Technology advances in casing running extend the reach of automation

Incremental advances in drilling technology have changed the face of operations. Today, machines perform many functions that were carried out only a few decades ago, using manual labor. Continuing investment is delivering technologies that are transforming those labor-saving devices into complete, automated systems. 

DELIVERING VALUE THROUGH AUTOMATION 

Drilling contractors are competing for projects in a complex operating environment. Operators want efficient and reliable rigs, and they also want to work with contractors who continuously apply technology to resolve operational challenges and deliver measurable improvements. At the same time, operators are looking for companies with a track record for strong drilling performance and a safety record that demonstrates a commitment to reducing risk and improving worker safety. 

Automation enables drilling contractors to deliver on every level, Fig. 1. When drilling activities are automated, people are removed from repetitive and potentially dangerous activities to focus on higher-level tasks that require thinking on a different level. Automation reduces human error and ensures consistency and reliability across complex drilling environments. Results from streamlining individual drilling processes have shown measurable performance improvements. This has led to the concept of integrating activities to enable more extensive automation for even greater gains. 

Fig. 1 A Nabors Rig X40 working in Colombia with integrated CDS technology to significantly reduce rig-down/rig-up time.

 A BETTER WAY TO RUN CASING 

In a conventional casing running process, the bail extensions are run with an elevator, carrying the string weight and moving the joints of casing to the well center after the catwalk, moving up with the casing joint in the carriage. In this process, the driller slacks off and positions the side-door elevator above the casing in the skate, then closes the elevator and floats the links to the well center. Workers tail the pipe with a tailing rope, apply thread compound by hand, and then position the pin into the casing box in the slips.  

After hoisting the casing joint from the catwalk and aligning it with the existing joint in the stump, the crew makes up the connection, using power tongs to connect the joint of the casing to the casing string. Then, the driller picks up the weight of the string, opens the slips, and runs the casing string into the hole. This process has failed to evolve over the past decades in onshore operations, and it relies on the crew to physically make up the casing string. 

Mechanization is the first step toward automation, because it shifts tasks from human muscle to machinery, leveraging the power of engines to perform physically demanding tasks. Machines continuously perform labor-intensive activities with consistent accuracy and precision, executing processes more efficiently and safely than a human crew. 

MECHANIZATION AND SAFETY 

Power tongs have been used to make up casing for decades, and they are one example of process mechanization that has improved oil and gas operations. With this tool, fewer workers can do the same amount of work as a larger crew that is using only manual tools. Power tongs increase control over torque application, making execution precise and the process repeatable, while reducing the amount of manual handling required. 

Despite the improvements that power tongs introduced in the makeup and breakout of casing connections, accidents continue to happen because of the need for manual intervention. Many workers have experienced strains, sprains and repetitive stress injuries (from repeated tasks like stabbing casing sections), as well as cuts, lacerations and pinched fingers and hands from inattentiveness when working with power tongs, elevators and other equipment. This is a significant driver for change. 

Improving mechanization to achieve automation—where machines perform tasks, make decisions and control processes with minimal human intervention—reduces the risk of injuries and accidents and takes performance to a new level. This approach uses an integrated solution, replacing power tongs and elevators with our CDS (CRT), which exemplifies our commitment to the mission, Fig. 2. 

Fig. 2 A drilling crew in West Texas running casing, using Autostab technology.

 DESIGNING A BETTER SOLUTION 

The transition to automated casing string make-up began with a review of the broader process. This assessment led to the identification of common contributors to flat time, including aligning the casing running tool (CRT) in the joint, making up the connection, and the intermittent filling up of the casing string with drilling fluid. 

Instead of focusing on isolated improvements, like applying power tongs to perform casing makeup and breakout more easily, this analysis placed the use of power tongs and other mechanized processes in the context of tubular running services (TRS), which integrates the casing running tool (CRT) into the rig and its rig operating system (ROS). It became apparent that automating key tasks like CRT alignment and making up connections could address common inefficiencies and eliminate many safety issues associated with running casing. 

The comprehensive Integra^TM TRS solution includes mechanical upgrades, in conjunction with software innovations, to optimize casing connection times and reduce the likelihood of joint damage resulting from human error, which historically has been the cause of safety incidents. 

The Integra^TM system includes the top drive, casing drive system (CDS) and SmartROS^® system (Fig. 3)—a proprietary, intelligent ROS that enables automation. The top drive powers the automated CDS, allowing it to rotate and reciprocate casing strings to total depth and leverages technology to streamline and automate the casing installation process, following automated workflows/recipes and implementing best practices to case the well while maintaining optimal wellbore integrity. 

This holistic approach eliminates silos that hinder efficiency and productivity in traditional drilling operations and seamlessly connects multiple processes under the control of an automated ROS. 

Fig. 3 A driller utilizing a SmartROS® rig operating system to automate actions from the chair.

UNDERSTANDING THE NUTS AND BOLTS 

Integrating the CRT with the rig’s hydraulics system diverts robotic flow to the CDS tool. Mechanically, three pressure transducers give feedback to affirm that the tool is safely operating before hoisting string weight, releasing string weight, or handling casing joints in the single-joint elevator. 

Software changes to logic in the top drive make it amenable to casing running applications. 

Interlocks and permissions that integrate casing running operations with the rig eliminate the risk of casing falling into the well or overloading the single-joint elevators. 

This technology allows parallel operations with the rig’s system. The drilling Human-Machine Interface (HMI)—the control panel the driller uses to interact with the rig—is placed into one of two optional casing running modes after the CDS is rigged up to the top drive. This augments the drilling HMI to have full functionality over the CDS tool and gives the driller access to the automation functions of autostab, auto-fill and auto-make up. These automation functions provide control of the casing running process and add value in the form of consistency and the ability to shave seconds off each connection. These add up over the course of a drilling program to substantial time savings on production casing runs. In one application, the time required to align the CDS tool with the joint was reduced from 30 sec to 10 sec. 

Time motion studies have shown that using a software-based sequence to automate operations can deliver consistent performance and connection integrity, regardless of who is in the driller’s chair, to bridge the gap between the skill level of a veteran driller and one with less field experience. In a West Texas field trial, CDS alignment time was reduced 67% by following the software-based sequence. 

Historically, the process of aligning the CDS tool in the joint was dependent on the driller, with the speed of completion determined by his level of experience, but with an automated recipe that guarantees consistency throughout the casing running operation, the need for experienced guesswork is eliminated. The recipe manager ensures that the distance to stab is always the same and that the torque and speed applied during each connection make up is unvarying. 

The system also includes parameters to detect cross-threading activity at the beginning of a make-up task. 

The programming has improved incrementally over time, beginning with integration of the CDS tool with the rig’s SmartROS^® system. As the gap is bridged between theory and physically controlling the rig based on data that shows what is happening at the rig site, software engineers are dialing in the code to operate equipment with a level of precision that historically was achieved only by the most experienced drillers. 

An example is the improvement to the block slack-off when using auto-makeup. Drillers typically keep an eye on the weight indicator and adjust slack-off to keep weight within a prescribed range. Initial code design focused only on threads per inch for slacking off the drawworks. After numerous trials to gather feedback from operations, the engineers modified the code to focus on weight, which enables a much tighter weight window to be maintained. 

PROVING VALUE IN THE FIELD 

In one application of drilling automation, an operator in Colombia employing conventional casing running operations needed to move several pieces of equipment to the rig floor, which required additional crew and exposed more personnel to safety risks in the red zone. 

The operator mitigated the risk to the crew by transitioning from conventional to Integra^TM TRS integrated casing running, installing an automated CDS and hydraulically connecting it to the top drive. Using an HMI screen, the driller was able to oversee operations as the system followed parameters entered to ensure a consistent connection was made throughout the casing run. This eliminated the guesswork of estimating the manual torque application needed for each connection and removed crews from the red zone. 

Automation shaved seconds off each connection, boosting the casing performance speed by 21% and cutting rig-up and rig-down time by as much as 70%, equivalent to 4 hr, (Fig. 4). 

Fig. 4. A comparison of rig-up (RU) and rig-down (RD) time demonstrates that automation reduces time between connections by as much as 70%.

 Automated stabbing is a critical part of the process for making up connections in the casing string. To enable Autostab, a recipe manager stores and applies the parameters recommended by the OEM, including top drive setpoints for rotation and torque, as well as speed inputs specified for each segment of the connection makeup process. Notably, cross-thread RPM is set low to detect cross-threading in the initial revolution, before rotation is increased to a higher spin-in RPM. In the final revolution to make up the joint, the shoulder-up RPM is adjusted to a lower speed and applies optimal torque. During the 30–40 sec when the top drive is controlling the CDS, rig workers can exit the red zone. 

The automated system also eliminates intermittent pauses when filling up the casing string with drilling fluid. An automated fill-up feature in the recipe manager allows the driller to enter the calculated strokes per joint to control the mud pumps, communicating through the CDS as the casing connection is made up. On a 500-joint production string where casing is traditionally filled every 20 joints for 10 min. each, there are 25 fill-up events, totaling 250 min. (a little more than 4 hrs). 

Another factor that contributes to flat time is aligning the CDS tool with the joint that has been boxed into the casing string in the rotary table. In manual operations, the amount of time this process takes is contingent upon the expertise of the driller. A link tilts stabilizer was added to the setup to mitigate external factors, like wind gusts that can sway the link tilts and affect alignment, and a bracket was placed over the actuator and secured to each link tilt, to limit the range of motion. Auto make-up is fine-tuned to reduce transition time between steps to expedite the process.  

These phases are combined in a complete makeup sequence, activated by the driller at the press of a button. If a connection is not properly made up, an interlock freezes the operation, preventing the driller from continuing until the warning is acknowledged and addressed. This feature drastically reduces the likelihood of a casing string dropping into the wellbore. 

The proprietary Autostab technology was deployed for the first time on a 7.625-in. intermediate casing run in the Permian basin. Automating the connection sequence eliminated four steps in the process for the driller. Field results show that the slips-to-slips connection time with Autostab was 2:12 min., compared to 2:06 min. following the traditional installation process. Although this first trial of the Autostab technology reflects a negligible difference in connection time between manual and automated makeup, it demonstrates the ability of the technology to achieve consistency that bridges the gap between an experienced and inexperienced driller in the field. 

A time/motion comparison shows less time was recorded between stabbing the CDS and making up the connection when relying on the automated software, Fig. 5.

Fig. 5 A time/motion comparison demonstrates that automation software reduces the time elapsed between stabbing the CDS and making up the connection.

 THE FUTURE OF AUTOMATION 

Automated casing running helps bridge the gap between inexperienced and experienced drillers and streamlines the entire process for greater consistency and efficiency. Integrating innovative technologies like remote torque turn, hydraulic elevators, and a catwalk tailing arm is revolutionizing drilling and mitigating potential risks at the same time. Untapped capabilities hold the promise of even greater automation in the near term. 

Automation for offshore drilling is already possible, with a TRS that provides a comprehensive suite of services and technologies for safely and efficiently running casing and tubing, allowing a single operator to control multiple devices. 

Engineers are looking at improving onshore automation, evaluating concepts for automating the tailing process from catwalk to well center to deliver completely handsfree casing running, making it possible for an operator to stipulate the depth and speed at which to run the casing, prescribe the amount of mud to fill each joint and to monitor displacement, so the driller needs only to oversee the process. 

Today, tying systems together with SmartROS^® technology enables the expansion of automation across a global fleet of onshore rigs. The depth-based recipes enabled by the intelligent rig operating systems have the potential to extend automation to allow casing makeup recipes based on depth and the ability to set depth triggers for running hole rates. 

It is clear that the industry will continue to pursue automation and optimization to capture increasingly greater value. Embracing technological advancements, like automation, enhances operational efficiency and creates a safer working environment for everyone involved in drilling operations.