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Teklu, Tadesse Weldu (Colorado School of Mines) | Akinboyewa, John (Colorado School of Mines) | Alameri, Waleed (Colorado School of Mines) | Kazemi, Hossein (Colorado School of Mines) | Graves, Ramona M. (Colorado School of Mines) | AlSumaiti, Ali M. (The Petroleum Institute)
Waterflooding is by far the most widely used method to increase oil recovery; however, it is less effective in heterogonous channelized reservoirs because injected water move easily to channels and left behind most oil unswept. Polymer augmented waterflooding is a technique by which recovery is enhanced in heterogonous channelized reservoirs. Injected polymer improves conformance hence recovery by diverting flooded water into unswept portion of the reservoirs. The stress change due to polymer adsorption could be significant and need to be accounted.
In this study, implicit in pressure and explicit in both saturation and polymer concentration (IMPES), finite difference numerical simulation was formulated and implemented. The implemented approach is used to study the performance of polymer augmented waterflooding by varying relevant reservoir and well parameters. Both homogenous and channel dominated heterogonous reservoir permeability cases were considered with more emphasis on channeled cases. A Langmuir adsorption as a function of polymer concentration was used to account for the irreversible adsorption of polymer during flooding. The effect of polymer adsorption on mobility and permeability was accounted for by a viscosity adjustment and residual resistance factor formulae. The stress change created as a result of polymer adsorption and pore pressure change is accounted by explicitly calculating the stress after pressure is computed from the fluid flow simulator in each iteration.
From the cases considered in this study, both permeability reduction due to stress change and adsorption of polymer has considerable influence on oil recovery. Hence it is recommended to investigate these effects for any reservoirs (especially for more stress sensitive reservoirs) during screening and implementation of polymer flooding.
Jain, Anil Kumar (Kuwait Oil Company) | Ahmed, Khalid (Kuwait Oil Company) | Ferdous, Hasan (Kuwait Oil Company) | Mishra, Prasanta (Kuwait Oil Company) | Al-Matrook, Mohammad (Kuwait Oil Company) | Al-Ali, Yaqoup (Kuwait Oil Company) | Al-Khamees, Waleed (Kuwait Oil Company) | Piwowar, Mike (Weatherford Laboratories) | Rick, Bujnowicz (Weatherford Laboratories)
Abstract The Neogene of North Kuwait comprises of unconsolidated sandstone reservoir having viscous crude. The field is to be developed by way of injecting steam into the reservoir. The XRD and SEM studies revealed that variety of the detrital clay minerals like Illite, Smectite, Chlorite, and Palygorskite commonly occurring within the formation. An experimental study was carried out to understand the implications of steam injection on the clay bearing formations and to determine temperature-dependent water-oil relative permeability to provide an indication of the recoverable reserves under steam injection. Sensitivity to different pH and salinity were also analyzed. Detailed laboratory study was conducted on nine plugs to determine the effect of hot water and steam injection on the permeability, relative permeability, residual oil saturation and mineralogical changes in the reservoir. The baseline steamflood was carried out to determine the residual oil saturation and evaluate the permeability changes due to clay swelling/dispersion in contact with brine and steam. The other six sensitivity steamfloods were carried out to determine the potential permeability damage resulting from clay swelling/dispersion when contacted with different pH fluid, salt concentrations (TDS) and clay stabilizers. Pre and post XRD and SEM analysis were done to see the effects of each steamflood on the core sample. This paper presents the discussion on results of core flood experiments conducted on nine preserved core samples at reservoir conditions. The results show that clays when contacted with steam induce significant permeability reduction. High salinity and pH control may not be sufficient to eliminate the loss of permeability. However, some clay stabilizers are found to be useful to improve the permeability and recovery.