Paper ID : 20100375 Successful, Proactive Managed Pressure Drilling Application Brought Added Value for Extreme Narrow Operating Windows in a 10 5/8-in x 12 1/4-in Hole Section in Southern Mexico

A significant number of various managed pressure drilling techniques (MPD) have been implemented in Southern Mexico at high-pressure, high-temperature (HPHT), depleted fields, especially in pay zones, to overcome challenging narrow window drilling scenarios. Although the MPD is normally used in reservoir sections, it is also considered as a solution in other nonreservoir sections where operational problems such as narrow window drilling, differential sticking, and gain/losses become serious obstacles to reach TD. This paper describes a case story where the use of a proactive MPD technique on a 10 5/8-in x 12 1/4-in hole section very successful solved such problems. Normally this hole section is drilled conventionally. However, the constant influxes and the subsequent partial and/or total losses of circulation during the well control events observed between 2,729 m MD and 2,989 m MD, coupled with the narrow operating window, made a feasible alternative technique mandatory in order to resume drilling without (or with less), influx/loss events. At the start of drilling the section, a pit gain was detected while drilling with 2.08 g/cc mud density. It was then necessary to increase the mud density to 2.09 g/cc and later to 2.10 g/cc in an attempt to bring the well under control. The mud weight was finally increased to 2.12 g/cc, switching the well into loss condition. 10 days were spent trying to advance in conventional drilling mode without successful. After the MPD call out, operations were restarted with an initial mud density of 2.08 g/cc and ECD of 2.11 g/cc; a constant bottomhole pressure (CBHP) feature was also added by applying suitable surface backpressure with manual chokes to effectively drill this critical stage. This paper explains how the MPD allowed us to successfully drill this intermediate hole section, optimizing drilling processes by decreasing nonproductive time (NPT) and mitigating problems seen in conventional drilling. Detailed planning aspects, such as MPD strategy, flow modeling, operational procedures, hazards and control operational risk are also described in this paper. Details