Striking a Balance Index

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4. Stewardship - making prudent use of natural resources Our Strategic Objective To ensure prudent use of resources in our operations through maximising recovery of oil and gas, by developing and applying new technologies, by making the best use of existing infrastructure and by adopting a whole life cycle approach to issues of design, energy use, waste generation, and the legacy we leave when our operations cease. Context Figure 32 The Exploration and Production Life Cycle Click on the image below for a larger view: Reservoir Management The management of the reservoir is one of the most complex and crucial parts of the production of oil and gas. The "recovery factor", the proportion of oil or gas which is recovered expressed as a percentage of the total oil or gas present, can vary widely from one reservoir to another, depending on its geological complexity. Advances in technology and understanding of reservoir behaviour as oil and gas are produced have resulted in substantial improvements in recovery, e.g. an early North Sea oil field might have had an expected recovery factor of 35% when production commenced, but now this could have risen to 50% or more. The search for improvements continues, to enhance the recovery factor and extend the lives of fields still further. This is both good economics and good stewardship. Case Study One Carbon Sequestration A partnership has been formed between seven major global energy companies and contractors aimed at developing the next generation of CO2 geological sequestration technology. A $20 million research project was launched in 2000, investigating the potential for capturing significant amounts of CO2 from power generation and industrial sources for storage in geological formations below surface. This research builds on the industry's extensive experience of handling large volumes of CO2 which are injected into about 70 oil fields worldwide to facilitate recovery. Case Study Two Design for Environmental Efficiency A recent development project illustrates how addressing environmental issues at an early stage enabled performance improvements to be incorporated during design. Most notable is the elimination of oil in produced water discharged to the sea, waste heat recycling and maximising efficient use of gas. The field produces some associated gas and this is used for power generation. The new platform includes waste heat recovery units that utilise hot exhaust gases from the platform turbines and redistribute the waste heat to production process areas. This measure significantly improves energy efficiency and reduces combustion emissions by reducing fuel demand. Excess gas not required for power generation is exported through a new gas line. The rationale behind construction of the line is that exporting the relatively small amount of surplus gas will reduce flaring and when the field becomes gas deficient in the future, the line will be used to import gas, removing the need to import and burn diesel. The new facility has also been designed to eliminate overboard discharge of produced water which is usually discharged into the sea, after a cleaning process to remove the oil it contains to within approved limits. In this case, however, due to the particular characteristics of the oil, the separation process would need more than usual use of energy to achieve the required performance specification, resulting in additional atmospheric emissions from burning the extra fuel. The solution was to design a capability of complete reuse of the produced water, either downhole to maintain reservoir pressure or as power to drive submersible pumps. This not only eliminates oil in water discharge to the sea, it also reduces the platform's energy requirements and, consequently, its atmospheric emissions. Case Study Three A significant energy reduction initiative An onshore gas terminal reduced its emissions, and increased its energy efficiency by installing a new boiler fuelled by gas which had previously been flared. The boiler burns two streams of gas. The first stream comes from the gas treatment system itself, and the second stream arises from leakage into the flare system. Both streams are captured and routed to the new boiler, which is used to supply steam for use in the terminal. This allows the energy previously lost in the flare to be recovered and increases efficiency.