TGS Luncheon and Dinner Meetings
September 11, 2007 Luncheon
Production and Outcrop/Reservoir Characteristics of the Woodford Shale in South-Central and Southeast Oklahoma
By: Rick Andrews [BIO]
Oklahoma Geological Survey
The Woodford Shale and equivalents have long been recognized as a petroleum source rock in Oklahoma and in parts of the eastern US. In Oklahoma, production was established from several oil and gas wells during the early 1930’s. To date, over 250 wells are completed in the Woodford with a cumulative production of about 69 BCF and 4 MMBO. When considering commingling (and/or inaccurate reporting), the Woodford probably is productive from more than twice this many wells. Since 2000, about 160 Woodford (only) wells have been completed with cumulative production of about 23 BCF and 74 MBO. Interest in the Woodford skyrocketed in 2004 largely because of success in the Barnett Shale play in Texas. With extremely high TOC contents and natural fractures, production from this formation became even more lucrative with improvement in horizontal drilling technology and huge fracture treatments.
This talk includes outcrop photographs of the Woodford Shale of southern and eastern Oklahoma. Although many geologists are interested in this emerging unconventional reservoir, few really comprehend its physical appearance and megascopic haracteristics. Additionally, production decline curves will illustrate the performance of this reservoir from vertical and horizontal wells. [TOP]
September 25, 2007 Luncheon
A Geologist’s Guide To Explaining Natural Fracture Phenomena with Fracture Mechanics
2007-08 AAPG Distinguished Lecture
Jon Olson [BIO]
University of Texas, Austin
Funded by the AAPG Foundation
This is a review talk designed to introduce a geologic audience to the concepts of fracture mechanics and how they can be applied to make conceptual and quantitative interpretations of natural fracture phenomena. Examples are driven by outcrop and core observations and explained conceptually with simple analytical equations from fracture mechanics. More complex fracture relationships are briefly treated using numerical model results. The talk focuses on opening mode fractures (joints, veins, dikes) and how fracture mechanics can be used to predict their geometric attributes.
Examples include the relationship between in situ stress anisotropy and propagation paths, theoretical predictions of fracture length, spacing and aperture versus length distributions, the role of subcritical (stress corrosion) cracking on fracture clustering, and the concept of natural hydraulic fracturing. The influence of simultaneous diagenesis and fracture growth will also be discussed in the context of preserved fracture aperture (e.g., how does a fracture stay open when the driving stress is gone?). [TOP]
October 2, 2007 Dinner
Tails of the South Pacific
By: Viola Rawn-Schatzinger [BIOS]
Richard A. Schatzinger, PhD
The Indo-Pacific Ocean is the center for coral diversity worldwide. Corals, sponges, crinoids, algae, fishes and associated species show an amazing abundance in species and numbers in the warm waters of the south Pacific and Indian Oceans. For comparison the Caribbean has fifty species of corals, the Indo-Pacific has over 800 species of corals and over 1500 species of fish. Join us for a stunning visual tour of the islands of Palau, Yap, Chuuk (Truk), Bali and the Komodo Islands.
Apologies to James Michener for the title of our presentation. Michener’s Tales of the South Pacific was the basis for the popular movie and music, South Pacific that introduced Americans to Bali Hi and the beauty of these tropical islands. Michener traveled on and above the water during WWII. The wonderland of color and species below him was scarcely known until scuba diving became a popular sport in the 1960s-1990s. Today diving locations in the South Pacific and Indonesia are renowned for the diversity of large and small fish; invertebrates; and beautiful colored soft corals, sponges and crinoids.
The species diversity and the biological process have a profound affect on reef building activities that are difficult to assess when geologists study fossil reefs. A great many of the living species seen on coral reefs leave little or no fossil evidence. However, they contribute to the mass of coral reef buildup and the processes that form the reefs. Soft corals are the glory of Pacific reefs, yet are not seen as major contributors in reef building. Sponges which form a major portion of living reefs serve both as reef contributors and degraders. Rare fossil sponge casts and molds are outweighed by the volume of sponge spicules that create sediment, but do not contribute form to the reef. Boring sponges contribute to the breakdown of hard corals, and encrusting species of sponge attempt to cover every surface on the reef, living and dead. Algae contribute substance to reef matrix, yet are rarely viewed as reef builders except for unique algal mats formations. The humble sea cucumber or Holotherium is almost unknown in the fossil record, but the numbers of species – small to large – brightly contrasting or blending into the background – excrete pellets of fine sands and clays, that help form the ocean floor sediments. Common in the fossil record, Bryozoans are rare on the living reef. Crinoids, which are represented mainly by fragments of stems in the fossil records, are common across the South Pacific, and in the islands of Bali and Komodo are striking in both abundance and color. [CONTINUES HERE] [TOP]
October 9, 2007 Lunch
Thoughts on the Future of Energy and Energy Education
Larry Grillot
Dean of OU College of Earth & Energy [TOP]
October 23rd, 2007 Lunch
Structural Geology of the Spiro Sandstone Reservoirs, Arkoma Basin, Oklahoma: Implications for Gas Exploration
Ibrahim ÇEMEN Boone Pickens School of Geology, OSU, Stillwater, OK. 74078 [BIO]
(e-mail: icemen@okstate.edu)
Since 1993, the structure group at OSU Boone Pickens School of Geology has been working on the lower Atokan Spiro Sandstone gas reservoirs along the Frontal Ouachitas-Arkoma Basin transition zone in Oklahoma to determine their structural geometry, sealing mechanisms, pressure-depth gradient and mineralogy. The group produced 12 M.S thesis projects and constructed over 50 balanced structural cross-sections with using data from the wire line logs of over 1000 gas-wells, available 2-D and 3-D reflection seismic data, and surface geologic maps.
The group has determined that the footwall block of the Choctaw Fault, the leading-edge thrust of the Ouachita fold-thrust belt, contains a well-developed triangle zone to accommodate strain partitioning from the highly deformed Ouachita Fold-Thrust Belt into the mildly deformed Arkoma Foreland Basin. The deep Woodford detachment ramps up to the stratigraphically higher Springer detachment and serves as the floor to the duplex that contains most the structural traps of the Spiro reservoirs. The Lower Atokan Detachment splays from the Springer Detachment forming both a roof to the duplex structure and a floor for the triangle zone. A north-dipping backthrust bounds the San Bois Syncline to the south, and serves as the northern boundary of the triangle zone. The thrust is at the surface in the Wilburton Gas Field area where it is called the Carbon Fault. Eastward along the strike of the transition zone, the backthrust becomes a blind backthrust and the duplex structure contains fewer horses. The triangle zone also continues west of the Wilburton Gas Field area.
Almost all of the successful gas wells producing from the Spiro sandstone in the footwall of the Choctaw Fault in the Arkoma Basin, Oklahoma, have two major characteristics: 1) They are drilled into the structurally higher parts of horses within the duplex structure where thrust faults together with the deformation bands along the fault zones provide seals; and 2) they penetrate the Chamosite-rich facies of the Spiro sandstone. Therefore, we recommend that gas exploration in the Spiro gas reservoirs of the Arkoma Basin should be concentrated in: a) the structurally high areas of the duplex structure, and b) in the areas where Chamosite-rich facies of the Spiro sandstone exist.[TOP]
November 13, 2007 Lunch
Getting From An Idea To Proven Resources: Integrating Geoscience and Engineering
Lee F. Krystinik, Fossil Creek Resources
Put yourself in this spot… Regional and local analyses of an opportunity were very encouraging but the cost of testing the new concept was large and the chance of economic success was low and gas prices were questionable. It would take a lot of work to reduce the risk and everyone in the team was pressed for any spare minute.
Sound familiar? Would you commit to the work or walk away?
Uncertainty was high for many key variables and a fully integrated analysis was undertaken involving sedimentology, stratigraphy, structural modeling, basin modeling, geochemical analysis, pore pressure prediction, hydrodynamics, water chemistry, 3-D seismic analysis of reservoir continuity and structural features, diagenetic studies, extensive petrophysics, optimization of logging suites, drill-bit re-designs, new mud motors, horizontal well design and production modeling, completion design, infrastructure issues, environmental issue assessment, multiple outcome analysis and more. Debates were intense on whether to use the continuous accumulation (basin centered gas) model or more of a conventional reservoir model. Achieving success ultimately would depend upon how well the team could work and communicate with each other in ways their colleagues could relate to and use in their respective analytical approaches.
The well was drilled down to 16,000 feet through .85 + psi/ft pressure gradients, encountered temperatures above 300 degrees and then turned horizontal for another 2,000 feet. The horizontal leg was drilled using real-time geosteering, involving continuous communication between the geologists reservoir engineers and drillers. Two world-record depth horizontal cores showing 25 micro-Darcy rock were taken and over 1200 open fractures were indicated in the image log from the well bore. The well flowed at 15MMCFD and was still flowing at more than 7MMCFD two years after completion. This 15BCF well was a poster child for highly integrated geoscience and engineering at every turn, but the reservoir characterization story did not end there.
Production, further drilling and ongoing reservoir characterization showed that the system contains mobile water in the fractures, is composed of several isolated pressure cells, and that lateral variability in reservoir quality and fracture intensity can be large. Effort continues and the play concept remains valid, but much changed in form. The results of this reservoir characterization effort challenged the widely held continuous accumulation concept, proved a new play concept and identified numerous additional opportunities.
Speaker Biography:
Lee F. Krystinik has specialized in applied sedimentary and stratigraphic analysis to predict clastic reservoirs since he received his Ph.D. in geology from Princeton University in 1981. In 2006, he formed Fossil Creek Resources, an independent exploration company that uses new technologies in the search for overlooked targets. Krystinik has held positions as Manager of Geology at Union Pacific Resources and Global Chief Geologist for ConocoPhillips. His areas of interest include syn-tectonic sedimentation and other controls on basin-fill architecture, integrated play assessment and cost-effective implementation of new concepts and technology. Dr. Krystinik has been President of SEPM (The Society for Sedimentary Geology), an AAPG Distinguished Lecturer in North and South America, has published numerous papers on various aspects of applied sedimentary geology and has won a number of awards for his achievements in petroleum geoscience. E-mail: rock-doc@sbcglobal.net. [TOP]
December 11, 2007 Luncheon
January 8, 2008 Luncheon
February 12 Luncheon
Evaluation of Potential Impacts of Geologic Carbon Sequestration
[BIO]
Long-term storage or sequestration of anthropogenic "greenhouse gases" such as CO2 is a proposed approach to managing climate change. Deep subsurface brine reservoirs in geological sedimentary basins are possible sites for sequestration, given their ubiquitous nature. We used a mathematical sedimentary basin model, including full coupling of multiphase CO2-groundwater flow, heat flow, and rock deformation, to evaluate effects of CO2 injection on fluid pressures and rock strain. We also analyzed residence times and migration patterns of CO2 in possible brine reservoir storage sites. Study areas include the Uinta and Paradox basins of Utah, and the Permian basin of west Texas.
Regional-scale hydrologic and mechanical properties, including the presence of fracture zones, were calibrated using laboratory measurements and field data. Our initial results suggest that, in general, long-term (~100 years or more) sequestration in deep brine reservoirs is possible, if guided by robust rock mechanical and hydrologic data. However, specific processes must be addressed to characterize and minimize risks. In addition to CO2 migration from target sequestration reservoirs into other reservoirs or to the land surface, another environmental issue is displacement of brines into freshwater aquifers. We evaluated the potential for such unintended aquifer contamination by displacement of brines out of adjacent sealing layers such as marine shales.
Results suggest that sustained injection of CO2 may incur significant brine displacement out of adjacent sealing layers, depending on the injection history, initial brine composition, and hydrologic properties of both reservoirs and seals.
Model simulations also suggest that as injection can induce abnormally high fluid pressures, or overpressures. Results indicate that injection-induced overpressures may migrate, and effective stresses may follow this migration under some conditions, as will associated rock strain. Such “strain migration” may lead to induced or reactivated fractures or faults, but can be controlled through reservoir engineering. Results of this work are being used to design and deploy four geologic sequestration field tests, including projects in Utah, New Mexico, and Texas. Injection rates range from 35,000 tons per year to 1,000,000 tons per year.
