Differential development and maintenance mechanism of reservoir space for marine shale gas in South China's deep strata

Abstract

The deep marine strata with burial depth greater than 3 500 m in South China have good geological conditions and huge potential for shale gas resource. However, due to the burial depth and relative poor understanding, the productive difference between horizontal wells in different positions is obvious, and exploration and development are still challenging. On the basis of investigating the current situation and development trends of global deep shale gas, this paper focuses on the differential development of reservoir of marine deep shale gas in South China, the pore preservation by pressure resistance of rigid minerals such as quartz, and the pore preservation of reservoir fluid overpressure. The differential development of reservoir space and effectiveness is one of the main factors for the controlling of gas content, productivity and EUR per well of deep shale gas of the Wufeng-Longmaxi formations in the southeastern part of Sichuan Basin, but the characteristics of differential development and maintenance mechanism is unclear, and the differentiated response process under in-situ conditions of near-deep reservoirs and the mechanism still need to be studied. Although it is recognized that rigid minerals such as quartz play an important role for the pressure resistance and pore preservation, its varied effect on different types of storage spaces is still unclear. It has been shown that the effect of reservoir fluid overpressure is of great significance to the preservation of deep shale gas storage space, it is still limited understanding of how reservoir fluid overpressure affects deep shale reservoir space. The key factor to answer the problems above is to study the characteristics and mechanism of differential development, response and maintenance of different types of reservoir space in a typical organic-rich shale in a near-deep in-situ state with multiple stress loading and high temperature.

Keywords

• deep shale gas
• differential development
• maintenance mechanism
• wufeng-longmaxi formations
• marine strata in south china