基于初次压裂地质工程条件及改造效果的页岩气井重复压裂选井模型

Candidate well selection model of shale gas wells for refracturing based on geological and engineering conditions and stimulation performance of primary fracturing

为了解决页岩气重复压裂候选井优选困难问题,基于初次压裂时地质条件、施工参数及改造效果,引入水平应力差异系数、页岩气储层评价指数、单井用液指数、单井支撑剂用量指数、初次压裂储层改造体积比等5个评价指标,建立页岩气重复压裂选井评价模型。首先通过水平应力差异系数及页岩气储层评价指数评价候选井初次压裂时的地质条件,其次通过单井用液指数、单井支撑剂用量指数评价候选井在较好的储层地质条件下初次压裂施工作业情况,最后根据地质工程条件及初次压裂储层改造体积比优选出重复压裂目标井。以四川盆地南部地区页岩气井为对象进行应用验证,优选出重复压裂目标井。结果表明该模型有助于川南页岩气水平井重复压裂井的优选,对页岩气井重复压裂技术具有重要意义。

It is difficult to select candidate wells for shale gas refracturing.In this regard,an evaluation model for shale gas refracturing candidate well selection was built with five evaluation indexes depending upon the geological conditions,treatment parameters and stimulation effects of primary fracturing.The indexes are the horizontal stress difference coefficient,shale gas reservoir evaluation index,single-well liquid injection index,single-well proppant injection index and primary SRV(stimulated reservoir volume) ratio.First,the geological conditions of candidate wells during primary fracturing were evaluated as per the horizontal stress difference coefficient and shale gas reservoir evaluation index.Second,the primary fracturing treatments of candidate wells with better reservoir geological conditions were evaluated according to the single-well liquid and proppant injection indexes.Finally,the target wells for refracturing were optimized in accordance with the geological and engineering conditions and the SRV ratios of primary fracturing.The model was validated via applications to shale gas wells in the southern Sichuan Basin to optimize the target wells for refracturing.The results show that the model is helpful to the optimization of refracturing candidates of shale gas horizontal wells in South Sichuan,and is of great significance to refracturing of shale gas wells.