The Rühlermoor oilfield with an OIIP of 110 × 106 m³ (692 MMbbl) has been producing for more than 45 years. Todays production is characterized by low average oil rates, high water cuts and increasing sand problems, which adversely affect the economics. Even after steam drive operations were started 18 years ago to mobilize the viscous oil (120 mPa ⋅ s, 25 °API), total recovery is still less than 25%, leaving considerable potential for additional reserves. With the objective of sustained profitability improvements a comprehensive study was carried out in 1994-1996. Based on re-evaluations of the reservoir, all surface facilities, and the cost structure, various development scenarios were analyzed by a multi-disciplinary team. A number of cost cutting measures were recommended and mostly realized. However, it turned out that a purely cost saving approach would improve the economics only for a short term.

Treatments like frac packs and water shut-off were tested with limited economic success. Cost effective infill drilling (re-entry) was identified as the most economic means to accelerate production and increase reserves in Rühlermoor. By upgrading a field workover rig, total drilling and completion costs could be reduced by 60% compared to a conventional rig.

The key conclusion of the study was that the combination of cost saving measures and production acceleration projects is the only approach to keep the field alive in the longer term.

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