Abstract
Compared with conventional reservoirs, shale gas reservoirs usually have no natural productivity or lower productivity, and the rate of production decline is high in the later stage. The production of shale gas can be effectively improved by designing reasonably or fracturing. Therefore, it is critical for shale gas reservoir to study how to design proper parameters to make it effectively developed. Based on data of block-A region of the Zhejiang gas field, considering the contribution of rock compression to the production, the productivity formula of horizontal well at different seepage stages is deduced. Data from block-A are verified by orthogonal experiment, including gas reservoir parameters and engineering parameters. The results show that the order of reservoir parameters that affect the development of shale gas is as follows: Langmuir pressure, diffusion coefficient, cross flow coefficient, and Langmuir volume; the order of engineering parameters that affect the development of shale gas is as follows: number of fractures, horizontal section length, production pressure, fractures length, row spacing, and well spacing. The research results have been applied to the Zhejiang gas field. The initial rate of decline after adjustment is reduced by 26.08% and production increases by 17.06% after stabilization compared to wells without adjustment parameters. The research has important reference significance for the efficient development of similar gas reservoirs.
Highlights
With the continuous development of economy at home and abroad, the demand for coal, oil, and natural gas resources is increasing (Ma et al, 2020a; Ma et al, 2020b; Milkov et al, 2020)
In the process of establishing a productivity model, the assumed conditions are as follows: 1Shale gas reservoir belongs to dual media, which contains two kinds of fluids: gas and water phase. 2The water, matrix, fracture, and gas in the reservoir can be compressed, and they are all constant, without considering the influence of gravity. 3Due to the decrease of reservoir pressure, natural gas is desorbed from the matrix at first, enters the fracture in the form of diffusion under the action of concentration difference, and enters the wellbore as Darcy flow. 4In the process of exploitation, the free state and adsorption state of shale gas are in dynamic equilibrium, and the temperature of the reservoir keeps invariant
Radial flow: the radial flow of a single fracture is similar to the radial flow of the unfractured horizontal well, and the fracture is equivalent to the horizontal section
Summary
With the continuous development of economy at home and abroad, the demand for coal, oil, and natural gas resources is increasing (Ma et al, 2020a; Ma et al, 2020b; Milkov et al, 2020). As a representative of clean energy, shale gas has been widely paid attention to all over the world and plays an irreplaceable role in solving the current energy problems (Szolucha, 2019; Shu et al, 2020; Solarin et al, 2020; He et al, 2020). The past 2 decades have borne remarkable progress in our understanding of flow mechanisms and numerical simulation approaches of shale gas reservoir, and Tao Zhang reviews the flow mechanism and numerical simulation approaches of shale gas reservoirs in 2018 according to a much larger Block Gas reservoir Well section (m).
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