Browsing by Author "Zhang, Nanlin"

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    Coupled THMC model-based prediction of hydraulic fracture geometry and size under self-propping phase-transition fracturing
    (2024-10-04) Zhang, Nanlin; Liu, Fushen; Jiang, Liangliang; Mo, Pinqiang; Xiao, Jingwen; Song, Qi; Luo, Yuhao
    Abstract The Self-Propping Phase-transition Fracturing Technology (SPFT) represents a novel and environmentally friendly approach for a cost-effective and efficient development of the world’s abundant unconventional resources, especially in the context of a carbon-constrained sustainable future. SPFT involves the coupling of Thermal, Hydraulic, Mechanical, and Chemical (THMC) fields, which makes it challenging to understand the mechanism and path of hydraulic fracture propagation. This study addresses these challenges by developing a set of THMC multifield coupling models based on SPFT parameters and the physical/chemical characteristics of the Phase-transition Fracturing Fluid System (PFFS). An algorithm, integrating the Finite Element Method, Discretized Virtual Internal Bonds, and Element Partition Method (FEM-DVIB-EPM), is proposed and validated through a case study. The results demonstrate that the FEM-DVIB-EPM coupling algorithm reduces complexity and enhances solving efficiency. The length of the hydraulic fracture increases with the quantity and displacement of PFFS, and excessive displacement may result in uncontrolled fracture height. Within the parameters considered, a minimal difference in fracture length is observed when the PFFS amount exceeds 130 m3, that means the fracture length tends to stabilize. This study contributes to understanding the hydraulic fracture propagation mechanism induced by SPFT, offering insights for optimizing hydraulic fracturing technology and treatment parameters.
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    Research and application of acid fracturing stimulation mechanism in ultra-deep subsalt dolomite reservoir in Tarim Basin
    (2022-10-31) Liu, Jiangyu; Zhao, Jinming; Qin, Shiyong; Zhang, Nanlin; Ren, Dengfeng; Luo, Zhifeng; Xie, Yaozeng
    Abstract Deep and ultra-deep carbonate reservoirs are the focus of exploration and development in future. However, the problems of high pressures in the treatment process, a limited effective etching distance of acid, great acid leak-off, and poor adaptability of the acid system are encountered in this type of oil and gas reservoir. The mechanism of acid fracturing stimulation under different processes and parameters is not clear. Aiming at these issues, the treatment schemes, process optimization, parameter optimization, and liquid system screening are studied in this paper, try to clarify the acid fracturing stimulation mechanism, and the following conclusions are drawn: The acid network fracturing could activate natural fracture to generate a complex fracture network to the greatest extent, and thereby a high output could be achieved; By using of weighted fracturing fluid, the wellhead injection pressure, as well as the performance of equipment required, could be effectively reduced; With 20% gelling acid and 20% retarded acid system, the non-uniform etching could be realized to improve the effective etching distance of acid liquid. The conclusions in this paper shed light on the acid fracturing treatment of deep and ultra-deep carbonate rocks.