Abstract A micro-CT experimental system was used to scan a specimen of oil shale subjected to pyrolysis at different temperatures. From 3D CT images based on X-ray attenuation coefficients,the evolution of pores and cracks in the specimen was analyzed at different stages of pyrolysis. The results show that:(1) From 20 ℃ to 600 ℃,the specimen is transformed from a compact state to a porous medium. (2) At the higher temperatures,increasing numbers of voids become interconnected. At 100 ℃,the voids are restricted to a very small region;but as the temperature is raised to 200 ℃,channels for oil and gas seepage are formed within the study region. At 600 ℃,the pyrolysis rate of the specimen is calculated to reach 39.80%;and the largest void is 97.45% of all the voids. All voids are interconnected into one large void,forming a channel for the seepage of oil and gas running through the entire X-rayed region. The study conclusions are of great significance for discovering how the channels for oil and gas seepage developing during in-situ pyrolysis of oil shale.
|
Received: 01 March 2013
|
|
|
|