柴达木盆地东坪地区侏罗系分布及基岩岩性预测
Jurassic distribution and bedrock lithologic prediction of Dongping area, Qaidam Basin
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摘要: 柴达木盆地东坪地区东坪1井天然气的发现揭开了柴达木盆地基岩天然气藏勘探的序幕。勘探和研究认为, 东坪地区基岩气藏以侏罗系烃源岩为气源, 纵向上通过断裂、裂缝系统迁移, 横向上通过不整合面、优质砂体运移, 在花岗岩和片麻岩基岩中聚集成藏。因此, 侏罗系分布和基底岩性预测是该区基岩气藏勘探的关键问题。通过CEMP勘探结合重磁资料研究, 明确了侏罗系的分布, 预测了东坪-冷湖地区基岩分布及特征, 与钻井吻合良好, 对东坪-冷湖地区的基岩气藏勘探具有指导意义。Abstract: The discovery of natural gas from Dongping 1 Well in Dongping area has triggered the large-scale exploration of bedrock gas reservoirs in Qaidam Basin. Plenty of exploration and research work shows that the bedrock reservoirs in Dongping area were mainly sourced from Jurassic coal type gas and Tertiary oil type gas, and that the Jurassic hydrocarbon source rocks and bedrock reservoirs in Dongping were accumulated and entrapped in granite and gneiss after upward migration in the fracture system and lateral migration in sand pores. However, the unclear Jurassic distribution and basement lithology have limited the exploration of Dongping bedrock gas reservoirs. The combination of CEMP study of piedmont and the comprehensive analysis of magnetic data can define the distribution characteristics of the Jurassic strata and determine the rock characteristics of Dongping-Lenghu(Cold Lake) area, and the result coincides well with drilling. The results achieved by the authors have practical significance for guiding the exploration of bedrock gas reservoirs in this area.