The in-situ stress of coal reservoirs in east margin of Ordos Basin and its influence on coalbed methane development

Abstract

For a better analysis of the in-situ stress distribution and its influence on coalbed methane exploration and development in east margin of Ordos Basin, the evolution of in-situ stress field and its variation of horizental and vertical extensions were acquired, and its effect on coalbed methane reservoirs was discussed, based on regional tectonic evolution and injection falloff well test parameters.The results show that:the direction of principal stress changed from NW-SE in Yanshan Movement to the NE-SW in Xishan Movement, which released the strata compaction to some extent;the lateral pressure coefficient is generally lower than 1, which shows that the study area is of an tension environment;the present reservoir pressures are low, result in the most of the reservoirs in under-pressure conditions;the in-situ stresses generally show a positive linear relationship with depth, which are generally banded by the 800~1, 100 m, with the deeper strata in more compressed conditions.The study area is generally favorable for coalbed methane development, however, different areas show different development transition depths, with the Liulin area of 800 m and Hancheng of 1, 000 m.

Keywords

• coalbed methane
• in-situ stress
• reservoir pressure
• east margin of ordos basin