Characteristics and exploration potential of shale oil reservoir in the Upper Member of the Xiaganchaigou Formation in the Ganchaigou area,western Qaidam Basin
Characteristics and exploration potential of shale oil reservoir in the Upper Member of the Xiaganchaigou Formation in the Ganchaigou area,western Qaidam Basin
[Objective]Well C902,located in the Ganchaigou area of the western Qaidam Basin,achieved a breakthrough in shale oil exploration as indicated by the high-production oil flow in the Ⅳ-Ⅵ layers of the Upper Member of the Palaeogene Xiaganchaigou Formation.However,ambiguities in evaluation criteria and resource po-tential limit the efficiency of shale oil development in the Upper Member of the Xiaganchaigou Formation in the Ganchaigou area.[Methods]Thus,the exploration potential of shale oil in the Ⅳ-Ⅵ layers of the Upper Member of the Xiaganchaigou Formation in the Ganchaigou area was comprehensively evaluated by comparing the lithology,physical properties,pore structure,and organic geochemistry between Well C902 and other wells.[Results]The complicated lithofacies of laminar/lamellar dolostone,laminar/lamellar limestone,laminar clay shale,and lamellar mudstone suggest the mixed carbonate and siliciclastic deposition of the Ⅳ-Ⅵ layers.The high brittleness index implies the good fracability of the Ⅳ-Ⅵ layers.The intergranular pores and laminar fractures,with a total propor-tion of 85％in the pore system,were dominant in the Ⅳ-Ⅵ layers that can be roughly classified as low-porosity and ultralow-permeability reservoirs.The organic matter,dominated by type Ⅰ-Ⅱ 1,shows an average TOC con-tent of more than 0.9％in the Ⅳ-Ⅵ layers.Both chloroform asphalt"A"and S1+S2 indicate a high hydrocarbon generation capacity.[Conclusion]Summarily,the widely deposited the Ⅳ-Ⅵ layers of the Upper Member of the Xiaganchaigou Formation have the characteristic of source-reservoir integration and show not only good quality of source rock but also strong fracability of the shale oil reservoir.The excellent source-reservoir-caprock assemblage is also widely developed,which ensures good sealing ability and favors improving oil and gas recovery after fractu-ring.This study can theoretically improve the development efficiency of shale oil in the Ganchaigou area.
关键词
页岩油储层/下干柴沟组上段/古近系/资源潜力/干柴沟区块/柴达木盆地
Key words
shale oil reservoir/Upper Member of Xiaganchaigou Formation/Paleocene/resource potential/Gan-chaigou area/Qaidam Basin
维普
万方数据