Freshwater sensitivity of corrensite and chlorite/smectite in hydrocarbon reservoirs - an ESEM study

An Environmental Scanning Electron Microscope (ESEM) has been used to investigate the freshwater sensitivity of secondary corrensite (regularly interstratified chlorite/smectite) and chlorite-rich chlorite/smectite in order to determine whether hydrocarbon reservoirs hosting these clays should be regarded as freshwater sensitive. ESEM experiments involved an examination and close comparison of selected clay areas in three samples at high magnification before, during and after prolonged freshwater treatments. Corrensite and chlorine/smectite in the samples did not visibly swell when immersed in fresh water. After soaking in fresh water for up to three months, these clays retained their original morphology and associated porosity. Hence, the presence of corrensite or chlorite/smectite in a hydrocarbon reservoir need not indicate that the reservoir is freshwater sensitive. © 1994.