Use casing-while-drilling technology and ruggedized RSS
Schlumberger and Saudi Aramco captured baseline data by conducting feasibility studies that included modeling torque, drag, equivalent circulating density, standpipe pressure, and hydraulic lift. Shock and vibration simulations on multiple BHA configurations were also performed to determine the relative impact of each option and to identify the best solution for the challenge. Based on the challenges experienced during previous runs and the results of the preplanning simulations, Saudi Aramco chose to run an integrated solution that included the Allegro CD directional casing-while-drilling service and the PowerDrive Xceed RSS.
The Allegro CD service can be used with any retrievable BHA when the interval must be logged while drilling or drilled directionally. The Allegro CD service offers several key capabilities, including consistent casing rotation to break static friction, allowing even weight on bit; rotation and high-annular velocity to improve borehole cleaning; and the plastering effect (or smear effect) to maximize borehole strength and stability. This service also includes a drill lock assembly, which connects the BHA to the bottom of the casing shoe joint and enables torque and weight to be applied by the casing during drilling. The rig’s topdrive rotates the casing, and a downhole motor provides additional rotational speed and torque to the BHA and bit.
The PowerDrive Xceed RSS is a fully rotating point-the-bit system, which
features internal steering mechanisms that exceed performance limits of
externally steered tools. This provides significant wear and reliability
advantages for productive drilling in abrasive environments. PowerDrive Xceed
systems do not depend on contact with the borehole wall to build angle,
allowing the RSS to drill doglegs and sidetracks at high build rates and
reducing the tendency of the hole to spiral because of variations in
trajectory. Another advantage of directional casing-while-drilling technology
is the ability to retrieve the BHA at any point without the need to pull the
casing out of the hole.
Achieved Middle East record for footage drilled
The customized casing-while-drilling system set the 95/8-in section and
drilled the 4,747-ft section, achieving a new Schlumberger record for footage
drilled in the Middle East. The drilling BHA was retrieved three times without
any latching or unlatching problems and without any stuck casing events. The
maximum overpull experienced was 28,000 lbm [12,701 kg]. Well control drills
were refined to approximately 3 min for effective well control response. The
directional drilling plan was achieved with the maximum dogleg recorded of
2.77°/100 ft [2.77°/30 m]. Additionally, no tight hole or hole cleaning
issues were recorded.
Central to the project risk management was creating the internal project
readiness assessment, risk register, and drilling timeline to ensure that
appropriate risk prevention and mitigation plans were in place and continuously
reviewed. Other measures to reduce possible causes of nonproductive time and
unplanned events were also conducted, including a two-day Drill Well on Paper
exercise and a prespud meeting held on location and attended by Saudi Aramco,
Schlumberger, and the drilling contractor before drilling began. As a result,
no HSE incidents were reported.