Development practice and challenges of deep shale gas in southern Sichuan Basin

Abstract

There is great potential for developing deep shale gas resources, but the engineering geological conditions are relatively poorer, making it difficult for benefit development. In order to support the benefit development of deep shale gas, taking the development practices of Weirong and Yongchuan gas fields in the southern region of Sichuan Basin as an example, focusing on the difficulties of complex deep shale gas structures, developed fractures, thin high-quality reservoirs, rapid production decline, and low EUR, with the goal of "good well placement, good well drilling, and good well management", a key development technology system is formed by use of the integrated method of geophysics, geological modeling, fracturing simulation, and numerical simulation based on the research on precise gas reservoir description and seepage experiments, which is characterized by geological sweet spot evaluation and prediction technology, well network optimization design technology in complex tectonic areas, "four in one" drilling tracking guarantee technology, and full life cycle production control technology. At the same time, based on the problems exposed during development process, the difficulties and challenges in the coupling mechanism of "structure-fault-stress field", characterization of small-scale and microscale fractures, optimization of development technology strategies were summarized, and the problems that need to be continuously studied were proposed. The conclusion is that: ① The geological parameters such as porosity and gas content of deep shale are basically equivalent to those of medium-deep strata, but the engineering parameters are more complex, characterized by high in-situ stress, high horizontal stress difference, and high fracture pressure, making it difficult to transform; ② Key supporting technologies in dessert evaluation and prediction, modeling-numerical simulation integration technology, and fine production management has been formed in deep shale gas, with good development results; ③ At present, deep shale gas is mainly faced with challenges such as casing deformation, pressure channeling, and EUR non-compliance. It is necessary to further advance technical research in geological fine evaluation, fluid migration patterns, and modeling-numerical simulation integration.

Keywords

• development practice of shale gas
• development technology progress
• deep shale gas
• weirong gas field
• yongchuan gas field
• southern sichuan