Oil and gas resources of shale formation orderly accumulation and coexistence as well as its prospecting significance: A case study of Chang 7 shale formation in Ordos Basin

Shale system contains abundant unconventional oil and gas resources and has become a hot area of exploration and production. This system includes such resources as shale oil and gas, tight oil and gas, and oil shale. These unconventional resources are related to the organic-rich shale and are in orderly accumulation along with the maturity and coexistence in space. However, there is a blank in the systematic study of unconventional resources. Based on the shale system, the authors studied the world's oil and gas resources distribution and put forward the argument of the shale oil and gas resources orderly accumulation and coexistence in the shale system. Taking Chang 7 shale formation of Ordos basin system as an example, the authors used the shale oil and gas resources orderly accumulation method and divided the Chang 7 shale system resources into outcrop oil shale, moderate buried depth fracturing shale oil, moderate buried depth ICP shale oil, large buried depth shale gas and tight oil areas. Based on this understanding, the authors suggest stereoscopic exploration and development in the shale system, which will provide guidance for oil and gas resources exploration and development in the shale system.