页岩气水平井产能预测方法及应用——以四川盆地威远区块为例

Productivity prediction method for horizontal wells in shale gas horizontal well in Weiyuan block of the Sichuan Basin

四川盆地威远区块国家级页岩气示范区开发效果显著,但单井产量差异较大,影响产量的地质、工程因素数量多,因素间内在联系尚无定量表征,且各因素与产量间存在不严格的数学关系。为指导井位部署论证,顺利开展压裂前水平井地质评价,实现目的层的有效压裂改造,以威远页岩气61口典型水平井为例,利用灰色关联法筛选出水平井产能的6个主控因素,包括:压裂段长、优质箱体钻遇段长、含气量、龙一11小层厚度、加砂强度、总射孔数,基于威远页岩气区块主控因素分析结果,建立多元线性回归产能预测模型。实例选取区块内W1平台、W2平台共计6口水平井计算预测产量,预测产量与实际测试产量的相对误差率为0.32%~18.25%,平均8.1%,表明该产能预测模型准确可靠,可满足威远页岩气产量评价的实际生产需求。

Weiyuan shale gas block in Sichuan,belongs to Weiyuan-Changning national shale gas demonstration area,has obtained favorable development effect,but the production of single well varies greatly。There are many geological and engineering factors that affect the output,and the internal relationship between the factors has not been quantitatively characterized,and there is not strict mathematical relationship between the factors and the output.In order to guide the well location deployment demonstration,carry out the geological evaluation of the horizontal well before fracturing,and achieve the effective fracturing of the target stratum,the six main controlling factors for the productivity of horizontal wells are screened by using the grey correlation method based on the data of 61 horizontal wells in Weiyuan shale gas block,including:the length of fracturing section,the length of dessert drilling section,the gas content,the thickness of the first layer of Longmaxi-1 Formation,the proppant injection intensity,and the total number of perforations.Based on the analysis results of main controlling factors in Weiyuan shale gas block,a multiple linear regression productivity prediction model is established.Six horizontal wells on W1 platform and W2 platform in the block are selected to calculate the predicted production.The error rate between the predicted production and the actual test production is 0.32%~18.25%,with an average of 8.1%。The productivity prediction model is accurate and reliable,and can meet the actual production demand of Weiyuan shale gas production evaluation.