Managed Pressure Drilling (MPD) Technology Applied to a High Potential Oil/Gas Producing Well Enabled Operator to Drill to Planned Target Depth in an Area of South Texas Where Conventional Drilling Has Been Unsuccessful-a Case History

摘要

Multiple operators had attempted to conventionally drill wells in an area of south Texas targeting an over pressurized sand. A majority of them were unsuccessful showing a history of lost time events and poor well results related to kicks and losses. Information suggests little was known about the pore and fracture pressure gradients, and that uncertainties regarding real stratigraphic distribution were present, resulting in improper casing points and mud trends not in accordance with actual wells requirements. For these reasons, one operator decided to implement Managed Pressure Drilling (MPD) technology in order to safely and efficiently drill a well to the pay zone. The scope of the operation was a re-entry sidetrack on a vertical well that originally encountered well control and multiple mud losses events. The first interval was an 8-1/2 inch intermediate section to be cased with a 7 inch liner. The liner shoe was to be set approximately 80 feet above the over pressurized target sand. The second interval was a 6-1/8 inch production section targeting the well pay zone, to be cased with a 4-1/2 inch production casing. Both intervals were considered critical, the first one having depleted zones interbedded with gas bearing formations with a final depth immediate to abnormal gas pressures, and the second demanding accurate ECD management to avoid well control events, losses and formation damage, this of cardinal interest for the operator.