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The primary objective of this paper is to demonstrate the successful application of maturation modelling using velocity-based thermal conductivity in the whole cycle of hydrocarbon exploration (frontier, developing and mature) on the Halten Terrace, Offshore Norway. This seismic geochemical method, used as a critical technique for selecting a favourable block in the early stages of exploration in the early 80s, enabled Conoco and its partners to make the first oil discovery and the subsequent discovery of the giant Heidrun Field in the area north of the 62nd parallel.Additional data (modelled and measured) on the thermal conductivity and Ro values are now available, and provide an excellent opportunity to compare the original (pre-drilling) basin models and related modelled results of the early 80s with 1990s (post-drilling) state-of-the-art data and models. The results of the comparative study indicate that the velocity-based conductivity compares very well with measured data, particularly in an overpressured area where conventional porosity (modelled) based thermal conductivities were inadequate. The pre-drilling predicted values of heat flow, geothermal gradient and vitrinite reflectance (based on Arrhenius equation) and oil window limits also compared favourably with post-drilling measured results. Thus, the method of calculating thermal conductivity from seismic data provides a useful tool to integrate geochemistry and geophysical (seismic) data, to calibrate maturation models, and to enhance the value of geochemistry and basin modelling in hydrocarbon exploration.for basin modelling and hydrocarbon exploration.

Investigation oftwo deepwatergasaccumulationsint he NorwegianSea indicatethatp hasea nd amplitude spectraderived usingspectraldecomposition canbe used ashydrocarbon indicators. Specifically,this techniquee nhancest he ability to evaluatephasea nda mplitude anomaly conformance to structurea nd complements the moretraditionalutilization ofspectraldecomposition for thinbed analysis.The 6707/10-1Luvawell on the NykHigh encountered a156mthick column ofdry thermogenic gasandwas the first deepwaterdiscovery inNorway. Despitethe factt hatt he accumulation ischaracterized byawell developed flatevent,e xamination ofpartials tack broadband3Dreflectivity dataproved inconclusivei n substantiatingthe presence ofa namplitude anomaly conformant withstructurea tall offsetr anges. Amplitude andphasetuningcubeswerederived usingspectraldecomposition from near,farandfull offset-stack3Dseismic data.Strongamplitude anomaliesmost notably atfrequenciesless than10Hz,structurally conformant withthe observed gas/watercontact,a reobserved atall offsetr anges. Phasei nstability,a ssociated withrock property differencesbetweent he gascharged andb rinesaturated portions ofthe reservoir,results inananomaly int he phasetuningcube thatisalso most evident atlow frequenciesandisalso conformant withthe observed gas/water contact.Similarspectraldecomposition evaluation ofseismic dataoverthe OrmenLange gasdiscovery gaveequally dramatic results. Traditionalamplitude extraction methodologieso nt he full stack broadbandd atasets how an ambiguous amplitude anomaly withlimited conformance to structure.Spectraldecomposition ofthe samef ull stack datasets how well defined anomaliesatfrequenciesl ess than1 2Hz,i nbotha mplitude andphasetuning cubes,conformant withthe gaswatercontactprovenbydrilling.3Df orwardmodels built usingrock propertiesfrom the Luvaa ndO rmenLange wells haveb eenp rocessed withthe samespectraldecomposition softwareandsubstantiateobserved results. Spectraldecomposition analysis ofuntested prospects ino therareaso fthe NorwegianSea show bothphasea nda mplitude anomaliesatl ow frequenciesthatappearconformant withstructure.

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