科研之友
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摘要
P>Tertiary igneous rocks in Qikou Depression, East China are primarily basic rocks. Two types of igneous reservoirs including the effusive basaltic reservoir and the near-surface intrusive doleritic reservoir have been identified so far and each has different reservoir spaces. In this paper, the lithofacies and reservoir properties of Tertiary igneous rocks are described through a systematic analysis of the characteristics of seismic reflection and well logs and selected cores observation. Both of the two types of igneous rocks present strong and low-frequency reflection events on seismic profiles, however, intrusive diabases exhibit the characteristic of strata penetration with a small intersection angle. Effusive basaltic lavas are divided into upper, middle and lower subfacies. This can be distinguished from the well log curves. Observation of sampled cores finds that primary vesicles and amygdales are abundant in the upper and lower subfacies of basaltic lavas. These vesicles can be favourable reservoir space if connected by cracks formed in the late-stage. Intrusive diabases can also be separated into inner subfacies as well as the upper and lower marginal subfacies, of which the former is well crystallized because of slowly cooling, whereas the latter is vitreous due to fast descending temperature at the contact zone between intrusive rocks and host rocks. Hydrothermal metamorphism left the surrounding mudstones metamorphosed to form shrunk fissures and structural fractures as reservoir space, making mudstones of poor porosity and permeability to be metamorphic and have certain reservoir potential.
- 出版日期2010-5
- 单位中国地质大学（北京）
