Abstract
In the process of stimulated reservoir volume of tight reservoir, horizontal well can form three zones, the inner zone is multistage fracturing zone, the middle zone is skin damage zone, and the outer zone is undamaged zone. In this paper, a transient well test analysis model of multistage fracturing horizontal well in three area composite reservoir is proposed. Based on Laplace transformation, point source integration, and superposition principle, the infinite conductivity multifracture model of three area composite reservoir is obtained. The linear equations of finite conductivity multifracture in Laplace space are established by using the equal conditions of flow and pressure at the fracture wall. Gauss-Newton iteration method and Stehfest number are used to obtain the solution of wellbore pressure. The accuracy of the results is verified by numerical simulation. Then, the flow characteristics of multistage fracturing horizontal wells in three area composite reservoirs are analyzed by type curves. The flow is divided into ten stages, which are the bilinear flow, the linear flow, the first radial flow stage, the inner zone linear flow, the inner zone radial flow, the middle zone linear flow, the middle zone radial flow, the outer zone linear flow, the outer zone radial flow, and the boundary dominated flow. The pressure derivative curves show different characteristics in different flow stages. The influences of fracture conductivity, fracture spacing, radius ratio of the middle zone to inner zone, radius ratio of the outer zone to the middle zone, permeability ratio of inner zone to the middle zone, permeability ratio of inner zone to outer zone, storage capacity ratio of inner zone to the middle zone, and storage capacity ratio of inner zone to outer zone on type curves are analyzed. Finally, the application and reliability of the proposed model are verified by a case example.
Highlights
China is rich in unconventional oil and gas resources with great development potential
The analysis of pressure dynamic characteristics is an important method for evaluating reservoirs and obtaining physical property parameters of reservoirs and is of great significance to providing guidance to the development of oil and gas fields
Assuming that the number of fractures in the multistage fractured horizontal well is N f, the pressure drop of each section of fractures can be obtained as follows by means of point source integration and superposition principle: Nf ð1
Summary
China is rich in unconventional oil and gas resources with great development potential. The purpose of the paper is to establish a new well test analysis model for multistage fractured horizontal wells in a three-region composite reservoir. The typical curves and flow characteristics have been analyzed using the obtained solution, thereby, establishing a theoretical foundation for the well test analysis of multistage fractured horizontal wells in the threeregion composite reservoir. Assuming that the number of fractures in the multistage fractured horizontal well is N f , the pressure drop of each section of fractures can be obtained as follows by means of point source integration and superposition principle: Nf ð1. According to the idea of Cinco-Ley (1988), the dimensionless governing equation of flow in the single wing of a one-dimensional fracture can be written as follows:. By solving equations (29) and (30), m flow values and the pressure in the horizontal well can be obtained
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