The Niobrara is characterized by sweet spots that are isolated and small in size compared to the expansive area of the play. A new approach developed in the mineral industry that considers Niobrara sea floor chemistry and the effects of underlying basement lithology and fault reactivation, has the potential to augment seismic and help identify sweet spots earlier in the exploration process. Although the relatively soft Niobrara is characterized by variable structure, reservoir quality, and rock properties, sweet spots are associated with reactivated basement faults, heat, and fluids. Identification of basement lithology and faults using potential fields data in light of far-field stress modeling of basement fault reactivation, overlying sedimentary rock deformation, and heat and fluids predicted by specific basement lithologies, identifies areas favorable for sweet spot development. Geochemical analysis of drill cuttings and surface soils reveal specific geochemical fractionation sequences that are interpreted to reflect paleo-sea floor patterns of chemical deposition of groups of elements and hydrocarbons (HC's) that traveled together leaving =chemical trails' from a source to a depositional site on the sea floor. These patterns can be mapped and =vectored' because they provide directional and magnitude information. They are characterized by proximal anomalies that lie within and above petroleum accumulations and the distal anomalies that lie adjacent to and distant from petroleum accumulations. They can also be modeled in light of kinematic analysis of basement fault reactivation and overlying sedimentary rock deformation.
A Niobrara sweet spot is defined by profitability, which is determined by oil price minus production costs. Engineering and technology can improve productivity and is essential for the development of a low-porosity/permeability, self-sourced oil reservoir resource play such as the Niobrara. Geology of a sweet spot cannot be enhanced, only discovered. Although the geology of every sweet spot is unique, most are characterized by a concentrated oil accumulation, rich source beds, abundant seals, thermal maturity (often anomalous), dual matrix/micro-fracture porosity storage capacity, brittle reservoir facies, open natural fracture systems with the ability to be enhanced, adequate fracture permeability, and active basement faults. Seismic, in light of well data, is the primary tool used to find geologic sweet spots.
URTeC 1582697
