The Leonardian Series of the structurally complex Permian basin had shelf to open marine depositional environment with many sedimentary features. Previous studies show the sediments were deposited as a large basin-floor submarine fan system and are commonly interpreted as deposits of turbidity currents. We interpreted the source of sediments coming in from the North and pro-grading into the basin as a gravity flow mass transport deposit. The following study investigates the nature and cause of this mass transport deposit within the Spraberry Formation and understand its compressional architecture. The feature mapped in the study area is 3.8 miles wide and extends 10.4 miles respectively. Seismic attributes such as a coherence and structural curvature are used to map the discontinuous mass transport deposit along with the lateral extent of the feature.

The Permian Basin is a structurally complex sedimentary basin with an extensive history of tectonic deformation. As the basin evolved through time, sediments dispersed into the basin floor from surrounding carbonate platforms leading to various mass movements. One such mass movement is observed on a 3D seismic survey in the Upper Leonard interval (Lower Permian) of the Midland Basin that is characteristic of a mass transport deposit (MTD). The 350 ft thick MTD mapped in the study area is 5 mi wide, extends up to 14 mi basinward, and covers only the translational and compressional regime of the mass movement. A unique sedimentary feature, unlike those observed previously, is mapped and interpreted as gravity spreading. MTDs have been extensively studied in the Delaware Basin of Permian-aged strata; however, only a few works have been published on the geomorphological expression of MTDs using seismic and seismic attributes to delineate the shape, size, and anatomy of this subsurface feature. The MTD in the study area exhibits an array of features including slide, slump, basal shear surface, and MTD grooves. In cross section, the MTD is characterized as chaotic with semitransparent reflectors terminating laterally against a coherent package of seismic facies, or the lateral wall. Sobel filter-based coherence, structural curvature, dip magnitude, and dip azimuth attributes are used to map thrust faults within the discontinuous MTD. Kinematic evidence provided by the Upper Spraberry isopach suggests that this MTD was sourced north of the Midland Basin and deposited on the basin floor fairway. Slope strata are interpreted from well-log analysis showing MTD as a mixture of carbonates and siliciclastics with a moderate to high resistivity response.

We analyzed a synthetic transfer zone and its associated fault planes and relay ramp in Penobscot, a potential offshore field in the Scotian Basin. Transfer zones are structural areas where one fault dies out and another fault begins, forming a relay ramp in the middle. They can be categorized as divergent, convergent, and synthetic transfer zones depending on the relative location and dipping directions of the faults. These zones not only play an important role in fluid migration but also help interpreters delineate secondary features such as fractures, splay shears, and Riedel faults. Commonly those faults would branch into smaller splays and the relay ramp can get “breached” with connecting faults with the increase of slip. The study area in the Scotian basin is characterized by two major listric normal faults dipping in the same direction giving rise to a synthetic transfer zone. These faults are clearly visible on seismic attributes, including curvature and coherence slices extracted along the top of the Cretaceous Petrel Formation. However, when analyzing the seismic attributes along the overlying Wyandot Formation’s top, we observe channel-like features, which run parallel as well as at an angle to these faults. However, when we performed further analysis using seismic amplitude’s vertical slices, interpreted horizons, and seismic attributes, we found that these features are not channels. We divided the features into two types, the first is parallel to the main faults and can be associated with the grabens formed by synthetic and antithetic secondary faults (NE-SW). The second type is related to the polygonal faulting associated with differential compaction and gravitational loading of the Wyandot Chalk Formation. Apart from the two lineations, there are NNE-SSW oriented lineations which are an impression of basement faulting, and NNW-SSE oriented lineations representing acquisition footprint.

Transfer zones  a feature where deformational strain is transferred from one fault system to another  play an important role in controlling fluid migration in the subsurface. More specifically, a synthetic transfer zone occurs where strain is transferred between two parallel normal faults in an extensional system. A previous study used surface curvatures derived from a clay model to highlight different geological features related to a synthetic transfer zone, including fault planes and relay ramps. We follow the same approach, applying our understanding to a 3D seismic survey to identify geological features related to a synthetic transfer zone. This study discusses the effect of synthetic transfer zones on an intrabasin extensional system, and describes listric normal faults and a relay ramp using the curvature and coherence seismic attributes. Our research area focuses on Penobscot, an offshore potential field in the Scotian Basin.

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