In view of a significant STOIIP (3000+ million m3) of medium/heavy oil (less than 31° API), EOR development in Oman has been and remains a major strategic option in its challenge to increase recovery and to meet long term production requirements.
The initial EOR Development Programme (1980-89) of which results are highlighted in this paper was based on a series of pilots and tests to gain experience and reduce uncertainties prior to embarking on wider EOR application. The processes tested included Steam and Polymer Flooding in the Marmul field. Steam Soak in five South Oman heavy oil fields and Hot Water Injection in the Qarn Alam field. A wide range of reservoir types, oil characteristics and reservoir drive mechanisms have been covered in this test programme.
Results on Polymer Flooding and Steam Soak were rather encouraging and presently small-scale follow-up projects are being pursued in the Marmul and Amal (Eastern High) fields respectively.
Due to geological complexities and reservoir heterogeneities in the Al Khlata sands of the Marmul field pilot area, Steam Flood performance was rather poor and performance extrapolation to other reservoirs is difficult. However, scope exists for those fields with thick, well connected homogeneous sands, with
Steam Soak considered as a precursor to Steam Flood.
The Hot Water Injection Test performed in the unusual oil-wet fractured carbonate reservoir in Qarn Alam, did not provide the predicted wettability reversal for field-wide application. Processes to accelerate gas-oil gravity drainage mechanism in this reservoir are currently being evaluated.
The initial programme has provided the necessary operating/technical knowledge to enable new projects to be better defined. Thus, an overview of future EOR scope taking into consideration the current oil economic climate is developed and presented.