Growth Juxtaposition Diagrams - A New Angle on an Old Technique

1D juxtaposition triangles provide a quick way to evaluate across-fault horizon juxtaposition and sealing capacity in the absence of a 3D model. The diagrams are traditionally derived from a single well source and therefore do not incorporate across-fault horizon growth; an assumption which negatively impacts on the accuracy of the modelled juxtapositions. However,constraints on the extent of sedimentary growth is often readily available from secondary wells or adjacent seismic reflection data. Using this data two new types of juxtaposition triangle, “Two-Well” and "Percentage Growth”, can be constructed. Deriving growth data either from a secondary well or as a percentage increase in across-fault thickening, the new techniques are used to model juxtaposition and shale gouge ratio on a kilometre-scale growth fault in the Taranaki Basin, offshore New Zealand. The results indicate that Two-Well and Percentage Growth diagrams provide a more realistic representation of the fault sealing capacity than a 1D solution.