Source Rock Analysis (SRA)

SRA is run for the purpose of safety monitoring and yields information about thermal maturation and source of hydrocarbons, as well as petroleum potential, in the sediment or rocks at a drilled site. Samples are heated in a pyrolysis oven in an inert atmosphere to quantitatively and selectively determine free hydrocarbons contained in the sample and the hydrogen- and oxygen-containing compounds that are volatilized during the cracking of unextractable organic matter in the sample (kerogen).

Data file format

    Exp: expedition number
    Site: site number
    Hole: hole number
    Core: core number
    Type: type indicates the coring tool used to recover the core (typical types are F, H, R, X).
    Sect: section number.
    A/W: archive (A) or working (W) section half.
    Top offset on section (cm): position of the sample being measured relative to the top of the section.
    Bottom offset on section (cm): position of the sample being measured relative to the top of the section.
    Depth CSF-A (m): position of observation expressed relative to the top of the hole.
    Depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user.
    S1 (mg HC/g C): indicates quantity of free hydrocarbons (gas and oil) in the sample and normally increases with depth. Units are milligrams of hydrocarbon per gram of rock; multiply by 1000 to convert to ppm.
    S2 (mg HC/g C): indicates quantity of hydrocarbons that the rock has the potential of producing if burial and maturation continue and normally decreases with burial depths >1 km (also referred to as kerogen). Units are milligrams of hydrocarbon per gram of rock; multiply by 1000 to convert to ppm.
    S3 (mg HC/g C): indicates the amount of oxygen in the kerogen evolved as carbon dioxide during pyrolysis. Units are milligrams of organic carbon dioxide per gram of rock.
    Tmax (°C): indicates the stage of maturation of the organic matter. It is determined by the temperature at the maximum S2 yield. Units are degrees Celcius, and the range is generally 400°-550°C.
    TOC (wt%): TOC represents the convertible carbon fraction (pyrolized carbon + residual carbon). Units are unit weight of carbon per unit weight of whole rock (wt%).
    Hydrogen index (HI) (n/a): normalized hydrocarbon content of a rock sample (S2 x 100/TOC); HI decreases as the hydrocarbons in the sample mature. Range is generally ~100-600.
    Oxygen index (OI) (n/a): normalized oxygen content of a rock sample (S3 x 100/TOC). High OI values (>100) indicate continental or immature organic matter.
    Pyrolysis carbon (PC) (mg/g): represents carbon content of free hydrocarbons generated plus the carbon content of the remaining potential hydrocarbons ([0.83 x (S1 + S2)/10].
    Production index (PI) (n/a): indicates conversion of kerogen into free hydrocarbons and increases with increasing thermal maturation ([S1/(S1 + S2)] x 100).
    CSV filename: summary csv of measurement results.
    PDF filename: pdf of measurement chromatrogram. 
    Raw data filename: raw instrument measurement data.
    Instrument: abbreviation for the source rock analyzer used to take this measurement (SR).
    Timestamp (UTC): point in time at which an observation or set of observations were made. Precise meaning of the value varies between systems due to variation in capability and/or implementation.
    Text ID: automatically generated unique database identifier for a sample, visible on printed labels.
    Test No.: unique number associated with the instrument measurement steps that produced these data.
    Sample comments: observations recorded about the sample itself.
    Test comments: observations about a measurement or the measurement process; some measurement observations may be under Result comments.
    Result comments: observations about a measurement or the measurement process; some measurement observations may be under Test Comments.