Powered rotary steerable system boosts deepwater well ROP 157%

Minimize effect of stick/slip on ROP and BHA wear while drilling 9½-in hole sections of deepwater wells in very abrasive formations offshore Angola.

Minimize stick/slip

The 9½-in hole sections of deepwater wells in a field offshore Angola were being drilled through very abrasive formations. This resulted in severe stick/slip that damaged BHA components, quickly wore out stabilizers, and adversely affected drilling performance. To avoid the damage, abnormal wear, and low ROP, the operator wanted to minimize stick/slip.

Optimize BHA design

SLB used a BHA incorporating PowerDrive vorteX™ powered rotary steerable system (RSS), polycrystalline diamond compact (PDC) bit, Scope™ MLWD services, and geoVISION™ 675 imaging-while-drilling service to minimize stick/slip, increase ROP up to 157%, and avoid abnormal BHA component wear.

The Scope services used were EcoScope™ 675 multifunction drilling-while-logging service, StethoScope™ 675 formation pressure-while-drilling service, and TeleScope™ high-speed telemetry-while-drilling service.

To find the most efficient set of drilling parameters, SLB used modeling and simulations that included i-DRILL™ integrated dynamic system analysis service design and BHA-TV, a model that analyzes how a drilling system changes over time. Modeling and simulation also were used to optimize the BHA design and to select the proper type of bit and the bit hydraulic horsepower per square inch that would be required.

The PowerDrive vorteX RSS power unit—a PowerPak™ steerable motor with greater torque for drilling with aggressive bits—maximized ROP. To achieve the planned dogleg severity (DLS) in the abrasive formations, the powered RSS control unit was a point-the-bit PowerDrive Xceed™ ruggedized RSS for harsh, rugged environments. A C-Link electromagnetic induction propagation (IMAG) communicator provided wireless transmission of real-time measurements of rotation speed and torque from the control unit across the power unit to the TeleScope telemetry service, which sent the data to the surface along with the Scope services and geoVISION service data. The real-time availability of the torque and rotation speed measurements enabled the driller to adjust drilling parameters to maximize ROP and minimize stick/slip.

Increase ROP

Use of the PowerDrive vorteX RSS BHA to drill the 9½-in well sections and the application of lessons learned enabled the drilling team to minimize stick/slip, avoid abnormal BHA wear, and significantly increase ROP. Average ROP improved from 6.67 m/h in the first 9½-in hole section drilled to 11.01 m/h in the second, then to 17.16 m/h in the third—an increase of 157% from the first section to the third.

Japan Oil, Gas and Metals National Corporation (JOGMEC), formerly Japan National Oil Corporation (JNOC), and SLB collaborated on a research project to develop LWD technology that reduces the need for traditional chemical sources. Designed around the pulsed neutron generator (PNG), EcoScope service uses technology that resulted from this collaboration. The PNG and the comprehensive suite of measurements in a single collar are key components of the EcoScope service that deliver innovative LWD technology.