Abstract
Due to a large number of natural fractures in tight oil reservoir, many complex fracture networks are generated during fracturing operation. There are five kinds of flow media in the reservoir: “matrix, natural fracture, hydraulic fracture network, perforation hole, and horizontal wellbore”. How to establish the seepage model of liquid in multiscale medium is a challenging problem. Firstly, this paper establishes the dual medium seepage model based on source function theory, principle of superposition, and Laplace transformation and then uses the “star-triangle” transform method to establish the transient pressure behavior model in the complex fracture network. After that, perforating seepage model and variable mass flow in horizontal wellbore were established. Finally, continuous condition was used to couple the seepage model of dual medium seepage model, transient pressure behavior model in the complex fracture network, perforation seepage model, and the variable mass seepage model in horizontal wellbore, to establish a semianalytical coupled seepage model for horizontal well in tight reservoir. This paper provides theoretical basis for field application of horizontal well with complex fracture networks.
Highlights
Domestic and foreign development practice proves that horizontal drilling technology and large-scale fracturing technique are the core technologies of successful development of tight reservoir [1]
The multiscale medium flow process in tight oil reservoirs consists of four parts: dual media flow, internal flow in complex fractures, perforation flow, and horizontal wellbore variable mass flow
Combining the previous understanding of the well test curve, the seepage of horizontal well with complex fracture networks can be divided into eight flow regimes: Stage I is linear flow in complex fractures, Stage II is bilinear flow, Stage III is reservoir linear flow, Stage IV is transition flow, Stage V is fracture interference flow, Stage VI is the pseudo-radial flow of the natural fracture system, Stage VII is cross flow, and Stage VIII is pseudo-radial flow in the entire system
Summary
Domestic and foreign development practice proves that horizontal drilling technology and large-scale fracturing technique are the core technologies of successful development of tight reservoir [1]. Scholars at home and abroad have established a large number of seepage models for horizontal wells with complex fracture networks in tight oil reservoirs. These models can be divided into three types: analytical model, semianalytical model, and numerical model. The numerical model has the advantage of describing the heterogeneity of multiscale media It has disadvantages such as complex modeling process and unstable calculation result, which limits its application in practical engineering problems. There is still lacking multiscale coupled seepage model in tight oil reservoir considering “matrix, natural fracture, hydraulic fracture, perforation, and horizontal well”. (c) Four fractures intersection (d) Multiple fractures intersection Figure 2: Fracture intersections
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
