Offshore Chemical EOR: The Role of an Innovative Laboratory Program in Managing Result Uncertainty to Ensure the Success of a Pilot Field Implementation

Abstract

Abstract Ensuring a pilot project a success operationally, while gathering reliable data for a full-field implementation is critical. For this reason, various aspects of project planning and operational considerations need to be addressed. This include conceptual design, facilities and operational considerations, resources planning, integration of activities and most importantly, pilot objectives. However, all these planning will not be successful without a properly designed and executed laboratory test program. Such laboratory program will minimize result uncertainty and ensure the proposed pilot meet its objectives. The first Chemical EOR (CEOR) pilot project in Malaysia involved an Alkaline-Surfactant injection utilizing high salinity injection water in a high temperature reservoir. It pioneered the Single Well Chemical Tracer (SWCT) method for EOR project evaluation in Malaysia. The main objective of the pilot is to assess the effectiveness of the Alkaline-Surfactant formulation to improve oil ultimate recovery through the reduction of residual oil saturation. Being the first of its kind in Malaysia, an extensive laboratory program is required to ensure the injected alkaline surfactant formulation performed at its most optimum and conclusive data is gathered. This data will be used as input to the future field development plan. This paper presents a comprehensive laboratory test program covering pre-pilot, pilot and post-pilot laboratory analysis designed for offshore high salinity injection water and high temperature reservoir. It highlights the challenges imposed by offshore operation to design an optimum chemical solution considering that salinity and hardness of the water used to dissolve the chemicals are critical for an alkaline-surfactant system. It also discusses the continuous and controlled quality check process to validate the performance of the alkaline-surfactant solution. Finally, it presents the chemical adsorption study to evaluate chemical flood potential for the future full field CEOR implementation. Introduction PETRONAS has undertaken a 3-year R&D project which evaluated the feasibility of a CEOR process for Malaysian oilfields. The research also identified suitable chemicals that can withstand the high temperature and high salinity environment and suitable candidate reservoir for pilot implementation (Othman et al. 2007). Based on the R&D study, Angsi field, located east coast of Peninsular Malaysia was selected for pilot implementation. The execution of this pilot project was also targeted to establish the required technical, operational and management skills before embarking on a large scale full field chemical flood. The results of the CEOR pilot project are crucial to the future decision making for full field implementation. A lot of considerations were given to gather reliable and conclusive data, within which, will manage results uncertainty. One of the ways is to ensure accuracy of the chemical preparation and injection process. All these can be achieved by a properly designed laboratory test program to tackle specific issues on optimum chemical slug design and quality of chemicals injected. It also aimed to measure the degree of chemical loss to reservoir rock, in which will evaluate the sustainability of the chemicals in a high temperature reservoir.