CO2 flooding is the most promising enhanced oil recovery method. However, the CO2 tends to bypass a high percentage of the oil in the flood pattern causing early breakthrough and low recovery efficiency. An unconventional approach for CO2 mobility control is to modify the reservoir permeability profile by chemical precipitation. This method employs water soluble salts of earth alkali group that react with CO2 to form carbonate precipitate. Chemical precipitation occurs in the high permeability zones and the subsequent fluid flow will be diverted to unswept portion of the flood pattern. The overall objective of this study has been to evaluate the feasibility of carbonate precipitation to improve the recovery efficiency by reducing CO2 mobility. The earlier experimental studies have shown that carbonate precipitation can alter the core permeability under reservoir conditions. In addition, the relative permeability measurements have revealed that precipitation reduces the gas permeability in favor of liquid permeability. This paper reports the preliminary results of modeling of the process for field application. A numerical reservoir model has been utilized to study the effect of precipitation on sweep efficiency and oil recovery.

Keywords:
efficiency, slug, precipitation, precipitate, fluid dynamics, permeability zone, enhanced recovery, operation, oil recovery, permeability
Subjects:
Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Flow in porous media
Copyright 1989, Not subject to copyright. This document was prepared by government employees or with government funding that places it in the public domain.
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