Study on shale gas resource evaluation and exploration favorable area of Niutitang Formation in Longshan Block

In order to carry out the research on the evaluation of shale gas resources and the optimization of favorable exploration areas in Niutitang Formation of Longshan Block, Hunan Province.This paper analyzes the main controlling factors and preservation conditions of shale gas accumulation in this formation through geological investigation and experimental testing, and makes a comparative study with the geological parameters of shale gas in adjacent areas.The results show that the average TOC and R_o of the shale of Niutitang Formation in this area are 2.73% and 2.57%, which belong to the high mature over mature stage and have good hydrocarbon generation conditions.The average content of brittle minerals in Niutitang Formation shale is 60.42%, the average content of clay minerals is 25.73%, the average porosity is 2.09%, and the average permeability is 0.017 6 mD, which has good reservoir space and development conditions.The shale roof and floor of Niutitang Formation are sealed by tight lithology, and there is no fracture cut in, so it has good shale gas preservation conditions.The shale gas resource calculated by volume method is 1 499.90×10⁸-4 555.96×10⁸ m³, with good resource potential and resource abundance better than that of adjacent areas.The low-risk areas for exploration in this area are the two wings of Luota Syncline and the position with a buried depth of less than 4 000 m in Mengbi Syncline.It is the primary preferred area for the next exploration.The research results have deepened the understanding of the occurrence conditions of shale gas in Longshan Block and provided a reference for further shale gas exploration.