A Study of Polymer Solutions Filtration in Unconsolidated Reservoir

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Abstract:

A promising way to develop high-viscosity oil fields is polymer flooding. The reservoirs of such deposits are often represented by unconsolidated sandstone. Injection of high viscosity solutions in such conditions is associated with the risk of negative geomechanical changes, which affects the efficiency of the method of reservoir development as a whole.

This article presents the analysis of results of laboratory studies of polymer solutions filtration in unconsolidated sandstone. In particular, it performs a unique research experiment aimed at identifying possible geomechanical changes in the samples of a weakly-cemented core during the pumping of the polymer solution. The authors reveal the main factors determining the efficiency of oil displacement (such as the concentration of the polymer solution and its rheology), as well as the permeability and initial oil saturation of the reservoir. In particular, when the filtration rate decreases, the viscosity of the polymer solution increases, resulting in more effective displacement.

The authors have assessed geomechanical risks of development during a polymer flooding. When using high concentrations of the solution and high-pressure drops, negative geomechanical changes can be observed in the core samples. During the development of the field, these effects lead to the emergence of breakthrough channels, an increase in the water cut, and a significant decrease in water flooding efficiency.

In conclusion, the analysis has confirmed the high technological prospects of flooding with high-molecular polymer solutions in this field.

References:

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