Salt formations are common trap zones for prolific reservoirs. Recent discoveries in the Brazilian coast include light oil carbonate reservoirs below massive salt zones. Well construction challenges in such environments include salt creeping, leaching and proper zonal isolation.

This article presents a comprehensive integrated methodology for cementing design which accounts for the following hydraulic aspects:

  • Adequate fluid substitution design supported by numerical simulation considering two phase flow in eccentric annuli and lubrication theory

  • Downhole pressures in the operational window considering free fall effects for deepwater environments

  • Open hole volume prediction based on salt leaching phenomena due to the circulation of unsaturated fluids. Flow rate fluctuation as a result of free fall is considered

  • Increase in salt concentration due to conduction effects after placement and its impact on slurry properties.

The methodology is exemplified by two typical scenarios for offshore salt cementing in the Brazilian pre-salt cluster. Slurry design, slurry placement schedules and borehole stability considerations are addressed.

Keywords:
drilling operation, salt concentration, exhibition, drilling fluids and materials, martin, displacement flow rate, casing and cementing, simulation, salt zone, drilling fluid management & disposal
Subjects:
Drilling Operations, Drilling Fluids and Materials, Casing and Cementing, Drilling fluid management & disposal
Copyright 2012, Society of Petroleum Engineers
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