Fault Seal Prediction in Sandstone Reservoirs - A Quantitative and Calibrated Geo-mechanical Method

Sealing faults form a major element in trapping hydrocarbons. They can form crucial elements for trapping hydrocarbons and isolated compartments in reservoirs. Alternatively, faults can form leak zones and conduits for fluid flow. Prediction of fault seals is therefore essential for efficient hydrocarbon exploration, field development and underground storage of natural gas and CO2. Presented is a geo-mechanical method to predict the sealing potential of faults in sandstone reservoirs. The method is based on a field case with core samples, rock-mechanical tests and numerical calculations and was successfully applied and tested in two additional field cases. The result is a reliable quantitative, calibrated method and a newly developed tool, the reactivation circle, with which it is possible to predict fault the fault seal quality in sandstone reservoirs. The method is especially useful in clean sandstones in which abundant disperse clay or ductile clay layers present are not present. The key to predicting fault sealing in clean sandstone reservoirs requires predicting the formation of a sealing cataclastic gouge on a fault plane and the conditions that control its formation and sealing capacity. In predicting the formation of a sealing cataclastic gouge required the development of a technique for palaeo stress analysis.