The original Mars A-14 well was drilled and completed in 1996. The well was worked over in 2000 because of a sand control failure. In 2003, the A-14 was again shut in due to increased sand production with concomitant decreased oil production. In 2004, after the slot had been recovered, the M1/M2 objectives were re-drilled.
Because of depletion and wellbore geometry, development drilling after years of production has become increasingly challenging. It is unavoidable to intersect both depleted and virgin pressured sands in the same interval. The high mud weights required for wellbore stability coupled with a narrow Pore Pressure / Frac Gradient window potentially subjected the well to the loss circulation – stuck – kick cycle, making any sidetrack an expensive and potentially hazardous endeavor.
Three sidetracks in close proximity to one another in the
Nearly 32 days were spent attempting Sidetrack02 with 60% of the time attributed to unplanned non-productive time; primarily lost circulation and wellbore instability. Over 3,000 barrels of synthetic base mud were lost.
Both Sidetracks 1 and 2 were drilled in the conventional manner – overbalanced and in an open vessel. Managed Pressure Drilling equipment and techniques were employed to drill Sidetrack03 over a 33 day period. Seepage accounted for losses of 600 barrels of synthetic base mud. There were no recorded incidents of lost circulation, kicks, or wellbore instability that would have otherwise interrupted drilling operations. Unplanned non-productive time was less than 2%.
Significant improvement in drilling efficiencies were realized utilizing Managed Pressure Drilling technologies. A direct comparison of equipment and operational technologies will be discussed.