Research on pressure maintaining and core sampling technology for deep coalbed methane and its application

Abstract:

During the coring process of coalbed methane， changes in pressure can directly cause changes in parameters such as gas content and porosity of the coalbed core， which can lead to deviations in the detection of coalbed gas content and theoretical research on coalbed methane reservoir formation. At present， the pressure holding coring tool used for coalbed methane resource exploration has a pressure holding capacity of less than 50MPa， which cannot meet the precise exploration needs of deep coalbed methane resources. In response to this problem， a deep coalbed methane pressure holding coring tool has been developed with a pressure holding capacity of 60MPa and a single core length of 6.5m. The strength and safety of the tool have been verified through theoretical analysis， numerical simulation， indoor testing and other methods. Three pressure holding coring operations were carried out in a coalbed methane exploration well in Inner Mongolia， with a cumulative footage of 9.4m and a total core length of 9.12m. The average core recovery rate was 97%， and the pressure holding success rate was 100%.The research results indicate that the developed deep coalbed methane pressure holding coring tool has reliable performance and can provide new tool and method support for precise detection of unconventional oil and gas resources such as coalbed methane and shale gas.