Tue, Oct 12|
FWGS October 2021 Luncheon
Jeffrey Dravis presents 'How Understanding Physiographic Setting Enhances the Pursuit of Carbonate Plays: Case Studies from the Cretaceous of the Ancestral Gulf of Mexico'
Time & Location
Oct 12, 2021, 11:30 AM – 1:00 PM
Fort Worth, 777 Main St, Fort Worth, TX 76102, USA
Abstract: “Physiographic Setting” refers to a geographic region influenced by unique climatic and other
environmental controls that impact shallow-marine carbonate deposition. At both a global and
local scale, physiographic setting should be factored into the exploration for most subsurface
carbonate plays. By doing so, the geographic areas for delineating prospective carbonate plays
are greatly expanded.
Physiographic setting at a global scale determines a basin’s proximity to the paleoequator and
whether carbonate deposition occurred in a tropical, subtropical or temperate climatic belt. The
climatic belt determines paleotrade wind directions and strengths and their potential influences
on carbonate play type. At a local scale, physiographic setting controls bottom topography (i.e.,
platform versus ramp, or something in between), which strongly influences carbonate facies
occurrence and distribution.
This talk will demonstrate the influence of physiographic setting on modern shallow-marine
carbonate platforms in the Bahamas Platform Complex, by contrasting styles of sedimentation
across the northern Great Bahama Platform with those across Caicos Platform in the southeast.
Our newer models from the windier Caicos Platform (strong easterly trade winds) expand the
potential for discovering high-energy facies (isolated reefs; oolitic and/or skeletal-oolitic
grainstones; leeward margin reefs) in areas not predicted by the established northern Bahamian
models. Further, the strong easterly trade winds shed more carbonate sand off the leeward
margins of Caicos Platform, producing pronounced onlapping wedges of grainstones. Thus,
many ancient leeward platform margins that were influenced by strong easterly paleotrade winds
may be prospective as well. Caicos Platform trade wind models have direct applications to
Phanerozoic subsurface shallow-marine carbonate sequences that were located between 5 and 22
degrees north or south of the paleoequator.
Caicos Platform models translate beautifully to lower and middle Cretaceous carbonate
sequences around the ancestral Gulf of Mexico Basin. During this time, carbonate deposition
occurred in a tropical belt 10-15 degrees north of the paleoequator, influenced by strong easterly
paleotrade winds. Those winds better explain the paleogeographic location of several large
carbonate pools whose settings were problematical, based on guidelines from the northern
Bahamas. These pools are: Black Lake Field in Louisiana (Sligo-aged; 156 MMBOIP); Fairway
Field in east Texas (Pearsall-aged; 410 MMBOIP) and the interrelated Golden Lane and Poza
Rica Fields in Mexico (Edwards-aged; >2 BBOIP for each pool). For each pool, I will show
how their geological attributes confirm that strong easterly paleotrade winds played a key role in
their initiation and evolution, consistent with the guidelines developed from Caicos Platform.
Bio: Jeff Dravis is a consulting carbonate geologist, primarily focused on aiding
in the discovery of oil and gas deposits, or enhancing their development once they are
discovered. He also conducts numerous applied training seminars for industry every
Jeff received his Bachelor of Science degree in Geology from St. Mary’s University in
San Antonio, Texas. He obtained a Master of Science degree in Marine Geology from the
University of Miami’s Rosenstiel School of Marine and Atmospheric Sciences in Miami,
Florida. His thesis was entitled “Holocene Sedimentary Environments on Eleuthera
Bank, Bahamas.” Jeff then entered Rice University, Houston, Texas, to begin work on
deep-water carbonates under the direction of Dr. James Lee Wilson. He was awarded a
Ph D in Geology; his dissertation was entitled “Sedimentology and Diagenesis of the
Upper Cretaceous Austin Chalk Formation, South Texas and northern Mexico.”
Dr. Dravis began his professional career in Houston with Exxon Production Research
Company. There, he conducted applied research on carbonate facies, diagenesis and
porosity evolution, but also headed up Exxon’s worldwide training efforts in carbonates.
This training included teaching in-house seminars, as well as leading combined modern
(Bahamas and Florida) and ancient (Texas and New Mexico) carbonate field seminars for
In 1986, Jeff started his own consulting practice in Houston. First, he founded
Dravis Interests, Inc. to provide technical expertise and training in applied carbonate
petroleum geology to the oil and gas industry. Later, Dravis Geological Services was
created to handle all technical consulting projects. Jeff has completed 195 technical
projects worldwide, working on carbonate sequences ranging in age from Cambrian to
upper Tertiary. He has presented 310 in-house and field seminars to industry, both on a
public and private basis, including 73 seminars to Caicos Platform in the southeastern
Bahamas and numerous ancient field seminars to west Texas and New Mexico. His
training clients are domestic and foreign oil companies, both majors and independents.
Jeff is an Adjunct Professor of Geology at Rice University. Since 1987, he has taught
parts of graduate courses, taken students into the field, and served on thesis committees.
Starting in 2016, he began teaching the carbonate geology segment of the University of
Houston’s Professional Master’s Program in Petroleum Geology, and just finished his
fifth segment in mid-September.
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