Performance Testing of an In-Line Electrocoalescer Device with Medium and Heavy Crudes

摘要

ExxonMobil Upstream Research Company (EMURC) recently completed a subsea technology developmentand qualification program which included performance testing of an in-line electrocoalescer devicesupplied by FMC Technologies (FMC). This paper will summarize the results from these performancetests.Although heavy oil has been processed on-shore successfully for many decades, processing heavy oilin deepwater, subsea, or Arctic fields is extremely challenging. One key challenge is oil-water separation,in which physical separation is constrained by the high viscosity of the crude and the narrow densitydifference between oil and water. Installing conventional electrostatic coalescers or dehydrators is oftennot economical or impractical at remote locations. As part of ExxonMobil’s subsea program, severaldifferent separation technologies have been investigated and tested that could enable development of thesefields. One example of such a technology is FMC’s InLine ElectroCoalescer (IEC).FMC has developed an innovative, compact electrostatic technology that enhances the coalescence ofwater droplets dispersed in emulsified oils. This technology has the potential to considerably improve theperformance of the downstream oil-water separator. By applying an electrical field to an oil-watermixture, the dispersed water droplets become polarized and reorient themselves in the electrical field. Asthese water droplets approach one another, attractive forces between the individual water droplets lead tocoalescence. Larger water droplets are formed, that can be separated faster and more easily in thedownstream separation equipment. The IEC can be used to increase the throughput, performance, andreliability of existing oil processing systems while reducing the energy consumption and/or use ofchemical demulsifiers. In new processing systems, either subsea or topside, deployment of the IEC has thepotential to significantly reduce the size and weight of the downstream separation equipment, therebylowering the overall capital expenditure.The results presented in this paper are from performance tests that have been carried out on the IECat FMC’s testing facilities in the Netherlands, under EMURC’s supervision. Extensive testing wasexecuted with both medium and heavy crude oils. The operating temperatures were varied in a rangerepresentative for subsea processing applications, where heating of the process fluids is difficult. Thus, theperformance of the IEC was evaluated over a range of oil viscosities. Water-in-oil concentration, flow velocity, upstream shear, and electric field strength were also varied to investigate their effects on the IECperformance. The results demonstrate that the IEC is able to deliver high pre-conditioning performanceto medium and heavy crude oil emulsions, given the appropriate process conditions and electrical settingsare used.