Qualification of InLine DeWatering Technology

Abstract

Abstract Several fields on the Norwegian Continental Shelf are in the decline phase with an increasing production of water and gas, often in combination with reduction in production pressure. The available area for installation of new equipment on the platforms is often limited, and it is important to minimize both the operational and capital costs. Compact, inline separation technology could be a key technology for mature fields, and also for subsea fields at large water depths where the weight is critical. Statoil has identified inline separation as an important technology to increase the oil recovery at brown fields. Due to low foot print and low operation cost the technology could be suitable to increase and prolong water production from the reservoir. The technology would also make it easier for tie-in of new fields at existing installations. To utilize the technology there is a need for both inline gas/liquid and inline oil/water separation (dewatering). Statoil has been carrying out a qualification program to develop inline equipment for dewatering. The project has been a co-operation between Statoil and FMC Separation Systems, and has been carried out in the period 2008 – 2012. The technology is based on cyclonic separation devices with low or moderate pressure drops. An extensive development program has been performed with different geometries for the inline separators, including Computational Fluid Dynamics (CFD) study and testing activities both in laboratory flow loops and at the Gullfaks field. A full scale DeWaterer with 20 liners has been tested to investigate the effect of gas present. The operational window of the inline technology has been established, and the results show that gas and water can be efficiently separated from the well stream. The results will be presented in the paper. The conclusion from the work is that inline technology has a large potential to replace or reduce the size of conventional gravity separators topside, and also to be utilised for subsea separation at large water depths. The qualification work demonstrated that the dewatering technology for the Gullfaks application could separate water with a water quality of less than 500 ppm Oil-in-Water at low pressure drop (1 bar). Based on the qualification work the technology is considered ready for deployment in Statoil.