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.