Effect of a Polymer Solution Degradation at Reservoir Conditions, in a Polymer Flood Pilot Test Performed in an Extra Heavy Oil Reservoir. Orinoco Basin, Venezuela

Ramirez, Andres Eduardo (PDVSA Petrocedeño) | Ulacio, Ivon Maria (Universidad de Oriente) | Quevedo, Luis David (PDVSA Petrocedeño) | Vasquez, Edgar Martin (PDVSA Petrocedeño)



The objective of the study was to estimate how much the mobility of a polymeric solution is affected at reservoir conditions, in an enhanced oil recovery process using polymer. This document describes the different techniques and methodologies to establish polymer solution degradation, and its effects over the expected behavior.

The analysis was performed using the results from 4 fall off tests at different stages of the injection process, the test were executed every three months after the beginning of the injection of the polymer solution, following the surveillance plan established. Other diagnostics techniques were also studied, in order to discard geologic features that could affect the injection process, among then: Hall plot diagnostics and temperature logging with fiber optics sensors.

The mobility of the polymer solution at reservoir conditions was determined. The affectation of the polymer solution is related to particular conditions of each section of the reservoir, meaning that minerals in the reservoir rock, and salinity of the connate water, could be the possible reasons why the polymer was affected, and exhibited a higher mobility compared to the design parameters. Later it was observed that the polymer mobility decreased over time, indicating that the polymer solution was no longer affected by in situ conditions.

To establish the performance of an enhanced recovery process using polymer, in the case of extra heavy oil reservoirs, it is necessary to evaluate the actual performance, and depend not only of the core test and simulation results. The analysis accomplished in this work was used to obtain important information necessary to asset feasibility, in the case of a larger scale implementation.