FINAL REPORT STREAM DEPLETION ANALYSIS DENVER-JULESBURG BASIN NORTHEAST COLORADO Prepared for The Denver-Julesburg Operators Group Prepared by URS Corporation in conjuction with The Denver-Julesburg Operators Group and Dr. Robert J. Weimer and Dr. David T. Snow November 4, 2009 URS Corporation 8181 E. Tufts Avenue Denver, CO 80237 22241252.50000 004471 TABLE OF CONTENTS Section 1 ONE Introduction.....................................................................................................................1-1 1.1 Nontributary Ground Water Evaluation of Denver-Julesburg Basin Formations ............................................................................................... 1-1 1.2 Dual Modeling and Geologic/Hydrologic Analyses................................ 1-2 1.3 Delineated Nontributary Ground Water Areas ........................................ 1-3 Section 2 TWO General Geology of the DJ Basin..................................................................................2-1 2.1 Physiography............................................................................................ 2-1 2.2 Geology.................................................................................................... 2-1 2.2.1 Geologic History.......................................................................... 2-1 2.2.2 General Stratigraphy.................................................................... 2-2 2.3 History of Hydrocarbon Development In the DJ Basin........................... 2-7 Section 3 THREE Geologic and Hydrologic Analysis of DJ Basin Formations ......................................3-1 3.1 Support for the Lack of Vertical Connection........................................... 3-2 3.2 Support for the Lack of a Significant Lateral Connection....................... 3-3 3.2.1 Western Basin Margin Bounding Deformation Zone.................. 3-3 3.2.2 Stratigraphic Pinch Outs, Unconformities, and Facies Changes........................................................................................ 3-4 3.2.3 Nature of Trapping Mechanisms ................................................. 3-4 3.3 Other Supporting Evidence...................................................................... 3-8 3.3.1 Pressure Data Supporting Hydraulic Disconnect Between Basin and Outcrop........................................................................ 3-8 3.3.2 Permeability ............................................................................... 3-11 3.3.3 Water Chemistry........................................................................ 3-13 Section 4 FOUR Conceptual Model for Stream Depletion Modeling......................................................4-1 4.1 Analytical Model of Stream Depletion.................................................... 4-2 4.1.1 Description................................................................................... 4-2 4.1.2 Assumptions and Limitations ...................................................... 4-3 4.2 Model Inputs............................................................................................ 4-5 4.2.1 Fluid Density and Viscosity......................................................... 4-5 4.2.2 Water Compressibility................................................................. 4-6 4.2.3 Intrinsic Permeability................................................................... 4-6 4.2.4 Porosity ........................................................................................ 4-7 4.2.5 Rock Compressibility................................................................... 4-7 4.2.6 Formation Thickness.................................................................... 4-7 4.2.7 Produced Water Withdrawal Rates.............................................. 4-7 4.3 Calculated Model Inputs.......................................................................... 4-8 4.3.1 Hydraulic Conductivity and Transmissivity ................................ 4-8 4.3.2 Specific Storage and Storativity................................................... 4-8 W:\PROJECTS\22241252_ANADARKO_SDA\SUB_00\6.0_PROJ_DELIV\DJ_REPORT_MASTER_11-4-09_EKW.DOC\11/4/2009 3:10 PM i 004472 TABLE OF CONTENTS Section 5 FIVE Data Analysis Results for Stream Depletion Modeling ...............................................5-1 5.1 Statistical Evaluation of Formation Properties ........................................ 5-1 5.1.1 Intrinsic Permeability................................................................... 5-1 5.1.2 Porosity ........................................................................................ 5-3 5.1.3 Formation Thickness.................................................................... 5-5 5.2 Calculated Model Inputs By Formation................................................... 5-6 5.2.1 Hydraulic Conductivity and Transmissivity ................................ 5-6 5.2.2 Specific Storage and Storativity................................................... 5-7 Section 6 SIX Nontributary Evaluations by Formation .......................................................................6-1 Section 7 SEVEN Conclusions....................................................................................................................7-1 Section 8 EIGHT References ......................................................................................................................8-1 8.1 References Cited In Report...................................................................... 8-1 8.2 Published Geologic Maps for Contact Delineation ................................. 8-5 8.3 List of Sources ......................................................................................... 8-6 List of Tables Table 3-1: Geometric Mean Permeability Values for the Subject Formations..........................3-12 Table 3-2: Statistics for Total Dissolved Solids Data Obtained from COGCC.........................3-14 Table 4-1: Average Maximum BHT used in Calculating Input Modeling Parameters ...............4-6 Table 5-1: Intrinsic Permeability Summary Statistics for the Greater Wattenberg Area ............5-2 Table 5-2: Intrinsic Permeability Summary Statistics Outside the GWA ...................................5-3 Table 5-3: Porosity Summary Statistics for the GWA.................................................................5-4 Table 5-4: Porosity Summary Statistics outside the GWA..........................................................5-5 Table 5-5: Statistical Summary of the Gross Formation Thickness within the GWA in Feet.....5-5 Table 5-6: Hydraulic Conductivity Calculation...........................................................................5-6 Table 5-7: Transmissivity Calculation.........................................................................................5-7 Table 5-8: Reservoir Storage Calculation....................................................................................5-8 Table 6-1: Modeled Nontributary Distance for Ten Formations of Interest................................6-2 W:\PROJECTS\22241252_ANADARKO_SDA\SUB_00\6.0_PROJ_DELIV\DJ_REPORT_MASTER_11-4-09_EKW.DOC\11/4/2009 3:10 PM ii 004473 TABLE OF CONTENTS List of Figures Figure 2-1: Denver-Julesburg Basin Greater Wattenberg Area Figure 2-2: Example of a Typical Geophysical Log from Weld County Figure 2-3: Stratigraphic Column for the Denver-Julesburg Basin Figure 2-4: Hygiene Outcrop Correlation Panel Figure 2-5: Isopach Map of the “D” Sandstone Member of the Graneros Formation Figure 2-6: Surface Topography and Potentiometric Surface for the Dakota and Basal Cretaceous Sandstone Unit Figure 3-1: The Pierre Seaway Figure 3-2: Rocky Flats Seismic Line Figure 3-3a: Seismic Line-profile of the Western Denver-Julesburg Basin Sedimentary Section Figure 3-3b: Seismic Line-profile of the Western Denver-Julesburg Basin Sedimentary Section Figure 3-4: Hydrogeologic Units of the Denver Basin Aquifer System Figure 3-5: Geologic Mechanisms (Faulting and Continuous Gas Accumulation) Influencing Lateral Ground Water Flow Figure 3-6: 3D Block Diagram Depicting Outcrops of Basinal Formations along Turkey Creek 285 Roadcut Showing the Front Range Bounding Faults Figure 3-7: Front Range Bounding Fault at Several Locations along the Front Range from Wyoming to Canon City Figure 3-8: Schematic Cross Sectional View of Anticlinal and Fault Hydrocarbon Traps Figure 3-9: Raster Log Cross Section A – A’ in Dragoon Field (Arapahoe County, CO) Showing Stratigraphic Trap Figure 3-10: Map and Cross-sectional Examples of Compartmentalized Reservoir Trap Types in the Greater Wattenberg Area Figure 3-11: Producing Zone Map of the Denver-Julesburg Basin Figure 3-12: Area of Hydrocarbon Generation in the Denver-Julesburg Basin Figure 3-13: Schematic Illustration of the Continuous Gas Accumulation Setting Figure 3-14: Reservoir Pressure Conditions of the Sussex, Shannon, Niobrara, Codell, Dakota Group, and Lyons Formations Figures 3-15a and 3-15b: Pressure Gradients for Codell, Codell-Niobrara and “J” Sand (a-c); Shannon and Sussex Reservoir Pressure (d) Figures 3-15c and 3-15d: Pressure Gradients for Codell, Codell-Niobrara and “J” Sand (a-c); Shannon and Sussex Reservoir Pressure (d) Figure 3-16: Map and Log Examples of “D” Sand Channel Compartmentalized Reservoir Trapping Types in the Greater Wattenberg Area W:\PROJECTS\22241252_ANADARKO_SDA\SUB_00\6.0_PROJ_DELIV\DJ_REPORT_MASTER_11-4-09_EKW.DOC\11/4/2009 3:10 PM iii 004474 TABLE OF CONTENTS Figure 3-17: Potentiometric Surface Map For the “J” Sandstone