Nontributary Groundwater Assessment Weber Formation, Rangely Field, Colorado

NONTRIBUTARY GROUNDWATER ASSESSMENT WEBER FORMATION, RANGELY FIELD, COLORADO

Submitted to: CHEVRON U.S.A. INC.

Date: November 4, 2009

Norwest Corporation 950 South Cherry Street, Suite 800 Denver, CO 80246 Tel: (303) 782-0164 Fax: (303) 782-2560 Email [email protected] www.norwestcorp.com

Author: JAMES A. M. THOMSON, P. GEOL.

004671

TABLE OF CONTENTS

1 INTRODUCTION AND BACKGROUND...... 1-1 1.1 PURPOSE...... 1-1 1.2 DEFINITION OF NONTRIBUTARY GROUNDWATER ...... 1-1 1.3 RANGELY FIELD ...... 1-1 2 CONCEPTUAL MODEL ...... 2-1 3 DATA ...... 3-1 3.1 WEBER FORMATION PERMEABILITY DATA ...... 3-1 3.2 STORATIVITY DATA ...... 3-2 3.3 GEOLOGIC DATA...... 3-2 3.4 HYDROLOGIC DATA ...... 3-2 4 ANALYSIS ...... 4-1 4.1 GLOVER-BALMER ANALYSIS...... 4-1 4.2 HYDRAULIC DISCONNECTION...... 4-2 4.2.1 Willow Creek Fault ...... 4-2 4.2.2 Uinta Basin Boundary Fault ...... 4-3 4.3 GROUNDWATER SALINITY AND OTHER SUPPLEMENTARY DATA ...... 4-3 4.4 CONSERVATISM OF RESULTS ...... 4-4 5 CONCLUSION ...... 5-1 6 REFERENCES...... 6-1

LIST OF TABLES

Table 3-1...... 2 Average Results for Summary Data From Cored Wells in the Rangely Field...... 2 Table 4-1: Data For Eight Wells Drilled Through the Subthrust Between 1956 and 1983 ...... 3

LIST OF FIGURES

Figure 1-1: Rangely Field Location and Nontributary Boundary ...... F-2 Figure 1-2: Stratigraphic Column of Pre-Tertiary Rocks in the Vicinity of Dinosaur National Monument ...... F-3 Figure 1-3: Rangely Cumulative Production History ...... F-4 Figure 2-1: Rangely Anticline and Rangely Field ...... F-5 Figure 2-2: Generalized Geologic Map of the Willow Creek Anticline and Related Structural Features...... F-6 Figure 3-1: Oil and Water Relative Permeability Curves...... F-7

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Figure 4-1: South-North Seismic Profile From Tenneco and Conoco Data ...... F-8 Figure 4-2: South – North Subsurface Cross Section Transverse to Willow Creek Thrust Fault ...... F-9 Figure 4-3: Interpretative Schematic Subsurface Cross Section of Lower 2,000 Feet of Tenneco 1 Hicks Wildcat With Live Oil Showings...... F-10 Figure 4-4: Seismic profile through Rangely Field ...... F-11 Figure 4-5: Permian-Pennsylvanian Weber Maroon Lithofacies Map...... F-12 Figure 4-6: Illustration of Water Drive ...... F-13 Figure 4-7: Rangely Average Bottom-Hole Pressure History...... F-14

LIST OF APPENDICES

APPENDIX A: SUMMARY OF CORED WELL DATA APPENDIX B: TYPICAL LABORATORY REPORT

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD TOC-2 004673

1 INTRODUCTION AND BACKGROUND

1.1 PURPOSE

This report was prepared by Norwest Corporation (“Norwest”) of Denver, Colorado. This report provides a hydrogeologic and geologic assessment of produced water from the Rangely oil field, Rio Blanco County, Colorado (“field”), from wells operated by Chevron U.S.A. Inc (“Chevron”). This report presents information demonstrating that the produced water from the Weber Formation within this field meets Colorado’s nontributary standard. Using site-specific hydrogeologic data, and the Glover-Balmer analytical method, the Weber Formation is shown to be nontributary. This report also presents geologic data and interpretations and supporting data that indicate that the Weber Formation within the Rangely field is hydraulically disconnected from all surface streams such that there will be no depletion to any surface streams as a result of pumping, and the formation is therefore nontributary.

1.2 DEFINITION OF NONTRIBUTARY GROUNDWATER

Colorado groundwater use is governed by the Ground Water Management Act of 1965. Colorado presumes all groundwater within the state to be tributary to a surface stream, unless it can be proven otherwise. Under Colorado water law (37-90-103(10.5), C.R.S.), “nontributary ground water” means that ground water, located outside the boundaries of any designated ground water basins in existence on January 1, 1985, the withdrawal of which will not, within one hundred years of continuous withdrawal, deplete the flow of a natural stream, including a natural stream as defined in sections 37-82-101 (2) and 37-92-102 (1) (b), at an annual rate greater than one-tenth of one percent of the annual rate of withdrawal.

1.3 RANGELY FIELD

Chevron’s oil development interests in the Rangely Field are located in Rio Blanco County as represented in Figure 1-1. Chevron’s oil production in the Rangely field is entirely from the Weber Formation. Figure 1-2 shows a stratigraphic column for the field, showing the relative position of the Weber Formation.

The Rangely field is the largest oil field in Colorado based on cumulative production. Oil was first discovered in the Weber Sandstone in 1933. Development started in 1944 with production wells on 40-acre spacing. Water production started in 1947, i.e. the first three years of oil production were water-free. Since 1947 some amount of water has been produced along with oil. To recover remaining reserves, both enhanced oil recovery (EOR) techniques and infilling have been applied. Hydrocarbon gas injection was performed from 1950 to 1959. The gas source was the field’s gas cap, which was partially flared and partially reinjected for pressure maintenance. Waterflooding was performed from 1958 to 1983. Waterflooding eventually increases water

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD 1-1 004674

production. However, produced water is separated from oil and is re-injected, at which time the net water production is zero. Infilling from 40- to 20-acre density took place between 1963 and 1985, and from 20-acre to 10-acre density in limited areas between 1983 and 1990. Expansion of

CO2 injection and 20-acre infill drilling within the field to the west and north has been under way since 2003. The current operation consists of approximately 645 wells (Figure 1-1). Since 1986, production has been supported by Water Alternating Gas (WAG) Injection. Produced water is reinjected, alternating with injection of carbon dioxide (CO2). The CO2 is brought to the field by pipeline from the La Barge gas field in western Wyoming. As for injected water, recovered gas is separated and reinjected. Currently, produced gas is approximately 8-9% methane and 91 % CO2. Historically, about 22% more water has been injected into the field than has been produced, as shown by the “Rangely Cumulative Production History” (Figure 1-3), which shows 5,238,473,000 barrels of water injected versus 4,285,296,000 barrels of water produced to date. The additional water to start the waterflood in 1958 was initially obtained from the White River and the Entrada and Navajo Formations. Since the WAG flood was started, the required waterflood volumes are provided by Weber production.

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2 CONCEPTUAL MODEL

Figure 1-2 presents a stratigraphic column for the field. The Weber Formation is of Permian- Pennsylvanian age. The Weber Formation is approximately 5,900 to 6,500 feet below land surface. Figure 2-1 presents the structural setting of the Weber Formation. The field is a classic structural trap centered on the Rangely anticline. The origin of the anticline is considered to be the east-west trending Uinta Basin Boundary Fault which is mapped south of the field (Figure 1-1). A similarly aligned east-west trending fault, the Willow Creek Fault, is mapped approximately nine miles north of the field and is considered to be the origin of the Willow Creek anticline (Figure 2-2). The Willow Creek anticline includes the nearest outcrops to the field of both the Weber Formation and all Jurassic age formations (Figure 1-1). Several named streams cross these outcrops. The Willow Creek Fault lies between the Weber and Jurassic outcrops and the Rangely field.

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3 DATA

3.1 WEBER FORMATION PERMEABILITY DATA

For this study, Chevron provided summary data for 510 cored wells in the Rangely field. Core permeabilities, total and effective thickness, and residual oil saturation are tabulated in Appendix A. Typically one horizontal test plug was cut per foot of core sample collected from the Weber Formation, and submitted for laboratory analysis.

A typical laboratory test report (for well UP-19-28) is provided in Appendix B, showing that for the producing section of the Weber Formation at that well, 469 core plugs were collected and tested. To summarize permeability data for each well, zero permeability results were ignored and only non-zero permeabilities were arithmetically averaged in data provided by Chevron (Appendix A). Arithmetic averaging creates a conservative upward bias in average permeability, which is discussed further in Section 4.4. The effective thickness was then calculated based on the formation thickness represented by the non-zero permeability samples. Table 3-1 presents average results from all samples for the Rangely field. Oilfield permeabilities are conventionally determined in millidarcies (mD), where 1 ft/d = 365 mD. The thickness-weighted geometric mean permeability value is 3.18 mD (0.00759 ft/d).

In formations containing both oil and water, the presence of oil blocks pore space and acts as an obstacle to water flow. The core plugs submitted for laboratory analysis were stripped of oil before permeability testing. This will not happen in reality. Therefore, the laboratory permeability results do not represent the true formation permeability to water under field conditions, either now or in the future. The presence of oil in the pore space results in a reduction in the effective permeability to water in a predictable way. Oil saturation (the percentage of the pore space occupied by oil) reduces over the productive life of a field until it reaches a level where further production is uneconomic. This is usually much higher than the absolute minimum oil saturation, which is the irreducible amount of oil held in place by capillary forces. Figure 3-1 shows the Rangely field water-oil relative permeability curve based on relative permeability testing of cores from two wells in the field. The expected maximum oil recovery factor for the Rangely field is 50%, i.e. 50% of the pore space will remains occupied by oil in perpetuity, the remaining pore space being 50% water saturated. As shown in Figure 3-1, at 50% water saturation, the water permeability is 1.5% of the value it would have at 100% water saturation. Therefore, an appropriate value for the real-world Weber Formation water permeability is 0.0477 mD (3.18 mD x 1.5%). This is a conservative value, as at present the Rangely field is not depleted. Therefore the current oil saturation has not yet reached the residual level, and hence the water permeability is currently lower than it will be at residual oil saturation. The value of 0.477 mD (0.001307 ft/d) is therefore a conservatively high water permeability that can be used to represent the production zones of the Rangely field. This value is used in the Glover-Balmer analysis described below in Section 4-1.

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3.2 STORATIVITY DATA

There are no site-specific storativity data for the Weber Formation. As a default, Anderson and Woessner (1992) provide a range of specific storage values for fissured and jointed rock, from 2.1 x 10-5/ft to 1 x 10-6/ft (see 1). The lower value of 1 x 10-6/ft was selected for conservatism, and was used in the Glover-Balmer analysis described below in Section 4.1.

3.3 GEOLOGIC DATA

Geologic outcrops of the Weber Formation are represented on Figure 1-1 and were obtained from the Digital Geologic Map of Colorado (USGS 1992). Mapped and interpreted faults were obtained from Tweto (1979) by means of the Digital Geologic Map of Colorado, and are represented on Figure 1-1. Mapped and interpreted faults were digitized from papers by Hansen (1984, 1986), and Powers (1986), and are represented on Figure 1-1.

3.4 HYDROLOGIC DATA

For the purposes of this assessment, the point of evaluation (POE), i.e. the potential point of depletion, is considered to be that location where the stratigraphic top of the Weber Formation lies directly beneath the alluvium of a mapped perennial stream. Perennial stream locations were obtained from the United States Geological Survey’s (USGS) National Hydrography Dataset (NHD) (http://nhd.usgs.gov/index.html) and were mapped relative to geologic outcrops, as depicted in Figure 1-1. POEs were defined at the intersection of perennial streams and geologic contacts using GIS techniques, and are shown on Figure 1-1.

The NHD is a comprehensive set of digital spatial data representing the surface water of the United States using common features such as lakes, ponds, streams, rivers, canals, and oceans. These data are designed to be used in general mapping and in the analysis of surface-water systems using geographic information systems (GIS). The NHD often is used by scientists, specifically in surface-water analysis, using GIS technology.

1 Converted from 6.9 x 10-5 /m to 3.3 x 10-6 /m.

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4 ANALYSIS

4.1 GLOVER-BALMER ANALYSIS

The Glover-Balmer Equation requires input values for permeability, saturated thickness, transmissivity, storativity, and distance from the pumping well to the point of depletion as a means to assess the potential that groundwater produced by these gas wells will meet the statutory definition for nontributary groundwater as discussed previously.

The Glover-Balmer Equation is as shown below:

q  S 2   erfc  ...... (Equation 1)   Q  4tT 

Input parameters for Equation 1 are in terms of length (L) and time (T) as follows:

q/Q = ratio of the quantity of stream depletion (L3/T) to pumping rate (L3/T)

erfc = probability function that returns a proportion between 0 and 1

S = storativity of water-bearing materials (unitless)

α = distance from pumping well to the point of stream depletion (L)

t = time (T)

T = transmissivity of water-bearing materials (L2/T)

Storativity can be calculated as follows:

S = Ss x H

Transmissivity (T) can be calculated as follows:

T = k x H

Where:

Ss = specific storage (1/L)

k = permeability (L/T)

H – formation thickness (L)

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As H appears in both the numerator and the denominator in Equation 1, it cancels out and Equation 1 reduces to:

q  Ss 2   erfc  ...... (Equation 2)   Q  4tk 

Using the statutory definition of nontributary groundwater (q/Q < 0.001 after 100 years continuous pumping [36,500 days]), the Glover-Balmer Equation was used to establish the location of the nontributary boundary as the distance from the POE where q/Q is equal to 0.001. This analysis was performed using an Excel spreadsheet and the Solver function.

The following values were used in Equation 2:

q/Q = 0.001

Ss = 1 x 10-6/ft

t = 36,500 days

k = 0.001307 ft/d

The resulting value for α is 32,142 feet (6.09 miles). Figure 1-1 shows a radius of 1.92 miles from the nearest POE (where an Unnamed Tributary to the White River crosses the Weber Formation outcrop).

4.2 HYDRAULIC DISCONNECTION

4.2.1 Willow Creek Fault The Weber Formation is hydraulically disconnected from its respective nearest outcrop to the north by the north-dipping Willow Creek Fault. Figure 1-1 shows the surface trace of the Willow Creek Fault as published by Tweto (1979), Hansen (1984 and 1986), and Powers (1986). Faults, particularly shallow-angle thrust faults, are of interest as potential structural traps for oil and gas. This fault was studied by Powers (1986). His interpretation was based on seismic profiles by Tenneco and Conoco (Figure 4-1), and on logs of eight wells drilled through the subthrust between 1956 and 1983 (Table 4-1). A south-north subsurface cross section based on these data is shown in Figure 4-2. On this cross section, the Rangely field is to the south of the thrust fault, and the nearest Weber outcrop is to the north. The north to south horizontal displacement on the thrust is approximately 5,800 feet (Powers, 1986). As a result, the Weber Formation is overlain by approximately 2,000 feet of hard orthoquartzite and conglomerate of the Precambrian Uinta Mountain Group and overturned Cambrian strata. Drilling observations indicate that the fault acts as a seal. Live-oil showings in the Weber Formation below the fault at the Tenneco 3-3N-103W well (drilled in 1960) indicate the presence of mobile oil (Figure 4-3), and demonstrate that the

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fault acts as a structural trap preventing groundwater flow across it. The absence of oil showings along the surface trace of the fault demonstrates that the fault prevents the upward migration and that the fault does not act as a conduit between the Weber Formation and the land surface. These observations demonstrate that the fault separates the Weber Formation in the Rangely field from the equivalent formations on the north side of the fault and also from the land surface.

4.2.2 Uinta Basin Boundary Fault The Weber Formation is hydraulically disconnected to the south by the north-dipping Uinta Basin Boundary Fault. Figure 1-1 shows the surface trace of this fault as published by Hansen (1984), Hansen (1986), Powers (1986), and Stone (1991). Figure 2-1 is a cross section perpendicular to the fault published by Hefner and Barrow (1992). This fault is shown on seismic lines interpreted by Stone (1986), shown in Figure 4-4. This interpretation is the same to that of Figure 2-1 in that the Weber Formation is shown as completely offset across the fault and truncated by significantly older beds on the footwall side. The vertical separation at the base of the Paleozoic section is approximately 7,000 feet. Immediately south of the fault, south of Rangely field, a deep Chevron well documents the Weber Formation at a measured depth of 10,294’. This is 3,850 feet lower than the oil-water contact in the Rangely field. Producing wells in that area produce from shallower Cretaceous-age Dakota strata. The trapping of oil in Jurassic strata on the footwall side of the fault demonstrates that the fault acts as a structural trap which also prevents groundwater flow across it.

4.3 GROUNDWATER SALINITY AND OTHER SUPPLEMENTARY DATA

Produced water from the Weber Formation, as indicated by samples collected before the start of waterflood operations, was very high salinity (greater than 115,000 ppm). This high salinity, which is three times higher than seawater, strongly supports the interpretation that there is no connection between the Weber Formation in the Rangely field and surface outcrops or streams. Samples collected following waterflood operations have shown progressively lower TDS, as would be expected given the river source of injected water.

In 1998, the Colorado Water Quality Commission reviewed the salinity and related data from the Weber Formation in the Rangely field and concluded that the groundwater in the formation should be classified of “Limited Use and Quality” over all of T2N, R101 through R103W, and Sections 1 through 12 of T1N, R101 through R103W. This area includes the entire Rangely field. The Colorado Oil and Gas Conservation Commission’s prehearing statement to the Water Quality Commission included the statements that “impacts to this groundwater in these formations do not cause any effects on surface water bodies within the specified area”, and “the groundwater is not in communication with any surface water bodies within the specified area so that water quality standards of any classified surface water bodies are not affected by this groundwater” (emphasis added).

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Further support for the hydraulic isolation of the field is provided by the pressure history for the reservoir. From the start of operations in 1944 for the following seven years, average pressures showed a steady decline, indicating lack of water drive (Figure 4-6). Projected bottom-hole pressures would have reached zero by 1958 (Figure 4-7). The history of field operations could be summarized as a struggle to maintain pressure. Pressures would have continued to decline were it

not for the introduction of gas injection in 1950, waterflood injection in 1958, and CO2 injection in 1986.

4.4 CONSERVATISM OF RESULTS

For the purpose of this study, Norwest has used consistently conservative assumptions in its analyses, thus leading to a result that should be considered acceptable. Examples of these conservative assumptions include:

 Because permeability values are geometrically distributed (Appendix B), the use of arithmetic averaging of the plug permeability values for each well, rather than geometric averaging, results in an over-estimate of the average permeability for each well. For example, for well UP 19-28, the arithmetic mean value reported by Chevron is 20 mD, whereas the geometric mean value (excluding zero values) is 5.4 mD, or 27% (see Appendix B). Because arithmetic averages were used to characterize each well’s average permeability, permeability averages are biased upwards approximately fourfold, which is conservative.

 The Glover Balmer analysis assumes that the Weber Formation is continuous, isotropic, and homogeneous. The Weber Formation is not continuous, and thins and grades laterally into the lower-permeability Maroon Formation to the south, east, and northeast (Figure 4-5). The Maroon Formation has poorer reservoir characteristics than the Weber (Hoffmann, 1957).

 The use of the lowest value in the range of published specific storage values causes the calculated distance to the nontributary boundaries to be conservative and therefore farther from the outcrop.

 Calculated nontributary boundary distances from the outcrop were measured horizontally rather than along the flow path within the subject formation.

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5 CONCLUSION

The following conclusion is based on the data presented in this report:

 Groundwater produced from Chevron’s oil production wells completed in the Weber Formation within the Rangely field meets the statutory definition of nontributary groundwater if produced from south of the Willow Creek fault or from a location that is greater than 6.09 miles from the potential point of depletion where an Unnamed Tributary to White River crosses the Weber Formation outcrop.

As presented by Figure 1-1, the entire Rangely field meets both of these criteria; hence this report concludes that produced water generated by Chevron’s oil production wells within the Rangely field satisfactorily meets the definition of nontributary.

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6 REFERENCES

Anderson, M. P. and W. W. Woessner. 1992. Applied Groundwater Modeling: Simulation of Flow and Advective Transport. Academic Press. 381 p.

Gregson, J. D. and D. J. Chure. 2000. Geology and Paleontology of Dinosaur National Monument, Utah-Colorado. pp. 155-188. In, T. C. Chidsey and P B. Anderson, eds. Geology of Utah's Parks and Monuments, Utah Geological Association Millennium Guidebook, Publication 28.

Gregory. 1992. Digital Geologic Map of Colorado. USGS Open File Report 92-507 after Tweto 1979.

Hansen, W. R. 1984. Post-Laramide Tectonic History of the Eastern Uinta Mountains, Utah, Colorado, and Wyoming in the Mountain Geologist, Vol. 2, No. 1. p 5-29.

Hansen, W. R. 1986. History of Faulting in the Eastern Uinta Mountains, Colorado and Utah, Rocky Mountain Association of Geologists. 1986 Synposium.

Hefner, T.A. and K.T. Barrow. 1992. Rangely Field – U.S.A., Uinta/Piceance Basins, Colorado.

Hoffman. Floyd H. 1957. Possibilities of Weber Formation Stratigraphic Traps, Rangely Area, Northwest Colorado. American Association of Petroleum Geologists Bulletin, Vol. 41, No.5, p. 894-905.

Powers, R.B. 1986. The Willow Creek Fault, Eastern Uintah Mountains – Geologic Analysis of a Foreland Subthrust Play. 1986 Symposium.

Stone, D.S.. 1991. Wilson Creek Field – U.S.A., Piceance Basin, Northern Colorado.

Stone, D. S. 1986. Rangely Field Summary: 2. Seismic Profile, Structural Cross Section and Geochemical Comparisons, in Stone, D.S., ed. 1986. New Interpretations of Northwest Colorado Geology. Rocky Mountain Association of Geologists, p 226-228.

Tweto, O. 1979. The Geologic Map of Colorado.

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TABLES

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TABLE 3-1 AVERAGE RESULTS FOR SUMMARY DATA FROM CORED WELLS IN THE RANGELY FIELD Gross Brine Net Effective KH Thickness Permeability Thickness (ft.) Thickness (ft.) (mD-ft) (ft.) (K in mD) 526 327 199 3.18 906.4

See Appendix A for individual summary results for 510 cored well samples.

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TABLE 4-1: DATA FOR EIGHT WELLS DRILLED THROUGH THE SUBTHRUST BETWEEN 1956 AND 1983 (Source: Powers, 1986)

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FIGURES

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-1 004688 Yu MC-ml PPw C-l Pmr Mm Yu Data Sources:Tbp Pmr Yu PPw Mm C-l Pp ~ COGCCPmr "WELLS"PPw spatial file C-l downloaded 10/13/09 TRc PPw TRPcp Tbp TRc Mm * TwetoTRPcp "USGSJTRmg Geologic Map of Colorado" 1979 Kfd PPwPPw Pp Pp Pp Hansen "History of Faulting in E Uinta Mtns" PPw PPw Pmr Tbp RMAG, 1986 Tbp Pp TRm Tbp Hansen "Tectonic History Eastern Uinta Mountains" Pp TMG vol21 no1, 1984 Yu TRm TRc TbpTbp MC-ml Powers "Willow Creek Fault", RMAG 1986 Yampa Fault Pp JTRmg Qa JTRg KmStone "Wilson Creek Filed", BAAPG vol75, no1, Kfd 1991 Yu TRc PPw Qa Yampa Fault Maudlin Fault Yu PPw Yu PmrYampa Fault PPw MC-ml Yu MC-ml JTRg Pmr

Pm Km Km Ki Tbp TRPcp Pmr Tbp Kfd MC- Tbp Tbp TRPcp Tbp Jmce Slough, The Km Tbp Jmce Tbp Tbp Wolf Creek Tbp Km PPw PPw Wolf Creek PPwPPw Km Tbp Wolf Creek Fault TbpKm PPw Km JTRg Kfd PPw Ki K Creek Km TRPcp Qa Jmce Kfd Ql Ksc JTRg Ki Kfd Turners Creek Kfd TRPcp Km Jmce Willow Cr eek A Ksc PPw ntic Ql line Red Wash Jmce Qa JTRg Kfd Qa Kfd Km 1.92 miles Km Non-Tributary Groundwater - Ki Willow Creek Sjukk Creek this side of line WillowKm Creek Fault Groundw Kw Km tary ater - Qa Qa ribu this sid Qa nt e of o k W N e illo e w Tf r C Willow Creek Fault Ksc re C e Qa 6.09 mi k F r au e l t t a W Moffat g n Kmvu i k Ksc Km n Rio Blanco i Ksc t Ki Ki S Tw Kw Tf Kw Qa Tf Qg Tw

k Tw

e Tw

C Km Tglw g Tu n i Y Tgp Tgl r Tu Qe p el S l ow C Tglw re e

k Ki Kw Km Ksc Range ly An Qa Km Ksc tic line Uinta Basin Boundary Fault Tw Tw

Tgp Tw k Tgp e e r C Tu s la Tgl g

u o Tgl

West Fork Spring Creek Tw Tglw Tu ek Qa re Tgp C Tw ow ll e Y Qa

Big Duck Creek Qa Qa Tu Qa LEADVILLE, GILMAN, DYER, PARTING, FREMONT, Kmvu HARDING, MANITOU, DOTSERO, PEERLESS, Tu Tgl Two AND SAWATCH FORMATIONS; SOME FORMATIONS ABSENT LOCALLY, MC- Qa

MADISON LIMESTONE AND LODORE FORMATION PiceanceCreek MC-ml MADISON LIMESTONE (MISSISSIPPIAN), Mm Upper part includes equivalents of Upper Mississippian Doughnut Tgp Tu and Humbug Formations (shale, limestone, and sandstone) MANCOS SHALE, Km Tgl Tw Intertongues complexity with units of overlying Mesaverde Group or Formation; lower part consists of calcareous Niobara equivalent and Frontier Sandstone and Mowry Qa Shale Members ek re MESAVERDE GROUP OR C FORMATION, KmvuQa Tgp Tw Ksc Upper part - in Moffat andu Rior Blanco Counties, sandstone, Ksc ph Ksc shale and coal bedsu labove Sego Sandstone. Along Kmvu E Grand Hogback southS of Colorado River, sandstone and as t shale above coalck bearing sequence D la o MINTURN BFORMATION IN WEST-CENTRAL AND u Tgl g SOUTH-CENTRAL AND OTHER UNITS OF l a MIDDLE PENNSYLVANIAN AGE, Pm Tw s Arkosic sandstone, conglomerate, shale, and limestone.

Tw C Includes Madera Formation and SharpsdaleFawn Creek Formation of Tglw r Other Geology: Chronic (1958) in Sangre de Cristo Range and Gothic e Formation of Langenheim (1952) in Elk Mountains e Ca BROWNS PARK FORMATION, Tbp k t Tgl h Sandstone and siltstone; west of Park Range MODERN ALLUVIUM, Qa Tgl ed Includes Piney Creek Alluviym and younger deposits CHINLEra FORMATION, TRc Redl siltstone,C sandstone, and limestone-pellet conglomerate MOENKOPI FORMATION, TRm re Red siltstone, mudstone, sandstone, and local gypsum Tw Tw CHINLE, MOENKOPI,ek AND PARK CITY E Tw FORMATIONS, TRPcp MORGAN FORMATION (LIMESTONE, SANDSTONE, va Red and gray siltstone, shale, and sandstone AND SHALE) AND ROUND VALLEY LIMESTONE, Tw cu k Pmc EOLIAN DEPOSITS, Qe e a Tw e In far northwest ti Includes dune sand and sil and Peoria Loess r o Tw MORRISON, CURTIS, AND ENTRADA Tgl n Tw Two FORT UNION FORMATION, Tf C C Tw Tgl Tgl Shale, sandstone, and local coal beds n FORMATIONS, Jmce Tw Tgl Tu o In extreme southwestern Moffat County, includes thinHunter Creek re Tgl FRONTIER SANDSTONE AND MOWRYy SHALE e Tw Lake Creek n wedge of Carmel Formation (red siltstone and sandstone) k Tgl MEMBERSTwo Tgl OF MANCOS SHALEa AND Tu Tu C beneath Entrada DAKOTA SANDSTONE, Kfd Locally includes, at base, Burro Canyon Formation (shale MORRISON, CURTIS, ENTRADA, GLEN and sandstone) or, in western Moffat County, Cedar CANYON FORMATIONS, JTRmg Legend Mountain Formation (conglomerate and shale) Curtis is absent OLIGOCENE SEDIMENTARY ROCKS, Tos GLEN CANYON SANDSTONE, JTRg Includes Duchesne River Formation (sandstone and shale; COGCC Wells: ~ In northwest includes some rocks of Eocene age) and Bishop Conglomerate GREEN RIVER FORMATION, Tgp near Utah border Chevron Weber Producing Wells (645) Points of Evaluation Parachute Creek Member - Oil shale, marlstone, and siltstone; in Piceance basin PARK CITY FORMATION, Pp Calcareous siltstone and sandstone Chevron Weber Abandoned Wells (263) Geology:* GREEN RIVER FORMATION, Tgl Lower part - Shale, sandstone, marlstone , and limestone SEGO SANDSTONE, BUCK TONGUE OF MANCOS Chevron Other Producing Wells (1) WEBER SANDSTONE, PPw in Anvil Points, Garden Gulch, and Douglas Creek SHALE, AND CASTLEGATE SANDSTONE, Ksc 1:250,000 Members; in Piceance Basin UINTA MOUNTAIN GROUP (AGE 950 - 1,400 Other Formations LOWERPART OF GREEN RIVER FORMATION M.Y.), Yu Chevron Other Abandoned Wells (68) AND WASATCH FORMATION, Tglw [11x17 format] Shale and sandstone WASATCH FORMATION, Tw Other Operators Wells (568) Fault (Powers) Claystone,shale and sandstone ILES FORMATION, Ki WASATCH FORMATION (INCLUDING FORT UNION Perennial Streams Fault (Tweto) Sandstone and shale. Trout Creek Sandstone Member EQUIVALENT, Two 0 1 2 3 4 5 at top, coal beds in upper half Claystone, mudstone, sandstone, and conglomerate Other Streams Fault (Hansen) LODORE FORMATION (CAMBRIAN), C-l WILLIAMS FORK FORMATION, Kw Miles Sandstone, shale, and conglomerate Sandstone,shale, and major coal beds Study Area Anticline (Powers) 10/29/2009, M.Dohnalová 004689 Figure 1-1: Rangely Field Location and Nontributary Boundary

FIGURE 1-2: STRATIGRAPHIC COLUMN OF PRE-TERTIARY ROCKS IN THE VICINITY OF DINOSAUR NATIONAL MONUMENT (Source: Gregson and Chure, 2000 )

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-3 004690

FIGURE 1-3: RANGELY CUMULATIVE PRODUCTION HISTORY

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-4 004691

FIGURE 2-1: RANGELY ANTICLINE AND RANGELY FIELD (Source: Hefner and Barrow, 1992)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-5 004692

FIGURE 2-2: GENERALIZED GEOLOGIC MAP OF THE WILLOW CREEK ANTICLINE AND RELATED STRUCTURAL FEATURES (Source: Powers, 1986)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-6 004693

FIGURE 3-1: OIL AND WATER RELATIVE PERMEABILITY CURVES (Source: Chevron)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-7 004694

FIGURE 4-1: SOUTH-NORTH SEISMIC PROFILE FROM TENNECO AND CONOCO DATA (Source: Powers, 1986)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-8 004695

FIGURE 4-2: SOUTH – NORTH SUBSURFACE CROSS SECTION TRANSVERSE TO WILLOW CREEK THRUST FAULT (Source: Powers, 1986)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-9 004696

FIGURE 4-3: INTERPRETATIVE SCHEMATIC SUBSURFACE CROSS SECTION OF LOWER 2,000 FEET OF TENNECO 1 HICKS WILDCAT WITH LIVE OIL SHOWINGS (Source: Powers, 1986)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-10 004697

FIGURE 4-4: SEISMIC PROFILE THROUGH RANGELY FIELD (As interpreted by Stone, 1986)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-11 004698

FIGURE 4-5: PERMIAN-PENNSYLVANIAN WEBER MAROON LITHOFACIES MAP (Adapted from Hoffman, 1957)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-12 004699

FIGURE 4-6: ILLUSTRATION OF WATER DRIVE In water drive reservoirs, oil is driven from the reservoir formation by the action of water invading the lower reservoir from adjoining aquifers (Source: Schlumberger Oil Field Glossary – www.glossary.oilfield.slb.com)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-13 004700

FIGURE 4-7: RANGELY AVERAGE BOTTOM-HOLE PRESSURE HISTORY (Source: Chevron)

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD F-14 004701

APPENDIX A SUMMARY OF CORED WELL DATA

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-1 004702 Log Frequency Dsitribution

All Rangely Wells Log Average Well Permeability 90

0 0.077 0.218 0.359 0.500 0.641 0.782 0.923 1.064 1.205 1.346 -0.628 -0.487 -0.346 -0.205 -0.064 Log Average Brine Permeability

Page 1 004703

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 203 77 60 54 8.6 462.4 205 111 81 61 10 605.8 207 110 78 61 10 603 405 152 112 98 9.3 914.8 407 170 100 94 5.8 543.2 603 72 48 33 11.2 370.3 609 248 148 138 4.9 679 613 252 186 111 7.4 817.8 805 151 114 93 6.6 609.6 807 233 178 146 13 1899.4 811 332 140 125 9.2 1154.1 908 296 250 227 8.8 1998.3 912 361 274 226 13.5 3034.8 1003 142 131 122 4.7 570.8 1005 200 129 94 14.6 1372.3 1009 336 258 227 11.5 2607.1 1011 363 291 252 8.9 2239 1013 413 242 168 8.4 1403.4 1019 311 223 129 3 379.9 1106 223 186 152 15.5 2353.1 1108 312 293 246 12.8 3150.5 1110 326 282 238 24.2 5763.9 1114 414 330 263 8.1 2122.5 1116 475 339 272 11.4 3095 1118 440 333 245 4.7 1149.2 1203 129 103 94 7.1 665.2 1209 292 255 217 13.4 2904.2 1215 500 409 290 5.7 1643.2 1219 426 253 175 7.8 1360 1221 369 202 127 6.2 788.8 1306 243 199 138 9.1 1253.9 1308 295 217 180 13.4 2406.8 1310 318 280 251 18.8 4719.7 1312 444 370 297 10.5 3101.1 1314 457 315 238 12.2 2895.5 1316 470 360 286 14 3991.2 1322 488 322 185 4 746.3 1403 136 89 82 7.1 584

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-2 004704

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 1409 303 244 216 26.1 5633.6 1411 419 320 268 15.7 4208.3 1415 472 353 210 11.3 2363.5 1421 584 360 274 3.9 1065.7 1425 367 275 144 4.3 623.8 1506 233 172 132 9.7 1284.7 1510 328 292 252 11.7 2931 1512 429 381 312 10.6 3298 1514 526 408 313 7.1 2212.5 1516 571 416 296 7.8 2301.3 1522 603 340 185 1.6 294.5 1524 569 338 104 0.8 86.2 1603 116 100 63 7.6 472.5 1605 122 103 68 13.7 933.6 1607 276 219 173 21.2 3668 1609 298 263 240 16.2 3892.8 1617 564 334 304 11.7 3550.2 1621 684 445 327 4.8 1553.5 1623 670 353 248 4.4 1096.8 1627 333 231 112 1.8 201.8 1708 241 192 172 7.6 1306.1 1710 384 350 323 11.4 3682.4 1712 464 401 308 9 2768.5 1714 536 369 290 11.8 3418.2 1716 617 368 281 9.1 2552.7 1718 664 383 296 8 2368 1722 735 400 238 3.3 782.1 1724 665 391 233 1.3 309.5 1726 519 276 115 1.9 214.6 1803 118 90 73 14.7 1071.4 1805 176 151 109 10.3 1116.6 1809 290 183 162 7.4 1195 1823 696 496 282 2.8 792.9 1825 657 420 294 4.9 1439.5 1908 308 242 196 11.2 2193.6 1910 366 290 252 6.6 1658.8 1914 538 339 251 7 1763.6 1918 701 406 321 7.5 2420.9

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-3 004705

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 1919 723 419 291 5.3 1530.8 1920 751 408 272 5 1347.5 1922 750 404 220 1.7 369 1924 778 462 223 2.1 465.2 1926 700 449 266 4.8 1272.1 1928 547 302 192 4.5 861.7 2005 199 150 131 10.9 1432.3 2007 262 233 132 5.4 705 2017 657 397 332 8.6 2860.5 2018 696 469 346 4.8 1644.8 2020 754 427 306 4.7 1424.6 2027 637 436 218 2.8 603.7 2108 239 214 138 7.2 995.6 2110 344 275 245 11.7 2869.6 2112 458 370 274 8.6 2358.2 2114 551 402 322 5.7 1842.8 2116 585 389 333 4.5 1485.1 2119 737 422 309 3.7 1141.4 2121 791 467 275 2.7 740.1 2122 813 380 257 2.8 721.8 2124 827 538 303 1.5 445.4 2126 790 418 216 2.7 577.9 2128 681 401 218 3.5 770.7 2130 454 251 147 2.3 342.4 2203 95 52 31 7.1 217.3 2205 103 86 60 8.8 524.7 2207 248 221 131 7.9 1031.4 2209 323 223 142 7.1 1008.8 2220 760 427 294 3.2 941.2 2229 633 395 253 3 760 2308 253 193 172 6.5 1113.5 2310 329 259 214 5.5 1169.1 2312 458 399 291 8.8 2545.8 2314 533 449 383 9.9 3779 2316 634 456 378 7.8 2943.8 2318 715 469 359 5.1 1837.8 2320 781 461 320 6.2 1987.2 2322 821 426 184 2.8 523

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-4 004706

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 2324 857 448 199 4 788.3 2326 852 497 266 6.8 1821.5 2330 695 335 166 3.7 607.5 2403 88 75 68 8.1 549.3 2405 117 92 54 4.5 241.5 2409 299 248 212 13.7 2910.7 2411 355 313 266 8.6 2281.2 2418 695 427 318 3.7 1188.6 2428 800 451 184 2.7 492.4 2510 349 285 249 6.1 1518.4 2512 448 356 313 10.4 3243.4 2514 540 421 306 5.1 1572 2516 618 407 321 9.5 3040.2 2518 700 382 284 6 1698.4 2520 756 426 288 3.7 1073.3 2522 841 489 240 1.4 332.6 2524 874 535 256 2.8 718.7 2526 710 389 261 1.7 431.6 2528 670 427 314 2.5 789.5 2530 799 465 273 2.6 715.3 2532 665 398 237 1.8 431.8 2603 80 68 54 15.2 821.4 2605 153 137 115 8.1 924.6 2607 198 140 119 6 705.1 2609 299 277 244 8.1 1961.1 2710 297 261 211 10.9 2298.2 2712 425 341 275 8.8 2405.3 2714 529 375 242 7.1 1724 2716 628 432 320 5.8 1843.2 2718 697 434 331 6 1985 2720 774 493 266 4.5 1191.4 2722 847 524 318 4.4 1399.1 2724 884 507 293 1.9 569.2 2726 691 405 302 2.5 764.7 2730 637 386 239 2.7 652.2 2732 741 330 154 2.1 316.8 2805 138 117 82 4.9 397.4 2807 92 85 57 10 564.1

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-5 004707

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 2809 298 229 186 4.6 859.6 2819 646 415 314 4.8 1518.4 2912 423 363 306 7.7 2341 2914 505 343 219 5.3 1154.8 2916 616 429 284 4.8 1376.6 2918 704 399 326 13 4251.1 2920 759 465 349 4.8 1680.8 2922 826 387 278 4.1 1126.1 2924 894 419 246 3.6 880.2 2926 699 421 273 2.3 633.3 2928 836 544 321 3.3 1071.9 2930 857 420 196 4.4 864.2 2932 824 403 122 2.4 293.3 2934 637 302 85 0.8 71.2 3005 128 101 73 5.5 396.4 3007 115 92 70 8.6 603.9 3009 235 172 119 12.9 1532.4 3011 370 284 230 7.9 1815.2 3017 646 453 342 5 1716.4 3110 257 192 135 8.3 1124 3114 497 418 337 5.5 1856.6 3117 645 412 338 5.3 1789 3118 678 422 313 4.5 1391.3 3122 829 452 282 3.5 982.6 3124 891 503 237 2.5 585.9 3126 704 456 226 1.5 335.9 3128 902 450 202 3.5 696 3130 700 353 227 1.8 415.9 3132 588 297 159 2.3 360.1 3134 680 684 174 1.2 212.8 3205 58 43 33 9.6 315.3 3209 258 186 172 6.5 1107 3219 640 392 281 2.9 799.8 3312 410 319 282 6.3 1770.5 3314 466 390 288 4.5 1290.9 3316 582 398 248 5.7 1421.4 3318 657 328 237 4.5 1064.5 3320 761 466 259 2.8 716.2

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-6 004708

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 3322 824 463 285 6.5 1866 3324 877 569 264 1.6 421.1 3326 695 390 186 1 189.5 3328 694 316 191 1.1 218.8 3330 665 425 248 2.2 534 3332 876 397 115 2.5 282.6 3334 671 283 140 3.4 476.5 3409 252 218 199 12.5 2487.6 3411 334 214 144 6 869.4 3421 685 352 220 3.2 696.4 3510 265 207 185 3.9 716.5 3512 354 221 164 6.1 1002 3514 440 316 206 6.3 1292.8 3516 539 398 256 4 1020.9 3518 634 384 197 4.2 822 3520 725 436 286 1.8 527.9 3524 881 604 287 3.4 971.1 3526 718 397 212 1.5 315.1 3528 688 353 226 3.5 793.1 3530 691 351 193 2 385.1 3532 868 422 125 1.2 144.7 3534 753 387 174 2.2 378.7 3605 68 65 39 7.6 291.4 3609 209 142 127 5.4 686.5 3611 277 217 183 10.9 2000.7 3613 385 264 171 8.1 1384.3 3637 464 243 117 3.7 431.1 3710 242 184 137 4.2 579.9 3712 326 187 143 5.2 745.6 3714 450 325 235 5.4 1273.6 3718 623 448 295 3.9 1148.5 3720 719 416 247 2.6 629.8 3724 861 507 222 3.7 822.2 3726 741 436 158 1.7 265.8 3728 868 391 157 1.3 210.8 3730 802 466 272 1.4 384.1 3732 875 519 145 2.4 350.9 3734 798 310 123 1.9 231.2

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-7 004709

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 3736 685 337 100 1.5 150.8 3809 189 127 97 3.7 355 3813 345 242 170 7.6 1284.8 3910 230 204 145 4.8 698.1 3912 305 228 190 7.4 1405.7 3914 428 360 298 10 2976.3 3916 500 376 302 10.1 3038.9 3918 597 378 291 6.4 1853.5 3920 685 429 213 2.4 510.8 3922 766 446 218 2.2 473.8 3924 842 457 202 2.5 507.8 3926 823 452 197 1.2 231.1 3928 795 538 337 2.3 779.9 3934 835 396 96 1.6 148.6 3936 727 306 111 1.2 127.7 4011 217 185 152 5.6 851.0 4013 339 214 145 8.0 1165.7 4017 536 409 317 4.1 1285.6 4019 626 503 370 3.0 1093.5 4035 757 275 124 1.7 214.9 4114 386 311 208 4.7 983.1 4116 482 391 255 3.4 867.2 4118 587 436 307 4.8 1456.0 1420 657 435 298 3.4 1011.5 4122 740 494 276 4.9 1338.8 4124 690 489 259 0.8 196.3 4128 791 461 272 2.1 575.0 4130 883 521 223 2.2 479.4 4136 769 371 114 1.2 134.7 4208 74 68 52 7.2 370.5 4209 151 133 87 5.4 466.3 4213 286 189 143 3.5 499.4 4226 859 536 307 2.4 750.9 4312 267 219 153 2.3 355.7 4314 356 284 204 5.5 1114.0 4316 454 386 309 4.1 1265.7 4318 552 400 236 2.2 507.7 4320 665 454 329 3.6 1177.2

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-8 004710

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 4322 671 460 276 1.9 515.3 4324 791 406 286 1.2 350.2 4325 829 579 329 2.2 732.9 4326 672 459 273 0.9 247.6 4327 848 509 309 2.1 634.9 4332 867 526 293 1.8 525.6 4334 726 319 172 1.9 328.0 4336 794 505 242 1.5 372.9 4338 644 295 119 1.5 178.5 4411 211 150 107 4.5 483.6 4424 774 485 327 4.1 1346.6 4426 828 526 326 0.0 480.1 4512 267 225 180 6.5 1168.1 4514 326 257 189 4.6 873.0 4518 519 415 264 4.8 1274.7 4520 577 342 186 1.2 214.2 4523 725 476 319 4.1 1314.9 4524 723 493 362 2.4 863.5 4525 807 434 263 3.1 803.4 4526 807 488 243 1.1 274.4 4530 870 527 158 1.5 239.2 4532 803 533 275 2.0 553.2 4536 792 417 117 1.3 149.7 4538 721 400 70 0.7 50.1 4611 175 144 108 3.6 389.9 4613 274 244 161 4.9 782.1 4615 351 325 245 5.8 1414.0 4621 585 428 255 2.2 569.4 4624 735 421 241 3.2 775.0 4630 875 401 189 1.6 301.8 4712 193 169 106 1.6 168.4 1714 289 226 175 3.3 571.4 1716 400 325 202 3.2 646.0 1718 457 323 207 1.6 339.6 4720 575 267 198 4.3 840.4 4722 626 406 280 3.0 845.1 4724 717 374 225 1.8 403.8 4726 726 453 236 1.4 332.1

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-9 004711

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 4730 784 452 200 0.6 119.9 4732 847 478 216 1.1 243.9 4734 829 470 217 0.6 140.0 4736 725 354 193 1.2 227.8 4738 725 426 211 1.0 210.8 4811 90 73 42 6.6 272.3 4813 227 180 143 7.2 1027.0 4815 318 226 177 5.5 966.8 4823 628 364 217 2.5 545.0 4825 725 394 230 2.8 633.3 4912 153 143 101 2.4 238.3 4916 346 218 141 3.9 546.7 4918 424 334 221 2.2 475.7 4920 504 385 240 5.8 1403.6 4922 614 395 211 3.6 765.0 4930 819 465 233 1.0 235.9 4932 839 505 233 0.7 169.6 4934 838 506 192 0.6 113.3 4936 787 531 315 1.2 363.4 4938 770 434 246 2.8 690.5 5013 159 119 46 1.7 77.9 5015 277 157 73 3.0 221.0 5025 649 401 256 2.7 698.1 5040 681 322 58 0.8 46.6 5116 307 212 89 1.7 148.8 5118 381 288 184 1.5 268.2 5122 524 346 217 1.3 281.5 5124 648 388 205 1.2 236.5 5128 806 404 289 2.4 685.4 5132 844 551 335 1.4 470.5 5134 811 473 251 1.5 378.0 5136 799 475 290 1.4 410.6 5138 763 319 73 1.2 89.1 5211 66 63 16 3.6 56.5 5213 98 86 51 8.6 439.2 5215 186 98 64 3.1 195.2 5316 271 119 48 1.2 58.8 5320 395 311 195 4.7 907.8

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-10 004712

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 5322 535 377 183 1.0 189.4 5326 721 397 230 1.4 319.8 5327 755 363 262 5.0 1298.3 5328 760 437 259 1.3 343.9 5330 811 536 369 1.6 601.1 5332 815 462 289 1.1 312.4 5338 743 316 127 1.6 198.7 5425 572 404 114 0.9 105.9 5430 815 474 242 2.0 480.4 5437 793 473 258 2.5 634.6 5522 457 321 212 1.8 381.5 5526 628 402 225 1.6 359.8 5528 763 419 234 1.1 252.1 5529 777 505 292 2.2 650.2 5530 747 422 269 1.2 325.9 5531 827 453 248 4.3 1068.8 5532 798 483 302 0.9 268.2 5615 161 111 66 2.7 176.9 5625 596 321 172 2.4 410.2 5630 785 442 216 2.0 438.3 5631 682 438 287 2.4 688.2 5634 775 481 236 1.1 249.7 5637 751 396 202 1.2 235.1 5639 677 289 122 0.8 97.1 5720 316 186 65 0.7 44.3 5722 416 282 129 1.0 133.9 5726 618 431 261 1.3 338.6 5728 689 489 282 1.0 288.3 5730 788 509 321 1.0 334.4 5732 764 461 197 0.8 156.0 5834 722 389 215 1.2 248.1 5837 718 487 251 1.1 287.7 5839 639 297 150 1.0 151.4 5922 425 252 148 2.0 296.9 5924 526 377 205 1.5 309.4 5926 603 353 193 1.3 251.9 5928 684 357 191 0.9 168.1 5930 720 402 314 2.9 924.4

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-11 004713

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 5932 749 393 237 1.4 333.6 5934 795 475 281 2.3 638.1 6031 754 444 301 3.2 967.1 6035 740 481 343 2.6 897.7 6037 724 491 253 2.2 558.1 6039 635 373 140 2.3 316.9 6122 385 254 70 0.9 59.4 6124 496 308 117 2.2 252.5 6126 618 426 211 2.1 449.0 6128 604 420 223 1.1 255.8 6131 747 424 241 3.0 734.0 6132 692 373 263 3.8 1005.8 6136 708 324 210 2.9 600.0 6233 742 425 213 2.4 515.8 6235 723 360 118 1.3 155.5 6237 675 337 146 1.0 152.1 6238 591 315 212 1.2 260.4 6322 397 335 202 1.8 360.5 6324 356 194 92 2.1 190.0 6326 464 319 160 1.2 185.4 6330 604 372 214 2.3 496.9 6332 683 386 215 1.9 399.5 6336 588 363 173 1.2 202.1 6432 547 286 178 5.6 995.6 6435 672 337 130 2.4 309.1 6436 620 419 258 1.4 350.7 6439 607 329 169 0.9 151.0 6522 347 239 167 2.2 371.3 6524 384 298 169 1.2 194.3 6526 451 240 127 2.9 367.9 6528 489 306 177 1.5 264.2 6530 587 357 207 2.8 577.6 6633 549 336 126 2.7 343.9 6635 566 306 165 2.1 342.9 6637 507 262 167 2.0 341.2 6639 555 234 134 2.2 287.3 6722 305 204 95 2.0 188.3 6724 375 303 192 1.9 356.7

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-12 004714

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 6726 455 296 179 2.3 419.2 6730 508 373 232 2.0 460.5 6732 599 350 235 3.1 734.7 6736 526 307 205 3.5 708.7 6833 553 335 226 4.0 903.0 6835 558 277 149 1.8 268.0 6837 561 386 197 1.6 318.0 6838 532 348 177 1.5 260.3 6924 350 208 107 1.7 179.0 6926 401 261 131 1.3 172.5 6928 427 257 158 2.0 317.7 6930 505 321 225 2.7 601.7 7029 455 240 149 2.1 313.7 7035 543 265 144 1.3 183.5 7037 514 276 142 2.6 366.3 7126 376 206 115 2.1 243.4 7130 446 368 172 2.2 379.5 7132 478 281 196 3.0 597.5 7134 493 275 149 2.6 394.6 7137 490 304 196 3.3 644.3 7234 458 282 169 2.8 469.5 7238 433 307 117 1.0 120.1 7328 372 225 137 3.1 419.5 7330 411 280 157 2.1 326.3 7332 453 275 167 3.5 578.0 7435 450 312 221 2.9 637.6 7437 429 241 113 1.3 151.0 7439 387 244 126 2.0 247.4 7536 417 239 127 1.3 165.8 13203 13 0 0 . 0.0 16017 155 100 35 3.5 119.8 16217 136 125 64 1.4 86.6 16419 222 168 82 1.0 83.7 16619 214 157 77 3.3 250.6 16819 141 86 33 1.8 59.3 16843 301 116 59 1.8 106.0 17019 112 84 42 4.4 184.1 17021 206 112 60 1.4 84.9

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-13 004715

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 17043 256 146 45 1.0 47.1 17219 80 37 19 1.6 30.2 17221 166 112 61 1.5 89.8 17223 236 137 79 1.8 143.8 17419 41 23 16 4.9 76.1 17421 121 97 66 2.5 164.6 17423 209 137 51 2.5 125.1 17425 263 206 90 0.9 84.2 17621 100 79 41 0.8 32.2 17623 140 118 50 1.4 72.2 17625 207 147 44 1.1 49.0 17627 230 173 91 1.9 172.6 17629 292 172 70 1.7 115.0 17641 269 131 46 1.3 58.1 17729 278 158 16 0.6 10.1 17737 351 193 113 1.4 156.0 17827 227 160 40 1.7 69.6 17839 271 112 50 0.4 20.5 17931 258 120 45 0.3 14.9 17933 293 148 65 2.1 139.7 17937 273 145 7 0.2 1.5 17941 239 129 30 0.5 14.2 18037 233 110 33 0.5 15.3 18039 246 120 53 0.8 40.5 18133 237 129 49 0.3 15.5 21407 290 199 152 22.6 3419.4 21510 367 320 264 11.4 3020.9 21811 423 353 311 11.6 3619.9 22017 673 402 313 4.8 1487.2 22219 730 514 375 7.5 2825.3 22413 498 421 348 8.3 2889.3 22425 867 440 263 3.7 979.2 22619 723 426 302 4.8 1461.1 22623 865 571 338 2.9 988.9 22625 900 565 270 4.3 1171.3 22817 630 436 349 6.3 2182.2 22821 805 439 253 6.0 1517.5 22825 913 465 244 3.6 885.3

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-14 004716

APPENDIX A SUMMARY DATA FOR CORED WELLS IN RANGELY FIELD Average Gross Net Effective KH Well Brine Thickness Thickness Thickness (KH in mD- Coordinate Permeability (ft.) (ft.) (ft.) ft.) (K in mD) 23019 719 466 386 7.0 2713.9 23023 852 425 308 4.7 1449.4 23221 792 426 304 6.4 1953.5 23423 843 526 249 10.3 1282.9 23425 888 523 256 2.2 553.6 23435 677 271 83 0.7 58.8 23167 550 388 271 3.5 937.7 23629 933 459 154 2.3 351.1 23811 268 222 191 7.7 1459.7 23823 814 454 233 3.4 799.7 23837 573 267 116 1.3 148.4 24017 532 391 275 4.1 1129.4 24025 869 468 240 3.2 772.1 24027 897 569 235 1.5 361.8 24122 735 458 273 5.5 1490.3 24421 656 431 278 3.7 1031.9 25217 321 196 92 2.4 221.1 ------Average 526 327 199 2.8 906.4

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD A-15 004717

APPENDIX B UNION PACIFIC 19-28 CORE PERMEABILITY REPORT

CHEVRON USA INC. 4010-105 NONTRIBUTARY GROUNDWATER ASSESSMENT, WEBER FORMATION, RANGELY FIELD B-1

004718 Log Normal Frequency Dist

UP 19-28 Log Permeability Frequency Distribution 60

0 0.041 0.272 0.504 0.735 0.966 1.198 1.429 1.660 1.892 2.123 2.354 -0.884 -0.653 -0.422 -0.190

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