This paper describes how uncertainty in core analysis parameters are integrated into the appraisal and development stages of a project’s life-cycle using Decision and Risk Analysis techniques to focus data acquisition on the critical uncertainties influencing value.The process involves value-based decision-making using Monte Carlo techniques incorporating uncertainty in the factors controlling Net Present Value.At the appraisal planning and execution stage the process largely involves analytical reservoir prediction techniques incorporating uncertainty in the fundamental parameters that control reservoir performance.For example,the technique can determine the significance of uncertainty in core analysis parameters such as capillary pressure,relative permeability,and residual oil saturation relative to other uncertainties influencing value.As a result,the value of data acquisition,including core analysis data,can be established early in the life cycle.At the development planning stage a similar philosophy is adopted but more detailed analysis is performed when petrophysical and special core analysis data become available.For example,inter-well scale stochastic simulation of reservoir performance considering geologic body size,orientation,distribution,and permeability,relative permeability and residual oil saturation can be used to determine the factors controlling reservoir performance uncertainty.These factors can then be incorporated into an overall uncertainty assessment,including other variables such as costs and oil price,to identify the key uncertainties and the expected range of project value.Examples are presented where core analysis data and its associated uncertainty had a significant impact on value assessment at the appraisal and development stages of the life cycle.The examples include waterflooding of a complex carbonate,a fractured oil reservoir under water injection,and an over-pressured mini-basin reservoir under primary depletion.
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