Until recently many of the wells on US land that were drilled using Managed Pressure Drilling (MPD) technology utilized one size fits all equipment designed for the offshore market. Since the cost and personnel requirements needed to run the offshore manifolds became a challenge due to market conditions and Covid-19 restrictions, the drillers sought a cost effective and simpler system to conduct their day-to- day operations. The challenge was to drill long laterals in Permian and Haynesville without losing the necessary MPD functionality that proved beneficial to reduce the risks associated with safety and to enhance drilling efficiency. For the MPD control system experts, the task was to correctly identify and automate MPD system’s functionality that would be of greatest use to the drillers to sustain their drilling performance. The concept of developing an easier to operate control system was undertaken wherein system accuracy and precision was maintained at the forefront of the development process. Electric motors/actuators and necessary drivers that could work directly on rig power were selected and tested. Control system logic that operates the chokes was modified to quickly adapt to the changes in drilling conditions, maintaining the necessary accuracy. This was done by studying and understanding drillers activities and behaviors like automated pump ramp down speed during connections, pipe movement during tripping etc. Specific MPD engineering charts, simple to decipher graphs, and necessary calculation tables were developed for the drillers to use for managing bottomhole pressures. Calculations which included specific schedules for spotting weighted pills were provided to maintain simplicity of the operations and something the drillers could easily execute. Today, many drillers are using this MPD solution to drill long laterals (Hovland et.al 2020). This trend is slowly leading to reduction of rig MPD personnel, especially during Covid-19, while the drillers are getting familiar with and operating MPD systems. A few of the crucial items that have allowed the drillers to run MPD on their own include MPD controls connected to drilling automation systems and the subsequent continuous revision of these controls based on understanding drillers tasks and needs. The use of electric motors enabled quick adoption to the changing drilling conditions while making connections, tripping etc. The furnished MPD calculations and graphs that drillers could follow for applying required MPD choke pressures kept MPD adaption simpler. The modifications made to the MPD choke controls geared towards facilitating necessary automation enabled the drillers to get trained in few days and operate the MPD systems while maintaining the same level of speed and performance.
This paper highlights a case study where MPD (Managed Pressure Drilling) techniques were utilized while floating long string casings in the 10,000ft laterals in the Haynesville, saving the client more than 30-40% of rig time. The challenges encompassing the events that cause casing floating equipment conversion, either due to excessive gas, flow out from well or drag, are illustrated herein. This paper demonstrates the specific MPD techniques which facilitated floating casing to TD (Target Depth) and prevent its untimely conversion. The use of unique MPD methods illustrated herein enabled prevention of excess gas, hole collapse and situations relating to ballooning which enabled floating the casing to TD. These MPD methods helped reduce casing running times from 34-48hrs to 24-27hrs and prevented shut-in or "stop & circulate" scenarios during running casing. These shut-ins and/or "stop & circulate" scenarios were largely caused by increased flow out readings as the gas expanded at surface along with indications of well ballooning. Ballooning scenarios were later found to be associated with high surge pressures and higher SBP required to mitigate gas at surface. A holistic approach was taken to identify methods to mitigate such events. It was obvious that MPD pressures had to be manipulated for managing surge to mitigate ballooning, but excessive trip gas which necessitated higher MPD pressures while running casing had to be primarily evaluated. It was later found that excessive gas in these 10,000ft laterals were not just a function of swabbing pressures while POOH (pulling out of hole) with BHA (Bottomhole Assembly), but also related to POOH practices and methods which affected wellbore stability. To enable floating casing all the way to TD, first the MPD pressures and bottoms-up circulation strategy while POOH with BHA were analyzed and modified for the client. Second, the MPD balanced pill volume (which is typically spotted in the vertical) and its spotting procedure/calculations were revised to ensure minimizing gas encroachment and migration in vertical hole section. The design of this balanced pill accommodated automatic heavy pill displacement out of the well without the need for stopping and circulating pill while running casing. And third, the MPD control system was modified to automatically manipulate the MPD pressures as the casing was lowered to manage surge and prevent losses/ballooning. This paper illustrates how all of these methods enabled floating the casing in 10,000ft lateral in Haynesville.
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