Robust optimisation of well placement in geologically complex reservoirs

Abstract

In deepwater developments, economic constraints impose stringent limits on the number of wells that can be drilled without compromising economic profitability. Thus, optimal placement of wells has a significant impact on project rewards. A robust reservoir management strategy calls for rigorous techniques that account for subsurface uncertainty in geologically complex deepwater reservoirs. We develop a robust well-location optimisation method that is particularly suitable for such reservoirs. A steepest-ascent algorithm that takes advantage of distributed parallel computing constitutes the computational core of the optimisation method. The method operates in parallel on a number of probable reservoir models and maximises the expected value of ultimate recovery factor. A realistic reservoir-model ensemble with a thin oil-rim layout and complex lobate turbidite stratigraphic architecture is utilised for demonstrating the concept. Results validate the auspicious nature of the proposed robust well-location optimisation method for recovery forecasting in stratigraphically complex reservoirs.