عنوان مقاله [English]
In this paper the results from experiments of water injection in fractured carbonate rock are reported. The experimental setup consists of a column of 3 Asmari limestone outcrop cores that are taken from the southern part of Iran. The column of cores was placed in the center of a Plexiglas cylinder while the annulus between the core wall and the cylinder wall serves as the fracture. Injecting water from the bottom and producing from the top performed water injection tests. The system experienced an advantaging oil/water level in the fracture. The composite core was also under complete immersion for around 5-7 days after finishing the experiment that causes to change the boundary conditions from partially to fully cover. Immersion type experiment was also performed separately. The effect of rate and initial water saturation on oil recovery by imbibition mechanism was investigated experimentally. Water injection tests have been performed at three different rates and three different initial water saturations. It was found that breakthrough recovery is higher when injection rate is low while the final oil recovery is more or less independent of the rate. It is also clear that oil recovery increased with increase in initial water saturation.