Sequence-Stratigraphy as a Tool to Improve Reservoir Management of the Eich / Konigsgarten Oil Field (Upper Rhine Graben, Germany)
Authors: Jantschik R. , Straub C. , Weber R. 
Published: December 2007

Abstract
The Eich / Konigsgarten oilfield is the most recent discovery in the Upper Rhine Valley. It was discovered in 1983 and full production level was reached in 1987. Due to the very heterogeneous nature of the fluvial and alluvial sediments of the Tertiary Pechelbronn Beds, lateral extension and connection of single sand bodies are difficult to determine. This uncertainty of lateral and vertical communication within the reservoir was the essential factor leading to a suboptimal production strategy and hence a loss in reserves. In 1993 an integrated approach using sedimentology, well-log interpretation, quantitative biostratigraphy and genetic sequence stratigraphy was used to improve the static reservoir model. Sedimentological data from core descriptions and existing reports were reviewed and reinterpreted under chronostratigraphic aspects. Quantitative biostratigraphy yielded a few time lines (zone boundaries) as well as significant support to regional interpretation and correlation of base level changes (ecological signals). All information obtained from sedimentology and biostratigraphy were integrated in a well log supported genetic sequence interpretation combining the existing sequence stratigraphic models for shallow marine deltaic settings with those from fluvial/alluvial plain depositional domains. The results of this study were subsequently used as input to a reservoir simulation study to better understand the dynamic processes and to evaluate future field development options. The Field Development Plan (FDP) led to a significant amendment of the previous reservoir management strategy resulting in a drilling campaign with 3 wells in early 1995 and the implementation of a modified water injection scheme. As a result of the interdisciplinary approach of sequence-stratigraphy, production geology and reservoir engineering in optimizing the future Eich / Konigsgarten field development, the ultimate recovery will be increased from 25% to 35%.

Introduction
Since more than 40 years BEB operates oil and gas fields in South Germany. The structure Eich / Konigsgarten is amongst the most recent and largest oil field discovery in the Rhine Valley. Giving an overview on the procution history of the reservoir the geological model will be presented. The reevaluation of the fields future potential has been initiated by the outcome of an 2D seismic survey which led to a modified structure map. Based on a new sequence-stratigraphic framework the geological model was updated and used as input to a reservoir simulation study. The previous reservoir management philosophy was evaluated and new development potential has been identified. Subsequently results were incorporated into and documented in an optimized Field Development Plan (FDP).

Field History
Already in 1953 the old gas field Eich was discovered by the exploration well Eich 3. It is located in the Younger Tertiary above the present oil bearing Tertiary Pechelbronn Beds. The gas field was developed by 7 producers and the cumulative gas production from 1955 through 1973 amounts to 120 × 106 m3.
The oil reservoir was found in 1983 by the exploration well Eich 21 targeted to a Rotliegend gas prospect. The northern Konigsgarten block was discovered in 1984. The oil field is located in the 100% Elwerath-owned Worms concession approximately 15 km north of the city of Worms in the Upper Rhine Valley (Fig. 1).
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