Comprehensive study of naturally fractured reservoirs sensitizing the importance of grid block shapes and fracture capillary pressure existence on fluid flow dynamics

Abstract

Carbonate or naturally fractured reservoirs have vast reserves of hydrocarbons that can help to fulfill energy needs. However, the modeling of these reservoirs is a challenging task due to several technicalities involved. These include matrix-fracture transfer rate and subsequent flow of fluid towards the wellbore. In order to investigate this particular and complex fluid flow mechanism, the grid block shape has been varied from typical cubical to elongated parallelopiped and slab type during numerical simulation studies. Further, the effects of fracture capillary pressure on reservoir performance have been investigated for these block types in the water injection process. This in-depth investigation, at a broader level of its kind, shows that with the increase in fracture capillary pressure as a function of matrix capillary pressure, there is a significant decrease in hydrocarbon recovery. Moreover, a drastic change in recovery has been observed by switching to slab and matchstick-type grid block shapes rather than simple cubical grid block shapes. The obtained results provide a new insight into the modeling of naturally fractured reservoirs and fluid flow dynamics, which can lead to improved hydrocarbon recovery estimations along with better designing of the water injection process.