采用Laplace空间源函数方法的复杂离散缝网半解析试井模型  

Pressure transient analysis for discrete fracture network with semi-analytical method

作　　者：雷霆[1] LEI Ting(China University of Geosciences(Wuhan),Wuhan,Hubei 430074,China)

机构地区：[1]中国地质大学(武汉)资源学院,湖北武汉430074

出　　处：《油气井测试》2023年第1期1-7,共7页Well Testing

基　　金：国家科技重大专项“缝洞型碳酸盐岩油藏提高采收率关键技术”(2016ZX05014)。

摘　　要：分段压裂水平井的常规试井模型仅考虑主要的水力裂缝,忽略了在压裂过程中产生的大量次级裂缝。为了更准确的描述包括次级裂缝在内的复杂缝网对压力动态的影响,采用源函数方法建立了描述复杂离散裂缝网络的地层压力半解析模型。该模型由地层模型和裂缝模型两部分组成。地层模型将裂缝视为直线源,采用格林函数法累加多条裂缝的影响。裂缝模型将单条裂缝离散化,在每个小单元上使用Laplace空间的条带源函数,在考虑单个裂缝的压力动态时避免了繁琐的累加过程。使用该模型计算了单一裂缝、多条裂缝、复杂缝网三种情况下的压力动态。在单一裂缝情况下,考虑裂缝对称分布和不对称分布两种情况,计算结果与文献中的已有结果基本一致。在多条裂缝和复杂缝网情况下,计算结果显示次级裂缝的存在会使得压力动态偏离典型的双线性流或线性流。与现有模型的对比表明,考虑复杂缝网的模型能够更准确的描述导数曲线早期段。The conventional well test model of staged fracturing horizontal wells only considers the main hydraulic fractures,ignoring the large number of secondary fractures generated during the fracturing process.In order to more accurately describe the influence of complex fracture networks including secondary fractures on pressure dynamics,a semi-analytical model of formation pressure describing complex discrete fracture networks was established by using the source function method.The model consists of two parts:the formation model and the fracture model.The formation model takes fractures as line sources and uses the Green’s function method to accumulate the effects of multiple fractures.The fracture model discretizes a single fracture and uses the strip source function of Laplace space on each small cell,avoiding the tedious accumulation process when considering the pressure dynamics of a single fracture.Using this model,the pressure dynamics of single fracture,multiple fractures and complex fracture network are calculated.In the case of a single fracture,considering both the symmetrical distribution and asymmetric distribution of the fractures,the calculated results are basically consistent with the existing results in the literature.In the case of multiple fractures and complex fracture networks,the calculation results show that the presence of secondary fractures can cause the pressure dynamics to deviate from typical bilinear or linear flow.The comparison with the existing models shows that the model considering the complex seam network can describe the early segment of the derivative curve more accurately.

关 键 词：离散裂缝网络 多段压裂水平井 格林函数源函数 半解析模型 试井解释 缝洞型碳酸盐岩油藏 格林函数 压力动态模型 

分 类 号：TE353[石油与天然气工程—油气田开发工程]