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DocuSign Envelope ID:6BC32598-B737-464E-898A-81 F1 F7131339133 <br /> Zone of endangering influence(ZEI)methods <br /> Site-specific parameters were estimated from geophysical logs in the Colorado Oil and Gas <br /> Conservation Commission (COGCC) database from the nearby Gossard #1 well (spontaneous <br /> potential [SP] and resistivity logs) and the stratigraphically and structurally similar McBride Gov <br /> Little Creek 1 well (SP, resistivity, gamma and density logs). Locations of these wells are shown <br /> on Exhibit A3-1. <br /> Volumetric calculation methods <br /> The volumetric assessment for estimating the size of the AOR was conducted using geophysical <br /> well log information from the nearby Gossard #1 well and the McBride Gov Little Creek 1 well, <br /> and also completion information from the nearby Colowyo Mine Taylor Creek#3 well completed <br /> in the overlying Iles Formation. The method calculates the area over which a given volume of <br /> injected fluid will spread based on the total thickness and porosity of the injection zone. The <br /> volumetric calculation estimates the fluid front radius using the equation from Warner and Lehr, <br /> 1981, pp. 107-114: <br /> R= (V/23.4HP)1/2 (A-1) <br /> where R=radius of invaded zone, V=volume of fluid injected, H=net thickness of injection zone, <br /> and P=porosity of injection zone. The volumetric method does not consider pressure buildup <br /> which defines the Zone of Endangering Influence (ZEI). <br /> The target injection zone is the permeable sandstones within the Mancos Shale. Spontaneous <br /> Potential (SP)and resistivity logs from the Gossard#1 well located approximately 1 mile southeast <br /> of the proposed UIC location were used to identify four permeable zones corresponding to the <br /> named sandstone intervals in the Mancos Shale as shown in Table A-2. Stratigraphically <br /> equivalent zones were identified on SP and resistivity logs from the McBride Gov Little Creek 1 <br /> well, and density logs from this well were used to estimate the porosity of the four horizons. <br /> Table A-2. Proposed Injection Intervals and Porosity <br /> Mancos Shale Interval Depth Thickness Porosity <br /> Sandstone Member (ft, BGS) (ft) N <br /> Lloyd Sandstone 2690-2735 45 10 <br /> Duffy Mountain 2850-2875 25 5 <br /> Moropos Sandstone 3495 -3530 35 10 <br /> Meeker Sandstone 4570-4700 130 6 <br /> Total* 235 7.3 <br /> * - Net sand thickness and thickness weight average porosity <br /> Using the parameters in Table A-2 and assuming an average of 300 gallons per minute fluid <br /> injection over 20 years, a fluid front radius of 277 feet was calculated using Equation A-1. <br /> Generally, injected fluid will travel a larger distance due to dispersion and channeling through <br /> discrete higher permeable pathways within the injection formation. Equation A-2 was used to <br /> estimate a more conservative fluid front radius by including the effect of dispersion. <br /> R' = R+2.3(DR)1/2 (A-2) <br /> 2 <br />