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

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