Please Pass the Salt: Using Oil Fields for the Disposal of Concentrate

Transcription

1 Please Pass the Salt: Using Oil Fields for the Disposal of Concentrate Robert E. Mace Texas Water Development Board Jean-Philippe Nicot Bureau of Economic Geology September 29, 2004 Bureau of Reclamation

2 The problem: Communities interested in desalination need a cost-effective and safe solution for disposing of concentrate.

3 A possible solution: Inject concentrate into depleted oil fields.

4 Goal of the project: To develop the scientific foundation upon which we can support recommended policy change to allow an easier approval path for permitting concentrate injection wells in oil fields. Show location of oil fields across state that may be potential injection sites. Show through physical and geochemical modeling that oil fields can accept concentrate. Make a recommendation on how to streamline permitting.

5 TECHNICAL APPROACH Identify depleted oil and gas fields Historical perspective on fluid injection in oil and gas fields in Texas Characteristics of analysis areas Characteristics of concentrates Formation damage Scaling Clay sensitivity Formation damage control Injection rates

6 TR TUBB HORSE- PANHANDLE LIMESTONE IDENTIFY DEPLETED OIL AND GAS FIELDS N Percent 30% 25% 20% 15% 10% 5% 0% Major oil reservoirs Major gas reservoirs mi km Pressure Depletion and AOR MinTOF - MaxBUQW; Anadarko Basin N= Percent 30% 25% 20% 15% 10% 5% 0% MinTOF - MaxBUQW; Permian Basin Separation (ft) Separation (ft) 67% 50% 57% N= Percent 30% 25% 20% 15% 10% 5% 0% MinTOF - MaxBUQW; East Texas Basin Separation (ft) N= Water Well Oil Well Ground Surface Depth to BUQW Aquifer Minimum 500-ft Separation Formation Pressure Head Injection Formation SYSTEM QUAT. TERT. CRETACEOUS PERMIAN PENNSYLVANIAN MOR- ROWAN MISSIS- SIPPIAN ORDOVICIAN CAMBRIAN SERIES (AGE) p C COMAN- CHEAN GULFIAN UPPER OCHOAN GUADALUPIAN LEONARDIAN CISCO CANYON STRAWN ATOKAN WOLF- CAMPIAN DEVON- IAN SILUR- IAN UPPER MIDDLE UPPER LOWER DELAWARE BASIN ALLUVIUM CENTRAL BASIN PLATFORM ALLUVIUM OGALLALA MIDLAND BASIN ALLUVIUM OGALLALA EASTERN SHELF ALLUVIUM OGALLALA WASHITA WASHITA FREDERICKSBURG FREDERICKSBURG FREDERICKSBURG FREDERICKSBURG TRINITY SANDSTONE TRINITY SANDSTONE TRINITY SANDSTONE TRINITY SANDSTONE DELAWARE SANDSTONE SANTA ROSA DEWEY LAKE RUSTLER SALADO CASTILE BELL CANYON CHERRY CANYON BRUSHY CANYON BONE SPRING WOLFCAMP CISCO CANYON STRAWN ATOKA MORROW MISSISSIPPIAN??? KINDERHOOK WOODFORD DEVONIAN UPPER SILURIAN SHALE FUSSELMAN MONTOYA SIMPSON GROUP ELLENBURGER CAPITAN REEF DOCKUM DOCKUM DOCKUM DEWEY LAKE RUSTLER SALADO CASTILE TANSILL YATES SEVEN RIVERS QUEEN GRAYBURG SAN ANDRES CLEAR FORK WICHITA WOLFCAMP CISCO DEWEY LAKE RUSTLER SALADO TANSILL YATES SEVEN RIVERS QUEEN GRAYBURG SAN ANDRES SPRABERRY DEAN LEONARD WOLFCAMP CISCO Thin to absent RUSTLER SALADO TANSILL YATES SEVEN RIVERS QUEEN GRAYBURG SAN ANDRES CLEAR FORK WICHITA WOLFCAMP CISCO CANYON CANYON CANYON UNDIFFERENTIATED PERMIAN- PENNSYLVANIAN GRANITE WASH ELLEN- BURGER STRAWN MISSISSIPPIAN DEVONIAN UPPER SILURIAN SHALE FUSSELMAN MONTOYA SIMPSON GROUP STRAWN UPPER MISSISSIPPIAN MISSISSIPPIAN LIMESTONE DEVONIAN UPPER SILURIAN SHALE FUSSELMAN SIMPSON GROUP ELLENBURGER SHOE ATOLL SYLVAN SHALE MONTOYA WILBERNS STRAWN MISSISSIPPIAN LIMESTONE WOODFORD WOODFORD LOWER WOODFORD UPPER SILURIAN SH. SYLVAN SHALE ELLENBURGER WILBERNS HICKORY SHERMAN BASIN ALLUVIUM AUSTIN EAGLE FORD WOODBINE WASHITA FREDERICKSBURG TRINITY SANDSTONE STRAWN CANYON VIOLA SIMPSON GROUP OIL CREEK SS. ELLENBURGER CLEAR FORK ANADARKO BASIN- AMARILLO UPLIFT ALLUVIUM OGALLALA DOCKUM WHITEHORSE BLAINE SAN ANDRES CLEAR FORK TUBB RED CAVE WICHITA- ALBANY BROWN DOLO. ARKOSIC DOLO. CISCO CANYON STRAWN ATOKA ATOKA ATOKA BEND ATOKA ATOKA MORROW MORROW CHESTER MERAMEC OSAGE KINDERHOOK KINDERHOOK KINDERHOOK KINDERHOOK FUSSELMAN Area of circle represents relative oil cumulative production WOODFORD WOODFORD HUNTON SYLVAN SH. VIOLA SIMPSON GROUP ELLENBURGER (ARBUCKLE) REAGAN QA11721(b)x Percent MinTOF - MaxBUQW; Fort Worth Basin N=285 30% 25% 20% 15% 10% 5% Percent MinTOF - MaxBUQW; Maverick Basin N=121 30% 25% 20% 15% 10% 5% Percent MinTOF - MaxBUQW; Southern Gulf Coast Basin N=356 30% 25% 20% 15% 10% 5% 0% 0% 0% Separation (ft) Separation (ft) Separation (ft) 63% 36% 56% % values represent percentage of fields candidates for a AOR variance

7 Why Do We Care about Pressure Depletion? Create opportunity to inject fluid with little risk of exceeding maximum pressure that can be sustained by reservoir Simplify Area of Review Process Field production history guarantees surface infrastructure needed to move around fluids

8 Major Oil and Gas Reservoirs N 1 Analysis Areas 2 Major oil reservoirs Major gas reservoirs Anadarko 2 Permian 3 East Texas 4 Fort Worth 5 Maverick 6 Southern Gulf Coast mi km

9 SYSTEM SERIES (AGE) QUAT. TERTIARY CRETACEOUS JURASSIC T R PALEO- ZOIC MIOCENE/ PLIOCENE EOCENE OLIGOCENE PALEO- CENE GULFIAN COMANCHEAN COAH- UILAN MID. UPPER L. EAST TEXAS BASIN YEGUA COOK MOUNTAIN SPARTA WECHES QUEEN CITY REKLAW CARRIZO WILCOX MIDWAY LEWISVILLE HOUSTON EMBAYMENT AND SAN MARCOS ARCH BEAUMONT (HOUSTON) WILLIS FLEMING ANAHUAC HACKBERRY FRIO VICKSBURG RIO GRANDE EMBAYMENT HOUSTON GOLIAD LAGARTO OAKVILLE FRIO ANAHUAC VICKSBURG JACKSON JACKSON YEGUA (COCKFIELD) YEGUA COOK MOUNTAIN COOK MOUNTAIN SPARTA WECHES SPARTA WECHES QUEEN CITY QUEEN CITY REKLAW REKLAW CARRIZO CARRIZO WILCOX WILCOX MIDWAY MIDWAY NACATOCH NAVARRO NAVARRO ESCONDIDO UPPER TAYLOR OLMOS PECAN GAP TAYLOR WOLFE CITY SERPENTINE AND DALE SAN MIGUEL LOWER TAYLOR LIMESTONE ANACACHO UPSON COKER HARRIS GLEN ROSE AUSTIN SUB-CLARKSVILLE DEXTER BUDA GRAYSON EAGLE FORD GEORGETOWN Selected Strati- graphic Columns in Texas with Oil Production WOOD- BINE FREDERICKSBURG PALUXY UPPER GLEN ROSE MOORINGSPORT MASSIVE ANHYDRITE BACON LIMESTONE RODESSA JAMES PINE LIMESTONE ISLAND PETTET (SLIGO) PITTSBURG TRAVIS PEAK (HOSSTON) AUSTIN EAGLE FORD WOODBINE BUDA DEL RIO GEORGETOWN ED- PERSON WARDS KAINER GLEN ROSE PEARSALL SLIGO HOSSTON ED- WARDS AUSTIN EAGLE FORD BUDA DEL RIO GEORGETOWN SALMON PEAK MC KNIGHT WEST NUECES GLEN ROSE PEARSALL SLIGO HOSSTON COTTON VALLEY (SCHULER AND BOSSIER) COTTON VALLEY COTTON VALLEY GILMER-HAYNESVILLE GILMER GILMER BUCKNER SMACKOVER BUCKNER SMACKOVER BUCKNER SMACKOVER NORPHLET NORPHLET NORPHLET LOUANN SALT WERNER EAGLE MILLS LOUANN SALT EAGLE MILLS? STUART CITY LOUANN SALT EAGLE MILLS STUART CITY OUACHITA FACIES OUACHITA FACIES OUACHITA FACIES Tabulated reservoirs in a major oil play and comparitave importance as a producing unit QA11721(a)x Small or isolated reservoirs only SYSTEM QUAT. TERT. CRETACEOUS TR PERMIAN PENNSYLVANIAN MISSIS- SIPPIAN DEVON- IAN SILUR- IAN ORDOVICIAN CAMBRIAN SERIES (AGE) GULFIAN COMAN- CHEAN p C UPPER OCHOAN GUADALUPIAN LEONARDIAN WOLF- CAMPIAN CISCO CANYON STRAWN ATOKAN MOR- ROWAN UPPER MIDDLE UPPER LOWER DELAWARE BASIN ALLUVIUM CENTRAL BASIN PLATFORM ALLUVIUM OGALLALA MIDLAND BASIN ALLUVIUM OGALLALA EASTERN SHELF ALLUVIUM OGALLALA WASHITA WASHITA FREDERICKSBURG FREDERICKSBURG FREDERICKSBURG FREDERICKSBURG TRINITY SANDSTONE TRINITY SANDSTONE TRINITY SANDSTONE TRINITY SANDSTONE DELAWARE SANDSTONE SANTA ROSA DEWEY LAKE RUSTLER SALADO CASTILE BELL CANYON CHERRY CANYON BRUSHY CANYON BONE SPRING WOLFCAMP CISCO CANYON STRAWN ATOKA MORROW MISSISSIPPIAN??? KINDERHOOK WOODFORD DEVONIAN UPPER SILURIAN SHALE FUSSELMAN MONTOYA SIMPSON GROUP ELLENBURGER CAPITAN REEF DOCKUM DOCKUM DOCKUM DEWEY LAKE RUSTLER SALADO CASTILE TANSILL YATES SEVEN RIVERS QUEEN GRAYBURG SAN ANDRES CLEAR FORK WICHITA WOLFCAMP CISCO TUBB DEWEY LAKE RUSTLER SALADO TANSILL YATES SEVEN RIVERS QUEEN GRAYBURG SAN ANDRES SPRABERRY DEAN LEONARD WOLFCAMP CISCO Thin to absent RUSTLER SALADO TANSILL YATES SEVEN RIVERS QUEEN GRAYBURG SAN ANDRES CLEAR FORK WICHITA WOLFCAMP CISCO CANYON CANYON CANYON ELLEN- BURGER STRAWN MISSISSIPPIAN DEVONIAN UPPER SILURIAN SHALE FUSSELMAN MONTOYA SIMPSON GROUP STRAWN FUSSELMAN SIMPSON GROUP ELLENBURGER HORSE- SHOE ATOLL UPPER MISSISSIPPIAN MISSISSIPPIAN LIMESTONE SYLVAN SHALE MONTOYA WILBERNS STRAWN MISSISSIPPIAN LIMESTONE WOODFORD WOODFORD LOWER WOODFORD UPPER SILURIAN SH. SYLVAN SHALE ELLENBURGER WILBERNS HICKORY SHERMAN BASIN ALLUVIUM AUSTIN EAGLE FORD WOODBINE WASHITA FREDERICKSBURG TRINITY SANDSTONE STRAWN CANYON VIOLA SIMPSON GROUP OIL CREEK SS. ELLENBURGER CLEAR FORK ANADARKO BASIN- AMARILLO UPLIFT ALLUVIUM OGALLALA DOCKUM WHITEHORSE BLAINE SAN ANDRES CLEAR FORK TUBB RED CAVE PANHANDLE WICHITA- LIMESTONE ALBANY BROWN DOLO. ARKOSIC DOLO. CISCO CANYON STRAWN ATOKA ATOKA ATOKA BEND ATOKA ATOKA MORROW MORROW CHESTER MERAMEC OSAGE KINDERHOOK KINDERHOOK KINDERHOOK KINDERHOOK DEVONIAN UPPER SILURIAN SHALE FUSSELMAN Area of circle represents relative oil cumulative production WOODFORD WOODFORD HUNTON SYLVAN SH. VIOLA SIMPSON GROUP ELLENBURGER (ARBUCKLE) REAGAN UNDIFFERENTIATED PERMIAN- PENNSYLVANIAN GRANITE WASH QA11721(b)x

10 Target Formations Anadarko B.: Granite Wash Fm. Fort Worth B.: Atoka Fm. Permian B.: San Andres Fm. Maverick B.: San Miguel/Olmos Fm. East Texas B.: Woodbine Fm. Southern Gulf Coast B.: Frio Fm.

11 Pressure-depleted Fields Permian Basin Bottom Hole Pressure (psig) ,000 1,500 2,000 2,500 3,000 0 East Texas Basin Bottom Hole Pressure (psig) ,000 1,500 2,000 2,500 3,000 0 Southern Gulf Coast Basin Bottom Hole Pressure (psig) ,000 1,500 2,000 2,500 3,000 3,500 4,000 0 Depth below Ground Surface (ft) 1,000 2,000 3,000 4,000 5,000 6,000 BHP= (1/0.403)D R 2 = Depth below Ground Surface (ft) 1,000 2,000 3,000 4,000 5,000 D=(1/0.460)D R 2 = 0.84 Depth below Ground Surface (ft) 1,000 2,000 3,000 4,000 5,000 6,000 7,000 BHP = (1/465)D R 2 = ,000 6,000 8,000

12 HISTORICAL PERSPECTIVE ON OIL AND GAS FIELDS IN TEXAS

13 Water Injection in Oil&Gas Fields Reservoir drive mechanisms in oil&gas fields: Water drive Gas cap drive Solution gas drive Pressure maintenance and waterflooding with fresh, brackish, or produced waters Fresh water needs no treatment before injection Fresh water reduces or eliminates scaling in pipes but could generate downhole scaling and/or fine plugging Source for figure:

14 Injection Historical Data Injection Historical Data Data compilation up to 1982 Anadarko B. Permian B. East Texas B Water >3,500ppm Water <3,500ppm Fort Worth B. Maverick B. Sth. Gulf Coast B. Cumulative Injection (billion bbls) Anadarko B. Permian B. East Texas B. Fort Worth B. Maverick B Water >3,500ppm Water <3,500ppm Sth. Gulf Coast B. All Districts From RRC database (1982) last year with data compilation Cumulative Injection (billion bbls)

15 Conclusions Oil and Gas industry in Texas has an extensive experience with fluid injection Fluids include fresh, brackish and saline waters Source: Hycal.com

16 SELECT ANALYSIS AREAS N Injection Well Depth <3450 ft ft Major oil reservoirs Major gas reservoirs >6100 ft Counties with unmet needs 300 Miles m i 400 km Miles

17 Analysis Area Selection Criteria Counties with depleted oil/gas fields Counties with a predicted shortfall of water supply over the next 50 years Counties with brackish ground water resources Counties with injection wells not too deep

18 County Water Needs County Water Needs Met Unmet Cities Target Locations Miles Source: TWDB, 2002 Water for Texas

19 Water Quality of Shallow Groundwater Blue = Fresh water < 1,000 mg/l TDS Yellow = 1,000 3,000 mg/l TDS Orange = 3,000 10,000 mg/l TDS Red = > 10,000 mg/l TDS From LBJ Guyton Associates (2003)

20 Target Brackish Water Sources Anadarko B.: Ogallala Aq. Dockum Aq. Permian B.: Ogallala Aq. Dockum Aq. East Texas B.: Fort Worth B.: Trinity Aq. Maverick B.: Carrizo-Wilcox Aq. Southern Gulf Coast B.: Carrizo-Wilcox Aq.. Gulf Coast Aq..

21 CHARACTERISTICS OF ANALYSIS AREAS

22 Important Parameters Lithology/Mineralogy: Rock type Mineral in contact with flowing fluids Clay content and nature Formation water composition Flow properties: Porosity, permeability Other fluid present (relative permeability) Field characteristics Pay thickness Geothermal gradient Average pressure and depth

23 Mineralogical Characteristics of Analysis Areas Basin Anadarko Permian East Texas Fort Worth Maverick Rock Type Silico-clastic clastic Carbonate Silico-clastic clastic Silico-clastic clastic Silico-clastic clastic Important Minerals Feldspars, quartz, clays Calcite, dolomite Feldspars, quartz, clays Quartz, feldspars Quartz, feldspars S. Gulf Coast Silico-clastic clastic Feldspars, quartz, clays

24 Porosity/Permeability of Analysis Areas 1000 Permian Basin East Texas Basin 100 Permeability (md) 10 1 Permeability (md) Porosity (%) Porosity (%) Southern Gulf Coast Basin Fort-Worth Basin Permeability (md) Permeability (md) Porosity (%) Porosity (Percent)

25 Median and Range of Porosity/Permeability Basin Porosity (%) Permeability (md) Anadarko ~12 (4-20) ~20 (6 65) Permian ~9.3 (<3 - >20) ~5 (1 - >100) East Texas ~25 (20 - >35) ~500 (15 - >3,000) Fort Worth ~14.5 (6 28) ~20 (1 - >1,000 Maverick ~25 (19-32) ~30 (3 - >2,000) S. Gulf Coast ~25 (<15 - >35) ~305 (20 - >1,000)

26 CHARACTERISTICS OF CONCENTRATES 2 MGD Oceanside, CA RO Installation From R.W. Beck 12 MGD Sarasota, FL EDR plant

27 Concentrate Most feed water TDS between 1,000 and 3,000 mg/l Concentration factor of 4 (all ions have the same rejection rate) Closed system (no equilibration with CO 2 ) Two cases: Addition of antiscalant Addition of antiscalant and sulfuric acid to a ph=6 Difficulty in obtaining minor element (Si( Si, Fe, Ba, Sr) ) concentrations

28 FORMATION DAMAGE

29 Formation Damage Definitions A condition that occurs when barriers to flow develop in the near-wellbore region. Results in lower than expected production rate from (or injection rate into) Any process causing a reduction in the natural inherent productivity or injectivity of a producing or injection well

30 Mod. From Michael Dixon OMNI Laboratories, Inc. Mechanical Formation Damage Origin: injected suspended solids, formation fine migration plugging pore throats Fines bridged at pore restrictions Fluid flow Mobile fines

31 Chemical Formation Damage Origin1: deflocculation of clays, swelling of clays due to chemical changes (ph, ionic makeup) Origin2: formation of scales due to mixing of incompatible water and change in environmental conditions Flocculated Pore throats Pore Deflocculated Pore throats Pore Mod. From Michael Dixon OMNI Laboratories, Inc.

32 UCLA, Cohen et al SCALING

33 What is scaling? Precipitation of minerals in the wellbore or in the formation. Calcite, gypsum, barite, silica (iron oxides, brucite,, siderite, anhydrite, strontianite) Term also applies to corrosion products Fluid injection is typically less scale-prone than production

34 Approach Compute concentrate composition with the USGS geochemical code PHREEQC using standard industry pretreatment and a factor of 4 Mix in different proportions concentrate with formation water with the USGS geochemical code SOLMINEQ (able to handle high salinity fluids) Choose randomly 2x5,000 samples to mix Analyze statistically (histograms) saturation index for relevant minerals of resulting combinations Determine the fraction of mixing combinations above the SI threshold beyond which antiscalants are not effective

35 Examples of SI Histograms 0.16 Permian Basin - Mixed Water - Calcite SI 0.30 East Texas Basin - Mixed Water - Calcite SI 0.14 South. Gulf Coast Basin - Mixed Water - Calcite SI Probability Probability Probability Saturation Index Saturation Index Saturation Index Number of bins: 41; Bin size: 0.1; Number of data points: 20,000 Number of bins: 41; Bin size: 0.1; Number of data points: 19,580 Number of bins: 41; Bin size: 0.1; Number of data points: 19, Permian Basin - Mixed Water - Gypsum SI 0.25 East Texas Basin - Mixed Water - Gypsum SI 0.12 South. Gulf Coast Basin - Mixed Water - Gypsum SI Probability Probability Probability Saturation Index Saturation Index Saturation Index Number of bins: 41; Bin size: 0.1; Number of data points: 19,990 Number of bins: 41; Bin size: 0.1; Number of data points: 19,349 Number of bins: 41; Bin size: 0.1; Number of data points: 19, Permian Basin - Mixed Water - Barite SI East Texas Basin - Mixed Water - Barite SI 0.01 South. Gulf Coast Basin - Mixed Water - Barite SI Probability Saturation Index Probability Saturation Index Probability Saturation Index Number of bins: 41; Bin size: 0.1; Number of data points: 2,300 Number of bins: 51; Bin size: 0.1; Number of data points: 320 Number of bins: 61; Bin size: 0.1; Number of data points: 4, Permian Basin - Mixed Water - Silica SI 0.14 East Texas Basin - Mixed Water - Silica SI 0.16 South. Gulf Coast Basin - Mixed Water - Silica SI Probability Probability Probability Saturation Index Number of bins: 41; Bin size: 0.1; Number of data points: 17, Saturation Index Number of bins: 41; Bin size: 0.1; Number of data points: 14, Saturation Index Number of bins: 41; Bin size: 0.1; Number of data points: 18,043 With acidified concentrate

36 Summary of SI s of Mixing Combinations Most SI are <1 including amorphous (colloidal) silica Saturation Index Barite may be a problem locally (SI ( is also higher because of H 2 SO 4 ) Calcite Anadarko Gypsum Barite Calcite Perm ian Gypsum Barite Calcite East Texas Gypsum Barite Calcite Fort Worth Gypsum Barite Calcite Maverick Gypsum Barite Calcite Sout.Gulf Coast Gypsum Barite Median and 95 th percentile With acidified concentrate

37 Scaling Discussion Previous results assume thorough mixing between concentrate and formation water This is conservative because mixing is likely to be less than thorough owing to ~piston flow of concentrate displacing formation water

38 CLAY SENSITIVITY Source: hycal.com

39 Mod. From Michael Dixon OMNI Laboratories, Inc. What is Clay Sensitivity? Clay sensitivity is due to the ability of clays to exchange ions with surroundings and/or to absorb water (swelling) A change in environmental conditions (ionic makeup, salinity, ph) may also disperse clay particles (deflocculation( deflocculation) Before injection, two questions need to be answered: Is there any clay? What type of clay? Flocculation High salinity High Divalent Low ph + Low salinity + Low Divalent High ph Deflocculation

40 Clay Types in Analysis Areas Basin Anadarko Clay Abundance Clay Type Chlorite, illite, kaolinite Permian East Texas Fort Worth Maverick Rare Common Abundant S. Gulf Coast Abundant Kaolinite Smectite, illite,, chlorite, kaolinite Chlorite, illite, kaolinite Mx-layer illite-smectite smectite, chlorite, kaolinite Mx-layer illite-smectite smectite, smectites, kaolinite

41 Plot mod. from Scheuerman and Bergersen, 1990, SPE Paper No Clay Sensitivity Principles 10,000 Frio Formation - South Texas - San Patricio Cty Total Cation Concentration (meq/l) 1, Ka=kaolinite Il=illite Mx=mixed layers; Sm=smectite TCC=Total Cation Conc. Any water inside the delineated domain will deflocculate the corresponding clay at equlibrium. Total Cation Concentration (meq/l) Ka Il Mx Sm Ka Il Mx Sm 10 0% 10% 20% 30% Divalent Cations (% of TCC) Possible cation stripping and deflocculation in the transient stage 1 0% 5% 10% 15% 20% 25% 30% Divalent Cations (% of TCC) <4,000ft <5,000ft <6,000ft <7,000ft <9,000ft <11,000ft >11,000ft no depth data

42 MAR Study: East TX B. Analysis A Carrizo-Wilcox and Woodbine Formations East Texas Basin - CZWX Concentrate MAR / Woodbine Fm. MAR 1000 Probability Total Cation Concentration (meq/l) % 10% 20% 30% 40% 50% 60% 70% Divalent Cations (% of TCC) Mass Action Ratio (MAR) Ratio Number of bins: 31; Bin size: 0.1; Number of trials: 100,000 MAR Ratio = {[Na] 2 /[Ca]} conc / {[Na] 2 /[Ca]} form If MAR Ratio <0.5, problems are expected for smectite clay

43 FORMATION DAMAGE CONTROL

44 Chemical and Physical Solutions Matrix acidizing by HCl,, H 2 SO 4 (both for carbonates), HF (for silicates), organic acids Treatment with KOH and NaOH (for calcium sulfate) CaCl 2 brine treatment (to limit clay sensitivity). NaCl and KCl.. Clay stabilizers that bind clays to the substrate Hydraulic fracturing Heat treatment (?) Damaged Zone Mod. From Michael Dixon, OMNI Laboratories, Inc.

45 Operational Solutions Surface treatment to remove suspended solids Lower flow rate, increase perforation density Gradual change in salinity to avoid salinity shock Injection of a buffer solution Oxygen scavengers, antiscalant

46 INJECTION RATES

47 Injection Rate Issues Maximum injection rate controls number of wells needed Injection rate is dependent on formation parameters: P Qµ 2.25kt ln 4πkb φcµ r = 2 Frequency Frequency Average Injection Rate Distribution < Average Injection Rate (gpm) Number of bins: 22; Bin size: 25 gpm; Number of data points: 390 Maximum Injection Rate Distribution < Maximum Injection Rate (gpm) Number of bins: 22; Bin size: 25 gpm; Number of data points: 437 including 10 points >525 gpm (Limited sampling of injection wells)

48 Computed Injection Rates Probability Anadarko Basin - Computed Maximum Injection Rate Maximum Injection Rate (gpm) Probability West Texas Basin - Computed Maximum Injection Rate < Maximum Injection Rate (gpm) Number of bins: 36; Bin size: 100 gpm; Number of trials: 10,000 median = 7.3 gpm; 95 th = 23 gpm Number of bins: 36; Bin size: 100 gpm; Number of trials: 10,000 median = 13.2 gpm; 95 th = 153 gpm 0.14 East Texas Basin - Computed Maximum Injection Rate 0.90 Fort Worth Basin - Computed Maximum Injection Rate Probability < Maximum Injection Rate (gpm) Probability < Maximum Injection Rate (gpm) Number of bins: 36; Bin size: 100 gpm; Number of trials: 10,000 median = 466 gpm; 95 th = 3,347 gpm Probability Maverick Basin - Computed Maximum Injection Rate < Maximum Injection Rate (gpm) Number of bins: 36; Bin size: 100 gpm; Number of trials: 10,000 median = 6.3 gpm; 95 th = 270 gpm Probability Number of bins: 36; Bin size: 100 gpm; Number of trials: 10,000 median = 9.8 gpm; 95 th = 376 gpm Southern Gulf Coast Basin - Computed Maximum Injection Rate < Maximum Injection Rate (gpm) Number of bins: 36; Bin size: 100 gpm; Number of trials: 10,000 median = 278 gpm; 95 th = 9,038 gpm

49 Injection Rate Conclusions 1 MGD of concentrate: Is equivalent to 695 gpm Would require a couple of wells in the eastern half of the state in recent formations Would require one or several well clusters in the paleozoic formations Injection rate can be augmented by screening the pay thickness and stimulating the well

50 Summary of Technical Conclusions A significant fraction of the wells would qualify for a variance of AOR Scaling can be mitigated with standard approaches (acidification, antiscalant) Clay sensitivity may be a local issue for several fields. It could be dealt with but at a price Multiple wells/well clusters are needed to accommodate concentrate output of a typical plant

51 Policy procedures: Met with RRC and TCEQ Met with EPA Region 6 and headquarters Talked with other states about their solutions Researched permitting and permitting options

52 Current permitting process: History Class I Class II Class V

53 Possible permitting paths: Non-hazardous Class I Class II Class V Dual-permitted wells General permit, Class I Special Class I Change Federal regulations

54