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ATTACHMENT I:FORMATION TESTING PROGRAM Mineralogy Quartz is the predominant mineral in the Domengine sands. Small amounts of varicolored lithic fragments,pyrite,and glauconite may also be present. The shaley intervals consist primarily of clay minerals, and trace amounts of pyrite and glauconite. Structure The Domengine Formation near the injection well location dips gently about 1.5 degrees to the southwest. No other significant geologic structures, such as faults or folds, occur within a distance of a mile from the well. Figure I-2 is a map of the structural contours on top of the Domengine Formation. Description of Vertical and Lateral Continuity The Domengine Formation is laterally continuous throughout this part of the Central Valley depositional basin. The unit is readily correlated in electric logs,and has been encountered by deep wells for many miles in all directions from this location. Outcrops of the Domengine, and the upper confining layer Nortonville Shale, occur in the Potrero Hills about 30 miles west of the LEC-1 site,and at Mt. Diablo near the old town site of Nortonville. An isopach map of the Domengine Formation,presented at Figure 1-1, shows that the formation thickens to the southwest,toward the center of the depositional basin. Hydrologic Parameters 1. Permeability—The permeability of the Domengine sands in the completion interval of the STIG-1 well was estimated to be 54.4 md,and a reservoir value of 12,500 millidarcies per foot(md/ft) was obtained from the initial well testing,based on an effective completion interval length of 230 feet. Since the STIG-1 well is only about 800 feet from the proposed LEC-1,well conditions should be similar,but,as stated above,this will be evaluated and determined during drilling and testing of the LEC-1 well. 2. Porosity—Analysis of the Neutron and Density Logs performed on the STIG-1 completion zone indicated a porosity ranging between 26.2 and 45.8 percent,with an average porosity being 35.3 percent. Porosity within the injection zone at the LEC-1 well will be verified through geophysical logging and sampling of formation materials during drilling of the well. 3. Reservoir Pressure—The formation pressures for the top and bottom of the Domengine Formation at the STIG-1 well were calculated,using a hydrostatic gradient of 0.433 psi/ft,indicating that the pressure at the top and bottom of the formation ranged from 1,614 to 1,974 psi,respectively. Additionally, a measured reservoir pressure of 1,698 psi was obtained at a subsurface depth of 3,986 feet in the STIG-1 well at the conclusion of the shut-in period following the injection test on June 5,1993. Considering the calculated hydrostatic pressure of 1,726 psi at that depth,the shut-in pressure indicated the Domengine reservoir pressure initially was about 28 psi below hydrostatic. Since injection began,annular pressure tests have been performed on STIG-1. Currently, bottom hole shut-in pressure is about 1764 psi. After injecting 100 gpm for 6 hours, pressure builds up to about 2,173 psi,but within 3 hours of stopping injection and SACI3713221082550025(ATTACH MENT-I.DOC) 1-5