Taking Advantage Of Fines Migration For Improved Oil Recovery During Oilfield Depletion
Petroleum Engineering Honours Degree, 2011
University of Adelaide
The decline in permeability during corefloods with varying water composition, especially with low salinity water, has been widely reported in the literature. It has been explained by the lifting, migration and subsequent plugging of pores by fine particles. This effect can be considered to provide a relatively simple method for mobility control during isolated waterflooding.
This thesis is dedicated to the development of limited low salinity water injection for sweep improvement due to plugging of high permeable channel(s) and layers by lifted or mobilised fine particles. The proposal of a new technology is introduced by injecting a limited volume of low salinity water into watered up and abandoned production wells during pressure depletion in oil reservoirs with strong aquifer support. This results in the lifting of reservoir fines, their migration and plugging the pathway for invading aquifer water into the reservoir.
This work takes advantage of the already derived basic two-phase equations for waterflooding with salinity variation causing the detachment of fine particles, their migration and straining. It includes the equivalence between the model for two-phase flow with fines migration and the adsorption-free polymer flood model in large scale approximation, which allows taking advantage of the polymer flood option for reservoir modeling of the limited injection of low salinity water with fines.
Reservoir simulation modelling showed that permeability decline around the near well bore region, caused by limited injection of low salinity water and induced fines migration, improves ultimate oil recovery by delaying water breakthrough, increasing sweep efficiency and reducing water cut, thus providing a relatively simple and inexpensive method for mobility control. An economic evaluation based on a typical concessionary regime has identified the PVI for a range of oil viscosities and reservoir dip for the best possible recovery of oil.