火山岩气藏井控动态储量变化规律及预测方法

Prediction methods of the OGIP for the single well in volcanic gas reservoirs

火山岩气藏发育有不同尺度的孔洞缝多重介质,孔隙结构复杂,非均质性强,物性差异大,导致开发过程中单井井控动态储量差异较大。研究表明,火山岩气井井控动态储量会随气井的生产而发生变化,对于低渗低效储层及多重介质储层,气井井控动态储量随生产时间的延长而增加;低渗致密储层压裂产生的裂缝可以增大气井的控制面积,从而增大井控动态储量;同时,部分气井的井控动态储量受边底水的影响而减小。常规井控储量计算方法计算结果偏小,不适用于火山岩气藏。在分析不同类型储层气井的井控动态储量变化规律的基础上,建立了相应的井控动态储量预测方法。通过实际气井数据计算,结果表明,该方法可以在气井生产时间较短的情况下预测最终状态的井控动态储量,且结果较为可靠。

Different from conventional sedimentary reservoirs,the storage space in volcanic gas reservoirs,with different-sized pore-fracture array modes,is quite complicated.This leads to the variations of OGIP in volcanic gas wells,and the variations are as follows：for low-permeability reservoirs,the OGIP tends to increase with the extension of production time,due to the increasing drainage radius;for the dual-media reservoirs,the OGIP also increases with the extension of production time,but itis mainly caused by the effect of relay gas supply mechanism;meanwhile,fracturing can increase the gas well supply area,and thus increase the OGIP.According to the variation rules,OGIP prediction methods for different-types reservoirs are established.For the low-permeability reservoirs and the fractured reservoirs,the prediction methods are based on the prediction of the max drainage radius;while for the dual-media reservoirs,the OGIP predictions are built on a typical curve chart.The new methods are applied to actual production data calculation.The results show that the new methods are more precise in predicting OGIP when the gas well production time is relatively short.