

@mastersthesis {6473,
	title = {Numerical and experimental modeling of double displacement oil recovery in fractured carbonate reservoirs},
	year = {2011},
	note = {0828168},
	school = {Colorado School of Mines},
	type = {phdPh.{D}.},
	address = {Ann Arbor},
	abstract = {Waterflooding has been the most popular post-primary production approach for improving oil recovery. The remaining average oil after waterflood is typically much greater than sixty percent of the initial oil-in-place (National Petroleum Council, 2007). In reservoirs with large structural relief, gas injection can produce much of the post-waterflood remaining oil by gravity drainage. This tertiary oil recovery method is known as the double displacement process (DDP). One major reason for using gas injection after waterflooding is that the three-phase residual oil saturation is generally smaller than the two-phase residual oil saturation for water-oil displacement. A second reason is the high-efficiency of the gas-oil gravity drainage. Finally, another significant reason is the favorable wettability conditions of some formations. Field data gathered for this project indicates that the DDP has been successful in single-porosity sandstone formations. Intuitively, one would expect that DDP to produce similar results in reservoirs with ample intercommoned vertical fractures. This is the objective of this research, which specifically focuses on evaluating the DDP in fractured carbonate reservoirs where the wettability ranges from neutral to oil-wet conditions. The research is primarily about (1) assessment of the DDP based on experiments in fractured cores using a high speed centrifuge, and (2) simulating these experiments numerically. The procedure used to upscale laboratory results to field included numerical simulation and well-established scaling rules. The thesis includes the results of water injection oil recovery followed by gas injection oil recovery in fractured and unfractured cores, and numerical simulation results of matching the experiments. It is shown how the laboratory results can be scaled to field. The cores are from a major offshore Abu Dhabi carbonate reservoir. The incremental oil recovery was a function of reservoir facies, pore structure and presence of fractures. For an example, a DDP oil recovery from a 1.8-md fractured core, with rudist-bivalve facies, produced 50\% from forced water imbibition and an additional 32\% from gas-invoked gravity drainage. It was concluded that the DDP is a technically effective oil recovery method in fractured carbonate reservoirs depending on favorable permeability and pore structure.},
	keywords = {0765:Petroleum engineering, Applied sciences, Fractures reservoirs, Oil recovery, Petroleum engineering},
	url = {http://search.proquest.com/docview/921618085?accountid=14270},
	author = {Al-Sumaiti, Ali M.}
}
