储层中的沥青沉淀带及其对油气勘探的意义

在世界很多油气田的储集层中，都发现了天然形成的沥青沉淀带，说明储层中沥青沉淀带的存在是一个相当普遍的地质现象。前人的研究多集中在沥青沉淀的机理与成因判识、沥青的分布特征及其对储层物性的影响等方面，很少涉及沥青沉淀带对油气分布的影响，即使涉及的少数研究成果也都是从单一油田来进行分析，还未曾对其共性进行总结，此外，勘探家对钻探过程中出现的大量储层沥青重视不够，从而使得一些与沥青沉淀带有关的隐蔽型油气藏未能及时发现。根据前人的研究成果和实例，总结了3种不同成因储层沥青沉淀带的可能位置和储层沥青沉淀带的形成对油气分布的控制，指出沥青的沉淀对于油气藏不仅只有破坏作用,也有可能起到封堵作用而形成一种非常规类型的油气藏,关于这一点在勘探中应引起足够的重视。

BITUMEN SEALED BELT IN RESERVOIRS AND ITS IMPLICATION TO PETROLE UM EXPLORATION

Bitumen is universally distributed in the reservoirs of a large number of oil fields in the world. Many researches are focused mainly on the mechanism, genesis, and distribution character of the deposited bitumen. In a trap, solid bitumen can cause reservoir heterogeneity and form permeability barriers not related to depositional facies. When the precipitated bitumen fills pores totally, bitumen-sealed belts can be formed, and thereby hidden reservoirs formed. However, the occurrence of solid bitumen brings much difficulty in the decision of exploratory well sites, and prevents the prediction of favored intervals with the traditional geologic theories. The key to identify this sort of reservoirs is to find the sites of the bitumensealed belts. Based on the previous studies, this paper suggests three possible positions of bitumen-sealed belts of different genesis, and the most favoured exploration targets. More attention should be paid to the exploration when bitumen appears.