涠西探区D次洼流二段岩性圈闭地球物理预测及其形成机制

Geophysical prediction and formation mechanism of lithologic traps in the second member of Liushagang Formation,D Subsag,Weixi exploration area

涠西探区经历了始新世流沙港组时期的湖泊沉积和渐新世涠洲组时期的三角洲沉积,D次洼洼槽-内坡带成熟烃源岩范围区是寻找岩性圈闭的相对最有利地区。为扩大涠西探区的资源潜力,分阶段采用不同的地球物理技术识别流二段岩性圈闭构成元素。利用地震波阻抗反演技术、地震谱分解技术对岩性圈闭进行砂体预测;运用砂体自动追踪技术和地震同相轴解释技术进行砂体顶底界面刻画;运用地震吸收属性分析开展岩性圈闭的含油气性预测。在流二段识别出了浊积砂和砂岩上倾尖灭两种岩性圈闭,并对其做了形成机制分析。流二段岩性圈闭的识别增强了涠西探区的勘探前景。

The Weixi exploration area has experienced lacustrine deposits during the Eocene Liushagang Formation period and delta deposits during the Oligocene Weizhou Formation period.The range of mature source rocks in the D Subsag-inner slope zone is the relatively most favorable area for searching for lithological traps.In order to expand the resource potential of the Weixi exploration area,different geophysical techniques were used to identify the constituent elements of the lithological trap of the second member of the liushagang Formation in stages.Firstly,the sand body prediction of lithologic traps was carried out by using seismic impedance inversion technology and seismic spectrum decomposition technology.Secondly,the interface between the top and bottom of sand body was characterized by sandbody automatic tracking technology and seismic isomorphic axis interpretation technology.Finally,the oil and gas properties of lithologic traps were predicted by using seismic absorption attribute analysis.Two lithologic traps of turbidite sand and sandstone updip pinch-out were identified in the second member of the liushagang Formation,and their formation mechanism was analyzed.The identification of lithologic traps in the second member of the liushagang Formation enhances the prospects for exploration in the Weixi exploration area.