Sustainable Bio-Based cEOR Formulation for a Challenging Indonesian High Temperature Carbonate Reservoir

Abstract

Enhanced Oil Recovery (EOR) becomes increasingly important as the global crude oil reserves are being depleted. This is especially true in Indonesia where the growing internal demand exceeds its oil production as many fields are in their mature stages and thereby slowing down the overall oil production rate. Thus, it is imperative for Indonesia to look for alternative strategies to improve production from the maturing fields by adopting various tertiary techniques in order to achieve a national target of 1 MMBOPD oil production by 2030. Field X is an onshore mature carbonate field that has been identified as a potential chemical EOR candidate. Carbonate reservoirs with moderate high reservoir temperature, 90 °C in the case of Field X, are known to be creating additional challenges for chemical EOR, particularly in formulating a tailored surfactant blend that exhibits stable behaviour, high performance and trouble-free operations. In this paper, the surfactant-polymer (SP) formulation design, optimization and lessons learnt leading up to a successful bio-based robust chemical EOR formulation with suitable adsorption strategy for relatively low salinity (8000-9000 ppm of salinity) and high temperature (90 °C) carbonate field are presented. A multi component surfactant formulation using a novel bio-based surfactant, internal ketone sulfonate (IKS), as a primary surfactant was designed for the high temperature X reservoir. The raw materials for producing IKS surfactant that is used in this formulation is sourced and manufactured in Indonesia which also in turn creates circular economy benefits. In addition, the use of bio-based surfactant chemistry greatly decreases the carbon footprint compared to petroleum-derived chemicals and IKS has the significant advantage of improved raw material availability. The SP formulation was evaluated following a systematic workflow in order to achieve good thermal stability, SP compatibility, ultra-low interfacial tension (IFT) and favourable residual oil production with managed surfactant adsorption mitigation. As expected, the main challenge was the reservoir conditions and the nature of rock during the course of this study which resulted in a very promising oil recovery strategy in economically realistic conditions using sustainable bio-based chemistry.