石油地质理论新进展及其在拓展勘探领域中的意义

New achievements of petroleum geology theory and its significances on expanding oil and gas exploration field

近年来随着油气勘探工作的深入发展,陆续揭示了一系列有悖于传统石油地质理论的现象。对石油地质理论的产生,从以下几方面注入新思想:①富油气凹陷具有“满凹含油”特征,即由于优质烃源岩与席状砂体间互发育,在富油气凹陷内具有广泛的成藏几率,可跳出“二级构造带”的概念,实现满凹勘探。②叠合盆地中、下部组合有悖于传统的石油地质特征,表现为:高压条件下生烃过程滞后,液态窗变宽变深,从而增加了在深层寻找液态烃的机会;历经多期变动的深层油气藏,其分布不完全遵从“源控论”;受早成藏、晚埋藏、超压抗压实、构造托举与盐岩“悬浮”以及次生作用的控制,深层有好储层;受多期叠加作用形成的二级构造带含油气性变化大;退火背景下,油气超晚期成藏。③由于高效天然气成藏取决于生烃、成藏过程及要素组合有效性的时空配置,因而将生烃热动力学过程引入气源灶评价,提出了高效气源灶概念,并建立了新的评价指标,提出了中国含油气盆地环境下有效成藏过程及优质要素保持机理和分布规律。

With the great development of China s oil and gas exploration in recent years, some new petroleum geological phenomena couldn't be explained with the known knowledge of petroleum geology theories. It is important to input new theoretical concepts from following several aspects. The rich-hydrocarbon depressions have the characteristic of 'Sag-Wide Oil-Bearing', which means that there are very high probability of oil reservoir formation owing to alternations of source rocks and sheet sandbody in the rich-hydrocarbon depression. The exploration scope can be spread from 'secondary structural zone' to the whole sag and depression. There are new geological features for the middle and deep parts in the superimposed basins. The retarding process of hydrocarbon generation under overpressure can widen and deepen the liquid hydrocarbon window, which provides more chances for finding liquid hydrocarbon in deep horizons. The distribution of deep horizon reservoirs experiencing multiple-stage tectonic movements is inconsistent with the theory of 'source kitchen control theory'. Under the control of early reservoir formation, later burial, resistant compaction due to overpressure, structural uplifting as well as halite 'suspension' and secondary diagenesis, there are favorable reservoir rocks in deep horizons. The oil-bearing and gas-bearing abundance of secondary structural zones in the multistage superimposition process varies largely. There developed over-late reservoir in the deep formation under annealing geological background. The high-efficiency formation of natural gas reservoirs is controlled by time-space matching of hydrocarbon generation, reservoir formation process and combination of formation elements. Therefore, hydrocarbon generation thermodynamics was introduced to the evaluation of gas source kitchens. The concept of high-efficiency gas source kitchen was proposed, and the new evaluation index was established in this paper. The preserve mechanism and distribution rule of efficient process of reservoir formation and excellent elements of petroleum system in petroliferous basins of China were analyzed.