Closure Behaviour of Natural Rock Fractures

Abstract

Abstract In order to investigate the closure behaviour of natural rock fractures, a surface measurement system called as photoelectric surfometer was developed. It can survey and calculate automatically topographies of rock surfaces, being especially effective on natural rock surfaces which have larger heaves compared with polished rock surfaces widely used in previous publications. Computer simulation is then applied to mimic the closure behaviour of natural rock fractures by utilising both elastic and plastoelastic contact theory between rough surfaces. Experimental results confirmed computer simulation. Simulation and experiments show that plastic flow can be ignored for natural fractures within most concerned reservoir formation rock (carbonate rock and tight sandstone). An empirical model based on simulating results is then proposed, which includes rock properties, initial aperture and surface topographies. This model, being different from any other models proposed in previous publications, can be used to explain the different phenomena found both at laboratory experiments and in situ reservoir formations.