ABSTRACT
Early results of a successful polymer project started in 1985 in the Courtenay sand of the Chateaurenard field located south of Paris, France, were presented at the fall 1988 SPE meeting. We update these data and show that subsequent performance has confirmed the highly favorable oil recovery behavior of this project. The objective of this paper is to report the results of a detailed compositional simulation study conducted to understand this favorable result. Both alternative reservoir and process characteristics were investigated in these three-dimensional simulations. In particular, both a classical layered reservoir description and a geostatistical reservoir description were investigated. The latter represents a new approach to the interpretation of polymer flooding and played an important role in our study since the attenuation of reservoir heterogeneities is known to be an important attribute of polymer flooding. We also evaluated the importance of permeability reduction and adsorption of the polymer on process performance. After obtaining a good match of the production of oil, water and polymer, we then investigated the importance of design factors on the oil recovery performance. The actual polymer flood consisted of injecting a large polymer slug followed by five smaller slugs of decreasing polymer concentration to decrease the viscosity contrast with chase water, a classical polymer flooding design method called polymer grading. We found that this grading really made very little difference in the simulated oil recovery indicating that fingering was of little importance under these conditions. This was because the oil recovery was dominated by other factors such as polymer adsorption, fractional flow, and heterogeneity. Remarkably, this appears to be the first time that a study of this type with an accurate compositional simulator has been reported for polymer flooding. The combination of better reservoir characterization methodology and accurate process simulation of polymer flooding should aid in the successful exploitation of this technology in the future. This project clearly shows the high potential of polymer flooding under the appropriate reservoir conditions and with good design and implementation methods.
