The Impact of TAN from Heavy Oil EOR to Operation and Integrity: Case Study

Abstract

Abstract The reserve of conventional oil is decreasing as a trend and it is leading to the price hikes for conventional crude. Finding alternative energy sources including heavy oil is therefore a major agenda of the day. Thus there is an incentive to explore the heavy oil with a priority. One of the major issues dealing with heavy oil production is TAN (Total Acid Number) from crude oil. What is the impact of TAN to flow assurance? The value of crude oils is often dependent on the corrosivity of the oil, and corrosivity is mainly a function of the total acid number of the oil. TAN, in turn, is heavily dependent, although not completely so, on the naphthenic acid concentration of the oil. Consequently, crudes having a relatively high TAN, e.g., ≥2 have a significantly lower market value, on a per barrel basis, than crudes having a relatively lower TAN. The current approach to refine acidic crudes is to blend the acidic crudes with non-acidic crudes, so that the TAN of the blend is no higher than about 0.5. The case study have been conducted to predict the overall mix of crude TAN in main oil line and see the impact of TAN from heavy oil steam EOR operation in Oman. The workflow are covering: set up and define laboratory testing to see the root cause of TAN and the impact of heavy oil EOR crude to overall field, develop a worst case scenario and selecting the other alternative to lowering TAN. For example, the first basic strategy in managing TAN, high TAN crudes are often blended off with lower TAN crudes, the second strategy is to injecting some TAN reducing chemicals. Finally, the techno-economic matrix will help the decision of managing TAN.