Flow Mechanisms and Transient Pressure Analysis Study For Multi-Stage Fractured Horizontal Wells In Shale Gas Reservoirs
Compared with conventional natural gas resources, shale gas reservoir, as a typical unconventional natural gas resource, has the characteristics of low porosity and low permeability. Therefore, the fractured horizontal well technology has been widely used in shale gas reservoir development. At the same time, more and more attention has been paid to the study of seepage mechanism. At present, conventional research on the seepage theory of fracturing horizontal wells in shale gas reservoirs are not very systematic, and the comprehensive consideration of adsorption, desorption and diffusion in the seepage model, especially in the linear flow model, is rarely given. Comprehensive consideration of adsorption, desorption and diffusion, using computer programming knowledge, such as shale gas reservoir fracturing horizontal well trilinear flow and five linear flow model, to research the shale gas reservoir fracturing horizontal well pressure dynamic features, provide theoretical basis for the development of shale gas. This paper mainly completes the following work: (1) Conduct in-depth research and analysis of a large number of literatures, analyze the characteristics of shale gas reservoir, and summarize its production and migration mechanism. (2) The continuity differential equation of each zone of the conventional trilinear flow and five linear flow model is derived, which provides the basic theoretical basis for the establishment of the trilinear flow and five linear flow model of shale gas reservoir. (3) Trilinear flow models and five linear flow models were established for fracturing horizontal Wells in single-medium shale gas reservoirs, and corresponding ii pressure characteristic curves were drawn to divide the flow stages. The influence of parameters such as adsorption and desorption coefficient, apparent permeability coefficient, fracture and reservoir conductivity, fracture spacing and pressure conductivity coefficient on the characteristic curve was analyzed. Trilinear flow model and five linear flow model are compared. (4) Trilinear flow models and five linear flow models are established for fracturing horizontal Wells in shale gas reservoirs with dual media. The models include: fracture seepage-matrix pseudo diffusion model, fracture seepage-matrix unsteady diffusion model. The corresponding pressure characteristic curve is drawn and the flow stage is divided. The effects of parameters such as elastic storage capacity ratio, interfacial flow coefficient, adsorption-desorption coefficient, fracture spacing and reservoir boundary length on the characteristic curve were analyzed. Trilinear flow model and five linear flow model are compared. (5) The application of the established model in well test interpretation and analysis of the measured data verifies the practicability of the theoretical model in this paper.
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Faculty of Graduate Studies and Research, University of Regina