Abstract:

Shale oil and gas are a type of petroleum resource generated and accumulated in source rocks. The exploitability of this oilgas is obviously controlled by reservoir characteristics. The difference of depositional environment of various organicrich shale causes the multianisotropy of shale oil and gas reservoir in vertical, including lithology anisotropy, reservoir properties anisotropy, anisotropy of rock mechanical parameters, groupstress anisotropy and the anisotropy of gasbearing characteristics in vertical, which made the anisotropy of shale reservoir in vertical much stronger than that of shale reservoir in horizontal. The great variation of organic abundance, porosity, permeability, fracability, stress, gasbearing properties and ratio of free to adsorbed gas directly affects the design and implement of oilgas development strategies. The selection of advantaged objective layers for shale oil and gas exploitation should consider the following factors, including the single organicrich shale interval thickness (3050 m), TOC content with an average of >2.0%, high effective porosity (>2.0%), small poisson ration (<0.25), high brittleness, minor principle stress which is much smaller than other adjacent layers and good gasbearing properties. Moreover, the influence of this anisotropy must be fully considered for the selection of the types of shale oilgas development well, the design of horizontal drilling, the length of stage fracturing and the plan of perforation spacing.

Key words: shale oil and gas, shale reservoir, anisotropy, exploitability