Reservoir analogues of sand injectites - Internal heterogeneities and implications for reservoir modelling

Sand injectites have become increasingly important in the oil and gas industry. They have been identified in oil fields of the North Sea, West Africa and US Gulf Coast. Key to understanding the influence of sand injectites in hydrocarbon reservoirs is capturing the internal variation of geometry and petrophysics. However, little or no information is known about the internal architecture of these features. Outcrop analogues can be used to help predict this variation within the subsurface. The Yellow Bank Creek Injectite Complex (YBCC) of Santa Cruz, California is one such analogue. YBCC represents the largest sub aerial exposure of an injectite in the world. In fact, YBCC provides subsurface analogues for intrusions in the North Sea that act as reservoirs for the storage of hydrocarbons. The North Sea intrusions on seismic data extend laterally for kilometres. Numerous clastic intrusions occur on a similar kilometre scale over North West Santa Cruz and also store hydrocarbons. Accurate and quantitative description of sand injectites in the subsurface is essential for providing models for reservoir simulation. Outcrop analogues can help constrain sand injectite geometry and petrophysics within the subsurface. This improves the accuracy of predicting fluid flow behaviour within sand injectite reservoirs.