| Geological heterogeneities prevent efficient drainage and sweep of hydrocarbons, causing low recovery efficiency in many oil and gas fields around the world. In this thesis, I provide a rock physics and seismic characterization of structural, depositional and diagenetical reservoir heterogeneities, from the pore to the field scale, of Tertiary fluvial sandstones in the mature giant La Cira-Infantas oil field. I introduce various applications of theoretical rock physics and geological interpretation of 3-D seismic data to improve recovery factor in oil and gas fields. The approach is presented in three parts:; In the first part, I present a rigorous model of faulting, folding, and slip distribution for the La Cira-Infantas oil field. The structural style consists of a single alignment of anticlines, arranged in a left-handed en échelon pattern, which are highly fractured by coexisting normal and reverse separation faults. A simple parallel and small-displacement wrench zone, poorly developed during the Miocene to Pliocene, explains the folding, thrusting, and normal faulting of the Tertiary deposits in the La Cira-Infantas structure.; The second part describes a rock physics model for relating the elastic reservoir properties to porosity, mineralogy, pore fluid, and differential pressure. This study found that if subsets of log and core data are used that are constrained by a sequence stratigraphy framework, meaningful rock physics relations can be determined. These relations can be rationalized and explained by effective-medium models.; By analyzing well logs and core data, a governing rock physics model was determined. The model implies that velocity and acoustic impedance are reliable reservoir quality discriminators. Specifically, high velocity and impedance correspond to shales while low velocity and acoustic impedance indicate high-quality sands. I applied this concept to map heterogeneous reservoir properties.; Finally, in the third part of this dissertation I present a rock physics model for identifying the quality of rock and pore fluid in a cased hole from dipole sonic data, as well as for monitoring temporal changes in the reservoir from repeated compressional wave data in the well. By analyzing the Vp/Vs ratio from multi-pole velocity logs, it is possible to differentiate between nonhydrocarbon- and hydrocarbon-bearing sands. |
