Safety is critical to the oil and gas industry. Drilling contractors require reliable systems with consistent performance. The crews look for tools they understand to help carry out daily tasks. A fingerboard-mounted pipehandling system, the stand transfer vehicle (STV), eliminates the manual duties of a derrickman. The machine is the result of collaboration between NOV and the drilling contractor and provides a solution without sacrificing manual tripping speeds. Critical to operational success is tripping speed, simplicity, and following a procedure that mirrors manual operation. Eliminating the existing gripping devices and hoisting systems was one of many steps taken to improve safety.

The STV removes the derrickman from harm’s way and provides an affordable and robust solution to address the derrickman’s safety concerns. The main design parameters set for the tool are:

  • To maintain or increase tripping efficiency;
  • To mirror the operations of the manual derrickman;
  • Be capable of handling 3½-in. to 10-in. drillpipe and drillcollars without insert size changes;
  • Include modular installation and removal of STV during rig-up and rig-down;
  • Provide one-man operation with the derrickman running the tool from the rig floor;
  • Provide visual feedback of STV position and operation without use of encoders; and
  • Provide manual racking when tool is not operational.

Design approach

Vertical pipehandling systems are used offshore but have not been adopted in the land market. The products available for offshore do not meet the design requirements for land drilling due to size, weight, complexity, and cost. The current offshore offerings were evaluated before starting the prototype development for land drilling applications.

The initial design included installation above the fingerboard with a bridge and trolley system, a tubular guide head, a quick release of guide head from tubular stand with instant opening of fingers, and hydraulic controls. This design was installed on a customer-supplied 1,500-hp rig to prove the concept of the tubular guiding head moving the stand between the fingerboard slots and well center.

The key to this first design was to test the unique tubular guide head with a variety of pipe sizes and document the dexterity of the head when moving stands between the fingerboard and the elevator at the well center. The STV’s design needed to allow efficient installation and testing during repeated rig moves. The weight was addressed by supporting the STV guide arm from the diving board, which was integrated into the main fingerboard support structure. This allowed the machine to be fully factory-tested as a system prior to delivery to the field.

The guide arm trolley uses a fingerboard index camera that aligns the guide arm and head with the fingerboard slots. This allows the operator to stop the machine at the required slot, which allows seamless movement of the stand between the diving board alleyway and fingerboards. Additionally, the guide arm was supported below the diving board, improving the line of sight to the machine from the drill floor.

The final challenge in the design was a simple and robust control system that allowed manual hydraulic control from the fingerboard and remote control from the driller’s cabin. Because the STV does not incorporate encoders for position control, a dual camera and monitor system was used to provide visual feedback to the operator. One guide-arm-mounted camera follows the guide head along its path to and from well center. The other fixed, well-center view camera monitors handover between the machine and the elevator. These cameras and the monitors allow the operator’s joystick and switch commands to be immediately verified by the camera monitors, reducing the training time.

Prototype testing outcomes

The trial period started in 2010 in the Barnett shale and was a collaborative effort between the contractor and OEM, with efficient communication between the drilling crew and design engineering team. The testing period provided valuable feedback. Testing improvements included:

  • Breakaway diving board. During the trial, the top drive elevator contacted the diving board on the way up causing damage to diving board and fingerboard. The prototype diving board connection provided a breakaway design that clamps in place and uses replaceable shear pins to allow board rotation if contacted;
  • Passive fingerboard stand restraints. Each row of stands is held in place by a pneumatic latch, remotely controlled from the operator’s console. During the trial, inflatable air bags proved the most effective; and
  • Installation, transport, and storage frame. A multiuse STV support frame allows safe, efficient installation of the machine into the fingerboard. This frame also allows on-the-ground and in-the-mast testing and maintenance of the machine. When installed, this frame provides a storage area for maintenance and troubleshooting, allowing manual racking of the fingerboard.

Relocating the derrickman near the driller on the floor allows better communication and training among crew. The STV’s design is the result of a long design process and prototype trial period that has produced a unique but simple tool that is slowly gaining momentum with drilling contractors and their operators. The tool offers a combination of safety, reliability, and performance.

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