Integrated Structural and Stratigraphic Architecture of the Texas Hill Country

Disciplines
Geoscience
Category
Conventional Reservoir • Foundational • Reservoir Characterization • Unconventional Reservoir • Subsurface
Format
Field Course 
Available
Public • Private 

Who Should Attend

Geologists, geophysicists, engineers, managers, and technicians seeking to enhance their comprehension of the stratigraphy and structure of the Texas Hill Country will find that outcrop exposures provide invaluable insights into the relationship between these elements. This understanding is fundamental to improving hydrocarbon discovery, production, and storage in the subsurface.

Description

This field-based training focuses on understanding the development of Cretaceous carbonate reservoirs, analogous to those found in the Gulf Coast basins, Middle East, and southern hemisphere. By studying shelf-to-basin reservoir elements in the Texas Hill Country, we can gain valuable insights into the factors controlling hydrocarbon production in these regions.

 

Our understanding of reservoir analogs begins with a bottom-up approach. Starting in the Precambrian Llano area, we traverse significant stratigraphic units and examine the tectonic history that has shaped the Texas Hill Country and Gulf Coast basins. At each stop, we discuss subsurface accumulations and observe outcrop analogs of actual reservoirs. This direct observation allows participants to see how depositional and structural features interact to influence hydrocarbon recovery challenges.

 

As we progress from Precambrian and Lower Paleozoic reservoirs, we introduce elements that influence the deposition and deformation of Aptian through Campanian reservoirs. Throughout our journey, we witness a significant change in depositional style and discuss the impact of Oceanic Anoxic Events (OAEs) on shelf-to-basin stratigraphy. Post-depositional extensional faulting highlights the importance of heterogeneous rock properties on fault-related fractures, a crucial element in carbonate reservoirs. We conclude the trip by examining the Cenomanian-Campanian units of the Eagle Ford Shale and Austin Chalk.

 

During the field trip, the instructor discusses the petroleum systems of Texas, the deposition and stratigraphy of Pennsylvanian and Cretaceous sediments, and the characterization of faults and fractures in carbonate rocks. Participants are encouraged to consider how outcrop-scale features appear in subsurface data, such as seismic or well logs, and to explore how this information can be used to infer reservoir behavior across various scales.

Learning Outcomes

·         Improved knowledge of Texas Gulf Coast stratigraphy and tectonic elements. 

·         Appreciation of the importance of understanding the petroleum system as it develops spatially and through time.

·         Observe key reservoir elements in outcrop exposures and understand the shelf-to-basin stratigraphic relationships. 

·         Learn about OAEs and their importance to the Cretaceous reservoir-source rock systems.

·         Recognize secondary deformation in outcrop and learn to think of these elements as 3D objects that can be both seismically resolved and smaller than current seismic resolution.

Course Content

Day 1 

SCA Office to Stop 1.1 – 3.5 hrs

Stop 1.1 - Wirtz Dam – Precambrian basement – Tectonic overview, fracture shear zones 

·         Stand on the Precambrian

·         Discuss the role of uplifted blocks on tectonic and stratigraphic systems

·         Overview the Paleozoic tectonics

·         Discuss fractured basement reservoirs 

Stop 1.2 - Hoover Dam Overlook – Kingsland, TX 

·         Lower Paleozoic sandstones and carbonates 

·         Paleozoic Ouachita Tectonic Framework 

·         Extensional faults in compressional systems

·         Ordovician Ellenburger reservoirs

Stop 1.3 - Pedernales State Park

·         Paleozoic-Mesozoic unconformity

·         Onlap of Cretaceous Systems

·         Pennsylvanian faults and fractures

Stop 1.4 - Hammet’s Crossing

·         Conglomeratic erosional shedding from Paleozoic high

·         Onset of a significant carbonate system (Aptian Cow Creek Fm)

·         Influence of nearby exposed craton evident from the Hensel Sand

Stop 1.5 - Hamilton Pool Reserve

·         Nicely exposed Hammet (Pine Island) and James Lime

·         Discuss significant outcrop to basin core profile (Kerans, Phelps, Zahm and others) that extends into Pearsall Field in S. Texas

Stop 1.6 – Jacob’s Well

·         Tie Paleozoic structures to Oligocene Balcones Fault System

·         Discuss relationship between faults, dissolution and carbonate stratigraphy to aquifers

Overnight in Wimberley/Dripping Springs area

https://maps.app.goo.gl/XCTnkwpSfW8rFBwx8

 

 

Day 2 –

Stop 2.1 - Canyon Lake Dam (core for Cow Creek) and Spillway

·         Finalize the Cow Creek-Hammet-Pine Island-Bexar stratigraphic system

·         Observe seismic-scale extensional fault zone

·         Discuss the role of secondary structures on fault zone permeability

Stop 2.2 - Hwy 46 Rd Cut

·         Interaction of small faults and mechanical stratigraphy on fault-related fractures

·         Discussion of fault damage zone evolution and the importance of heterogeneous mechanical layering

 

Stop 2.3 – Natural Bridge Caverns

·         Confluence of faults, stratigraphy and secondary dissolution

Stop 2.4 - Hwy 3009 Eagle Ford slumps

·         Introduction of Buda, Eagle Ford and Austin Chalk systems

·         Syndepositional deformation of the Eagle Ford in the Late Cretaceous

·         San Marcos Arch and paleogeographic distribution of the Cenomanian-Santonian-Turonian system

Stop 2.5 - Green Mountain Outcrop (behind Target)

·         Deformation styles of the Eagle Ford-Buda system

·         Compare the deformation styles of heterogeneous stratigraphic zones within the Cretaceous

·         Summarize the day and trip

Return to SCA (3 hrs)

https://maps.app.goo.gl/xgcr5wUPcraHmfe37

 

In-Person

Length
2 Days

Upcoming Events

Instructor

Christopher K. Zahm, PhD headshotChristopher K. Zahm, PhD