A new plug-in for GoCAD, originally developed for TotalFinaElf, integrates risk assessment within the shared earth model.

T-Surf has released Jacta, a plug in for its flagship GoCAD geological modeling software. Jacta adds uncertainty analysis to reservoir description and modeling. Jacta walks users through the process of reservoir characterization and model building, capturing the uncertainty inherent in each domain measurement.


Jacta captures structural uncertainty at seismic resolution as well as time-to-depth conversion errors. Internal architectural errors due to well density can similarly be quantified. Other error sources such as facies, petrophysical property distribution, fluid properties and contacts are integrated. Jacta provides a focus for the asset team by bringing together different domain specialists. This enables an integrated analysis of model construction and highlights the impact of different inputs, their uncertainty and interdependencies, on reserve estimation.


The software was originally developed under contract to TotalFinaElf and is now used by Chevron, Texaco, BHP and other members of the GoCad consortium. Jacta links to Microsoft Excel for economic feasibility analysis. An optional link with StreamSim’s 3DSL, the streamline simulator, allows dynamic investigation of high-resolution geological models.

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