基于压裂液自发吸入模型的页岩气压裂液滤失定量预测OA北大核心CSTPCD
Quantitative prediction of fracturing fluid leak-off in shale gas reservoirs based on spontaneous imbibition model of fracturing fluid
非常规油气资源开发常使用水力压裂技术提高单井产量,然而压裂现场数据表明,大量压裂液会滞留在地层中导致压裂液的返排率较低,将对储层和地下水环境造成一定影响.为进一步研究压裂液滤失机理并准确预测压裂液滤失量,首先建立了由毛细管力作用引起的压裂液自发吸入模型,然后对压裂液滤失量进行定量计算,并在现场进行了验证.最后,引入无量纲吸入率参数分析了控制压裂液滤失的关键因素.研究结果表明:① 页岩气水平井压裂施工中大约 50%～95%的压裂液通过基质吸入,压裂液吸入量仅与吸入率参数、裂缝面积和吸收时间有关;②当润湿相黏度与非润湿相黏度之比超过阈值时,吸入率参数主要由岩石的孔径分布参数决定,流体黏度的影响非常有限;③当孔径分布参数介于 0.5～0.7 时,吸入率参数达到相对较高的值,即更多的压裂液被吸收到地层中;④当润湿相黏度与非润湿相黏度之比大于 10,孔径分布参数小于 0.8 时,优化后的自吸模型具有较大的适用性;⑤由毛细管力机理引起的压裂液滤失量与实际储层观察到的滤失量相近,可认为页岩储层有足够的存储滤失液的能力,不会影响地下水层中的饮用水.结论认为,建立的压裂液自发吸入模型,能够准确预测页岩气水平井压裂液滤失量,为非常规油气的生产及环境保护提供了技术支撑.
Hydraulic fracturing is often used for the development of unconventional oil and gas resources to improve the production rate of single well.However,the field data of fracturing indicate that a large amount of fracturing fluid retains in the strata,which results in a lower flowback rate of fracturing fluid and may have some impact on underground reservoirs and groundwater environments.In order to further study the leak-off mechanism of fracturing fluid and accurately predict the amount of fracturing fluid leak-off,this paper establishes a model describing the spontaneous imbibition of fracturing fluid caused by capillary force.Then,the amount of fracturing fluid leak-off is quantitatively calculated,and verified using the field data.Finally,the dimensionless imbibition rate parameter is introduced to analyze the key factors controlling fracturing fluid loss.And the following research results are obtained.First,during the fracturing construction of a horizontal well in shale gas reservoirs,about 50%-95%of the fracturing fluid is imbibed through the matrix.The amount of imbibed fracturing fluid is only related to imbibition rate parameters,fracture areas and imbibition time.Second,when the ratio of wetted phase viscosity to non-wetted phase viscosity exceeds the threshold,the imbibition rate parameter is mainly dependent on the pore size distribution parameter of the rock,while the effect of fluid viscosity is very limited.Third,when the pore size distribution parameter is between 0.5 and 0.7,imbibition rate parameter reaches a higher value,i.e.,more fracturing fluid is imbibed into the strata.Fourth,when the ratio of wetted phase viscosity to non-wetted phase viscosity exceeds 10 and the pore size distribution parameter is less than 0.8,the optimized spontaneous imbibition model has greater applicability.In conclusion,the spontaneous imbibition model of fracturing fluid established in this paper can accurately predict the amount of fracturing fluid leak-off,and provides a technical support for the production of unconventional oil and gas and the environmental protection.
王琳琳;蔺小博;冷静怡;周长静;马占国;肖元相
中国石油大学(北京)安全与海洋工程学院中国石油长庆油田公司油气工艺研究院巴黎高科路桥学院
页岩气藏毛细管力滤失自发吸入吸入率参数流体黏度孔径分布参数
Shale gas reservoirCapillary forceLeak-offSpontaneous imbibitionImbibition rate parameterFluid viscosityPore size distribution parameter
《天然气工业》 2024 (002)
92-98 / 7
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