5/2/2024 0 Comments Draugen platform design![]() Through partnership with Framo Engineering, Shell plans to install a subsea, multiphase booster pump downstream of the Garn West manifold, about 4 km from the platform in 280m water depth. In response, Shell will rely on technology similar to that first pioneered in 1993: mudline pumps. Subsea wells usually give a lower recovery than platform wells. This summer’s new seismic can hopefully tell us where we might locate additional future wells. We have planned four strategically placed subsea production wells for the upcoming drilling campaign, which will start shortly using the West Navigator drillship. The two last subsea wells were installed in 20. Four of the subsea wells were drilled and commissioned west and south of the platform in 20. Six of the 11 wells on Draugen today are subsea wells, while five are platform wells. Future subsea wells were included in the platform design phase and a significant subsea development was foreseen in the PDO (Plan for Development and Operation) document. This, too, would be done based on the “less is more” philosophy – not many, but efficient wells. Drilling additional subsea wells was part of the initial Draugen development concept. Seismic surveys have thus given us a good understanding of the reservoir dynamics, to see where the oil flows, and where it is trapped. Several of them have produced over 150 million bbl, which is more than many fields produce from all their wells throughout their entire field lifetime. There are relatively few wells on Draugen, only 11 production wells. If the location had not been changed, we would have ended up with a poorer well, with significantly higher water cut. That is one single well performing close to an entire oilfield. ![]() The outcome was a well that was tested at 78,000 b/d. To give an example: based on the seismic information acquired in 1998, we changed the location of a planned production well from west of the platform to more than 1km away to the north of the original target. Seismic surveys enable us to understand the reservoir dynamics and make even better decisions. The sixth seismic survey will be conducted in the summer of 2013, using PGS’ Atlantic Explorer. The next seismic will be broadband seismic, but still compatible with the previous seismic, such that 4D data still will be achieved. With the exception of one high resolution seismic acquisition in 2004, these have been conventional seismic acquisitions. The first seismic acquisition was made before production start-up and has since been repeated four times at regular intervals. We have continuously monitored the fluid movements in the Draugen reservoir by extensive use of seismic surveys. This approach raises the statistical recovery factor to 35-45%. By doing this, the reservoir pressure was maintained while also pushing the oil towards the middle of the field, where the platform is located. We installed water injectors at each end of a long and fairly narrow field. This key decision was already in Draugen’s Plan for Development and Operation (PDO), submitted in 1988. Our first step was to add pressure support. We therefore implemented an active reservoir management strategy. By natural underground pressure, the statistical recovery rate is expected to be only 5-15%. However, the good reservoir quality is not the only reason why Draugen has achieved such a high recovery rate. We are in the lead in Norway when it comes to extracting the maximum amount of oil out of a reservoir. The average recovery factor in Norway is 46%. Today the recovery is multiplied by four, now getting close to 70%. We assumed a recovery factor which seemed realistic at the time, in the late 1980s: about 17% of the oil would be produced. The producing formation had excellent characteristics. ![]() ![]() Oil from Haltenbanken had migrated eastwards and up, and Draugen was discovered at a shallower level than the other reservoirs in the area. Draugen was expected to reach end of field life in 2013, according to the initial plans, but we are currently in the process of extending Draugen’s lifetime till 2036.ĭraugen was discovered in 1984, in an area where most geologists did not bother looking for hydrocarbon-bearing reservoirs. In 2013, Draugen marks 20 years since the start of production. Draugen was the first field to be developed in the Norwegian Sea, pioneering production from an area which later became one of the important petroleum provinces in Norway.
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