The development of systems for improving the management of downhole pressure has gained significant attention from the industry throughout the last five years. Many different concepts have been proposed and developed, but only a few field tests have been performed to demonstrate their capability in authentic operational scenarios.
Considering this lack of operational experience, the present work describes the efforts for planning and executing a series of four wells using a new managed pressure drilling (MPD) technology based on the Micro-Flux Control (MFC) method. The first two tests are planned to occur by the first quarter of 2006 in a relatively benign land well environment prior to two other offshore applications.
The offshore wells are scheduled for the second half of 2006, but this drilling scenario is much more challenging than those of the first two wells. The MPD system will be installed to assist the construction of difficult HPHT well sections to be drilled from a jack-up rig.
Not only does the present work describe the main aspects related to planning and executing the four applications, it also presents an analysis of the overall performance including the hardware and the software of the MPD system as well as the interfaces with the conventional rig equipment. Along with the report of the aspects associated with training drilling crews and their performance during operations, all the main engineering information used for decision making while planning and operating at the well site are also included.
Exploration and development well construction keeps heading towards deeper targets in terms of both water and reservoir depth, yielding into a significant impact on operational costs. A recent study of historical data1 from the offshore activity along the Brazilian coast shows that longer operational times and technical complexity are responsible for those high costs. Besides that, it is observed that equipment failure and problems associated with geopressure, such as: well control events and loss of circulation, are, respectively, the first and second major contributors to non-productive time. The narrow margin between the pore pressure and the formation strength plays an important role in the well construction process. While drilling through salt layers, constructing high-pressure, hightemperature (HPHT) well sections or dealing with extended reach wells and long horizontal sections, the pressure increase at the bottom of the well caused by circulation often creates operational problems, leading to non-productive time. Particularly in deepwater, drilling through faulted, fractured or depleted formations frequently experiences losses of circulation. Depending on the drilling scenario, wellbore instability is a geopressure problem that may also occur. Conscious of these problems, the industry has been developing new techniques, labeled by the general name of MPD, in order to improve the management of downhole pressures. In other words, MPD is a family of technologies that offers more precise pressure management. It also provides fewer interruptions to drilling ahead.