Differences of Main Enrichment Factors of S1l11-1 Sublayer Shale Gas in Southern Sichuan Basin

Kesu Zhong,Wenbin Jiang,Mian Lin,Xuewen Shi,Yifan He,Yi Li,Chao Luo,Gaohui Cao

doi:10.3390/en14175472

Abstract

In this study, shale cores from 20 wells in the S1l11-1 sublayer of Longmaxi Formation buried in shallow shale (<3500 m) and deep shale (>3500 m) in the southern Sichuan Basin, China were collected to compare their pore structures and gas-bearing properties using multiple experiments. Results showed that the deep layer has relatively lower brittle mineral content, which is disadvantageous in terms of the higher requirements it imposes on hydraulic fracturing. Results also showed that the most important factor controlling the differential enrichment of S1l11-1 shale gas in southern Sichuan Basin is porosity. Moreover, the porosity composition of shallow shale and deep shale has significant differences: the porosity of shallow shale is dominated by organic pores, while for deep shale, both organic and inorganic pores are important. The inorganic pores provide significant storage space for free gas in deep shale; their contribution warrants more attention. We also found that the difference in organic porosity of the shallow and deep shale samples resulted from large differences in pore development ability, while the highest inorganic porosity was concentrated near the optimal mineral composition when the content of quartz plus feldspar plus pyrite was about 70%. This study revealed the primary factor controlling the difference in gas content between shallow and deep shale and detailed the characteristics of microscopic pore structure, providing a basis for the exploration and development of deep shale gas in the Wufeng-Longmaxi Formation in the southern Sichuan Basin.

Highlights

With the rapid growth in China’s energy demand and pollution caused by particulate matter, the government is promoting a clean energy plan to gradually replace coal with natural gas in the few decades
11-1; the results showed only a we only focused on the gas content inside a thin layer, S1l mations, results showed that formation pressure was not the main factor controlling
Deep only focused on the gas content inside a thin layer, S1l1 1-1 ; the results showed only a week correlation between gas content and total organic carbon (TOC)

Summary

Introduction

With the rapid growth in China’s energy demand and pollution caused by particulate matter, the government is promoting a clean energy plan to gradually replace coal with natural gas in the few decades. Among the natural gas resources in China, shale gas is rich in resources and expected to become one of the most important replacement resources [1]. Shale gas production jumped from 2.50 × 107 m3 in 2012 to 1.54 × 1010 m3 in 2019 in. Sichuan Basin and its surrounding areas possess huge shall gas development potential, which could play an important role in China’s shale gas production. With the reduction in drilling costs and the development of production technologies, gas exploration companies and academia have gradually shifted their focus to deep shale gas (>3500 m). Deep shale gas has been commercially developed in Eagle Ford, Haynesville and Woodford blocks in

Methods

Results

Conclusion