Control of Complex Structural Deformation and Fractures on Shale Gas Enrichment in Southern Sichuan Basin, China

Abstract

The research on the differential enrichment mechanism of shale gas under the complex tectonic background is a key problem to be solved currently. The southern Sichuan Basin is taken as the research object, and the geochemical experiment, overburden porosity and permeability experiments, direction test of a ground stress experiment, and seismic interpretation method are used to clarify the structural deformation characteristics and fault characteristics under different structural styles and structural parts and summarize the differences of shale gas preservation critical conditions in different structural units. The results show that (1) the fracture level controls the boundary and scale of shale gas reservoirs. The primary/secondary faults within 3 km greatly influence shale gas reservoirs, and the complex combination of fault systems will cause obvious indigenous damage to shale gas reservoirs. (2) The angle between the fault strike and the direction of the maximum principal stress determines the sealing of the fault, and the angle greater than 45° can effectively inhibit the loss of shale gas. (3) The coupling effect of burial depth and dip angle controls the migration of shale gas along the strata. The greater the burial depth and the smaller the dip angle, the better the page sealing and preservation conditions. Based on the enrichment factors of shale gas in different tectonic units, three enrichment models of syncline, anticline, and slope are established, and the enrichment favorable areas are optimized, which has important guiding significance for shale gas exploration and development in Sichuan Basin.

Pore Structure Heterogeneity of Deep Marine Shale in Complex Tectonic Zones and Its Implications for Shale Gas Exploration

“…The heterogeneity in pore structure between HSA-shale and BGS-shale would further affect shale gas enrichment, leading to a considerable gap in shale gas content and yield. ,, Shale gas mainly exists in a free state under high temperature and pressure when the burial depth exceeds 3500 m. , Therefore, BGS-shale in syncline could store more shale gas (especially free gas) with a higher pressure coefficient and larger storage space, which is conducive to improving the total gas content (Figure e,f).…”

Mechanism of Wettability and Pore Water Occurrence State in Overmaturity Shale: A Case Study of Longmaxi Formation Shale in South Sichuan Basin, China

“…The Sichuan Basin has experienced multiple phases of tectonic movements. According to the regional geotectonic background and evolutionary process, the Sichuan basin can be divided into five primary tectonic units, including the West Sichuan Depression Belt, the North Sichuan Low Steepness Fold Belt, the Central Sichuan Low Gradient Fold Belt, the East Sichuan High Steep Structural Belt, and the South Sichuan Low Steep Structural Belt. , The samples in this study are from the Changning and Luzhou blocks in the southern Sichuan Basin, tectonically located in the South Sichuan Low Steep Structural Belt (Figure a).…”

The Multitype Pore Structure Evolution Characteristics of Ziliujing Formation Shale from the Northeastern Sichuan Basin in China: Experimental Study Using Small Angle Neutron Scattering Technology

“…With the breakthrough of shale oil and gas exploration and development in the United States, the global exploration and development boom has been set off, and shale oil and gas development has great potential. − By 2021, shale gas production in China has reached 228 × 10 8 m 3 , showing great prospect for exploration and development . Unlike marine shale gas in North America, continental shale gas in China has a great contribution to shale gas resources in addition to marine shale gas.…”