Strategic Evaluation of MPD Application on DP Rigs

Abstract

In recent years, PETROBRAS has been using MPD (SBP/MCD) technology in ultradeepwater scenarios at development and exploratory wells. Although MPD techniques are an advance over conventional drilling, it also brings more complexity to the operation and, in some cases, increases the duration and costs of the interventions when compared to conventional drilling. Ideally, the rigs equipped with MPD system should only be used in wells, or in specific phases of the well, that requires MPD to conclude or where the NPT associated with fluid losses is considerable. In these scenarios, the extra costs and extra time necessary are negligible, compared to the NPT avoided, and the alternative would be not to reach target depth or drill the well. Geomechanics, pore pressure estimation and loss zone identification are not an exact science. There is always an uncertainty in predicting MPD (SBP/MCD) demand, pushing the development of techniques and strategies to optimize the allocation of MPD rigs in wells where the NPT would be so high that the use of the MPD is advantageous, or, where MPD is an enabler of well construction. This paper describes a probabilistic analysis developed to support the determination of MPD (SBP/MCD) demand, calculating the optimum number of rigs to be equipped with MPD (SBP/MCD) and RCD system, and which intervention strategy is the most cost effective for a development campaign, based on historic results.