Contract Reports

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Surface Casing Estimator Site, FY2024
(Bureau of Economic Geology, 2024-08-31) Paine, Jeffrey G.; Averett, Aaron R.; Grunau, Benjamin A.; Morris, Jennifer N.; Piejko, William
The DICE site (formerly the Surface Casing Estimator Site, or SCES), hosted at the Bureau of Economic Geology (Bureau), is an interactive website that provides depth and elevation estimates for select subsurface water-quality zones chosen by Groundwater Advisory Unit staff at the Railroad Commission of Texas (RRC). These depths enable users to estimate surface-casing needs for possible future drilling activity prior to obtaining a surface-casing determination letter from the RRC. Work during fiscal year 2024 (September 2023 through August 2024) for the DICE site included: (1) renaming the SCES to DICE at RRC’s recommendation; (2) scanning geophysical logs from the Q-log library for 21 counties; (3) constructing digital data sets composed of geologic information that relates to estimating surface-casing requirements and groundwater depths for four study areas that included two counties in north-central Texas, two counties in the northwest part of central Texas, two counties on the upper Texas Coastal Plain, and two counties on the middle Texas Coastal Plain; (4) adding the newly interpreted county hydrostratigraphic surfaces to the DICE site; (4) adding selected geophysical logs to the DICE site; and (5) continuing a major upgrade to the DICE site to include additional data sets requested by RRC and to allow privileged RRC access to additional data layers that are not accessible to the general public. For the study areas, the DICE site provides depth and elevation estimates for the base of usable quality water (BUQW) and the base of underground sources of drinking water (BUSDW), where appropriate. Critical water-bearing stratigraphic units, aquifer names, a selection of reference geophysical logs, and well locations are also displayed. All depths and elevations are estimated on the basis of picks provided by the RRC and on select supplemental geophysical well-log determinations made by Bureau staff.
Survey of Geophysical Log Collections Held by State Geological Surveys and Other Agencies, United States
(Bureau of Economic Geology, 2024-06-30) Paine, Jeffrey G.; Morris, Jennifer N.; Grunau, Benjamin A.; Averett, Aaron R.
Borehole geophysical log collections are an important and underutilized source of information that can contribute to the creation of accurate two- and three-dimensional models of the subsurface and augment geologic mapping efforts nationwide. In this report on a survey of geophysical well log collections held by state geological surveys and other state agencies, we have identified principal contacts, collected and analyzed key attributes, and identified locations for public-facing web sites and viewers. Through a 10-question survey sent to 74 state entities and follow-up investigations, we collated information on 70 log collections housed by 64 state entities across 44 states. These collections include approximately 4.5 million geophysical logs acquired in oil and gas, groundwater, mineral exploration, geothermal, and environmental monitoring wells. Common log media include printed paper, raster scans, and a lesser number of fully digitized logs. At least half of the state entities surveyed have collections that include all three log types in varying proportions. Most collections are available to the public, but accessibility and possible fees vary widely. Attributes of each of the state collections, along with a few major federal sources, are accessible through a GIS-based web viewer developed for this project. Numerous regional and local geophysical log collections are not included in this inventory, nor are commercial vendors. Recommendations for enhancing the discoverability, availability, and usability of the logs include (1) scanning logs and determining locations for unscanned paper logs, (2) digitizing high-priority logs into a standard format to facilitate import into log analysis software, (3) creating public-facing web viewers or other online interfaces to locate and download logs for widest possible use, and (4) allocating financial support for scanning, digitizing, and organizing logs to accelerate progress toward broader availability and use of this valuable subsurface data source.
The Installation, Operation and Analysis of Eddy Covariance for Quantifying Evapotranspiration
(Bureau of Economic Geology, 2024-04-01) McKinney, S. Tyson; Young, Michael H.
During the contract period from January 2021 through December 31, 2023, the University of Texas at Austin, Bureau of Economic Geology (UT-BEG) installed and maintained two eddy covariance stations across the Edwards Aquifer recharge region. The Cibolo station was installed on February 25, 2021, in the more humid eastern portion of the region within an oak-ashe juniper ecosystem adjacent to Cibolo Creek at the Field Research Park (FRP) operated by the Edwards Aquifer Authority (EAA). The Uvalde station was installed on April 8, 2021, in the more arid western portion of the region within a mesquite woody savanna northwest of Uvalde, TX, near the Nueces River. The Uvalde station was demobilized on March 1, 2023, and relocated to a permanent location approximately 30 miles north, within an oak-ashe juniper woody savanna on the Shield Ranch east of Camp Wood, TX, and renamed the Nueces station. Installation of the Nueces station was completed on July 19, 2023. Site visits were performed throughout the contract period for regular maintenance, such as calibrating (i.e., zero-spanning) the infrared gas analyzer, and as-needed maintenance such as troubleshooting issues with power, communication or individual sensors. The Cibolo, Uvalde, and Nueces sites have been registered with AmeriFlux (a collaborative network of flux site across North, Central, and South America with standardized processes and procedures) with site designations of US-EA4, US-EA5, and US-EA6, respectively. Data submission to AmeriFlux for the eddy covariance sites is ongoing.
Subsurface Oil-Shale Samples of the Upper Pennsylvanian Cline Shale, Midland Basin, West Texas: Core Sampling for Measured Vitrinite-Reflectance (Ro) Determination
(Bureau of Economic Geology, 2015) Hentz, Tucker F.; Roush, Reed S.; Breton, Caroline L.
This report summarizes activities carried out by the Bureau of Economic Geology (BEG) during fiscal year (FY) 2015 for the National Coal Resources Data System State Cooperative Program (NCRDS project). In a continuation of the sampling strategy for measured vitrinite-reflectance (Ro) determination initiated 6 years ago (Hentz and others, 2009) and conducted during the following five years (Hentz and others, 2010, 2011, 2012, 2014, 2015), this report provides a collection of oil-shale samples from the Upper Pennsylvanian Cline Shale of the Midland Basin in West Texas (Fig. 1).
Subsurface Oil-Shale Samples of the Lower Permian Wolfcampian and Lower Leonardian Mudrocks and Upper Leonardian Spraberry Formation, Midland Basin, West Texas: Core Sampling for Measured Vitrinite-Reflectance (Ro) Determination
(Bureau of Economic Geology, 2014) Hentz, Tucker F.; Baumgardner, Jr., Robert W.; Hamlin, H. Scott; Breton, Caroline L.
This report summarizes activities carried out by the Bureau of Economic Geology (BEG) during fiscal year (FY) 2014 for the National Coal Resources Data System State Cooperative Program (NCRDS project). In a continuation of the sampling strategy for measured vitrinite-reflectance (Ro) determination initiated 5 years ago (Hentz and others, 2009) and conducted during the following four years (Hentz and others, 2010, 2011, 2012, 2014), this report provides a collection of oil-shale samples from the prolific Lower Permian Wolfcampian and lower Leonardian mudrocks and upper Leonardian Spraberry Formation of the Midland Basin in West Texas (Fig. 1).
Using Geologic Maps and Seismic Refraction in Pavement-Deflection Analysis
(Bureau of Economic Geology, 1999-10) Paine, Jeffrey G.
Geologic maps provide much information about the distribution of rock types at and near the land surface. Deflections of Texas highways measured with the Falling-Weight Deflectometer (FWD) appear to be correlated to bedrock type, particularly at the most distant FWD sensors. To examine this apparent bedrock influence, we compared FWD data with mapped geologic units from six roadway segments in four physiographic regions of Texas. This analysis revealed differences in FWD response among regions that are likely to be related to systematic differences in either bedrock depths or physical properties of geologic units that range from Precambrian to Holocene in age and include many different sedimentary, igneous, and metamorphic rocks. At the W7 detector (6-ft [1.8-m] offset), average normalized deflections are highest for areas where roads are underlain by siliciclastic sedimentary rocks (sandstones, mudstones, and shales) and unconsolidated alluvial sediments. Lowest normalized W7 deflections are measured in areas underlain by Precambrian igneous and metamorphic rocks that include granites, schists, and gneisses and in areas underlain by chemically precipitated sedimentary rocks such as limestone.
Review of the 2008 resistivity surveys at the WCS facility, Andrews County, Texas
(2009) Paine, Jeffrey G.
Technos, Inc. completed two resistivity surveys on behalf of Waste Control Specialists, LLC (WCS) at the WCS facility in Andrews County, Texas. These surveys, conducted between January 24-27, 2008, and August 29-September 2, 2008, are summarized in three reports (Technos 2008a, 2008b, and 2008c). Results of the January survey, including processing and analysis of resistivity lines A and B extending northeast from the northern boundary of the proposed Federal Waste Disposal Facility, are reported in Technos 2008a. Discussion of those results led to additional resistivity surveying along lines C and D, which extend across and northward from the Byproduct Disposal Site as described in Technos 2008b. The general lack of agreement between processed resistivity data and known depths to a significant conductive layer (the redbeds) identified in boreholes and in geophysical logs led to additional processing and analysis of the resistivity data, which is summarized in a supplemental report (Technos 2008c). Technos subsequently provided resistivity data files from both surveys to allow a preliminary independent assessment of the resistivity data. Troubling aspects from the report on the January 2008 survey included: (a) the poor agreement between the resistivity-depth sections and the known depth to a relatively conductive layer (the resistivity data significantly overestimated the depth to the redbeds), (b) the poor agreement between borehole conductivity data and resistivity values in the inverted depth sections, and (c) the conclusion that surface resistivity data would not be useful in examining water saturation trends in the shallow subsurface at the site. Many of the same issues remained in the second report following the August-September acquisition and processing. The supplemental processing described in Technos 2008c was intended to address these issues by reprocessing the resistivity data and examining trends in unprocessed data at different electrode spacings to identify a possible relationship between water saturation and apparent resistivity but only partly satisfied that objective. We have briefly examined the raw resistivity data provided by Technos to further investigate issues of conversion of raw resistivity data to true resistivity-depth profiles and possible correlations between field data and water saturation along lines A, B, C, and D.
Optimization of Geological Environments for Carbon Dioxide Disposal in Saline Aquifers in the United States - Final Report
(2009) Hovorka, Susan D.
High permeability sandstones of the Frio Formation east of Houston, Texas, were selected to test the feasibility of using carbon capture and storage (CCS) in geologic formations as a method to reduce atmospheric buildup of greenhouse gases. The Frio Brine pilot study was based on two small-volume and short-duration CO2 injections into two previously unperturbed brine-bearing sandstone beds typical of the region. These injections were designed to answer key questions about CCS using a process of intensive multiphysics monitoring, pre-, syn-, and post-injection monitoring, and then history-matching to test the correctness of numerical models of flow and geochemical changes. The first test, conducted in September 2004, injected about 1,600 tons of CO2 at a depth of 5,050 ft (~1,540 m) below the surface over 10 days and collected observations over 18 months. The second injection, in September 2006, injected more slowly, about 250 tons over 5 days, into thicker sandstone at 5,400 ft (~1,650 m) below the surface. The injection period was brief, and the formation was on the flank of a steeply dipping structural compartment, resulting in monitoring over 5 years and lasting well into the post-injection phase of plume stabilization. This provided the experience and measurements of a complete project that will be helpful in predicting the performance of large-volume injections potentially lasting decades. The site was closed at the end of the experiment in May 2009.
Review of the State of Art: Ground Water Under the Direct Influence of Surface Water Programs
(2009) Chaudhary, Kuldeep; Scanlon, Bridget R.; Scheffer, Nathan
The objective of this study was to: 1. Evaluate the state of the art for groundwater under the direct influence (GWUDI) of surface water programs in the US and other countries. 2. Evaluate the existing groundwater under the influence (GUI) program in Texas with respect to hydrogeologic parameters and microbial indicators, including total and fecal coliform and microscopic particulate analyses (MPA). 3. Make recommendations to the Texas program based on a synthesis of best practices and elements from all reviewed programs. The driving force behind these evaluations is the fact that particles entrained in water can make the disinfection process ineffective because pathogens can be shielded within microscopic debris (LeChevallier et al., 1981). Further, some particles themselves, such as Giardia and Cryptosporidium cysts, can be pathogenic even if not encased in debris. Hence, groundwater sources that contain surface water-linked debris (algae, nematodes, etc.) that receive only disinfection have been implicated in many waterborne diseases.
Subsurface Jurassic and Cretaceous Gas Shale Samples Haynesville and Bossier Formations and Eagleford Group Core Sampling for Meausred Vitrinite Reflectance Determination
(2009) Hentz, Tucker F.; Breton, Caroline L.; Ruppel, Stephen C.
This report summarizes activities carried out by the Bureau of Economic Geology (BEG) during Fiscal Year (FY) 2008 for the National Coal Resources Data System State Cooperative Program (NCRDS project). In a continuation of the procedure initiated last fiscal year (Hentz and others, 2008), this report provides a collection of gas-shale samples from shale-rich formations of Texas and Louisiana that are currently experiencing significant natural gas production or are being closely studied for gas production potential (Cardott, 2008; Durham, 2008; Hammes and Carr, 2009). Gas-shale samples of the Upper Jurassic (Kimmeridgian and Tithonian) Haynesville and Bossier Formations were collected from whole cores of three wells in Sabine, San Augustine, and Harrison Counties, far east Texas, and of one well in nearby Sabine County, Louisiana (Fig. 1). We also provide samples from the Upper Cretaceous (Turonian) Eagle Ford Group shales of six wells in Bee, Wilson, Frio, Zavala, and LaSalle Counties, south Texas, and of one well in Ellis County, north Texas (Fig. 1). These samples are provided for vitrinite-reflectance (Ro) analysis by the USGS. Each sampled shale's precise geographic location is identified using GIS applications.
Sequence Stratigraphy, Depositional Systems, and Production Trends in the Atoka Series and Mid-Pennsylvanian Cleveland and Marmaton Formations, Western Anadarko Basin
(2009) Carr, David L.; Hentz, Tucker F.; Ambrose, William A.; Potter, Eric; Clift, S. J.
Slides from Sequence Stratigraphy, Depositional Systems, and Production Trends in the Atoka Series and Mid-Pennsylvanian Cleveland and Marmaton Formations, Western Anadarko Basin Workshop Presented by the Bureau of Economic Geology State of Texas Advanced Resource Recovery (STARR) Program and PTTC Texas and SE New Mexico Region November 10, 2009 Ellison Miles Geotechnology Institute, Dallas
Texas High School Coastal Monitoring Program: 2007-2009
(2009) Caudle, Tiffany L.
The Texas Coastal Monitoring Program engages people who live along the Texas coast in the study of their natural environment. High school students, teachers, and scientists work together to gain a better understanding of dune and beach dynamics there. Scientists from The University of Texas at Austin (UT) provide the tools and training needed for scientific investigation. Students and teachers learn how to measure the topography, map the vegetation line and shoreline, and observe weather and wave conditions. By participating in an actual research project, the students obtain an enhanced science education. Public awareness of coastal processes and the Texas Coastal Management Program is heightened through this program. The students' efforts also provide coastal communities with valuable data on their changing shoreline. This report describes the program and our experiences during the 2007-2008 and 2008-2009 academic years. During this time, Ball High School on Galveston Island completed its eleventh year in the program, and Port Aransas and Port Isabel High Schools completed their ninth and tenth years, respectively (Fig. 1). All three high schools are continuing the program during the 2009-2010 academic year. Through collaboration with the Lower Colorado River Authority, the program expanded to three schools in the Bay City, Texas, region. Tidehaven Middle School and Van Vleck High School completed their fifth year in the program, and Palacios High School completed its third year. Cunningham Middle School in the Corpus Christi Independent School District participated in its first field trip in late spring of the 2008-2009 academic year. All of the schools anticipate continuing with the program during the 2009-2010 academic year. Discussions of data collected by the students and recommendations for future high school projects are also included in this report. A manual with detailed field procedures, field forms, classroom exercises, and teaching materials was prepared during the first year of the project at Ball High School in 1997-1998. The manual was updated with the addition of the Bay City region schools in 2005.
Status and Trends of Inland Wetland and Aquatic Habitats in the Corpus Christi Area
(2008) Tremblay, Thomas A.; Vincent, Jeffrey S.; Calnan, Thomas R.
Wetland and aquatic habitats are essential components of estuarine systems along the Texas coast. These valuable resources are highly productive biologically and chemically and are part of an ecosystem on which a variety of flora and fauna depend. Scientific investigations of wetland distribution and abundance through time are prerequisites to effective habitat management, thereby ensuring their protection and preservation and directly promoting long-term biological productivity and public use. This report presents results of an investigation to determine the current status and historical trends of wetlands and associated aquatic habitats in the Corpus Christi area from Lamar Peninsula to Encinal Peninsula. The study area encompasses most of the mainland between the Gulf Intracoastal Waterway (GIWW) and the Texas General Land Office Coastal Management Program boundary, an area located within Refugio, Aransas, San Patricio, and Nueces Counties (Fig. 1). Natural environments include wetlands, wind-tidal flats, riparian woodlands, and bay shorelines. The methods and classification system used in this report follow those found in the Texas coastal barrier-island report for the Coastal Bend (White et al., 2002).
Geophysical investigations of salinization in Crittendon Field, Winkler County, Texas
(2008) Paine, Jeffrey G.; Collins, Edward W.
Researchers at the Bureau of Economic Geology, The University of Texas at Austin, noninvasively measured the electrical conductivity of the ground near pipelines and monitor wells in the Crittendon Field in Winkler County, Texas. This geophysical survey, which supplemented an earlier survey completed in June 2008 (Paine and Collins, 2008), was completed to determine whether there is geophysical evidence of significant near-surface salinization where highly saline (and electrically conductive) produced water has infiltrated the shallow subsurface. Relatively dry soils such as those common in Winkler County have very low natural electrical conductivities. Addition of highly conductive saline water can increase the electrical conductivity of the soil by a factor of ten or more, making salinized ground a favorable target for geophysical surveys that measure the apparent conductivity of the ground. The geophysical instrument used in this project produces electrical conductivity profiles along a chosen path at the surface, much like borehole induction logs produce traces of conductivity change along a borehole. Segments showing sufficiently elevated conductivity are likely to be salinized within the exploration depth range of the instrument, which ranges from as shallow as the upper few meters to as deep as 50 m depending on instrument configuration and conditions in the area. Electromagnetic (EM) induction methods have proven to be very effective in locating salinized areas, mapping the extent and intensity of salinization, and locating potential salinity sources (Paine, 2003; Paine and others, 1997, 2007). Early geophysical instruments employed to estimate soil salinity indirectly included transducers and electrode arrays to measure soil conductivity (Enfield and Evans, 1969; Halvorson and Rhoades, 1974). During the late 1970s and early 1980s, investigators began developing and using EM instruments to measure ground conductivity noninvasively and estimate soil and water salinity at depths ranging from less than 1 to more than 50 m. The EM method is popular because it can be rapidly and noninvasively applied. It is effective because a large increase in electrical conductivity typically accompanies the introduction of extremely conductive saline water (several hundred to several thousand millisiemens per meter [mS/m] [Hem, 1985]) into fresh water, soil, and rock that generally have low natural conductivities (a few tens to a few hundred mS/m [McNeill, 1980a]).
Ground Recharge in the Central High Plains of Texas: Roberts and Hemphill Counties
(2008) Reedy, R. C.; Davidson, Sarah; Crowell, Amy; Gates, John B.; Akasheh, O. Z.; Scanlon, Bridget R.
Reliable estimates of recharge are important for assessing and managing groundwater resources, especially in regions like the High Plains aquifer of Texas where declining groundwater levels due to large-scale pumping make recharge estimation even more critical. The purpose of this study was to estimate groundwater recharge in the vicinity of Roberts County. Three basic approaches were used to estimate recharge: 1. Chloride mass balance in groundwater, 2. Chloride mass balance in the unsaturated zone, and 3. Numerical modeling of recharge in the unsaturated zone. Groundwater chloride concentrations were used to evaluate regional recharge rates based on the chloride mass balance approach in Roberts County. Additionally, a limited number of groundwater well samples were analyzed for tritium-helium ages to supplement the regional groundwater chloride mass balance analysis. The chloride mass balance approach was also applied to the unsaturated zone to provide point recharge estimates in different land use settings. A total of 19 boreholes were drilled from 2006 through 2008 in different locations (14 in Roberts and 5 in Hemphill counties) to depths ranging from 18.5 to 88 ft (5.6 to 26.8 m). Natural rangeland represents the dominant land use in these counties, and nine boreholes were located in this setting. Two boreholes were situated beneath dryland agriculture, and three boreholes beneath irrigated agriculture. One borehole was drilled in a dry drainage channel, and four boreholes were drilled adjacent to stock impoundments that pond water in Roberts County. Soil samples were collected in the field for laboratory measurement of soil physics (water content and matric potential head) and environmental tracers (chloride, fluoride, nitrate, and sulfate). Groundwater recharge was estimated using the chloride mass balance or chloride front displacement approach. Groundwater recharge in Roberts County was also estimated using unsaturated zone modeling based on meteorological data from 1961 through 1990, representative online soils data from SSURGO, and representative vegetation types. Sensitivity analyses were conducted to estimate maximum recharge based on bare sand and to evaluate soil texture and vegetation controls on recharge.
Task 3 Milestone: Approaches for the Recognition and Management of Sensitive Features in the Edwards Aquifer Recharge Zones
(2001) Hovorka, Susan D.
During the past 3 months, I have been observing in the field how the TNRCC Geologic Assessment of sensitive features in the Edwards recharge zone is done by geologists and TNRCC staff. I have also reviewed karst literature, interviewed experts, and abstracted information relevant to the Geologic Assessment. This milestone describes the options for changing the assessment that I have collected and my recommendations on these options for consideration by TNRCC staff. The major proposed changes are: 1. Eliminate the category "possibly sensitive" and rank most active karst features as sensitive. 2. Keep a simple additive assessment and simplify it to include only three variables: classification by feature type, orientation with respect to structure, and a field-based assessment of relative infiltration rate. 3. Increase emphasis on matching appropriate engineering responses to sensitive features. 4. Evaluate features encountered during sewer construction to identify those where flow should be maintained. 5. Improve training by increasing the guidance provided in the instructions. 6. Reduce variability in assessment by better defining the criteria on which to evaluate relative infiltration rate. 7. Consider the requirements of other regulatory agencies on developers to reduce confusion and increase compliance. I recommend that current practices of managing excavation to explore features, and not requiring cave mapping, be retained as they are currently done during assessments. A number of logistical changes are suggested to the instructions and the table. In addition, I propose the following minor changes for consideration: require location of features with GPS and consider improving training by voluntary stakeholder field training days. After discussion with TNRCC staff, the Instructions to Geologists and Geologic Assessment Table will be revised to include the selected changes.
Impact of Mixed Gas Stream on CO2 Plume Characteristics during and after Carbon Storage Operations in Saline Aquifers
(2008) Nicot, Jean-Philippe; Choi, J. W.; Ghomian, Yousef, 1974-; Duncan, Ian
The goal of this short study was to explain the effects of CO2 stream impurities (CH4 and N2) on (1) plume spread, (2) rate and extent of major trapping mechanisms, (3) CO2 storage capacity, and (4) well injectivity. The injection-stream base case consists of a 95% CO2 stream with 2.5% CH4 and N2. We varied the CO2 fraction from 75% to 100% (on a mole basis), defining three bounding cases: CO2BC, CH4BC, and N2BC containing 100% CO2, 75% CO2 and 25% CH4, and 75% CO2 and 25% N2, respectively. In a parametric study of the stream composition, we defined a simple generic reservoir with a uniform permeability of 300 md, a dip of 2°, and porosity of 25%. The model contains 120 300-ft-long cells in the dip direction and also includes four baffles with no permeability parallel to its top and bottom. The gas was injected for 30 years at a depth of about 6,000 ft and at a rate of 26 MMSCFD (equivalent to 0.5 Mt/yr of pure CO2) in a single well located in the downdip section of the model and perforated in the lower third of the 1,000-ft thickness of the injection formation. Temperature is constant at 135°F. Results are numerically monitored for 1,000 yr after start of injection. The modeling was done using CMG-GEM software, and we used a user-defined set of PVT properties. A sensitivity analysis on important model parameters was also done to assess their importance relative to the parametric-study results. The study considers only the two trapping mechanisms (residual saturation and brine dissolution) largely impacted by injection-stream composition. Plume spread, or maximum extent, is a strong function of composition. The maximum extent ranges from 10,350 ft for CO2BC to more than twice the distance for CH4BC (22,250 ft) and N2BC (24,250 ft) and varies approximately linearly for intermediate values. Similarly, time for the plume to reach the top of the formation varies from 14 yr (N2BC) to 18 yr (CH4BC) to 60 yr (CO2BC). The main difference between gas components is solubility in brine—CO2 is approximately 10 times more soluble than CH4 and N2 on a mole basis. The buoyant driving force, expressed as the ratio of gas-brine density difference to gas viscosity, is also approximately four times higher in the CH4BC and N2BC cases, and the ratio keeps increasing because the fraction of CH4 and N2 increases as CO2 dissolves.
Subsurface Devonian and Mississippian Gas Shale Samples Barnett and Smithwick Shales (Fort Worth Basin) and Woodford and Barnett Shales (Delaware Basin) Core Sampling for Measured Vitrinite Reflectance Determination
(2008) Hentz, Tucker F.; Breton, Caroline L.; Ruppel, Stephen C.
This report summarizes activities carried out by the Bureau of Economic Geology (BEG) during Fiscal Year (FY) 2007 for the National Coal Resources Data System State Cooperative Program (NCRDS project). The report represents a departure from those prepared in previous years by providing a collection of Devonian-Mississippian and Mississippian gas-shale samples. Approval for this change in sample type was given by the USGS in March 2008. Samples were collected from whole cores of three wells in Wise and San Saba Counties, Fort Worth Basin, North Texas (Fig. 1), and Pecos County, Delaware Basin, West Texas (Fig. 2) for vitrinite-reflectance (Ro) analysis by the USGS. Other study activities include identification of the sampled shales' precise geographic location and their stratigraphic position.
Summary report for the 2007–2008 STATEMAP Project: Geologic mapping to support improved database development and understanding of urban corridors, critical aquifers, and special areas of environmental concern in Texas
(2008) Collins, Edward W.; Tremblay, Thomas A.
The Geologic Map of the Southeast Part of the Austin, Texas, 30 x 60 Minute Quadrangle: Central Texas Population Corridor Encompassing Bastrop and Smithville, scale 1:100,000, was constructed through digital compilation of eight 1:24,000-scale open-file geologic maps. The map is intended to be used by professionals and laypersons as a source of general geologic information that relates to land and resource use and management. Geology of the area consists mostly of Paleocene through Eocene mud- and sand-rich units. Minor Upper Cretaceous marine marl and calcareous mud deposits are in the western study area. Quaternary high-gravel deposits and well-defined terrace deposits of the Colorado River also occur. Bedrock units typically exhibit eastward regional dips of less than 2°. In the west and east parts of the study area, northeast-striking normal faults cut strata. Aquifer units include the Carrizo-Wilcox, Queen City, and Sparta. Resources include sand, gravel, clay, lignite, and oil.
Status and Trends of Wetlands and Aquatic Habitats on Texas Barriers: Upper Coast Strandplain Chenier System and Southern Coast Padre Island National Seashore
(2007) White, William Allen, 1939-
Wetland and aquatic habitats are essential components of barrier islands along the Texas coast. These valuable resources are highly productive both biologically and chemically and are part of an ecosystem on which a variety of flora and fauna depend. Scientific investigations of wetland distribution and abundance through time are prerequisites to effective habitat management, thereby ensuring their protection and preservation and directly promoting long-term biological productivity and public use. This report is the latest in a series of wetland status and trend investigations of barrier islands along the Texas Coast (White et al. 2002, 2004, 2005, and 2006). Presented in this report are results of two status-and-trend studies: one of the upper Texas coast along the strandplain-chenier system from Sabine Pass to East Galveston Bay, and the other of the southern Texas coast along Padre Island National Seashore (PINS) that includes the central section of Padre Island (Fig. 1). The two study areas are very different. Geologically, the upper Texas coast is characterized by a modern strandplain-chenier system with well-preserved chenier beach ridges with interlying marsh-filled swales (Fisher et al. 1973). Relict beach ridges and intervening swales have an orientation roughly parallel to today's shoreline marked by the Gulf beach. The swales are the sites of extensive linear estuarine marshes. The strandplain-chenier system has gradually evolved through erosion, deposition, compaction, subsidence, and locally faulting. The strandplain extends along the Gulf shore toward the southeast to High Island. High Island is a salt dome near the Gulf shoreline with elevations exceeding 75m (25ft) (Fig. 1); The study area extends landward to the Gulf Intracoastal Waterway.

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