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Jones O.,BP Exploration and Operating Company | Ewans K.,Royal Dutch Shell | Chuah S.,DHI Water - Environment - Health
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2013

Utilizing the independency of tide, through-flow, surge and high-frequency currents in the Singapore Straits, a Monte Carlo simulation method of combining the different components is proposed, expanding the horizon of available measured and modelled data and facilitating the definition of design current speeds. The statistical model proceeds by, first, making N number of random picks from the non-exceedence probability distributions of the surge, through-flow and high-frequency components. The number of random picks made in a given year for each component, N, is defined by assuming its occurrence rate is Poisson-distributed around a known annual mean value. N number of random start times are then chosen from each year and the maximum value of tidal current predicted over an ensuring 3-day window is combined with the randomly sampled component (either surge, through-flow or high-frequency current). Assuming an intended design life of 50 years, this process is repeated N number of times in each of the 50 years and for each current component, yielding 50 annual maximum values. For random 3-day windows that overlap, the model takes the vector sum of the maximum tidal current and the 2 (or 3) concurrent components. The process is repeated 1000 times, producing 1000 * 50 values of annual maxima which are then assigned non-exceedence probabilities. Return Period levels are obtained directly from the non-exceedence probabilities. The method provides a reduction in design current when compared to values derived by multiplying the exceedence probabilities of the varying independent contributions directly. Copyright © 2013 by ASME. Source

Ward M.V.,BP Exploration and Operating Company | Pearse C.,BP Exploration and Operating Company | Jehanno Y.,BP Exploration and Operating Company | Jehanno Y.,ConocoPhillips | And 3 more authors.
Geological Society Special Publication | Year: 2014

The Machar Field in the UK Central North Sea is a fractured Cretaceous chalk and Palaeocene sandstone oil reservoir, developed around a tall salt diapir. Machar was discovered in 1976 and, after a lengthy appraisal including extended flow tests starting in 1994, has been developed in a phased manner from 1998 through a multi-well subsea development. The steeper eastern flank has historically lacked coherent reflectivity on seismic data and has remained undrilled. The geological possibility of a reservoir on the east flank provided motivation for extensive seismic reprocessing between 2005 and 2007, and the seismic interpretation showed both a chalk and a sand presence in this area of the field. Simulation modelling suggested that a well here would deliver substantial incremental field volumes. Confidence in the new seismic interpretation reduced the subsurface risk associated with the area, and a new subsea drill-centre reduced the drilling risks and costs sufficiently to allow a Machar East well to be sanctioned. Successful well results in 2008 changed the entire perception of the field and acted as a springboard for further development including a sidetrack in the northern area and a third injection well to support the east, which was drilled and completed in the summer of 2010. © The Geological Society of London 2014. Source

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