Browsing by Author "Xu, Jinze"

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    Effects of Lean Zones on SAGD Performance
    (2015-09-09) Xu, Jinze; Chen, Zhangxing (John)
    In Canada, both Nexen’s Long Lake and Suncor’s Firebag steam-assisted gravity drainage (SAGD) Projects reported existence of intersecting lean zones that behave as thief zones. Thoroughly understanding the effect of lean zones and improving SAGD operations with such heterogeneity are critically important in reducing the disadvantages of lean zones during SAGD production. The mechanisms of how mobile water affects the SAGD production are thoroughly studied by developing analytical transient solutions. Meanwhile, the effects of the location, thickness, size, and interval distance of lean zones on SAGD are numerically discussed. The relationship between the steam chamber volume and steam-oil ratios is also highlighted. The ten-year history match is performed based on the geological model in the Lone Lake Field. A hybrid cyclic steam stimulation (CSS)/SAGD method is furthermore proposed and studied to overcome the practical problem of low injection pressure due to lean zones.
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    Multi-scale Real Gas Transport in Shale Matrix
    (2018-03-05) Xu, Jinze; Chen, Zhangxing (John); Chen, Shengnan; Lu, Qingye; Yin, Shunde; Cheng, Y. Frank
    As one of the clean energy resources, shale gas significantly reduces greenhouse gas emissions. The description of the gas transport behavior in shale rocks is one of the numerous challenges for further studies on economically developing shale gas reservoirs. In this work, real gas transport in the multi-scale porous structure of shale matrix is studied. Three models are, respectively, built at scales of single pores, a dual-porosity shale rock and a shale gas reservoir. These models are well validated with experimental, simulation and field data. Results indicate that increasing a taper ratio and an aspect ratio weakens a real gas effect and lowers bulk gas transport, including viscous flow and Knudsen diffusion, while the surface diffusion conductance first increases and decreases afterwards. More tortuous and complex pores weak the dominancy of the shale matrix in a dual-porosity shale rock. Transport conductance owns negative relationships with fractal dimensions of pore size and tortuosity of shale matrix, and positive relationship with minimum pore size. Gas production is underestimated without considering nano-scale pore size distribution-based gas transport mechanisms. A higher fractal dimension of a pore size and a higher variance result in higher cumulative gas production and lower sensitivity of gas production to a nano-scale pore size distribution.
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    Study on the Imbibition Characteristics of Different Types of Pore-Throat Based on Nuclear Magnetic Resonance Technology
    (2022-04-27) Liu, Xiong; Zhang, Yang; Zhang, Ziming; Xu, Jinze; Zhou, Desheng; Su, Jian; Tang, Ying
    “Fracturing network+imbibition oil production” is a new attempt to effectively develop low-permeability tight reservoirs. Fracturing fluid is not only a carrier for sand carrying but also a tool in the process of imbibition. On the basis of imbibition experiments, combined with nuclear magnetic resonance and pseudo-color processing technology, this paper clarified the dominant forces of different types of pore-throat and quantitatively characterized the contribution of different levels of pore-throat to imbibition oil recovery. The results show that gravity is the main controlling force of imbibition for reservoirs with higher permeability. Fluid replacement mainly occurs in the early period of imbibition. Macropores contribute most of the imbibition recovery, mesopores have a weak contribution, and the contribution of micropores and pinholes can be ignored. For the reservoirs with low permeability, capillary force is the main controlling force of imbibition. Fluid replacement mainly occurs in the later period of imbibition. Macropores contribute most of the imbibition recovery rate, mesopores contribute a small part of the imbibition recovery factor, and the contribution of micropores and pinholes can be ignored. This paper clarified that macropores and mesopores are the main sources of the contribution of imbibition recovery efficiency, and oil content and connectivity are key factors for the imbibition recovery efficiency.