To ensure a technically and economically viable chemical Enhanced Oil Recovery (cEOR) project in the Caracara Sur Field (Llanos Basin Colombia), several challenges were faced. One of the challenges described in a previous work (Cubillos et al. 2013), is the design of an efficient chemical formulation stable at reservoir conditions. Comprehensive laboratory work has been undertaken, resulting in an Alcali Surfactant Polymer (ASP) formulation containing hydrolysed polyacrylamide (HPAM) as a mobility control agent. HPAM is the most used polymer in the oil industry thanks to its low cost and availability in high quantities. However, initially it was not clear that HPAM efficiently worked for Caracara Sur, because HPAM properties limits its efficient application to low temperatures (<80 °C) and low-to-moderate salinity reservoirs.

In this paper, we present the laboratory work that lead to find an innovative solution founded on the synergy between the formation water properties (low salinity) and high temperature environment in the Caracara Sur Field. The study focused on the polymer screening process, rheological properties of HPAM with the low salinity brine of Caracara Sur, the HPAM performance in porous media and chemicals to enhance its thermal stability. This work is only focused on the polymer selection and the synergy between low salinity brine and polymer flooding.

The main results show that the developed formulation for the Caracara Sur reservoirs is a viable cEOR alternative. By injecting low salinity brine and HPAM with the right mix of other chemical components, it is possible to drastically reduce the cost of cEOR, whilst maintaining the same efficiency even at higher reservoir temperature. As a final product, an optimal ASP formulation has been developed and successfully tested both at laboratory and field conditions.

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