Reviving the Maui AD Sands by Integrated 3D Reservoir Modelling

摘要

Until now, the production behaviour of the condensate-rich Upper D Sands in the A-Area of the Maui Field, offshore New Zealand has never been adequately explained. In 1986, after seven years of production, all but one well on the AD-Sands were essentially abandoned due to water break-through. Thereafter the reservoir strongly repressurised almost reaching original pressure within a few years. A recent detailed review of the D-sands in the A-Area, using a scenario tree approach and integrating inverted seismic data with reservoir geology, petrophysics and reservoir engineering has allowed quantification of the key subsurface uncertainties and the building of new dynamic reservoir models. Sensitivity studies were carried out to assess the impact of GRV, reservoir architecture, petrophysical properties and different fault sealing scenarios on the dynamic performance of these models. Reservoir simulation models were calibrated with historical production and the results of the history match indicate that it is now possible to explain field performance with a fully-sealing Ihi fault, at initial reservoir conditions, breaking down at maximum pressure differential close to the time when production ceased. This implies that there is a very strong aquifer and that bypassed gas lies behind this fault system. This is supported by the results of appraisal well Maui-6 and has been confirmed by recently acquired pressure data. Reservoir modelling guided by seismic attributes has also identified other areas of possible by-passed gas which form future development study targets.