Integrated field Study in a Mature Oil Field on Economic Recovery of Remaining Potential using the Brown Field Ruhlertwist as an Example

摘要

The Ruhlertwist oil field is located in the West-Emsland area near the German-Dutch border. It represents the western part of the Riihle structure and is separated from the oil field Ruhlermoor to the east. GDF SUEZ E&P Deutschland GmbH is the operator of the field. Production commenced in May 1949, the cumulative oil production as of end 2014 is 5.9 million m3. This represents a recovery factor of 31%, which has been achieved with the help of 183 wells. The field production has been stabilized at 20,000 m3 of oil per year, predominantly by sidetracking six wells and improving the sweep efficiency with the help of managed water-flood taking the existing infrastructure into consideration. These projects were identified by means of Reservoir Monitoring as well as the application of conventional reservoir engineering principles. The identification of additional projects to accelerate oil production and to increase the recovery factor of the mature oil field Riihlertwist has reached its limit, especially regarding increased investment needs. Infrastructure expansions as well as the vicinity to the village Twist represent particular challenges here. However, GDF SUEZ as well as other international E&P companies are convinced that the recovery in brown fields in many cases can still be increased by applying both new and proven technologies, even when the field has produced for more than 50 years and when there is a dense wellborn pattern. For this purpose, a team of geoscientists and reservoir engineers of GDF SUEZ revisited the field to identify additional potential that can possibly be unlocked by sidetracking wells, drilling horizontal wells, or by applying tertiary recovery methods. These measures combined with optimized operational techniques have the potential to improve overall field economics significantly. It is the objective of GDF SUEZ to eventually in- crease the field recovery factor to more than 40%. In the following (i) the integration of 65 years of field production history, (ii) the creation of a geo-and simulation model, and (iii) the results and sensitivities of the history match process are presented. Subsequently, the possible oil potential as well as a first assessment of projects is illustrated, followed by an outlook of the steps required to complete a field optimization plan.