From characteristics to performance: a laboratory study of surfactantpolymer for CEOR
Abstract
Together with signs of renaissance, Oil and Gas sector faces serious challenges in both finding new reserves and sustaining poduction. Aside from the exploration, arresting production decline from existing wells seems more visible shortly.
Enhanced oil recovery (EOR) is the major focus in Indonesia where the majority of oil fields are on the declining stage. "K" field in South Sumatera is one amongst others that are included as the priority of EOR development which aims to sustain the production. After the screening process, chemical injection is the most feasible method to be implemented. Surfactant-polymer is considered effective in both lowering interfacial tension (IFT) and improving sweep efficiency.
Laboratory measurements were conducted to test numerous formulations of surfactants ranging from the concentration of 0.05% to 1 %. The best surfactant is then selected to be tested in a surfactant-polymer solution using a polymer with a concentration of 500 ppm to 2000 ppm. The interfacial tension between oil and surfactant-polymer was measured to understand the performance of formulations. The rheological test was performed to measure the viscosity of formulations. The thermal stability of surfactant-polymer at reservoir temperature (60oC) was also observed in a certain period. To ascertain selected formulations' capability on
producing incremental oil, the coreflood experiment was carried out. The high percentage of recovered residual oil (%Sor) is the key parameter indicating successful chemical injection.
This paper describes the process of selecting the most favorable surfactant-polymer formulation that can serve as a reference to mature oil fields in Indonesia. In particular, it demonstrates the necessity of formulating the right concentration of surfactant and polymer to yield a stable formulation.
