China Petroleum Exploration ›› 2024, Vol. 29 ›› Issue (3): 91-102.DOI: 10.3969/j.issn.1672-7703.2024.03.009

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Geology and engineering integrated development practice of fan well pattern shale oil horizontal wells in Ordos Basin

Cao Wei1,2, Qi Yin1,2,Ma Bing1,2,Bai Jie1,2,Xu Rongli1,2   

  1. 1 Oil & Gas Technology Research Institute, PetroChina Changqing Oilfield Company; 2 National Engineering Laboratory for Exploration and Development of Low Permeability Oil & Gas Fields
  • Online:2024-05-15 Published:2024-05-15

Abstract: Multi-platform and large-area well deployment is the key to high-efficiency unconventional resource utilization. Due to the geomorphic characteristics of loess tableland, as well as forest edge and water source areas in Qingcheng area in Ordos Basin, well placement for the development of the Triassic Chang 7 member shale oil is restricted. As a result, an innovative fan well pattern is proposed to further maximize the producing reserves of the platform. Based on the geology and engineering integrated method, the influence of various azimuths of fan well pattern on fracture propagation and production capacity is analyzed, and the fracture spacing and fracturing sequence are optimized of fan well pattern. Meanwhile, the practical cases are combined to analyze fracturing characteristics and compare production results of various fan well patterns. The study results show that, compared with conventional horizontal wells (the angle between the horizontal trajectory and the minimum horizontal principal stress is less than 15°), the predicted production capacity of oblique horizontal wells (the angle between the horizontal trajectory and the minimum horizontal principal stress is greater than or equal to 15°) decreases with the increasing deflection angle (the angle between the well placement and the minimum horizontal principal stress). When the deflection angle is greater than 45°, the difference in production capacity is further expanded with the increase of the deflection angle. In addition, the economic evaluation results of various simulation scenarios show that the economic feasibility is the worst when the deflection angle is 90°, and well deployment is not recommended. The predicted production capacity can be improved by increasing fracture spacing and adopting the “outside-in” fracturing sequence of fan well pattern. The fractures in oblique horizontal well first propagate along the vertical wellbore direction with a large microseismic magnitude, but the direction of the maximum horizontal principal stress is still the dominant factor for fracture propagation at a far-field scale. Compared with conventional horizontal well, the oblique horizontal well is characterized by a smaller stimulated reservoir volume, but more complex fractures, and more reconstructed fracture network. In terms of the actual production results, the cumulative production of oblique horizontal wells is lower than that of conventional horizontal wells, but the liquid level is higher and the daily oil production is close at present, indicating a promising development potential.

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