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Abstract: Principles for Full-Lifetime Reservoir Management

Koenraad J. Weber

Many fields show large changes in recoverable reserves, either positive or negative, with progressing time. Even at a late stage considerable uncertainty may remain on how to achieve optimal recovery. This is often the result of the lack of including a systematic assessment of the effect of the different possible geological models into the planning. At any stage remaining uncertainties have to be recognised, their influence assessed and plans for reducing them specified. The timely acquisition of data essential to sound development planning is the key to successful reservoir management.

It is useful to start the process of reservoir study at the exploration stage. Even the seismic acquisition and particularly the processing are major factors in the early assessment of an eventual discovery. Proper testing of an exploration well is equally crucial to a correct evaluation of the find as well as to the follow-up planning. Analogue data from neighbouring fields and outcrop examples of the reservoir formation should be available prior drilling the first hole.

In the early stages of fields appraisal the objectives should be both the assessment of the accumulation conditions and reservoir modelling. Dynamic reservoir models are required to test sensitivity to well type, well numbers and spacing and to completion policy. A major issue is the drive mechanism and production policy which both need an evaluation of the spread of dynamic models dictated by the remaining uncertainties. The economic risk inherent with these uncertainties is the factor controlling further appraisal and data acquisition expenditure.

Field development planning is a cyclical process that leads to refining the dynamic reservoir model at each planning round. Every time the economic consequences of remaining uncertainties can be evaluated and plans for dedicated additional data acquisition and monitoring can be incorporated in the next development plan. The above scheme for optimal field development planning is illustrated with case histories and practical planning schedules.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France