Brackish Groundwater Characterization, John Meyer and Sanjeev Kalaswad, Texas Water Development Board


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  • Most everyone familiar with the TWDB groundwater database.BRACS database was developed to handle new information obtained for the project
  • Gulf Coast Aquifer, Corpus Christi area. Comparison of Total Dissolved Solids (TDS) content of formation water and deep resistivity from geophysical well logs. 93 samples evaluated. High TDS water (> 15,000 mg/L) from USGS Produced Water Database. TDS < 15,000 from water well samples and one oil well DST sample set in the TWDB Groundwater Database. See map previous slide for well locations and formations where TDS samples were obtained.
  • John Estepp, P.G., TCEQ Surface Casing Program, prepared a book and training class on interpreting geophysical well logs for TDS.John’s formulas for analysis have been compiled and converted to Visual Basic code. There are currently 5 TDS methods that can be used.Automating the analysis will save staff time and offer better quality data.By saving all information in the database, new information (for example: better correction factors) can be incorporated and re-processed quickly.Staff can select a method and analyze the data. Staff can review the results before deciding if they want to save or discard the analysis.Example from Pecos Valley Aquifer project.
  • The TWDB WIID will be completely re-designed within the next few years.The display of our BRACS wells on this web page is a start towards providing information to the public.
  • Significant tasks, beginning in November of 2009.Two staff hired by the TWDB to conduct the BRACS project in November, 2009. Pecos Valley Aquifer pilot study began in February, 2010 with a final completion date of August 31, 2011.The TWDB Board approved three contracts in November, 2010 with a final completion date of August 31, 2011.
  • Activities: Funding and Outreach Activities Outreach: Partnerships & Workshops desalination technology workshops Bureau of Reclamation, SAWS and EPWU$7 million for desalination projects since 2000Nearly half of that for brackish groundwater desalination
  • Brackish Groundwater Characterization, John Meyer and Sanjeev Kalaswad, Texas Water Development Board

    1. 1. Brackish Groundwater CharacterizationbySanjeev Kalaswad, P.G.John Meyer, P.G.May 30, 2013Texas Alliance of Groundwater Districts
    2. 2. Why study brackish water?colored regionsrepresent estimatedbrackish extent ofmajor-minor aquifers• 2.7 billion acre-feet brackish groundwater• Need detailed information• Growing interest in desalination
    3. 3. 10.2%33.8%16.7%24.9%8.9%Cumulative Water Management Strategies by 2060SeawaterDesalination 1.4%ConservationSurface WaterGroundwaterGroundwaterDesalination 2%New ReservoirsConjunctiveUseASROtherWater ReuseSource: 2012 State Water Plan
    4. 4. 1214384422 MGD30 MGD75 MGD120 MGD0204060801001201401999 2001 2005 2010NumberofFacilitiesPlantCapacity(MGD)YearNumber of FacilitiesDesalination Plant Capacity
    5. 5. Regional assessment ofbrackish groundwater volumeLimited scope and dataLimited project timeframe
    6. 6. LBG-Guyton Map of Pecos Valley AquiferSource: Brackish Groundwater Manual for Texas Regional Water Planning Groups
    7. 7. LBG-Guyton Simplified Cross-section of the Pecos Valley AquiferSource: Brackish Groundwater Manual for Texas Regional Water Planning Groups
    8. 8. How does TWDB characterize brackish water?BRACS: Brackish Resources Aquifer Characterization System• build datasets (database, GIS) of project information• collect well logs (water, oil/gas) for interpretation• compile aquifer properties• map aquifer extent to 10,000 mg/L TDS• map key desalination parameters• calculate volumes of water• each aquifer may require unique analysis based on dataavailability and local hydrogeology• provide all information to interested stakeholders
    9. 9. TWDB Groundwater DatabaseWell DataRemarksWater LevelsWater Chemistry (2 tables)CasingTWDB BRACS DatabaseWell Data (location, depth, owner, …)Water LevelsWater Chemistry (2 tables)CasingForeign Keys (well ids)Well Geology (lithologystratigraphy)Net Sand and Sand PercentInterpreted TDS from Geophysical LogsAquifer Determination AnalysisDigital Water Well ReportsDigital Geophysical Well LogsGeophysical Well Log SuitesAquifer Test InformationTWDB Database TablesNewTables
    10. 10. BRACS Database MS Access relational design Contains all the new information we are collecting Designed to process information (Visual Basic Code) Link to additional databases through key fields Available on our website (with data dictionary) Will be merged with the TWDB Groundwater Databasein MS SQL Server
    11. 11. BRACS DatabaseForeign Key Table• Well name(s)• Number(s)• State Well Number• API Number• Q-number• Public Water ID• Report numbers• Cross-Section IDsSource: BRACS Database
    12. 12. Project Well Control: oil/gas and water wellsSource: Pecos Valley Aquifer Project
    13. 13. BRACS Geophysical Well Log CollectionScan paper logs into TIFF formatObtain digital oil and gas well logsScan TWDB paper log collection
    14. 14. Leverage work of other geologists
    15. 15. Formation LithologyGeophysical well log interpretationDriller formation descriptions from well reportsUsed for:Water volume calculationsSand thickness and occurrenceClay thicknessSource: Gulf Coast Aquifer Project, Corpus Christi ASR
    16. 16. Formation StratigraphyGeophysical well logsWater well reportsUsed for:Formation top and bottomFormation extentFormation sand contentCorrect aquifer assignment ofwater quality and aquifer propertiesSource: Sparta – Queen City Aquifer Project
    17. 17. Lithologic and Stratigraphic Data in the BRACS DatabaseSource: BRACS Database
    18. 18. Wilcox GroupWells defining bottom surfaceBottom Depth0 feet8,700 feetSource: Carrizo – Wilcox Aquifer Project
    19. 19. Wilcox GroupTop Surface GIS RasterTop Depth0 feet7,200 feetSource: Carrizo – Wilcox Aquifer Project
    20. 20. Pecos Valley Aquifer Thickness, based on > 2,000 wellsSource: Pecos Valley Aquifer Project
    21. 21. Cross-section Pecos Valley Aquifer based on GIS SurfacesSource: Pecos Valley Aquifer Project
    22. 22. Aquifer Determination• Assign aquifer(s) to each well in the project area• Use screen top/bottom or well depth or total depth of hole• Use the GIS-derived 3-D formation surfaces as vertical controlWhy?• Compare wells completed in same aquifer• Consistent evaluation of aquifer water quality and properties• Many new wells do not have TWDB aquifer code• Some TWDB wells have incorrect aquifer code
    23. 23. May include:• Well yield• Specific capacity• Hydraulicconductivity• Transmissivity• Storativity• Specific yield• Test length• Drawdown• Report Reference(Myers, R 98)Orange: BRACS DatabaseGreen: TDLR Submitted Driller LogsAquifer and Well Test DataSource: Carrizo – Wilcox Aquifer Project
    24. 24. Water Quality DataWells are biased towards fresh waterSource: Carrizo – Wilcox Aquifer Project
    25. 25. 10010001000010000010000000.1 1 10 100TotalDissolvedSolids(partspermillion)Geophysical Well Log Resistivity (ohm-meters)USGS Produced Water DatabaseTWDB Groundwater DatabaseSource: Gulf Coast Aquifer Project, Corpus Christi ASRGeophysical well log resistivity compared with water quality data
    26. 26. Interpreted TDS from Geophysical Well LogsSource: BRACS Database
    27. 27. Pecos Valley Aquifer Water Quality ZonesSource: Pecos Valley Aquifer Project
    28. 28. Queen City AquiferWater Quality ZonesGeophysical Well Log AnalysisWater Quality, USGS Produced WaterWater Quality, TWDB Groundwater DatabaseSource: Sparta – Queen City Aquifer Project
    29. 29. Estimated Groundwater VolumesTotal Estimated Recoverable Storage:• per aquifer• per county• per TDS RangeFour TDS Ranges (mg/L):• Fresh 0-999• Brackish 1,000 -2,9993,000 – 9,999• Very Saline > 10,000Similar method as TWDB Groundwater Resources Division
    30. 30. Project Deliverables• Published, peer-reviewed report• GIS Datasets• BRACS Database• Raw well data
    31. 31. Request for InformationNon-confidential data:• Groundwater reports• Water quality data• Well testing and aquifer parameters• Geophysical well logs• Water well reports
    32. 32. BRACS well locations in WIID(*)(*) WIID: Water Information Integration & Dissemination
    33. 33. • Pecos Valley Aquifer, West Texas (completed August 2011)• Gulf Coast Aquifer, Corpus Christi ASR ConservationDistrict (completed March 2012)• Queen City – Sparta Aquifer, Atascosa and McMullencounties (final review in progress)• Carrizo – Wilcox Aquifer, Central Texas (in progress)• Gulf Coast Aquifer, Lower Rio Grande Valley (in progress)BRACS Projects
    34. 34. BRACS Contracted StudiesGeologic BibliographyWell Log CollectionVariable DensityModeling
    35. 35. Desalination Studies and Demonstration ProjectsSeawater pilotConcentrateManagement InformationSourceCharacterization
    36. 36. Summary• Detailed brackish groundwater resource evaluation• Evaluating techniques of geophysical well log interpretation• BRACS project deliverables available on TWDB website• Geophysical well log files available upon request• Contract reports and deliverables available on TWDB website
    37. 37. www.twdb.texas.govSanjeev Kalaswad, P.G.(512) 936-0838Sanjeev.kalaswad@twdb.texas.govJohn E. Meyer, P.G.(512)