Managed Pressure Drilling (MPD) technology was used to successfully drill challenging hole sections, and to run and cement casing strings for a deepwater campaign in the Gulf of Mexico. Because this technology offered the advantages of precisely manipulating the annular pressure using a statically underbalanced mud weight within a narrow pressure window, MPD was also employed along with real-time downhole measurements (from XACT), to run the lower completion assembly into the drilled production interval and perform downhole operations.
For this specific case, the prognosed pressure operating window was around 100 psi, however; the actual window was found to be 50 psi when losses were encountered while drilling the openhole section through the target reservoir. Consequently, the completions operations required the most accurate modeling and planning to keep losses at an acceptable rate while avoiding an influx or formation collapse. MPD was utilized to precisely manage downhole pressures while running the lower completions assembly, displacing the drilling mud with completions fluids in the openhole section, and monitoring losses during the breaker acid job.
A complex pump schedule was created by analyzing the pressure at several critical points in the open hole. Through back pressure management and high-resolution losses rate seen through the Coriolis flow meter, these losses were kept at a reasonable level to avoid breaching the pore pressure gradient and the wellbore stability limit. This paper describes the planning and execution processes that made this deepwater managed pressure completion job a success.