Brazil: Drilling the Extra Mile in Soft Formations, Schlumberger

Brazil: Drilling the Extra Mile in Soft Formations In deep water offshore Brazil, drilling relatively simple well profiles in soft shales and marls is difficult. The introduction of PowerDrive rotary steerable system (RSS) technology for deepwater development wells has trimmed an average of two rig days per 12 1/4-in. hole section and one rig day per 8 1/2-in. hole section. In the Voador field, Petrobras drilled a pilot hole to establish reservoir boundaries. A sidetrack hole optimizes heavy-oil production from the well. The PowerDrive Xtra tool drilled the 84° inclined section of the 7-VD-10HP-RJS sidetrack hole with maximum build angle of 6.5°/30 m [6.5°/100 ft] into the target formation as planned. Instantaneous rate of penetration (ROP) was as high as 75 m/h [246 ft/h]. The average ROP using PowerDrive Xtra technology was 35 to 40 m/h [115 to 131 ft/h], twice the rate of a steerable motor in offset wells. The RSS sustained longer bit runs and better directional control than a motor because the friction of the motor limits ROP and decreases directional control. This type of drilling success in a soft formation requires more than downhole tools. In this case, using the PERFORM Performance Through Risk Management Process, the wellsite engineers closely monitored drilling parameters, cuttings morphology, real-time torque and drag, and equivalent circulating density. The PERFORM process ensured good hole cleaning and detection of wellbore-stability problems.[ note 15 ] Logging-while-drilling (LWD) images acquired during the trip out of the hole were downloaded at surface. When compared with images acquired at different times, for example, during drilling, these time-lapse images confirmed wellbore-stability problems in the shales, problems first indicated by the cuttings morphology and increasing drag. The PERFORM process helped engineers determine that the mud weight was too low and that hole cleaning was suboptimal. The well was drilled successfully to total depth (TD) by managing both these parameters while drilling. Previous Next: Norway: Openhole Sidetracking in Complicated Formations Related resources Summer 1999

Brazil: Drilling the Extra Mile in Soft Formations, Schlumberger