Abstract

A thermal steam trial is applied in a multi-billion barrel STOIIP oilfield with very complex reservoir and oil properties. With low permeability, and saturation, deep thinly laminated formation and ultra heavy oil viscosity (100,000 cp at reservoir temperature of 65o C), the field introduces extreme challenges for conventional thermal development. This requires innovative solutions to stretch the thermal development boundaries to achieve technical and commercial success. In order to accommodate such subsurface challenges, unique surface facilities were acquired which made it possible to inject heat at high pressures.

Despite all these challenges, Phase 1 of the trial successfully conducted 4 cyclic steam stimulation cycles where over 13,000 tons Cold Water Equivalent (CWE) were injected into the formation at high pressure (21,000 Kpa) and high temperature (360o C) environment. With such extreme conditions, the project team managed to perform 11 PLT runs during injection, soaking and free-flow periods, making such success an industry-first in the region.

Previous paper (Stretching the EOR Boundaries: Thermal Trial in one of Petroleum Development Oman's Deep Reservoirs containing Heavy Oil, M. Mandhari et al) provided an overview of the early stages of the development of the trial. This paper will provide a thorough overview of the surveillance data during Phase 1 of the trial. "It will also provide an extensive representation of the analysis done on the gathered data which led to the design of Phase 2 of the trial and the methods selected to achieve higher latent heat injection into the formation."

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