This paper details a study that was completed at the end of 1999 to investigate the suitability of using existing, high quality, conventionally processed 3D seismic data (hereafter 3D data) to replace specifically commissioned 2D seismic site survey data (hereafter 2D site data). For this study, three wells from an existing dataset of six in the West Delta Deep Marine Concession, offshore Egypt (WDDM) were investigated. A prescriptive workflow was developed using the 3D data and the results compared to those obtained from a conventional previously commissioned 2D digital site survey dataset. For this dataset from WDDM, the results obtained from the 3D data and the 2D data were similar, the main difference being that more numerous, smaller probable hazards were prognosed by the 3D data. After undertaking this investigation and following an independent review of the results, a recommendation was made to operate the 2000 WDDM drilling campaign using hazard prognosis from the conventional 3D data, i.e. not to acquire well-specific, new digital site surveys. This recommendation was followed and five exploration wells were drilled in 2000 with no specific, digital site survey data being acquired. No safety, operational or environmental implications were encountered as a result of this replacement and significant operational savings accrued to the operating partnership.
The Armada development comprisest hree gas-condensatefi eldsint he CentralNorthS ea: Fleming (PaleoceneM aureenFormation reservoir),D rake andH awkins (UpperJurassic FulmarFormation reservoirs). Armada cameon streamin1997,withsevenPhaseIwells producingataplateaurateof450 £ 10 6 SCFD.APhase II drillingc ampaign,c omprisingthree Armada wells,wasimplemented in2 002 withthe aimo fe xtendingthe duration ofthe Armada production plateauand, wherepossible, accessingnewr eserves. The first well wasa relatively straightforwardP aleoceneM aureenFormation producer,a lthough the targetw asr evised based on a newseismic attributestudy,which revealed important heterogeneitiesinthisdeep-marinereservoir. The second well targeted the undrilled western compartment ofthe Hawkins discovery. Unfortunately,the FulmarFormation wasw ater-wetw ithno evidence for any hydrocarbon charge, despitethe factt hatgashad beenp roved byan earlierexploration well inadowndipcompartment.Fortunately,to mitigatethe risks,which had beenrecognized pre-drill,the well had beendesigned withasecondary PaleoceneMaureenFormation targetwhich cameinbetter thanprognosed.Asignificant aspecto fthe Armada PhaseI Iprogrammewast he extensivei ntegration across anumbero f disciplines. The combined teamw ass oon ableto proposeaconvincinge xplanation for the failureofW est Hawkins,givingcomfort thatEast Hawkins shouldbef ully charged andwasworthdrilling.The finalPhaseI I well wasthereforetargeted on East Hawkins,although itwasadifficult well to planasthe keyreservoirhorizon had only minor stand-off from the gas-watercontact. Anumberofdifferent well trajectorieswereconsidered and 3Dvisualization proved invaluableinensuringthe finalwell pathwasoptimized.Inaddition,amajor benefitwas derived from arecently installed onsite3Dvisualization centrethatenabled the multidisciplinary Armada teamto worktogethervery effectively. For example, the drillingengineers weretruly ableto appreciatewhatwasdriving the geotechnicalr equirementsfor the well andvice versa.The well camei nv ery closeto prognosis,a dding valuablereservesandfurtherextendingthe Armada plateau.Witharig on the Armada platform the opportunity wastakentodrill the SouthWest Seymour prospect,whose chance ofsuccess had increased dramaticallyafterapossibledirecthydrocarbon indicator wasrecognized on an inverted seismic volume.The well discovered hydrocarbons inthe primary target,the FulmarFormation andalso inthe PentlandFormation andwasimmediately side-tracked to apreviouslyplanned updipFulmardevelopment location.
Slope channels are increasingly being recognised as highly prospective deep water exploration targets . An extensive dope channel system is exceptionally well developed in the West Delta Deep Marine Concession, offshore Nile Delta, operated since 1995 by BG with partner Edison . Withm the concession the Scarab, Saffron, Simian, and Channel 12 & 13 systems have all recently been successfully tested by a number of exploration Wells (Figure 1) . When gas-charged these Upper Pliocene E[ Wastani Formation channels are spectacularly imaged by 3D seismic, both in time sections and through a variety of amplitude extractions . Remarkable variations are revealed in their stratigraphic architecture, with changes apparent both withm individual channels and between the different channel systems .A variety of trap types are evident . The majority of the channels exhibit well developed flatspots to the north where dip-closure is evident . Up-dip closure varies between dip, fault and perched contacts . Typically, the shale-dominated channel margins provide the lateral seals . Gas trapeed witkin the structures is derived from a mixture of biogenie and thermogenic activity .An extensive program of core and wireline log acquisition and analysis kas enabled high resolution definition of the channel-fill sediments and their depositional geometries . The channels veere initiated by the introduction of coarse sediments to the shelf edge possibly at times of relative sea-level faal . Gravity transport of this material down-dope either initially caused slumping or followed the love topography of pre-existing slump stars . In some channels there was significant erosion in areas up depositional dip prior to infill/backiill from love and high-density turbidites, debris flows, slumps and slides . Subsequent channel evolution varies from backfilling, plugging by slumping to re-incision .Tere is an excellent match between the seismic expression of the channels and their fill and a channel model kas been developed based on integration of the well and seismic data . The model reveals significant variations in the architecture and likely production characteristics of the channels . Internat connectivity is promoted by the thin-bedded turbidite, laminated and levee facies . Detailed examination of the seismic data also reveals insights into the smaller state channel depositional architecturen and a vide variety of channel types have been identified . Some elements of the channels are characterised by near-vertical aggradational stacking of nested channels . In other channels the sands are laterally extensive and display welt developed accretion surfaces .
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