Gulong shale oil is an important practical field for resource replacement in Daqing Oilfield. The Gulong shale oil reservoirs have high clay content, well-developed beddings, great spatial change of geological and engineering properties and strong heterogeneity. Thus, how to use a lot of seismic and logging data to describe the heterogeneity of the entire reservoirs and predict the distribution of interwell and spatial sweet spots is the key to guiding the effective shale development. Based on previous exploration research, the first zonal model for lithofacies and geological and engineering parameter was created by lithofacies control and combination of well log and seismic data, finite element simulation, neural network method, etc., and the models of parameters such as bedding fracture density were supplemented to create transparent Gulong shale oil reservoirs with the work area of 2,778 km2 and the vertical accuracy of the target area of 0.48 m, achieving a breakthrough in reservoir description from interwell comparison to accurate characterization of the entire reservoir. On the basis of iteratively updating of the models, a zonal model for double-excellent sweet spots was created according to the evaluation criteria of double sweet spots so that the double-excellent sweet spot zones could leap from two-dimensional speculation to three-dimensional characterization; the method for determining the optimal target interval of the longitudinal sliding window was innovatively formed, and the optimal target window is focused from the general sweet spot layer to the 2–4 m optimal target window. By guiding the design and fracturing plan of development wells for Member Q9, the coincidence rate of drilling the sweet spots reached 92.3%, fully supporting the production capacity of Gulong shale oil from Member Q9 in Daqing.

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Characterization of Gulong Shale Oil Reservoirs by Zonal Model and Evaluation of Sweet Spots by Geological and Engineering Data

  • Chuan-gang Xiang,
  • Gui-nan Yang,
  • Hao Qin,
  • Shu-xia Liu,
  • Zhi-hui Yang

摘要

Gulong shale oil is an important practical field for resource replacement in Daqing Oilfield. The Gulong shale oil reservoirs have high clay content, well-developed beddings, great spatial change of geological and engineering properties and strong heterogeneity. Thus, how to use a lot of seismic and logging data to describe the heterogeneity of the entire reservoirs and predict the distribution of interwell and spatial sweet spots is the key to guiding the effective shale development. Based on previous exploration research, the first zonal model for lithofacies and geological and engineering parameter was created by lithofacies control and combination of well log and seismic data, finite element simulation, neural network method, etc., and the models of parameters such as bedding fracture density were supplemented to create transparent Gulong shale oil reservoirs with the work area of 2,778 km2 and the vertical accuracy of the target area of 0.48 m, achieving a breakthrough in reservoir description from interwell comparison to accurate characterization of the entire reservoir. On the basis of iteratively updating of the models, a zonal model for double-excellent sweet spots was created according to the evaluation criteria of double sweet spots so that the double-excellent sweet spot zones could leap from two-dimensional speculation to three-dimensional characterization; the method for determining the optimal target interval of the longitudinal sliding window was innovatively formed, and the optimal target window is focused from the general sweet spot layer to the 2–4 m optimal target window. By guiding the design and fracturing plan of development wells for Member Q9, the coincidence rate of drilling the sweet spots reached 92.3%, fully supporting the production capacity of Gulong shale oil from Member Q9 in Daqing.