| Popis: |
GeoTap®, a new formation testing while drilling (FTWD) service, was introduced to the Valhall Flank Drilling campaign in May 2003. Introduction of this service was anticipated to be the most cost effective solution for gathering pressure data on these long horizontal wells. After the first well, the equipment was modified; and the rate of success increased from 20% to 90 %. As of November 2004, the service has been run in seven wells. In this paper, we review the value the service has added to the drilling campaign and also review the experience gained with the service during its first year. The drilling environment is dynamic with hydrostatic pressure constantly changing. The new tool offers the capability to perform pressure tests in this environment with the mud pumps on or off. As an essential part of FTWD job planning, estimates are made concerning the impact of hydrostatic pressure changes and supercharging prior to logging a well. In most cases, these estimates show that pressure data gathered with this service compare favorably to other pressure measurements, such as those gathered during perforating and stimulating. The field examples presented demonstrate the field procedures used to gather pressure measurements and the added value from acquiring this data during the drill phase. Knowledge of the reservoir pressure distribution in these wells was crucial to understanding flow dynamics across the field and optimizing well decisions. These data have also impacted perforation and stimulation procedures that would not have been foreseen using conventional wireline tests. The data have been used to optimize the drilling process by providing key information for the TD decision. Finally, conclusions are drawn regarding FTWD technology today and regarding its future direction for the Valhall Flank drilling campaign in particular. |
