Well Planning Quality Improved Using Cooperation between Drilling and Geosciences

Abstract

Abstract To improve the quality of well planning and decrease the risks involved in drilling complex wells, E&P companies have been focusing during the last decade on collaborative work of asset team. A new workflow consisting in separating multi-disciplinary feasibility evaluation from detailed engineering has now been used on several projects. This workflow decreases dramatically the necessary cycle time to plan a well since only those alternatives that are viable for all disciplines are going through detailed analysis. The angle block of this method is the combination of a shared earth model with advanced three-dimensional visualisation techniques and quick, but precise evaluation tools. The use of constraints to define default values makes it simple to plan targets and wellbores only with 3D interactive graphic editing. Those constraints can themselves be relative to the structural geological model. Therefore the generated design is accurate enough to be trusted when used by the various evaluation functions. To assess the value and feasibility of a target/well solution, the asset team can use interactively drainable volume, wellbore position uncertainty, driller's target, wellbore collision and drillstring mechanical calculations. This approach has been used in different contexts for planning wells in an oil field in deep water western Africa and a gas field in Norway. For the field in the golf of Guinea, reservoir simulation has been used to define the location of horizontal drains. In Norway, an extended reach well has been planned using a 3D-reservoir model. The methodology has helped improve the overall understanding of the problem by sharing and explaining each other's constraints, thus improving the well planning quaAlity and reducing the design cycle time. Introduction Exploration and Production is synonymous with progress. New and always higher challenges demand new and always higher exploits, and all disciplines contribute to these achievements with advances in their respective field. In drilling, for example, there has been spectacular progress in areas such as directional drilling, bit technology and trajectory control. In geology and geophysics, there have been leaps and bounds in logging technology, seismic treatment, reservoir characterization, and geostatistics. In addition, progress in all disciplines has been propelled by "external" advances ranging from always greater computing power to 3D visualization and virtual imaging. This traditional pattern of progress in each discipline has been altered by new givens. Growing pressure from the financial side has radically increased in the space of ten years, putting a tight harness on spending. Efforts have become focused on cost-cutting and on higher, faster returns on investment. Teams have shrunk drastically. At the same time, Exploration and Production objectives have grown more ambitious, demanding better, faster improvements all the time. These demands focused notably on wells with complex geometry. At TotalFinaElf, earlier experience in Libya had demonstrated the benefits of collective efforts in solving such complex problems. By combining expertise in reservoir engineering and subsurface geology and drilling, rapid and efficient solutions were found at the time with the limited means available. For processes and activities requiring the participation of several disciplines, it was clear that a synergy of know-how, with all teams and disciplines working hand-in-hand, offered promising potential for progress.