Kinematics and Growth of Supra-Salt Faulting in the Paradox Basin: A Field and Subsurface Analysis
Abstract
Salt can provide the structure and seal necessary for hydrocarbon entrapment, however, it may lead structural complexities, such as compartmentalizing a hydrocarbon reservoir through supra-salt faulting. Outcrop analog studies provide exceptional opportunities to observe how salt-influenced fault
geometries evolved spatially and temporally. The Paradox Basin in southeastern Utah is an example of a salt-influenced petroleum basin where the petroleum system is directly associated with evaporites. Decades of petroleum exploration in the region have yielded in a broad subsurface dataset (e.g., seismic reflection data and well penetrations), with close proximity to world-class outcrops. Exposed supra-salt
fault
scarps have preserved kinematic evidence which provide tangible evidence to populate kinematic models that quantify the temporal and spatial evolution of this
fault
system. This study focuses on the Salt Valley salt wall, the northernmost and largest salt structure within the northern Paradox Basin. A 40 km long supra-salt
fault
array trends parallel to and detaches downward onto the NW-plunging salt wall. Through the use of 3D seismic reflection data, wells, published maps, satellite imagery, and a collection of structural field measurements, we are able to build a database that was used to make an integrated interpretation of the spatial and temporal evolution of the
fault
array. Several kinematic analyses coupled with detailed geometric
fault
descriptions were used to determine the growth history of the studied
fault
array that consists of a series of overlapping
fault
segments up to 12.5 km long, with throws of hundreds of meters, defining a series of crestal grabens and half-grabens. Secondary faults of similar length are present on the flanks of the salt wall. Along the strike of the
fault
array, there are notable changes in the dip direction of the half-graben master faults and regions of varying
fault
strikes. These changes reflect heterogeneities of the top-salt geometry.
Fault
linkage analyses such as:
fault
throw-length (T-L); throw-distance (T-x); throw-depth (T-z), as well as qualitative distribution of
fault
throws from map and strike views show that these segments are over-displaced, with a complex
fault
segment linkage history. We hypothesize that these over-displaced faults evolved with a hybrid
fault
growth model, where they initiated as isolated
fault
model but spent the majority of their growth history through coherent
fault
growth.
AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017