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Click to view Poster.The Migration and Accumulation Conditions and the Exploration Prospects in Large Low Permeable Lithologic Oil & Gas Fields — China Ordos Basin as an Example
Yanru, Guo 1; Yanling, Zhang 1; Wanglin, Xu 1;
Junbang, Liu 1
(1)Research Institute of Petroleum Exploration &
Development Petrochina, Beijing, China.
Large low permeable lithologic oil &gas field is actually "lithologic reservoir group". Its characteristics are low permeability and porosity, small oil (gas) column, low abundance, large-scale, hard development, difficultly stable production etc. Recent years, with the development of advanced exploration and development technology large low permeable lithologic oil &gas fields have become the exploration and development igge. This kind of oil &gas field in Ordos basin in China is occupied 95%. Its basic migration and accumulation conditions are large thin layer high-quality hydrocarbon source rocks provided a lot of hydrocarbon source. The sandstone reservoir which is high diagenesis, low permeability and porosity, heterogeneity constituted the main space for the oil-gas accumulation. The lacustrine mudstone which is high quality, thick layer and wide continuous distributed prepared the good regional cap rock. The large delta sand body which is Vertical and horizontal large compound sectors-connecting distribution provided the lithologic trap group. The reservoirs experienced the process which is reservoiring first and then compacted. In early stage the reservoirs are large-area hydrocarbon-charging reservoiring which is near source and multi-point planar. In late stage the reservoirs are dense compaction to form low (normal) pressure and low permeability and porosity reservoirs. Small lithologic reservoirs which are superimposed and contiguous distribution formed large oil and gas fields. The research indicates that, the inclined area to semi-deep-lake has good prospects to find large lithologic reservoir. This cognition already plays a guiding role in the hydrocarbon exploration in Ordos basin. “Half basin oil, full basin gas ” distribution pattern has appeared and it also have good development potential in the future.
AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.