Shell U.K. Exploration and Production, operator in the U.K. sector of the Southern North Sea on behalf of Shell and Esso, has developed Block 49/26 of the Leman field, located at the southern end of the Sole Pit Basin. Gas production from Leman commenced in 1968, built to plateau level by 1971 and began declining in 1982. The field produces under natural depletion and reservoir pressure has declined from 3022 psia to 300 psia in central areas of the field. Maintaining field revenue above operating expenditure is the key to maximising recovery. The challenge of accessing the economic reserves from Leman has been tackled by maximising deliverability from the existing low rate producers, minimising operating expenditure and pursuing opportunities for productive infill drilling.

The capacity of existing wells is optimised by maximising drawdown on the reservoir. This is achieved through ongoing facility rationalisation and the tailoring of operating practices to manage the phenomena of liquid hold up and salt deposition associated with operating at low pressures. Novel completion technology has been developed to optimise the lifting of liquids from wells.

The planned rationalisation of the field's compression facilities and the conversion of six of the seven production platforms to not normally manned status will reduce operating expenditure by a third and ensure retention of high sales gas availability. In order to reduce the installations operational visit frequency, novel completion technology has been developed to provide downhole control of proppant back-production which currently occurs from some fracture stimulated wells.

The successful performance of a horizontal well in a poorly drained area of the field has opened the way for infill drilling opportunities and possible development of the low relief flank areas of the field. Future appraisal and development drilling requirements will be better defined following full interpretation of the recently acquired 3-D seismic survey.

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