Heavy-Oil Uncertainties Facing Operators in the North Sea

摘要

Rising oil price and demand has led to increased effort torndevelop reservoirs in the North Sea that were previouslyrnconsidered uneconomical by major operators. The recent DTIrn‘Promote’ licensing initiative has encouraged smaller oilrncompanies to apply for exploration/appraisal acreage on arnlimited financial commitment basis for two years beforerninitiating a more traditional work program.rnCompanies using this option to develop heavy oilrnreservoirs in the North Sea, many of which were discovered inrnthe 70’s, face a number of uncertainties traditionallyrnassociated with heavy oil. These include the determination ofrndensity and live oil viscosity at reservoir temperature where nornclear correlation exists and the determination of reservoirrnproperties from a limited range of historical data. In thernoffshore environment heavy oil developments are furtherrncomplicated by the high front-end costs, limited reservoir sizernand uncertainty in geology and productivity. Only four of thernheavy oil fields discoveries on the UK Continental Shelfrn(UKCS) have reached development and we review these fieldsrnto illustrate the challenges.rnMany of the reservoir and fluid uncertainties can bernaddressed with modern logging and analysis methods andrnrecommendations for data gathering campaigns in thesernenvironments are provided. The technological challenges ofrnan offshore heavy oil development can be met with advancesrnin sand control, ESP technology and EOR techniques.rnCombined together these solutions provide more accuraternproduction forecasts, which help the economics of developingrnthe resource to be better understood.rnThe proposed appraisal and development of a heavy oilrnfield situated in Block 9/3b is used as a case study to highlightrnthe challenges faced by operators in the development of heavyrnoil fields in the North Sea. Re-evaluation of historical data was used to develop a range of production forecasts that fullyrncapture the potential and risk of the development.