| Popis: |
The Santos Basin Pre-Salt Cluster (SBPSC), Offshore Southeast Brazil, is a unique scenario, posing great development challenges. The microbial carbonate reservoir is unusual regarding its origin and petrophysical properties; the fluids have a variable CO2 content; the few analogue reservoirs around the world do not compare in terms of volumes, water depth and distance to the coast; and there are also flow assurance issues. Considering the importance of these reserves for the Brazilian economy and the opportunity to accelerate cash flow, Petrobras and its partners have opted for a fast track development, including extended well tests (EWTs) and production pilots. The current Petrobras Business Plan (2011–15) foresees that the SBPSC areas alone will produce over 500,000 boe/d in 2015 and over 1,100,000 boe/d in 2020. These numbers refer only to Petrobras share and do not include the transfer of rights with economic compensation from the Brazilian government to Petrobras. Therefore, the initial development phase will have to cope with several uncertainties, mainly the subsurface ones. Some of the most relevant are the quality and the heterogeneity degree of each reservoir zone; the compositional grading of the fluids; the performance of different EOR methods; and the presence of fractures affecting the flow. How to specify and anticipate the acquisition of expensive equipment, such as FPSOs and subsea devices, with uncertainties to be clarified? When is it worth to invest in more data acquisition, such as EWTs, core and fluid sampling, extensive lab analysis or even more appraisal wells? The timing and the uncertainty reduction foreseen for each initiative must be taken into account. On the other hand, when is it better to pay for extra flexibilities, accepting the inevitable CAPEX increase? Some examples would be: smart completions and possibility to inject different chemical products in the wells; gas and water separated lines for each satellite injector; flexible subsea layout, allowing multiples strategies and the addition of more wells; FPSO plants designed to inject desulphated water, or to export, import or reinject the gas, and also to separate variable CO2 contents in the produced fluids. This paper aims to discuss the influence of the main subsurface uncertainties in the selection of alternatives to develop the giant fields in the SBPSC, in a fast track way. |
