Work performed to on the McKittrick samples include optical and SEM photomicrographs, EDS analyses of mineral phases present, and random point analyses for non negative least squares (NNLS) modelling. NNLS modelling using MATLAB was attempted using EDS compositional point analyses of a sandstone section of known composition; the results were less than satisfactory. Chevron Oil Co. has agreed to use their ESTMIN program to predict mineral chemistry. Recommended work to complete includes X-ray diffraction of specimens for mineral identification and day percentages, and possibly supplementary analytical data (ICP, FTIR, LOL etc.) for ESTMIN modelling.

Twenty core specimens which had characteristics of importance were selected to produce polished thin sections. We decided on thin sections so that optical and electron analysis could be performed on the same specimen. Sections were impregnated with blue stained epoxy to clearly show porosity and fractures under the optical microscope. Two sections were requested for each sample-one cut parallel to the core and one cut perpendicular to the core. The purpose of having two sections cut from each specimen was to determine whether the porosity measurements change depending orientations. The following is a list of completed sections.

418 1228.8 VH Opal A-Low clay, High So (68.1)

418 1230.4VH Opal A-High clay, Low So (35.2)

418 1399.5VH K=46md. Excellent opal A.

418 1401.5VH Carbonate Hard Streak

418 1424.5 VH First Transitional A/ CT, G.D. =2.2, So = 52%

418 1522.6 VH Opal A/CT transition

418 1526.7 VH Sample w/ carbonate cement above and below

418 1572.4 VH So=70.3

418 1573.5 VH So=21.9

418 1631.5VH Opal A/ CT transition: cherty appearance

418 1634.8 VH High So, doesn't fluoresce.

418 1662.0 VH High So, doesn't fluoresce.

418 1681.5 VH Opal CT G.D. =2.46

418 1723.7VH Opal CT, no fluorescence

418 1753.5VH Cherty opal CT

418 1754.5VH Siltstones

418 1756.5VH Probably CT

418 1757.5 VH Opal CT-Fractured, cherty appearance

Petrographic evaluation using optical and electron microscopes indicates that in the McKittrick samples, silica phases predominate as the major mineral phase. Polished thin sections were used for optical examination, and half of the section was carbon coated for SEM examination. Grain mounts were gold coated prior to examination. Shallower samples (to approximately 1800 ft) are from well #418, Deeper samples are from #415. Semi-quantitative EDS (energy dispersive spectroscopy) analyses were also performed on grain mounts from some specimens.

Preliminary results of the studies indicate that silica phases (microfossil tests, opal, and other silica polymorphs) predominate. In shallower depths, the silica consists of microfossil tests composed of opaline silica, which apparently dissolves and re-precipitates in another form, assumed to be Opal CT. Major accessory minerals include carbonate, feldspar, pyrite, and possibly Ca-zeolites. Other minerals which will require electron microprobe for analysis include Mg silicate and and an Fe/ Mg aluminosilicate. Clay minerals and shaly units have not been observed or evaluated as of this time.

In the shallower levels (approx. 1200ft), the overall bulk composition of major elements is approximately 88%, SiO2, 4% Al203, 3% CaO, and 2% FeO, as determined by semi-quantitative EDS. Hydrocarbons are abundant and grain size is so small that individual phases are not recognizable in thin section. In the SEM, calcite and silica microfossil tests were identified some of the microfossils show evidence of extensive dissolution. It also appears in SEM images that some re-precipitated silica is present. Some pyrite was observed optically in some levels.

By approximately 1700 feet, recognizable fossil fragments are present in only limited horizons, and fine-grained aggregates of silica predominates. There appears to be a vuggy porosity on a small scale (10 to several hundred micrometers) in these specimens, still very high porosity. NaCl is present in some pores, possibly an artifact of drilling fluid. At some levels, fractures appear in the silica matrix material which are filled with hydrocarbons. Some optical images suggest that the hydrocarbon, previously disseminated, are segregated from the cherty lamellae (during recrystallization, possibly?). SEM backscattered images show dark regions along the fractures. They do not analyze differently, but may contain more hydrocarbon (and therefore would appear darker on BEI). Tiny carbonate rhombs occur in the altered region along fractures.

The deepest specimen was taken from another well, the McKittrick 415, and SEM examination only of a grain mount has been performed at this time. The specimen examined (4827 ft) is drastically different from the shallower specimens in 418. Silica occurs as fine grained aggregates. Porosity is still extremely high. Calcium sulfate is common; it has nucleated on the surface of silica phases and is possibly a late stage precipitate of circulating fluids, or drilling fluids. Also present and not observed before are filaments which are a nucron or less wide, and hundreds of micrometers long. It is not clear whether they represent a late-stage precipitate, or are an authigenic pore filling phase. They appear to analyze (although analyses are contaminated by surrounding phases due to small size) the same as the Ca-Al-Si "zeolite," with proportions of approximately CaAlSi 4-5. A stubby, equant crystal was also observed with the same composition. Zeolites are of concern for the effect they will have on porosity logs, and their structure may also trap large organic molecules such as hydrocarbons. Barite was seen, although it might be contaminant from drilling fluid. Clays were not observed.