To meet the ever-growing demand for oil and gas, operators today are forced to search for reservoirs in more challenging environments characterized as high-pressure high-temperature HPHT using extended-reach drilling (ERD) techniques. A major operator in the Central North Sea successfully drilled a complex extended-reach drilling (ERD), HPHT exploration-production well in the central North Sea presented numerous challenges, This well contains one of the largest outstep HPHT wellbore ever drilled, and contains one of world's heaviest production casing strings. The HPHT environment causes various drilling problems, such as accelerated thickening of drilling fluids, reduction in rate of penetration (ROP), lost circulation, swabbing during pulling out the string, stuck pipe, and hardware failure. The complex nature of this ERD well created specific problems, including torque and drag, hole cleaning, casing running, equivalent circulating density management, and wellbore stability. The operator planned to drill this HPHT exploration and production well by sidetracking from an existing well. In addition to the HPHT and ERD challenges, other drilling challenges consisted of hard rock, high-pressure reservoir, differential sticking risk, a one-way casing/liner run, potentially depleted sands, and possible severe casing wear. These numerous and varied challenges required quick operation decisions to avoid costly overruns.
This paper presents the method used by the operator to successfully drill and complete this complex ERD, HPHT well access a reservoir containing several challenging drilling conditions and potential obstacles to achieving the well objectives. The successful operation demonstrates the importance detailed engineering, communications, and an integrated effort played in successfully delivering this challenging well.