Title: The difficulties and frontiers of subtle oil/gas reservoir research
Abstract: Subtle oil/gas reservoirs have become one of the main exploration targets in China. As petroleum exploration goes into a more mature stage, the search for subtle oil/gas reservoirs expands into areas with more complicated conditions. The accumulation and preservation of petroleum in deeply buried subtle traps, the structure of the unconformities in relation to subtle oil/gas reservoir distribution, the reasons for the loss of petroleum in the former subtle traps ,and for the preservation of adjusted subtle oil/gas reservoirs have become the difficulties of petroleum exploration and the frontiers for scientific research. The existence of active source rocks and reservoir rocks with relatively high porosity and permeability in the deep part of basins is fundamental for petroleum accumulation in deeply buried subtle traps. Advances made in recent years on the kinetics of hydrocarbon generation in overpressured environments will improve our ability to predict the maturity and hydrocarbon potential of deeply buried, overpressured source rocks. Several mechanisms causing abnormally high porosity in deeply buried sandstones may become the basis and principle for predrilling assessment of the quality of the reservoirs. The structure of unconformities, especially the thickness and the sealing ability of paleo-soil layers, and the thickness and permeability of semi-weathered rocks below the paleo-soil layers are keys to the study of subtle oil/gas reservoirs associated with unconformities. In superimposed basins, the formerly accumulated subtle reservoirs usually have undergone adjustments owing to the effects of multiple-stage tectonic movements. The adjustments of former subtle reservoirs could lead to the occurrence of a series of genetically related oil layers with complicated oil/water or gas/water contacts. The stacking pattern of different tectonic movements is very important for predicting adjusted subtle oil/gas reservoirs. In the center part of the Junggar Basin,for example, the subtle oil/gas reservoirs have all the above attributes: having been deeply buried; having complicated unconformities; and having undergone tectonic adjustments. Therefore, the central part of the Junggar Basin may become a “natural lab” for research on complicated subtle oil/gas reservoirs.
Publication Year: 2005
Publication Date: 2005-01-01
Language: en
Type: article
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Cited By Count: 7
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