低熟油气成因理论与勘探实践

本文对低熟油气的源岩评价、成因机理、油气运移、成藏特征及油气勘探等几个方面进行简要剖析。源岩在低熟阶段仅能生成一部分烃类,因而对各个地区的低熟源岩评价标准应适当调整。低熟油的源岩主要形成于淡水湖相、沼泽相和半咸水-咸水湖相,可通过多种成因机理早期生烃。低熟油的排烃仍受源岩层与储层流体的压差驱动,因而排烃较为有利,且运移距离较短。低熟油藏常位于储层物性好、靠近油源区、继承性好的同沉积构造圈闭上。

GENETIC THEORIES AND PETROLEUM EXPLORATION OF IMMATURE AND LOW MATURE HYDROCARBONS

In this paper the source rock evaluation, oil generation mechanism, oil migration and characteristics of oil reservoir in immature and low mature oil system are analyzed and studied. The normal evaluation standard must be properly adapted for a special situation due to only parts of hydrocarbons being released in the low mature stage. The source rocks include fresh water lake facies, marsh lake facies and brackish-saline facies. They can generate hydrocarbons at early stage under many kinds of genetic mechanism. The expulsion of low mature oil is still controlled by thepressure difference between source rock and reservoir, so it is favorable for oil expulsion and the migration distance is shorter. The low mature oil expulsion show that the immature and low mature oil accumulate at the well-inherited synsedimentary trap which is near the source rock region and has the good physical property of reservoir.