Sample Screening

• Headspace gas (c1-c5) Hydrocarbon gas composition indicates the maturity of an oil or gas source. Thermally immature sources generally produce only small amounts of gas dominated by methane. With increasing maturity, more gaseous hydrocarbons, enriched in ethane and higher hydrocarbons, are produced. As maturity increases beyond the peak hydrocarbon generating stage, the amounts of ethane and higher hydrocarbons relative to methane decrease until in overmature source rocks, methane is again the major gaseous hydrocarbon.

• Total Organic Carbon (TOC) (LECO) TOC content allows potential petroleum source rocks to be identified. Conventionally, 0.5-0.7 % TOC is taken as the lower limit for a petroleum source rock.

• Total Inorganic Carbon and Total Carbon (TIC and TC) (LECO) Rock-Evaluation This is a pyrolysis technique that artificially matures petroleum source rocks to allow the potential to generate oil or gas; from that, the maturity of the source rock can be estimated.

• c3-c10 by Capillary GC (cuttings) Analysis provides a hydrocarbon fingerprint which can be used to correlate light oils and condensates.

• Vitrinite Reflectance (VR) An optical technique for determining the maturity of source rocks.

• Thermal Alteration Index (TAI) An optical technique for determining the maturity of source rocks. TAI and VR techniques complement each other.

• Kerogen Type An optical technique for identifying the kerogen source type, which determines the potential of the source rock to produce oil or gas.

• Maturation Series (kerogen isolation, VR, kerogen type, TAI)

• API Gravity (oil)

• Ni and V (oil or fraction)

• Elemental Analysis (C,H,N,S) (kerogen and/or oil)

• Elemental Sulfur (LECO) (rock or oil)

• Elemental Nitrogen (rock or rock extract)

• Geochemistry of Oil and Source Rock

• c8+ saturated hydrocarbons by Capillary GC GC analysis of the saturated hydrocarbons in an oil or in a source rock extract provides a hydrocarbon fingerprint, which can be used to correlate one oil to another oil or to bitumen extracted from a potential source rock. Ratios of hydrocarbons in the fingerprint can help determine the maturity of the oil or source rock and the environment of deposition of the source. Hydrocarbon ratios can also help determine the degree of biodegradation of oils.

• High Res GC/MS (saturated and/or aromatic fraction) (biomarkers) Analysis of saturated and aromatic biomarkers can be used to correlate one oil to another oil or to bitumen extracted from potential source rocks. Biomarkers are particularly useful when alteration of the oil by biodegradation or migration has changed the saturated hydrocarbon fingerprint of the oil.

• ¹³C/¹²C, D/H, ³⁴S/³²S, and ¹⁵N/¹⁴N (kerogen, whole oil, extract and fractions) Stable isotope ratios can be used to correlate one oil to another oil or to bitumen extracted from source rocks. Stable isotope ratios are characteristic of the bulk composition of the oil and are relatively unaffected by changes caused by biodegradation or migration - factors which would ordinarily alter the saturated hydrocarbon or biomarker composition drastically. Stable isotope ratios also allow correlation of oils to source rock kerogen. This is particularly useful when the only samples of potential source rocks are undermature or overmature and contain few hydrocarbons to allow correlation to oils. Certain oils and source rocks contain significant amounts of sulfur and nitrogen. The sulfur and nitrogen isotope ratios can allow oil-oil and oil-source rock correlation.

• Kerogen by Pyrolysis GC A source rock kerogen is artificially matured to generate hydrocarbons, the composition of which may be compared with an oil to allow correlation of the oil with the source rock.

• ¹³C/¹²C, D/H of methane (c1), c2, c3, n-c4, I-c4 or total c4 Isotope ratios of methane and higher hydrocarbons indicate the source type and maturity of the oil or gas source. Methane produced by terrestrial source rocks can have a different carbon and hydrogen isotope signature from methane produced by marine source rocks. ¹³C/¹²C and D/H isotope ratios of methane and higher hydrocarbons also show a progressive change with maturity that, along with the gas hydrocarbon composition, can give a fairly reliable estimate of the source rock maturity. ¹³C/¹²C and D/H isotope ratios of methane also allow petroleum related natural gas to be distinguished from the other major source of natural gas: bacterial processes (also referred to as marsh gas). The isotopic signature of bacterial methane is quite different from petroleum-related methane.