According to Hal Owens, drilling manager, Occidental Petroleum-Oman, the project underscores the ability of a slimhole rotary steerable system to satisfy industry objectives in Oman. "We recognize that new technology such as this should deliver a more effective result by reducing drilling time and time to market on production," said Owens. "We were pleased that a tool just out of engineering performed so well on its first run and delivered on all our requirements.

"To penetrate the planned targets using our current standard systems," continued Owens, "requires drilling in the slide mode, in our case, 30 percent of the time. During these periods, our penetration rates drop by two-thirds. The PowerDrive Xtra system allows us to maximize our penetrate rate. Also staying in rotary mode allows for additional lateral length to be reached when needed. Based on our success with the system to date, we will utilize the PowerDrive Xtra system on two additional wells with the second well getting under way within a few weeks."

Adds Ken Feather, marketing manager for Schlumberger Oilfield Services-Oman, "As Oman's E&P industry intensifies its focus on cost-efficient enhanced oil recovery techniques, operators are looking to produce more oil from fewer wells. PowerDrive Xtra allows faster and better execution of steering decisions during drilling. A single well trajectory can now intersect multiple targets and can be adjusted more accurately for optimum reservoir drainage. This new capability has arrived at the right time to help operators increase production and ultimate recovery."

Advanced planning between the two companies enabled real-time monitoring of the geologic orientation in the reservoir, which delivered information used to make steering decisions. Services used in addition to the PowerDrive Xtra system on the Safah well included VISION475* 4 3/4-in. measurement-while-drilling and logging-while-drilling system and INFORM* integrated modeling. A geosteering screen was used and the well was drilled using a 6 1/8-in. Schlumberger drill bit.

Although the well had significant gas influx from a nearby injector well, all horizons registered as planned and log responses proved accurate. To respond to the gas influx, mud weight had to be increased and drilling rates had to be controlled at times. Use of conventional mud motors on Safah 198 would have been slow and it may not have been possible to reach total depth.

The PowerDrive Xtra system enables greater control of directional drilling using constant rotation to intersect more targets in a longer hole section and minimizes the risk of stuck pipe. Conventional technology can produce an uneven well path when changing from sliding to rotating mode. The action of continuously rotating the drill string while steering reduces creation of an uneven path and results in faster, more controllable well placement. PowerDrive Xtra 475 operates independent of mud weight and depth, allowing for longer runs and fewer trips.