Development characteristics and shale gas exploration prospect of Sinian–Cambrian organic−rich shale in the eastern part of the southern Guizhou depression, China: A case study of the Well Guidandi 1 and its adjacent areas

This paper is the result of oil and gas exploration engineering.

Objective The organic-rich shale of the Sinian–Cambrian is an important shale gas exploration layer in the eastern part of the southern Guizhou depression, which is still in the early stage of exploration, and the development characteristics and exploration prospects of shale are unclear.

Methods The study investigates the development characteristics and preservation conditions of the Sinian–Cambrian shale in Well Guidandi 1 by lithology, organic geochemistry and reservoir characteristics analysis, supplemented by the results of adjacent drilling and field section observations, and the exploration prospect of shale gas is discussed.

Results The high-quality shale of deep-water shelf facies is developed in Sinian–Cambrian, which belongs to the inherited deep-water facies-ramp facies as a whole. Water gradually deepens from northwest to southeast, with the characteristics of simultaneous heterogeneity. The total organic carbon content and maturity gradually decrease from old to new, and the organic matter type is type I, and overall hydrocarbon generation conditions are superior. The shale has high silicon content and brittleness, which is easy to be fractured. As a whole, shale reservoir is of low porosity and low permeability, and the reservoir space types are mainly fractures and nano-scale pores. The local intervals have high gas content and total hydrocarbon value, which are shale gas sweet spots.

Conclusions The area around Danzhai is a relatively stable tectonic zone away from fracture zones and main faults, with superior sealing conditions and shale gas preservation conditions, and has the prospect of multi-layer shale gas exploration considering the shale development characteristics and preservation conditions.