Naturally fractured carbonate reservoirs which possess most of the remaining oil in the world, can fulfill the needs of widely nowadays energy demand. Most of the oil remains in the matrix block during production from naturally fractured reservoirs. Water flooding is a technique implemented in naturally fractured reservoirs to recover additional amounts of oil from the matrix blocks. In this paper, for the first time, an analytical model for water flooding in the naturally fractured carbonate reservoirs is developed that describes the transient behavior of the imbibition mechanism in the dual porosity models. Using the fracture-matrix fluid transfer of the dual porosity model, the presented analytical model takes the account of viscous-capillary and capillary imbibition mechanisms in fracture and matrix system, respectively. The analytical solution is validated using both laboratory data and a numerical solution. In order to consider the effect of the heterogeneity in fractured reservoirs, the proposed analytical model is developed for various distributions of block sizes. In addition, a graphical method is developed to estimate capillary diffusion coefficient and matrix block size distribution based on the water saturation data in the monitoring well during water injection. The monitoring well is used to monitor and evaluate reservoir during water flooding. The proposed methodology which is based on water saturation data in the monitoring well, does not call for a specific test in the reservoir. Moreover, the relating shape factor is calculated with the aid of dual porosity model equipped with variable fracture intensity distribution. The findings imply that the fluid transfer is highly dependent on the distribution of matrix block size.
- Capillary diffusion coefficient
- Capillary imbibition
- Different fracture intensity distribution
- Fractured aquifer
ASJC Scopus subject areas
- Water Science and Technology