oa Controls on Economical Hydrocarbon Accumulations in the Askeladd Field, Barents Sea – A Post-mortem Fault Seal Analysis

The post-mortem study of a dry well is done by comparing the vertical and lateral sealing capacities of the faults bounding a dry structure with those of a proven gas filled structure. Comparison of buoyancy pressures measured in the discover well with threshold pressures calculated along the faults bounding the gas structure suggests that membrane seals estimated from shale gouge ratio are capable of holding the proven gas column. Lateral fault seal analysis in the faults bounding the dry well also suggests that they should be able of holding a gas column of similar dimension. Fault activity during Miocene time and the presence of seismic amplitude anomalies in sediments of Miocene age in both the dry an discover wells, the observation of a gas peak and oil inclusions in carbonate cement at the main fault and the presence of a paleo-hydrocarbon column in the reservoir in the dry well might suggest vertical leakage along the main faults bounding both the dry and gas filled structures. Considering the close geographical location and similarities in fault-zone processes and properties, fault seal analysis by itself does not explain why one well contains an economical hydrocarbon accumulation and the other not.