China Petroleum Exploration ›› 2021, Vol. 26 ›› Issue (5): 113-124.DOI: 10.3969/j.issn.1672-7703.2021.05.010

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Characterization of migration pathway and analysis of oil accumulation process of heavy oil reservoirs: a case study of LD16 oil-bearing structure in Liaodong Bay Depression in Bohai Sea area

Zhao Dijiang, Jiang Shangkun, Qiao zhu, Xu Kunming, Kong Shuanshuan   

  1. Tianjin Branch of CNOOC (China) Co., Ltd.
  • Online:2021-09-15 Published:2021-09-15

Abstract: The heavy oil reservoir varies greatly from conventional oil reservoir in terms of oil properties, oil-water contact and preservation mechanism, and its oil accumulation process is extremely complicated. Taking the LD16 oil-bearing structure in Liaodong Bay Depression in Bohai Sea area as an example, the main characteristics of heavy oil reservoir is summarized in this study by using logging, core description, seismic and geochemical analysis data. Based on the characterization of reservoir heterogeneity and stereoscopic fault analysis, a quantitative migration simulation technique combining the charging section and reservoir heterogeneity is proposed to fi nely describe the hydrocarbon migration pathway, and further to study the heavy oil accumulation process. The results show that: (1) The active rate and curvature shape of faults determine the effective hydrocarbon migration section in fault zone; (2) The reservoir physical property and structural morphology jointly determine the dominant migration pathway of heavy oil, and the amount of oil charging and high porosity/permeability zone result in the irregular distribution of heavy oil; (3) The heavy oil reservoir is formed by the migration and adjustment of crude oil along the fault that was primarily degraded of Dongying Formation paleo oil reservoir during the neotectonic movement. The stable caprock and the abrupt increase of oil viscosity due to the decrease of temperature and pressure are the key factors for hydrocarbon accumulation in glutenite reservoir of Guantao Formation.

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