Investigation of the Regional Extent and Controlling Factors of Residual Oil Zones in the Permian Basin
West, Logan M.
Residual Oil Zones (ROZ) are a growing target of investigation and production activity in the Permian Basin. ROZ is essentially refers to oil-charged reservoir rock from which oil has been displaced leaving behind low remaining oil saturation (ROS). The association of ROZ with tilted producing oil water contacts, unique diagenetic features, and oil saturations similar to ROS post engineered water floods has led to the attribution of ROZ to the 'natural water flooding' of oil reservoirs by increased hydrodynamic forces resulting from uplift and tilting during the Miocene , . Initial research into ROZ in the Permian Basin has focused on the San Andres formation, the primary unit of production across the Permian Basin. This study aims to further constrain the extent of ROZ presence, and in doing so, better understand the regional and/or local controlling factors. A literature review is carried out to identify fields known for ROZ or possessing traits that are commonly associated with ROZ presence. These fields are mapped and analyzed for in general geological characteristics. Initial results indicate that potential fields with ROZ are possibly stratigraphically and geographically constrained. To further investigate causal and controlling factors, an estimate of regional tilting is made by correlating regional Cretaceous strata originally deposited on a flat carbonate platform. The degree of tilting among the modern carbonates is sued as a proxy for changes in the paleo-potentiometric surface and hydraulic gradient as well as reservoir geology. Tilting and change in hydraulic gradient are compared to known locations of ROZ to estimate measurable influence of tilting on ROZ formation in the San Andres and what implications that has for ROZ throughout the Permian Basin.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013