Taking the “hurt” out of running casing

Meshing the intersection between safety, efficiency, and costs drives the incessant quest to automate the drilling process. While overall success has been sporadic, pipe handling represents one well construction component that has generally realized step-change advancements in automation. These advancements have since progressed to the casing running operation, long regarded as among the most hazardous of drill floor activities.

More recently, a new-generation automated casing running tool (CRT) has emerged as a significant breakthrough in the safe handling and running of casing strings by removing all personnel from the hazardous. The uniquely engineered CRT, comprising a fit-for-purpose wireless controller and built-in redundancies to eliminate dropped casing, is fingertip-controlled from the driller’s cabin, thereby requiring only one person on the rig floor to remove thread protectors and stabbing guides. By contrast, conventional manually-intensive casing running operations typically require up to four drill floor hands directly in the red zone, accounting for numerous incidents of serious injuries.

Fig. 1. The installed Top-Tek CRT is operated with plug-n-play wireless control technology.

The hydraulically controlled Top-Tek CRT technology (Fig. 1) incorporates remote control capabilities and flush-mounted slips (FMS) that enable casing handling without the need for manual slips or power tongs. A specially engineered safety spring keeps the CRT in the default set position and, should a loss in hydraulic pressure occur, the tool remains mechanically set. Furthermore, a safety interlock between the CRT and the hydraulically-operated FMS ensures that tools are always engaged with the string.

A comparative analysis of casing runs, including conventional applications, throughout the Middle East over a two-year period shows the automated Top-Tek CRT technology helping to maintain a consistent zero lost time incident (LTI) rate. Specifically, this adds up to a cumulative 39,536 man-hours on location and 5,410 total working hours over a total of 877 days with zero LTI. Moreover, average non-productive time (NPT) related to overall casing running operations has declined from 5.2% to 1.7%. In one country in the region, casing running efficiency (defined as time to bottom) saved a cumulative 49 days of rig-time over an 18-month timeframe, again with zero LTI reported to over 14,205 hr of operations. The system was used in a wide range of casing sizes and grades, from 24-in. to 95/8-in., with VETCO-JVLW, BTC, VAM TOP and TENARIS 3SB connection types.

Notably, the advanced CRT, with associated advancements in control and data software technologies and indiscrete rig communication links, serves as the springboard for the evolving development of closed loop automation of the entire casing handling, landing and diagnostic operation.

Hazard-mitigation design. Despite well-documented advancements aimed at improving safety outcomes, running casing has been identified as one of the most incident-prone activities on the drill floor. According to Hubler,¹ casing running operations have been responsible for more than half of drilling deaths, despite casing-related operations accounting for a mere 10% or so of well cycle time. Documented incidents ranged from dropped casing to stabbers being fatally struck by traveling equipment and/or fill-up tool assemblies.

Efforts to mitigate those risks, while promoting casing running efficiency, have stimulated the development of myriad casing running tools and methodologies, all of which harness the performance and power of top drives.^2–5 Compared to the conventional technique, the deployment of casing running tools reduces the hazards, mainly by decreasing rig floor personnel’s exposure and interaction with rig equipment, while simultaneously enabling rotation, reciprocation and circulation through the casing.

Fig. 2. The Torque Turn system enables the overlaying of the last 10 makeup graphs (shadowing). This capability helps identify unusual profiles, and capture trends, to visualize average readings for a set of graphs.

The advanced CRT capitalizes on state-of-the-art developments in wireless control and data communication technologies to provide casing running services, without the need for a stabber or any personnel beneath the top drive or wiring scattered hazardously about the rig floor. The CRT is applicable for any type of top drive, which is used to apply torque and, if required, rotate, reciprocate and circulate (fill) while running casing and effectively navigate high tortuosity and equally challenging wellbores. The system delivers diameter and torque capabilities very similar to that of the power tongs employed in a conventional casing run.

Proprietary software comprising the plug-n-play wireless torque turn monitoring system interacts with external hardware to control and continually analyze connection make-up, which is graphically displayed in real-time, Fig. 2. A companion wireless torque sub is connected directly to the torque turn monitoring system, where it communicates RPM, torque in both directions, and both tension and compression hookloads.

Moreover, unlike standard mechanical or pneumatic control mechanisms, the full hydraulic controls of the automated CRT enable the application of constant force and torque, with fewer moving parts to be damaged or otherwise fail. In addition, rollers incorporated in the specially designed gripping mandrel eliminate marking or scarring of the casing, thereby promoting long-term integrity. The rollers also provide the capability to handle chrome casing without requiring any modifications, unlike conventional running tools.

Owing to the industry’s history of dropped casing, integrated redundancies, such as the safety interlock, were incorporated into the CRT design, effectively eliminating any dropped casing incidents.

OPERATIONAL SEQUENCE

The intrinsic hazards of conventional casing running are exemplified by the once-ubiquitous sight of a crew member physically stabbing each joint from a platform or basket, well above the rig floor. The preceding sequence in a labor-intensive conventional operation begins with setting the manual slips, manually latching the elevator, and stabbing the pin-to-box connection. The joint of casing is picked up from the V-door, using either bails and the side door or the center latch elevator. The joint is tailed in until hanging precariously over the well center, at which point the stabber guides the joint into the previous string now set in the slips. Floor hands then engage the power tongs to make-up the connection. The manual slips are pulled to release the string, which is raised before being lowered into the wellbore.

By contrast, once a crane installs the advanced CRT in the top drive, the casing is delivered to the edge of the V-door, whereupon the only direct manual involvement is one person to remove the thread protector and to control the stabbing guide. From this point forward, the successive steps for hoisting, connecting and landing the casing to bottom are largely conducted remotely from the driller’s cabin.

Once the flush-mounted slip, or FMS, is electronically activated and the gripping mandrel disengaged, the automated CRT elevator latches onto the next joint, which is picked up by the automatic catwalk. The link tilt assembly is remotely retracted, and the gripping mandrel is re-engaged in preparation for the lowering and automated stabbing of the joint. This is followed by the make-up connection with the torque turn monitoring system. Afterwards, the pipe is filled, and the FMS disengaged, before the casing string is lowered via push-button control from the driller’s cabin, with no direct human involvement on the drill floor.

COMPARATIVE FIELD ANALYSIS

A comparative analysis of casing running operations in one Middle East country illustrates the effective balance achieved between the time-tested reliability of the conventional methodology and the safety of the automated CRT technology. The introduction of the CRT notwithstanding, drilling programs in the region still stipulate that casing be run conventionally, specifically for smaller pipe sizes. Indeed, while conventional casing running consistently delivers dependable operational performance, the safety aspect is the primary driver for use of the CRT, in that strings can be connected and landed to bottom in optimum time, with zero LTI. Consequently, from the perspective of Parker, which also manufactures the advanced CRT, a snapshot of runs performed in 2018 shows the advantages in casing running speed when using the CRT, but the greatest benefit is found in the safety of the crews.

Fig. 3. Comparison of casing running speeds for conventional casing runs and those using the CRT in the Middle East in 2018, showing the most commonly used casing sizes.

Figure 3 compares conventional and automated CRT-enabled casing running operations in the Middle East during 2018, detailing the most widely used casing sizes, the number of joints and runs, as well as the casing speeds. Generally, for casing sizes larger than 7-in., operators chose to employ the advanced CRT, while smaller sizes typically were run with the conventional method. The average casing running speed of the CRT has improved consistently, while rig floor incidents remain at zero throughout the Middle East.

The analysis also points out an interesting trend in operators’ casing running strategies and whether to use the CRT or go with the conventional method. Specifically, the analysis shows the automated CRT being used largely for longer casing strings (133/8-in. and 95/5-in.), while clients typically prefer the shorter strings (20-in. and 185/8-in.) be run conventionally as a cost-saving measure. Full-string 7-in. casing is usually run with the automated CRT, unless it is being used as a short-string liner, in which case it is installed conventionally. Any diameter below 4½-in. is always run conventionally, as that is the smallest size capable of being run by the current CRT.

CLOSED LOOP EVOLUTION

Meanwhile, the barrier to automating the entirety of the casing running operation has been the lack of automation hardware and the inability to tie together various discrete systems. The new-generation CRT, in combination with advanced controls and specially designed data software technologies, however, clears the pathway for achieving the elusive semi or fully closed-loop casing running operations. Specifically, integrating the TopTek CRT with a cutting-edge control and data software platform overcomes the interoperability issue, where different vendor systems cannot operate in unison. Independent of rig type, the CRT, in tandem with equally rig-agnostic abstraction control hardware and software, can enable closed-loop on most, if not all, contemporary drilling rigs.

The data and automation platform enables connecting the newly designed CRT control with the rig equipment control network, to allow seamless coordination of all the activities necessary for full casing running automation. Establishing communication between the CRT and all the relevant rig equipment, including the top drive, draw works, mud pumps, automatic catwalk, and FMS, represents the first step in automating the casing running process. Additionally, the data platform can communicate with the rig operating system (OS) in its native protocol, be it modbus, OPC/UA, or something similar, which is likewise coupled with the CRT in its native protocol (i.e. modbus, OPU/UA, or private protocol). The data platform acts as a control abstraction layer, and therefore allows for full data and control commands between any variety of the rig OS and the Top-Tek system.

Further, the data and automation platform permit additional real-time algorithm deployment for streaming data computation. For example, as data are aggregated real time, a running torque-turn streams algorithm monitors the torque and turn measurement, but also delivers direct control of the rig equipment to precisely execute the casing make-up torque.

Full casing running automation will build further on the capabilities of the advanced CRT to improve even more on rig safety and efficiency. As a case-in-point, engineers are building off the success of the automated CRT to design a super-compact version, earmarked for the fast-paced unconventional drilling sector. 

REFERENCES

1. Hubler, W., “Hazards of casing operations,” presented at the IADC Health, Safety, Environment and Training (HSE&T) Conference, Houston, Texas, Feb. 5, 2014.
2. Shahin, N.D., T. Cummins and E. Abrahamsen, “Top drive casing running and drilling tools reduce well construction costs and increase safety,” SPE paper 105304, presented at the SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, March 11-14, 2007.
3. Saleh, K., A. Al-Shammari, N. Shadad, E. Mujahed, M. Abdullah Al-Jarid, D.G. Smith and C.D. Mattia, “Benefits of utilizing a fully mechanical casing running tool on a 630-ton casing string in Kuwait,” SPE paper 189411, presented at the SPE/IADC Middle East Drilling Technology Conference and Exhibition, Abu Dhabi, UAE, Jan. 29-31, 2018.
4. Zhang, H., T. He, N. Wang, G. Liu, L. Zou, Y. Huang, “Top drive casing running: Improving safety and efficiency of the operation,” SPE paper 155694, presented at the IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Tianjin, China, July 9-11, 2012.
5. Heenan, D., “Advantages of top drive moving to casing running,” Drilling Contractor, July-August 2003.