FORT WORTH GEOLOGICAL SOCIETY

P.O. Box 17075
Fort Worth TX 76102

 

 


September 12th, 2011

Dr. Joel Le Calvez

Microseismic Mapping of Hydraulic Fractrue Treatments

 


October 10th, 2011

Helge Alsleben

Effects of confining stress and rock strength
on fluid flow in low permeability rocks.

 


November 14th, 2011

Y. Lynn Clark, P.G.

TexasBoard of Professional Geoscientists'
Rule Making Process and the "Oil & Gas Exemption."

 


December 12th, 2011

No Meeting

Holiday Break

 


January 9th, 2012

Brian Dupuis

Horizontal Production Logging

 


February 13th, 2012


 


March ?th, 2012

Ft. Worth Joint Societies

Casino Night

 


March 12th, 2012




 

April 9th, 2012


End of Year Members and Spouses Monday Lunch
May 14th, 2012Scholarship
Recipient
Presentations
 - Baylor
 - TCU
 - UTA


January 9th, 2012

Horizontal Production Logging

by

Brian Dupuis

Schlumberger Senior Production Log Analyst & Technical Team Lead

Brian Dupuis is a Senior Production Log Analyst & Technical Team Lead - US Land East (MidCon - Southeast - Northeast Basins) for Schlumberger’s Data & Consulting Services (DCS).  Brian graduated with a B.S. in Chemical Engineering from Louisiana Tech in May 2000, and began working for Schlumberger in June 2000.  Brian has 5 years field experience running Vertical & Horizontal Production Logs (Memory, Surface-Readout, Coil Tubing Conveyed, Wireline, Slickline, Low Temp, High Temp) & 7 years in Data Services as a Log Analyst interpreting Production Logs from all over the United States.


November 14th, 2011

Texas Board of Professional Geoscientists’ Rule Making Process and the “Oil & Gas Exemption.”

Under state law, the TBPG has rulemaking authority and uses this authority to promulgate legislation involving the public practice of geoscience in Texas.  Recent proposed rules created a controversy with the oil & gas industry, which enjoys certain exemptions under the enabling statute.  This presentation will provide insight and background concerning the rulemaking process within state agencies and the factors to consider when invoking the “oil & gas exemption”.

Y. Lynn Clark, P.G.

Lynn Clark is a Dallas native and member of both the Fort Worth and Dallas Geological Societies.  He recently completed a 6-year appointment to the Texas Board of Professional Geoscientists, where he was Chairman from 2007 to 2009.  He is Vice President and Principal Geoscientist of LCA Environmental, Inc. and President of PerTect Detectors, Inc. (where he holds three U.S. patents on a shallow subsurface vapor monitoring system).  He worked in oil & gas with Core Laboratories, Inc. throughout Texas, Louisiana and the Gulf coast from the late 70’s through 1985.


October 10th, 2011

 

Effects of confining stresses and rock strength 

on fluid flow in low permeability rocks.

 

Enderlin, Milton and Alsleben, Helge

School of Geology, Energy, and the Environment

Texas Christian University

TCU Box 298830

Fort Worth, TX 76129

 

Changing stresses can modify rock properties such as porosity and permeability, but can also affect the ability of fluid to flow along planar mechanical discontinuities such as faults, shear fractures, tensile cracks, or bedding planes. The degree to which the flow of fluids will be altered with variation of confining stress depends on the spatial orientation of the mechanical discontinuity and the strength of the rock. Similarly, if hydraulic fracture stimulation is conducted in the vicinity of a mechanical discontinuity and the pressurized fracture fluids establish hydraulic continuity with the discontinuity, then the pressurizing fluids can alter the stresses at the mechanical discontinuity. These changes can cause the mechanical discontinuity to reactivate in shear resulting in an increase in the ability of the mechanical discontinuity surface to allow fluid flow, thus potentially diverting the stimulation fluids off in a direction other than anticipated.

 

A key component in the characterization of fluid flow along mechanical discontinuities is an understanding of the surrounding subsurface stress field. To constrain the present-day horizontal stress magnitude, a stress-strength equilibrium approach is employed using overburden rock density estimation and insights into the present-day tectonic setting. Stress orientation can also be inferred from structural geology principles via interpretation of mapped active features and wellbore information such as drilling history and image logs. Once information about stress magnitudes and orientation is available, one can calculate the shear and normal stress magnitudes acting on planar mechanical discontinuities of all possible strikes and dips. Furthermore, one can evaluate what magnitude of fluid pressure within each mechanical discontinuity would be required to encourage shear failure reactivation. An example from the Barnett shale play is presented as an application of the method, offering various solutions to the likely orientations of fractures that could interact with hydraulic fracture treatment.


Helge Alsleben

Helge is a structural geologist and Associate Professor in the School of Geology, Energy, and the Environment at TCU. Helge is a native of Germany and holds a B.S. equivalent from the University of Hamburg, Germany, a M.S. in geology from San Jose State University in San Jose, California, and a Ph.D. in geology from the University of Southern California in Los Angeles, California.

He teaches undergraduate and graduate courses in “Structural Geology”, “Global Tectonics and Basin Analysis” and “Geomechanics” (co-taught with Milt Enderlin). He is primarily a field-oriented geologist with a background in strain analyses as well as structural and microstructural analyses of rocks. His academic expertise about stress and strain provides the theoretical background for applied geomechanical problems that are part of his current research interests. He has authored or co-authored numerous publications and regularly presents his research results at regional, national, and international conferences. He is a member of AAPG, AGU, and GSA.

 

 


September 12th, 2011

‘Microseismic Mapping of Hydraulic Fracture Treatments: Application of High-Quality Geophysics to Interface between Geologists, Geophysicists, Geomechanicists and Engineering’

 

 

 

Yearly, thousands of hydraulic fracture stages are monitored in the oilfield.  Microseismic event locations and basic characteristics are routinely used for engineering interpretations of hydraulic fracture geometries.  Additional event characteristics such as “moment tensor” can be used to distinguish the different types of events.  These characteristics can be used for more advanced engineering analysis, including explanation of fracture behavior around faults and other naturally occurring features. The value of microseismic hydraulic fracture monitoring is only realized when geophysicists and engineers work closely together to integrate all the details of the microseismic event cloud into the engineering interpretation.  The detailed application of geophysical expertise ensures that engineers do not over-interpret or misinterpret the event clouds. In conjunction, engineering and geological knowledge helps geophysicists identify and correct spurious events or features caused by velocity model limitations, including inadequate descriptions of anisotropy. This presentation will discuss the pros and cons to be considered when considering a fracture monitoring campaign such as data acquisition, processing, and interpretation to demonstrate how the basic data is transformed into valuable information, which can then be used to understand hydraulic fracture geometry and complexity.

Dr. Joël Le Calvez

 

Joël Le Calvez graduated with a B.Sc. degree in Physics from the University of Nice, located in Nice, France.  He completed a M.Sc. degree in Geosciences from the University of Nice-Sophia Antipolis before graduating from the University of Paris VI with a pre-doctoral degree in Geodynamics.  He has since completed a Ph.D. in Geology at the University of Texas at Austin where he specialized in structural geology, salt tectonics and physical modeling.  While working for the Bureau of Economic Geology at the Applied Geodynamics Laboratory, his main interests were graben and fault linkage, extensional tectonics, and modeling.  Since 2001, he has worked for Schlumberger as a geologist, where his work responsibilities have led him to the challenge and task of analyzing data associated with the field of induced microseismicity and hydraulic fracturing. He actively participates in the development of processing, visualization, and interpretation software currently utilized by Schlumberger in relation to hydraulic fracture monitoring using induced microseismicity coupled to hydraulic fracture treatment. He is currently the US Land Project Manager of the Hydraulic Fracture Monitoring group based in Houston.




September 13th, 2010

Understanding Lateral Heterogeneity in Shale Using LWD Measurements


Historically, complete formation evaluation in shale gas horizontal wells have been infrequent and challenging due to operational complications.   These complications require extra rig time, can be difficult to obtain, and provide no real-time benefit for the well being drilled. In recent years, Logging While Drilling (LWD) measurements have been successfully employed to evaluate formation heterogeneity, provide assurance for geosteering in more complex reservoirs and enhance completion design to improve well production.

Early LWD data acquisition in the laterals revealed challenges behind real-time well placement using gamma-ray; a single non azimuthal measurement that is commonly applied for correlating and steering horizontal shale gas wells. With borehole images, the ability to compute structural dips, identify fractures and potential fault along the lateral becomes possible. Information from images can be effectively used to assist in real-time decision making while confirming lateral correlation between the thin beds found in shale plays.

With LWD measurements, the detailed evaluation of the unconventional gas play can be performed using a robust shale gas interpretation that is developed and calibrated using core data. This method combines conventional triple-combo data and spectroscopy to provide a gamma-ray independent clay content while computing the total gas volume consisting of adsorbed gas and free gas.  With the addition of sonic acquisition, geomechanical rock properties can be calculated and used to enhance completions design, tuned with key petrophysical information. The additional details offered by today’s technology can be applied to provide an understanding of a reservoir-production relationship with the objective to improve on future well deigns for consistent production results.  

Yen Han Shim

Yen Han Shim is a petrophysicist coordinating evaluation of unconventional reservoirs using LWD formation evaluation measurements across the lateral. She joined Schlumberger in 1996 after graduating as a Petroleum Engineer from University Technology of Malaysia. She commenced began her career as a drilling engineer, joined the field as a LWD engineer, then advanced to a well placement engineer. to later advance into the   Her next position was petrophysicist providing LWD technical and petrophysics support in land and offshore environments for Malaysia and China prior to her current role in the United States.




October 11th, 2010

Distinguishing Noise from LWD Gamma Ray Data
in Horizontal Wells

 
Other than drill rate and directional information; Gamma Ray is often the only MWD/LWD data gathered during the drilling of a horizontal well.  While the tool and the telemetry system are simple; there are many parts that must work together in order for the geologist to have usable data to properly place and steer a well.  While the Gamma Ray tool is simple by design; it’s value is often misunderstood or overestimated by those that use it.

Elementary techniques of log/data evaluation are often overlooked because of trust in technology.  Understanding the technology, breaking down the parts of the system and a review of available data can often help identify problem data or noise gathered during the drilling of a horizontal well.


Joe Schindler

Joe is a local geologist and has been in the industry for almost 30 years; the last 20 in the DFW area.  Much of those 20 years have been spent planning, drilling, and completing horizontal wells in the Austin Chalk, Buda/Georgetown, Cotton Valley, Barnett, and Bakken formations.  Joe has luckily had the good fortune to be married to the best geologist and mentor in the world throughout his career. 




November 8th, 2010

The Boquillas (Eagle Ford) Formation of South Texas

Potential Outcrop Analogs for Nonconventional 

Eagle Ford Shale Reservoirs in the Subsurface

 
The Eagle Ford Shale (and the laterally equivalent Tuscaloosa Shale) of the Gulf Coast Basin has long been considered to be a source rock for Mexico, Texas, and northern Louisiana production but is now drawing interest as a resource play.  With industry focus on non-conventional reservoirs and advancements in multilateral horizontal completion technology, fractured bituminous shales have become viable exploration targets. Well known examples of shale reservoirs include Bakken Shale (Mississippian of Williston Basin), Barnett Shale (Mississippian of Forth Worth Basin), Woodford Shale (Late Devonian/Early Mississippian of Arkoma Basin), and Marcellus Shale (Middle Devonian of Appalachian Basin).  The Cretaceous experienced three major Oceanic Anoxic Events, including one at the Cenomanian-Turonian boundary, represented by the Eagle Ford, and it is not surprising that exploration interest is now being attracted.

 

The current study is concerned with outcrops observed along U.S Highway 90 in Val Verde and Terrell counties, Texas, where the Eagle Ford (locally called the Boquillas Formation) lies on the northern margin of the Maverick Basin.  The Boquillas Formation (Cenomanian-Turonian) is about 200 ft thick in this area but thickens ten-fold in northern Mexico.  It was deposited during a time of exceptionally high sea levels and represents a transgressive-regressive sequence.  For the purpose of the study, the formation was divided into three members based on lithological differences, including limestone to shale ratio.   Attention was focused on the lowest member, which has characteristics of slope depositional conditions. Features seen in this member contradict previous interpretations of the Boquillas in this area, which had been thought to be composed of tidal-flat or shallow shelf sediments.  The sedimentary features of the lower member include slump folds, debris flows, probable turbidites, and possible contourites (previously interpreted as hummocky cross bedded grainstones).  The strata consist mainly of interbedded limestone and calcareous shales. These sediments were probably once black and organic-rich, but there are no exposures where the lower member is sufficiently unweathered.  Diagenetic differentiation, the repartitioning of carbonate from the shales into the limestone, has selectively exaggerated the geometry of the contourites and caused their resemblance to hummocky cross-stratification.  When freshly broken, the limestone beds emit a hydrocarbon odor. The faunal assemblage of the lower and middle members consists mainly of planktonic foraminifera, calcispheres, and ammonites. Bottom dwelling fossils are less common and are mainly found in the matrix of debris flow deposits, with the exception of  Inoceramus sp.  This bivalve genus has species that are adapted to low oxygen conditions. The lack of bioturbation and scarcity of fossils suggests deep water and possibly anoxic bottom conditions.  The combination of lithofacies observed in outcrop, and the fauna, suggest that the lower member of the Boquillas represents the beginning of sea level rise with sediment accumulating on the upper margin of the basin’s slope, in moderately deep water. 

 

The transition between the lower and middle members is marked by the abrupt end of the unstable slope features and a much higher proportion of organic-rich shales to limestones.  At the base of the three deepest road cuts along Highway 90, fresher rock is exposed.  When freshly broken, these shales are black. They are very finely laminated on a millimeter scale, and contain planktonic foraminifera and calcispheres.  Coarser laminae, ranging from millimeter to centimeter thick, consist of microfossil concentrations that are thought to be a product of winnowing by bottom currents. Inoceramids are also present in the middle member.  Some of the interbedded limestones are laterally continuous while others are more nodular in appearance.  The preservation of fine laminae, with little to no bioturbation, combined with the fauna present, indicate anaerobic to dysaerobic conditions with a total lack of infauna during the time of deposition.  Water depth for the majority of the middle member was probably deeper than for the lower member, with sediment being deposited on the middle to lower basin slope.  Nearing the top of this member there is an increase in limestone beds suggesting a decrease in water depth, consistent with the interpretation of a transgressive-regressive cycle.

 

The upper member consists mainly of somewhat bioturbated limestones that are much thicker than those of the other two members. Trace fossils include Chondrites, which still suggests relatively low oxygen levels. The upper member appears to lack the high organic content present in the rest of the Boquillas.  This top unit represents a progressive return to shallower, better oxygenated conditions.  Along with pyrite-filled burrows, an abundance of regular and irregular echinoids supports this interpretation.

 

Lauren Peschier

Lauren Peschier received her B.S. in Geology in 2004 and M.S. in Geology in 2006 from the University of Louisiana at Lafayette.  She has 6 years of experience as a geologist in the oil and gas industry working exploration, development, and operations in the Gulf of Mexico.  She worked for Marlin Energy, LLC in Lafayette, Louisiana from 2004 through 2006 as an associate geologist and is currently employed as a geologist by Newfield Exploration.  At Newfield, she worked the Gulf of Mexico Shelf from 2006 to 2009 and currently works the Eagle Ford in Maverick Basin Texas.  



January 10th, 2011

Eagle Ford Shale Prospecting with 3D Seismic Data within a 
Tectonic and Depositional System Framework

 
Galen Treadgold and Bill McLain, Weinman GeoScience
Steven Sinclair and David Nicklin, Matador Resources Company

The Eagle Ford Shale in South Texas is one of the more exciting shale plays in the United States at the current time.  Recently published reports of well tests describe gas well rates exceeding 17 mmcf/d and oil well rates in excess of 1500 bopd and unconfirmed rates of 2000 bopd.  Acreage lease rates continue to climb as more positive results come from drilling within the trend.  A key issue for the exploration companies is finding where to focus acreage acquisition and optimize drilling plans for optimal gas and oil recovery.  Our paper will first consider the geologic context of the Eagle Ford and then look at geophysical techniques, in particular, comparing and contrasting the value of 3D Processing seismic attributes in building a successful exploration plan.

Conventional subsurface data, such as wireline logs, cores and cuttings, are limited in availability to many companies currently exploring the play.  Interpretation of these data is often ambiguous at best.  As a result, thorough understanding of the regional aspects of the play remains elusive to many companies.  It is our belief that modern seismic data and interpretation techniques can add significantly to the database and greatly enhance regional understanding of the play for many companies. Newly acquired 3D datasets provide a continuous characterization of the subsurface, which highlights drilling hazards (faults), and also offers the potential for identifying better reservoir quality intervals (higher TOC shale sections with greater porosity and fractures).  Extracting rock properties from the seismic should be the goal of any processing and interpretation effort.  Linking the results of well tests to the attributes derived from the seismic will provide operators with a far more reliable predictive capability in any shale play.

Ultimately, the pursuit of Eagle Ford acreage and the designing of an Eagle Ford drilling campaign is best accomplished through a comprehensive understanding of the geologic framework coupled with a focused interpretation of the seismic.  This shale is one of the more exciting domestic shale plays, and presents ample opportunities to make and lose money.  The smart operator will utilize all the tools available to study the target section while recognizing the limitations of the technology.

Galen E. Treadgold

 Galen E. Treadgold, vice president of Weinman GeoScience (a division of Global Geophysical), received a BS in Geology and Marine Science in 1982 from the University of Miami before starting his geophysical studies at the University of Texas at Austin and receiving an MA in Geology/Geophysics in 1985.   Galen joined ARCO that same year and over the next 15 years worked in various technology, exploration and management positions including coordinating AVO projects, teaching the first ARCO AVO school, managing the ARCO British technology group and managing ARCO’s Trinidad and Venezuela exploration effort.   In 2000, Galen joined Weinman Geoscience where he’s held the position of chief geophysicist and now, vice president.  Galen’s main interests are reservoir characterization and azimuthal analysis for fracture detection.  He’s given recent talks at the SEG in Las Vegas, the 2008 Unconventional Reservoirs Symposium in Vancouver, the GSH Sherwood Symposium in Houston, SPG conference in Hyderabad, India and the 2010 RMAG conference in Denver.  Galen is a liaison to the SEG Global Affairs Committee and an SEG council representative.  


February 14th, 2011

A Detailed Look Inside a Complex Channel Belt:
Processes, Rates, and Reservoir Architecture/Connectivity
for an 8K-Duration Mississippi River Meander Belt
with Reach-Restricted Tectonic Signature

The Lower Mississippi River has long stood as a type model for meandering-river deposition, and is well understood at both the regional floodplain and individual meander-loop scales.  We have taken the next step, and produced the first detailed study of a single and entire channel belt (30 X 100 km) in order to better understand belt-scale architectural elements, reservoir and baffle structure, formative processes, and depositional rates for meandering river systems.  The channel belt studied here records a complex and long-standing (>8 ka) trunk belt from which no less than six contemporary belts disperse downstream.  The belt is also impacted over its middle third by active tectonics of the New Madrid seismic zone.  This belt serves as a rare type model for complex meander belts in both tectonically and non-tectonically impacted subsurface reaches.

Meander amplitude overall is variable, producing amalgamated and reworked lateral-accretion elements/point bars of 1 km to 19 km amplitude with 5-6 km as typical.  Channel-fill elements constitute 40% of the belt deposits.  While the more familiar chute and neck cutoff channel fill process are common, additional process of splay fill, avulsion fill, and re-occupation fill are also commonly recognized.  Splays are common, but generally small and thin, except where filling tectonic and depositional lows on the floodplain surface.  Overbank fines are generally minimal within the belt, but thick on the belt flanks.  Belt architecture is hierarchal in the middle fault-influenced 30 km, and includes three subbelts that record tectonically initiated river straightening and in-belt avulsion not observed elsewhere within the belt.  Meander growth rates are approximately 5m/year, tectonic response rates are on the scale of a few centauries, tectonic recovery rates are on the scale of one millennium, and channels require several hundred years to a few millennia to fill depending upon process.  

Detailed mapping reveals several levels of potential reservoir and flow barrier induced by both autocyclic processes and local tectonic influence.  Most notably, mapping reveals that a direct hit into a Mississippi-type meander belt while drilling still has only a 3-in-5 probability of striking a full interval of reservoir sand.  Reservoir sands are also highly compartmentalized to the bar scale, but potential exists to connect point bar reservoirs below channel belts as these rarely fill completely with sealing mud.  Likewise, connectivity between belts has high potential if the belts are not separated vertically by more than one quarter belt thickness. 

John Holbrook, University of Texas at Arlington, holbrook@uta.edu

Current Position: PROFESSOR, DEPARTMENT OF EARTH AND ENVIRONMENTAL SCIENCES, UNIV.TEXAS AT ARLINGTON - Education: Univ. of Kentucky, BS (Geology) 85; Univ. of New Mexico MS (Geology) 88, Indiana Univ. PhD (Geology, Minor Geophysics) 92. Honors & Awards: Outstanding Teacher, UTA College of Sci. and Tech. 09. Professional Experience: Peabody Ventures Petroleum 88, Southeast Missouri St. Univ., Asst.- Prof. 92-04, Univ. of Texas at Arlington Prof. 04-pres., Guest Prof. Enugu St. Univ. (Nigeria) 99 and St Petersburg St. Univ. (Russia) 08, Straight Creek Solutions Env. & Pet. Consulting (Proprietor) 09-pres. Other Positions and Service: GCSSEPM President 10, AAPG/SEPM Annual Meeting Organizing Committee 10,08,99,&98, Assoc. Editor, Jour.Marine and Petroleum Geo..08-11; GSA Sedimentary Geology Division Chiar 09-11, SEPM Research Counselor 08-10, EDMAP panel 09-11, PRF panel 10-12, NSF SG&P panel 06-09, AAPG Academic Liaison Comm. 10-12 Missouri Board of Geologist Registration 03-04 Memberships: GSA, AGU, SEPM, AAPG, Licensed Geologist (P.G., Missouri). Research:  Controls on surface processes and patterns of deposition in both modern and ancient sedimentary environments with concentration on terrestrial systems.  Patterns of organization in the sedimentary record and application to environmental, resource, and global-change issues. 



March 14th, 2011

Wellsite Geochemistry: New Analytical Tools Used
to Evaluate Unconventional Reservoirs to Assist Drive
Smart Completions in Vertical and Horizontal Wells

New field deployable analytical techniques like GC-Tracer, SRA, XRF, and XRD are proving to be valuable tools when drilling and completing horizontal shale wells. Experience in different shale plays throughout the US (including the Barnett, Haynesville, Marcellus and Cretaceous Shale members in the DJ Basin) have shown significant potential in predicting fluid type; delineating potential pay zones, and reservoir compartmentalization for a better placement of fracturing staging based on rock and chemical properties.

The GC-Tracer tool analyzes real-time hydrocarbon (C1 – C8, benzene, toluene) and nonhydrocarbon gases (CO2, N2) dissolved the in drilling fluid. Drill cuttings are collected and evaluated onsite using SRA, XRF, and XRD. The Source Rock Analyzer (SRA) estimates residual oil content in source rock (S1), remaining hydrocarbon generation potential (S2), thermal maturity (Tmax), total organic carbon (TOC); X-Ray Fluorescence provides elemental breakdown while X-Ray Diffraction provides clay, carbonate, and other mineral proportions. Cutting samples are normally collected every 100’ throughout the majority of the wells, while increasing sampling frequency to 10’ or 30’ samples in the zone(s) of interest for a more accurate way to monitor variability.

In unconventional reservoirs, such information can aid in the delineation of pay zones and be used to design horizontal completion and stimulation programs. Unfortunately, logging horizontal wells using downhole tools can be somewhat cumbersome and expensive; therefore, new wellsite techniques can offer a more viable alternative to real-time data gathering and reservoir characterization. This compilation of case histories demonstrates that new analytical tools for well site can provide insights into potential productive shales and identification of potential intervals within lateral sections considering an organic and inorganic geochemical analytical approach.


Diego Ortiz, Weatherford International

Diego Ortiz graduated from The University of Oklahoma with a B.Sc. in Chemistry and currently holds the position of GC-TRACER Formation Evaluation Specialist for Weatherford Surface Logging Systems. 

He has helped with the introduction of the GC-Tracer tool in the North American market and now driving the new initiative to growth presence in Latin America.

Before joining Weatherford, Diego worked for Crown Geochemistry as a field chemist where he was first introduced to the worldclass Woodford and Barnett plays in 2006 by studying the gas analyzed with Mass Spectrometry. In 2008 he joined International Logging as a GC-TRACER Analyst where he learned Gas While Drilling and other industry known Gas Evaluation methods.

His main focus has been the development of gas ratio techniques exclusively for Shale evaluation using traditional and advanced gas detection equipment as well as the integration of new field-deployable analytical techniques for geochemical characterization of unconventional reservoirs.

   

April 11th, 2011

Production of Liquid Hydrocarbons from Organic Shales


The domestic energy industry has undergone a revolution over the last eight years due to the production of gas from organic shale. The quantities of gas within these reservoirs are considerable, and shale gas accounts today for a significant fraction of U.S. gas production. This increase in gas production has led to a depressed price for gas when compared to the price of oil. Our industry has responded by focusing significant effort in producing oil from these same organic shale reservoirs.

Much of the producible pore volume in organic shale is believed to reside within the kerogen fraction. These nanoscale pores form during kerogen maturation, and they have very low water saturations. Fluids within these pores are believed to include adsorbed gas with either free gas, oil, or a combination of the two (this assumes a reservoir below the critical point). Liquids production can come from either the oil within the pores or from condensate that drops out of the gas as its pressure is reduced.

Gas production mechanisms are well demonstrated for organic shale reservoirs. Condensate production would follow the same flow mechanism until the bottom hole flowing pressure falls below the dewpoint. If the condensate does not build up in the nanopores, where it would reduce the relative permeability to gas, then the production of condensate could be significant. And this has been amply demonstrated in numerous condensate-producing organic shale wells.

Production of oil from the nanopores of an organic shale is more difficult to understand. Oil is ~50 times more viscous than gas, so application of Darcy’s law would suggest a very much lower flow rate for an equivalent pressure drop. The flow of a liquid through nanopores may not be governed by Darcy’s Law; however, there really aren’t any quantitative alternatives today. The production of oil from these reservoirs suggests 1) the matrix has a higher intrinsic permeability than typical gas shales, 2) there is a permeable network within the shale formed either through fractures or dissolution, or 3) a combination of the two.

 Most oil production from shale occurs today in the Bakken. This production comes primarily from the middle member of the Bakken, a dolomitic silt encased within two organic shales. The middle Bakken is a poor quality conventional reservoir with intrinsic permeabilities less than 0.1 mD; however, these permeablities are still around 1000 time greater than those encountered in gas shales. The application of drilling and completion practices initially developed for gas shales has been critical to the success of this play.

 Bakken Shale equivalents may occur elsewhere in the United States. Potential targets would be tight reservoirs in intimate contact with source rocks. These source rocks would charge the reservoir and provide a seal.

 

Rick Lewis

Rick Lewis is the Shale Petrophysics Technical Manager for Schlumberger Oilfield Services in Oklahoma City. Rick was a developer of the gas shale evaluation workflow that was initially fielded eight years ago and has been applied to well more than 1000 wells in North America. In his current position, Rick manages a group responsible for the continual improvement for this workflow, and for its introduction and application to the international market. He is also the interface to the Schlumberger research and engineering groups for the development of evaluation technologies for organic shales. Prior to this assignment, Rick was responsible for wireline interpretation development for the central and eastern United States. Rick has also worked for Shell Oil and the U.S. Geological Survey. He received a BS degree from UCLA and MS and PhD degrees from Cal Tech, all in geology.

 


May 9th, 2011

Scholarship Recipient Presentations

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Garrett R. Felda - Baylor

Developing a 3-dimensional sequence stratigraphic model for the late Triassic (Norian) Owl Rock Member exposed at Petrified Forest National Park, Arizona:  A reconstruction of paleodepositional environments and paleoclimatic conditions.

The goal of this research is to develop the first comprehensive sequence stratigraphic model for the late Triassic (Norian) Owl Rock Member (Chinle Formation) exposed at Chinde Mesa near the northern boundary of Petrified Forest National Park, Arizona.  The purpose of this model is to characterize temporal and spatial distributions of alluvial and lacustrine facies using outcrop observation and stacking pattern analysis techniques to reconstruct cyclic depositional environments.  The specific utility of this project is to serve as a useful analog for similar subsurface alluvial and lacustrine deposits having high hydrocarbon reservoir potential.  In particular, this study will provide a high-resolution depiction of lithofacies continuity equivalent in scale and style to terrestrial subsurface counterparts.
In addition to detailed sequence stratigraphic analysis, this investigation will also assess paleoclimatic conditions during the time interval preceding the end-Triassic biotic crisis.  Climatic factors to be considered include atmospheric carbon dioxide concentrations (using stable carbon isotope analysis of pedogenic carbonate), and mean annual temperatures (using stable oxygen isotope analysis of both pedogenic and lacustrine carbonate).  Variations in clay mineralogy and abundance will also be measured using X-Ray Diffractometry to help constrain precipitation amounts and infer soil moisture conditions.

Finished products include a series of measured sections accompanied by high-resolution digital photopan images depicting fluvial aggradation cycles (FAC’s), as well as, inferred fluvial architectural elements across the southernmost extent of Chinde Mesa.  GPS coordinates will be used to precisely locate and orient sections and photopans to a digitized basemap.  Alluvial clastic and lacustrine carbonate samples collected in the field will be evaluated using petrographic microscopy and reported in terms of facies specific controls on reservoir quality as indicated by the presence or absence of porous textures and fabrics related to environmental modes of deposition.  Calculated atmospheric carbon dioxide concentrations and mean annual temperatures will be presented comparatively in graphic form to identify temporal trends and illustrate potential relationships.

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Clark H. Osterlund - TCU

Overview of the “Atoka Shale” formation in northern Midland County

The Permian Basin of west Texas and southwestern New Mexico comprises a surface area greater than 86,000 mi2, and has provided in excess of 35 BBO from over 3,000 fields (Ball, 1995).  The Permian Basin is currently in a mature stage of development, though advances in completion technology, specifically tailored for unconventional plays, and a favorable economic climate, has spurned new plays on.  One formation, termed Atoka Shale, could prove to be a viable play within the Permian basin.  The lack of a definite age for the interval has hindered the development of a concise model of deposition.  Increased understanding of the stratigraphy associated with the Atoka formation will improve chances for well success.  I propose to integrate age data garnered from conodonts within a 3-Dimensional stratigraphic framework developed from logs and seismic in order to assign a model of deposition, in conjunction with assessing the Atoka Shale as a possible horizontal oil play.

Clark Osterlund

Having been born in west Texas, I was fortunate to learn the importance of geology at a young age.  Numerous scouting trips to the Guadalupe Mountains initially stimulated my interest in geology.  During my undergrad studies, I was most drawn to soft rocks and sequence stratigraphy. 

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Krystin Robinson - UTA

Chemostratigraphy of the Pearsall Formation, Lower Cretaceous, Maverick Basin, South Texas

The lower Cretaceous Pearsall Formation of the Maverick Basin, South Texas, represents sedimentation in a mixed carbonate-siliciclastic system during Aptian time, potentially preserving paleoceanographic information during a segment of Oceanic Anoxic Event-1 (OAE-1). The objective of the project is to develop and interpret stratigraphic changes in the geochemistry of the Pearsall Formation for the purposes of 1) understanding the paleoceanography of South Texas during a unique period in Earth history, 2) developing regional correlation using multiple cores, and 3) refining the stratigraphy for the oil and gas industry.  Methods used to carry out the project include:  real-time geochemical analysis using x-ray fluorescence (XRF) of the core face, TOC (total organic carbon), and TIC (total inorganic carbon) analysis. Geochemical results from the Comanche Ranch #34 drill core suggest that the Pearsall Formation can be divided into at least four discrete units based on %Ca content and/or variability. The bottom ~55 feet of strata in the core preserves the lower Cow Creek member.  This member is characterized by highly variable calcite concentrations (<10% to 90% CaCO3).  Above the lower Cow Creek is the Upper Cow Creek member which represents ~60 feet of strata.  This interval is characterized by slightly lower overall %Ca concentrations (~35% CaCO­3) and much lower variability.  On top of the Cow Creek member is the Bexar member.  The lower Bexar member is most abundant in this core, representing ~135 feet of strata.   Here it is further divided into two different zones: a) A stable %Ca zone (~45% CaCO­3 ) for the first ~65 feet,  b) A zone of intermittently punctuated  % Ca (~90% CaCO3 ) represented by the upper ~70 feet.  Earlier work on more thermally mature Pearsall strata from outside the Maverick Basin indicates that TOC values range from <1% up to 3%. TOC from the Comanche Ranch #34 core range from <1 to 5%.  Chemostratigraphic results will be compared with well logs in order to demonstrate the potential for linking stratigraphic changes in bulk geochemistry and mineralogy with log interpretations.