Oil & Gas Geology ›› 2005, Vol. 26 ›› Issue (2): 230-236.doi: 10.11743/ogg20050216

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Discussion on characteristics and reservoiring mechanism of deep basin gas in Upper Paleozoic in Ordos basin

Ma Xinhua   

  1. Ordos Branch of Petroleum Exploration and Development Research Institute, PetroChina, Beijing
  • Received:2004-12-26 Online:2005-04-25 Published:2012-01-16

Abstract:

He 8 and Shan 2 plays in the study area have the characteristics of and conditions for accumulation of deep basin gas. The reservoirs are characterized by high compactibility, sporadic water production in gas-bearing area and strong compartmentalization of gas reservoir pressure, mainly due to continental sedimentary sequence and later reconstruction of gas reservoirs. Geologic analysis and physical modelling show that sandbodies have regional connectivity (along) strike, thus migration and accumulation processes of gas displacing water might occur in reservoiring conditions. A development stage and a reconstruction stage of deep basin gas can be divided at the end of Early Cretaceous. Reservoir pressure evolved from overpressure to underpressure in the reservoiring process. The main factors that caused the pressure drops in different areas are not the same. In Suligemiao area, it is mainly caused by the enlargement of dissolution pores in reservoirs, and temperature drop also has certain influences. While in Yulin and Shenmu-Mizhi areas in eastern Ordos Basin, it is mainly caused by the uplifting and temperature drop.A specific reservoiring pattern is presented based on comprehensive analysis of reservoiring features and process.

Key words: Ordos basin, Upper Paleozoic, deep basin gas, tight reservoir, reservoiring mode

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