Electrical Wellbore Heating in Environmentally Sensitive Llancanelo Field, Argentina

Abstract

Abstract Steam injection processes were abandoned due to environmental regulations in Llancanelo heavy oil field. This reservoir consists of a series of interbedded sandstone and conglomerates in cretaceous aged Neuquen Group. Down-hole electrical well bore heating technique, which is insensitive to the environmental regulations, was implemented. Despite that electrical heating for heavy oil reservoirs are established methods for in situ viscosity reductions, the commercialization and wider application of this heating technique required detailed analyses to determine optimal application conditions in horizontal well trajectory design for a heterogeneous reservoir. Recovery factor obtained with natural depletion was less than 0.2%. Viscosity and temperature relationship was the most critical parameter to determine the applicability of the project in the productive interval. In this paper, it has been shown that electrical well bore heating can be an alternative in this environmentally sensitive reservoir with two different oil viscosity layers; Green zone with 11200 cp and Olive zone with 3880 cp at the surface conditions. The impact of the different heating temperature and heating time on additional oil recovery were analyzed for the reservoir rock and fluid properties. Detailed simulation runs were conducted to understand recovery mechanism of convective and thermal conductive processes for well heating. By increasing the well bore temperature from initial 56 °C to 100 °C, the following results were obtained; 1- An additional oil recovery for Olive zone can be increased up to 110%, on the other hand an additional oil recovery for Green zone can be increased up to 62%, respectively.2- Energy consumption of 1 MM BTU for Olive zone will lead an additional oil recovery of 6 STB, whereas 1 MMBTU consumption for Green zone will lead an additional oil recovery of 3 STB.3- Energy rate per horizontal length is in range of 40–60 Watt/ft per the Green zone.4- Well bore heating will not change the reservoir temperature and viscosity of the oil beyond 30 m far away. In this paper, it has been shown that electrical well bore heating was economically viable in environmentally sensitive and heterogeneous reservoirs.