvalue correction formula and chart,and theαvalue was determined to be 0.2 under the original formation pressure,and established The one-point productivity empirical formula of Jinqiu gas field is compared,and the difference of calculation results between different empirical formulas is compared.The results show that the variable coefficient one point productivity formula has smaller calculation error and wider application range.Compared with the corrected isochronal well test results before and after production,the error is only 2.78%~4.27%.One point productivity formula suitable for Jinqiu gas field provides a basis for productivity evaluation and reasonable production allocation of channel type tight sandstone gas reservoirs.