岩性油气藏勘探的沉积体系域表征技术——以柴达木盆地为例

Characterization of Depositional System Tract for Exploration of Lithologic Pools-An example of Qaidam basin

体系域是同期沉积体系的组合,是主要受控于水平面(湖平面或海平面)升降的三级层序内的基本单元。油气赋存于不同体系域的沉积砂体中。通过体系域表征和沉积体系分析与研究,可以预测岩性油气藏类型及其分布。柴达木盆地柴西南地区体系域表征结果表明,湖侵体系域发育,储集体类型丰富,主要为三角洲前缘砂体、滨浅湖滩坝砂体和局部的半深湖浊积砂体。综合地质地震的特征分析,在体系域框架内应用数字地震处理技术包括Jason储集层反演等,可以指出砂体分布特征,预测柴西南区块的岩性油气藏,主要发育着SB、TU、DT和SS等四类岩性油气藏。

System tract, a basic unit of Ⅲ-grade sequence, is a combination of the same-term depositional systems controlled by water level changes (lacustrine level or sea level). Petroleum tends to being accumulated in the depositional sand bodies of different system tracts. The type and distribution of lithologic pools could be predicted by characterization of system tracts and analysis of depositional systems. In southwestern Qaidam basin, the characterization of system tracts shows that there exist developed transgressive system tract (TST) and various types of reservoirs such as sand body of deltaic front, lacustrine beach and dam as well as local turbidite of semideep lake. Based on synthetically geologic and seismic analyses, using digital seismic processing techniques (Jason's reservoir inversion, etc.), the sand body distribution could be described, hence predicting that in southwestern Qaidam basin mainly developed the lithologic pools of SB, TU, DT and SS types.