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This paper describes some successful applications of Managed Pressure Drilling on deep exploration wells drilled in the Mediterranean Sea. Building upon successful experience utilizing MPD from HPHT jack-up wells, the Operators transferred the experience across to deepwater exploration projects. This represented the first known use of MPD on a floating rig with water depths up to 1,100 m, HPHT environmentand wells drilled to over 6000 m and BHP of up to17,000 psi. Extensive engineering, training and development of procedures were carried out prior to spud. MPD was utilized to drill up to drill four hole sections in the same well. Specific techniques were developed to handle floating drilling operations. The resulting benefits associated with MPD led to improvements in drilling performance, and eliminated many of the traditional problems faced on other HPHT wells in the area. MPD has now become an integral part of the well operating philosophy and has established new standards for drilling wells of this type in the area. Some critical wells were classified as wildcats with considerable pore pressure unknowns, coupled with narrow pore-fracture drilling window characteristic of HPHT conditions. MPD was able to minimize the problems faced on the wells by enabling various techniques to be utilized. These techniques included the use of pressure build up analysis to quantify formation pressures, the application of dynamic flow checks, dynamic formation strength limits, and the application of constant bottom hole pressure during dynamic and static drilling fluid circulation conditions. The planning, development and execution phases of the MPD projects are detailed in this technical paper. |
