Abstract:

The present paper made a re-recognition of Jurassic oils in Sichuan in terms of the four aspects, such as resource potential, reservoir types, fractured reservoirs and techniques of exploration and development. The paper has drawn the following conclusions. ①The Jurassic oil resource in Sichuan may be much more than the presently discovered amount of 1.0~ 1.1 billion tons.②The Jurassic oil resource is a special large-area and non-conventional compact oil accumulation that has no clear trap boundaries, no clear edge-water, bottom-water and oil-water boundaries like a “water-free reservoir”, and no clear differentiation between buoyancy and gravity. Their reservoirs are characterized by inner-source or near-source accumulation rather than large-scale secondary migration, ultra-low permeability, dual media, large-area entire oiliness, superimposed and linked multi-measures, “continuous” occurrence on slopes or in depressed areas, being restricted by lithology rather than local structures, and delimitating oil-bearing and well distribution areas frequently by output instead of reserve.③Jurassic reservoirs can not be simply defined as “fractured type” because various pores contribute significantly to both the reserves and long-term low but stable production though fractures are the prerequisite for a high output at the testing or production beginning. ④These exists a great reserve for this kind of non-conventional compact oils in the central-northern Sichuan, however, a non-conventional technique consisting mainly of hydraulic fracturing should be adopted in development. It was proposed that Shaximiao Formation in the Longgang area should be a prospecting target, which will be a breakthrough to open a new era for petroleum exploration in Sichuan Basin.

Key words: Sichuan Basin, resource, non-conventional oil accumulation, compact oil layer, fractured oil layer, prospecting potential, fracturing alteration

摘要：

通过对四川盆地侏罗系石油的资源潜力、油藏类型、裂缝型储层及勘探开发技术适应性等4个方面进行的再认识，作者认为：①四川盆地侏罗系的石油资源量可能比目前的（10~11）×10⁸ t 要大得多。②它是一种特殊类型的大面积非常规致密油聚集，没有明显圈闭界限；没有明显边、底水及油水界面，属“无水油藏”；浮力与重力分异不明显，缺少大规模二次运移，源内或近源聚集；储层具有特低孔渗、双重介质特征；大面积整体含油，多层系叠合连片，“连续”分布在斜坡及凹陷区，不受局部构造控制而受岩性控制，含油范围以油井分布范围划定，往往是先有产量后有储量。③不能把侏罗系油层简单定性为“裂缝型”，裂缝是测试及生产初期获得高产的必要条件，但各类孔隙对储量和长期低产稳产有重要贡献。④这类非常规致密油的储量规模很大，但是要采用以压裂为主的非常规技术进行开采。建议以龙岗地区沙溪庙组为突破口，推动四川盆地石油勘探开发打开一个新局面。

关键词: 四川盆地, 资源量, 非常规石油聚集, 致密油层, 裂缝型油层, 勘探潜力, 压裂改造