Dr. Alissa Henza presents:
Structural Inheritance in Rift Basins: Understanding Complex Fault Geometries and Interactions through Physical Modeling
Abstract:
Many basins have undergone multiple phases of extension, commonly with differing extension directions. Fault geometries and interactions within these basins are complex and vary both laterally and with depth. The faults within these basins influence local stress orientations, associated deformational features, and fluid flow. Therefore, documenting how these fault patterns develop and the controls on deformational patterns is crucial for understanding fluid flow in the subsurface for both hydrocarbon exploration and production and for carbon capture and sequestration (CCUS).
Bio:
Dr. Alissa A. Henza has over 12 years of experience in the oil and gas industry and has worked both conventional and unconventional assets worldwide. She received her B.S. degree from Cornell University in 2003, followed by a Ph.D from Rutgers, the State University of New Jersey under Martha Withjack and Roy Schlische in 2009. Although rift systems were the focus of her dissertation, Alissa is interested in any basin with a complex deformation history. Currently, she is working at Equinor US on the Deepwater US Gulf of Mexico.
We use scaled experimental (analog) models with wet clay to investigate how the properties of a population of pre-existing normal faults influence fault development during a subsequent phase of extension. In the first series of models, we vary the angle between two noncoaxial phases of extension by up to 45° (Henza et al., 2010). These models illustrate that the orientation of pre-existing normal faults significantly influence (1) the likelihood of fault reactivation, (2) the magnitude and sense of slip of the reactivated faults, and (3) the attitude, number, and length of the new normal faults depend on the orientation of the first-phase faults relative to the second-phase extension direction. In the second series of models, we vary the magnitude of first-phase extension, and kept the angle between the phases of extension constant (Henza et al., 2011). By varying the magnitude of first-phase extension, we control the degree of development of the first-phase fault population (i.e., the number, length, and displacement of the first-phase normal faults). This series of models reveals that the magnitude of first-phase extension strongly influences the fault geometries that develop during the second phase of extension and the interactions between the pre-existing faults and new faults.
After the initial publication of these models, several research groups published seismic examples of fault geometries and interactions from rift basins with multiple phases of extension. These papers provided us with new analogs for the models and motivated us to look at the three-dimensional variability in fault geometries and interactions with depth (Withjack et al., 2017). Serial sections through the model highlight that the style and geometry of faulting can vary both laterally and with depth. In addition, individual faults are complex structures, composed of linked fault segments with strike, dip, and slip (magnitude and sense) that vary with depth and through time.
15 сен 2024
