Steam-over-Solvent Injection in Fractured Reservoirs (SOS-FR) Technique as a New Approach for Heavy-Oil and Bitumen Recovery: An Overview of the Method

Abstract

Heavy-oil recovery from tight naturally fractured carbonate reservoirs is a great challenge to the oil industry, yet no well-established recovery technique has been adopted by the oil industry. Steam-over-solvent injection in fractured reservoirs (SOS-FR) is a new technology proposed as an alternative method to the sole injection of steam or solvent, and this paper introduces this method through extensive experimental evidence and analysis. The method consists of three phases: (1) steam (or hot water), (2) solvent, and (3) steam (hot water) injection. Phase 1 produces heavy oil by thermal expansion and conditions the oil for phase 2, which is solvent injection. Phase 3 is applied mainly to retrieve the solvent. Several static experiments were conducted mainly to test four critical parameters: (1) wettability of the matrix, (2) solvent type, (3) initial water saturation, and (4) matrix boundary conditions. This was followed by several dynamic experiments, which were aimed at testing the effect of the solve...