Mapping of Lower Cretaceous (Knurr Sandstone) turbidite lobes using Seismic Stratigraphy and prospectivity along the southern Loppa High Margin, Hammerfest Basin, Barents Sea, Norway

Abstract: The Hammerfest Basin was formed through downfaulting in Late Jurassic-Early Cretaceous times, allowing the deposition and preservation of Jurassic sediments which later were covered by thick Cretaceous sequences filling in the basin. This study has been conducted along the southern margin of the Loppa High to develop a complete sequence stratigraphic framework and to map Early Cretaceous Knurr Formation turbidite lobes along the slope of the High. Six seismic profiles have been selected for interpretation along the southern margin of the Loppa High on the basis of the availability of good quality data. A complete sequence stratigraphic framework has been developed to mark the major surfaces (Sequence Boundary, MFS) by geologic characterization of high-resolution seismic reflection geometries (truncation patterns, sigmoidal reflections) and seismic facies using the coarsening-up, fining up and blocky GR log motifs from both the offset wells and the wells located on the seismic section. Two Wheeler Diagrams (Chronostratigraphic Charts) have been constructed for type sections to obtain better insight into the time relationships of the depositional system, and define surfaces of non-deposition, condensation and erosion. WinPICS interpretation software has been used for seismic interpretation. Sequence stratigraphic analysis has been carried out on two scales (3rd order and 2nd order cycles). The whole sedimentary package is divided into various sequences and system tracts. In addition to a detailed sequence stratigraphic analysis to investigate the hydrocarbon prospectivity, an Early Cretaceous turbidite sand lobe has been mapped (LHSG-84-428) using seismic stratigraphy and compared with a drilled analogue (well 7122/2-1). Two paleogeograhic maps have also been constructed to show the Early to Late Cretaceous progradation and accommodation space filling in the Hammerfest Basin.