The cyclical nature of the business has stripped depth from the industry’s workforce and has resulted in competition for personnel, felt keenly in field operations. The combination of deeper gas drilling and the acceleration of less skilled workforce into the field services has the potential to produce “train wrecks” if care is not taken to manage this situation.

Running casing is an area of drilling operations where the needs and benefits of automation

Figure 1. TESCO 95¼8-in. Internal Grip Casing Drive System below top drive is conveying 95¼8-in. casing up into derrick. (All photos courtesy of TESCO)
are significant. Running casing is personnel, equipment and performance intensive and is mission critical for wells. The technology and practices of running pipe downhole has changed little in the last half century. Automation of pipe running has progressed to a greater degree in offshore operations, perhaps best illustrated in North Sea operations and later generation deepwater drilling vessels, but for the most part automation techniques are only more recently migrating into land based operations.

TESCO has addressed this issue. After 4 years of running casing with the Casing Drive System (CDS), this technology is field proven. The automation benefits of this system and associated equipment are providing step changes in improvements of safety, performance and cost savings.

Casing Drive System

The CDS, originally designed for Casing Drilling applications, attaches to the top drive API threaded connection and grips the casing without attaching to the casing threads. As part of the load path it provides tensile and rotational integrity between the top drive and the casing and includes a fail-safe system to guard against inadvertent dropping of the string.

The CDS is hydraulically actuated using a standalone hydraulic power unit (HPU) with the operator and controls positioned near the driller. The CDS accommodates pipe sizes from 20 in. down to 41¼2-in. with working load capacities up to 500 tons, depending on casing size. The Link Tilt attachment provides an automated method of picking up the casing from the V door and conveying it up into the derrick. It provides the added benefit of holding the casing in position as the driller lowers the CDS to grip the casing, eliminating the need for a stabber and stabbing board. Hydraulically actuated single joint elevators attached to the Link Tilt provide further automation, eliminating a man position for latching and unlatching the elevator. This system of tools is not only effective but comes in a kit that is highly portable and adapts to all top drives.

Safety benefits

The most important benefit of CDS automation is safety. By their nature, pipe running
Figure 2. TESCO Internal Grip Casing Drive System and Link Tilt with 16-in. casing.
operations are monotonous and physically strenuous activities with significant hazards that contribute to significant injuries to personnel, including fatalities for the stabber position. IADC annual safety statistics report that approximately one third of rig recordable and lost time incidents are attributable to equipment including power tongs, elevators, slips and other pipe handling equipment, results even more significant considering the small portion of total time associated with running pipe. Regrettably, the trend of these incidents over recent years is increasing.

Safety is increased by reducing or eliminating exposure to risks, and the CDS provides a method to achieve this goal by taking personnel out of harms way and by reducing the number of personnel required in the running operation. This can be achieved through lessened exposure to falls, pinch points and material handling and by reducing the number of personnel required in this operation. The system reduces risk in a number or ways:
• The stabbing board and stabber position is eliminated. The stabber position is associated with serious injuries, further compounded with recent rig designs where clearances between the derrick and traveling gear has become progressively more restricted. Additionally, elimination of the board reduces risk of overhead equipment falling, a significant risk.
• Use of power tongs is eliminated, along with associated risks of pinch points, moving parts and high-tension snubbing lines.
• Elevated platforms are eliminated along with associated risks of falls and pinch points from assembling platforms on the rig floor.
• Manual latching single elevators and associated pinch point risks are eliminated.
• Mud fill-up operations are eliminated. These operations can spill mud on the rig floor, with associated slip, trip and fall risks.
• There is a reduction in the bulk of heavy equipment handling through loading and unloading operations.
• Crew size is smaller. Only two personnel are required to install the CDS and thereafter only one technician is required to operate the system.

Safety is further enhanced with improved well control. Running casing with the CDS is similar to having drill pipe in the hole; circulation can be established quickly and easily by turning the pumps on when the CDSTM is engaged on the casing.

Performance benefits

The CDS technology provides a step change of performance improvement in getting casing to bottom. With this system, the driller controls more of the functions of running casing: conveying casing up into the derrick, connection makeup with the top drive, circulating, and, when necessary, rotation and reaming.

For power-tight connection makeup, the CDS is effective for API and proprietary connections
Figure 3. Rigging up TESCO 20-in. Casing Drive System to the top drive is quick and simple.
with quick and accurate make up using the top drive. Top drive torque is calibrated for each job to ensure accurate assembly torque. An advantage of top drive makeup includes the elimination of the snubbing line, which induces a bending load across the connection, and a top drive can hold steady torque at final makeup, an important advantage for some proprietary connections. When torque monitoring is required, the company’s torque monitoring system can provide torque versus position and torque versus time providing traditional connection quality control.

Perhaps the most compelling performance related benefit relates to improved capabilities of getting casing to bottom in circumstances where hole trajectory and wellbore stability contribute difficulties in getting casing to the planned depth. The CDS gives the driller the capability to simultaneously rotate and circulate to get the casing through tight spots. If necessary, the casing can be reamed and circulated to bottom with the aid of a reaming shoe on bottom. Additionally, the CDS eliminates the need for a separate fill-up tool or circulating swage.

Case history – extended reach well
Well: Offshore California
Casing: 95¼8-in. 47#/53.50# P110 Hydril 563 (446 joints)
Measured Depth: 19,261 ft (5,872 m), 80° inclination, “S” shape
Total Vertical Depth: Approx. 7,800 ft (2,378 m)
Results: Casing was run in 29.5 hours. Run rate was approximately 15 joints per hour. There was no thread damage, no joints laid down, and casing was successfully run to total depth.

The CDS provides significant improvements to drilling operations, benefits often magnified in offshore operations:
• Increased safety — the most important improvement;
• Personnel — reduced personnel costs can become more significant for offshore operations in terms of reduced logistics and “personnel onboard” costs;
• Rig time — savings from reduced time dealing with trouble zones and well bore problems add up quickly. Also, CDS rigup times are routinely less than an hour and a rig crew that has become accustomed to rig up procedures further reduce that time; and
• New performance standards — the added freedom of designing wells where known casing problems provide barriers to design can be significant.

Operators can take advantage of new technology that brings automation and step change improvements in safety, performance and costs related to running casing on top drive equipped rigs.

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