A Review on Utilization of Crosslinked Polymer Gels for Improving Heavy Oil Recovery in Turkey

Abstract

Abstract The oil reservoirs in Turkey generally produce from naturally fractured carbonates with high WOR's. This high WOR easily causes rapid decline in oil rates, especially with heavy oil of about 18-20° API. As crosslinked polymer gels are one of the major means to remedy this problem, gels for WOR reduction in oil producers have been applied in TPAO oilfields. Treatments have provided several folds of increase in net oil (from 30 b/d to 120 b/d) production and reduction in WOR from 96-98 % to 30-75%. Another application of crosslinked polymer gels is conformance control in IOR processes, e.g. CO2 injection, where mobility reduction and improved sweep efficiency is required. Polymer gels provide mobility control by decreasing the permeability of the porous medium, hence CO2 injection pressure is increased and also it is diverted to the previously bypassed zones to recover more incremental oil. This process is extremely important if the displaced oil is heavy; where that is the case in Bati Raman CO2 injection project of TPAO, which is a well known field project that has been going on for more than twenty years. Crosslinked polymer gels for conformance control have been employed recently in Bati Raman field providing improved sweep efficiency and 12 % increase in net oil recovery. Field application of polymer gels for water shutoff and conformance improvement have provided both technically and economically successful results in naturally fractured carbonate heavy oil reservoirs in Turkey. The design and field operation process and experience gained from these applications may be very helpful and encouraging for the operators who look for new, reliable and low-cost methods to improve their oil production under today's harsh economic conditions.