Author(s): | K. Fujine | ||
Reviewer(s): | L. Brandt | ||
Manager Approval (Name, Title, Date): | D.J. Houpt | ||
Audience: | Scientists, Laboratory Technicians | ||
Origination date: | 5/12/08 | ||
Current version: | V1.0 | 8/20/13V371T | July 2017 (V. Percuoco) |
RevisedPrevious versions: | 5/5/15 E. Moortgat, 7/21/17 V. PercuocoV1.0 | 8/20/13 | |
Domain: | Chemistry | ||
System: | Rock Maturity | ||
Keywords: | Rock-Eval, Tmax, Source Rock, Hydrocarbon Maturity |
Source Rock (SR) Analyzer: User Guide from (SRA_UG_371T_draft)
This user guide contains standard operational procedures for the Source Rock Analyzer (SRA). The chemistry laboratory technician performs maintenance and configuration of the SRA. Information for the laboratory technician is presented in the SRA Analyzer Advanced User Guide.??? [Ithink that we should combine the two. EM][Agreed DJH][DH1]
[DH1]Erik and/or Lisa, Vinny indicated that he is not familiar enough with the inner workings of the SRA to do a thorough revision of the AUG (and combination with the UG, I still agree with that), so I’m leaving this for you guys to work on together. (To complete 31 December 2017.)
Pyrolysis analysis is conducted on dried ground sediments or rock for the purpose of safety monitoring. The analysis yields information about thermal maturation, source of hydrocarbons and petroleum potential.
The pyrolysis method consists of programmed temperature heating in a pyrolysis oven of a sample (80 – 100mg), in an inert atmosphere (helium), to quantitatively determine free hydrocarbons contained in the sample and the hydrocarbon- and oxygen-containing compounds that are volatilized during the cracking of unextractable organic matter (kerogen).
Pyrolysis data may be compromised in samples containing greater than 10 wt% carbonate and for young (<1 Ma) samples or very immature organic matter (Tmax < 400°C). Samples with less than 0.5 wt% TOC may not give reliable results because of the small size of the S1, S2, and S3 signals.
The data obtained from the TPH-TOC analyses are defined by the following parameters
S1 (milligrams of hydrocarbon per gram of rock) is an indication of free hydrocarbons (gas and oil) in the sample. S1 > 1 may be indicative of an oil show. S1 normally increases with depth. S1 is measured via an FID (Flame Ionization Detector).
Free thermally extractable hydrocarbons in the rock sample that vaporize at temperatures up to ~ 330°C are included in S1. Heavier, free hydrocarbons and nonhydrocarbons that vaporize or crack at higher temperatures are included in the S2 peak .
S1 can be elevated by contamination from organic drilling fluid additives such as diesel, walnut shells, Qwik-Seal, Lubra beads, gilsonite, etc. Nonindigenous hydrocarbons expelled from source rocks elevate the S1 value in a reservoir rock. To convert S1 to ppm, multiply the S1 value by 1000. To convert the original S1 value to an approximate barrels of oil per acre foot, multiply by 20.082.
S2 (milligrams of hydrocarbon per gram of rock) hydrocarbons result from the cracking of kerogen and high molecular weight free hydrocarbons that do not vaporize in the S1 peak. S2 is an indication of the quantity of hydrocarbons that the rock has the potential of producing should burial and maturation continue. This parameter normally decreases with burial depths >1 km.
To convert to ppm, multiply the S2 value by 1000. To convert the original S2 value to an approximate barrels of oil per acre foot, multiply by 20.082.
This is the temperature of maximum rate of evolution of S2 hydrocarbons (top of S2 peak). Tmax indicates the stage of maturation of the organic matter. Tmax values are affected by low organic matter content where low S2 peaks are encountered. When the S2 value is < 0.5 and the S2 peak does not have a definitive peak (i.e., is broad and flat), Tmax values may not be reliable. Also, organic-lean clayey sediments with S2 values as high as 2.00 may have unreliable Tmax values values.
Tmax may be affected by the presence of heavy free hydrocarbons in the S2 peak, which may cause Tmax to be anomalously low (<400°C). Also, Tmax may be affected by reworked organic matter or salt ionization, which may cause Tmax to be anomalously high (>550°C).
Tmax values and true Tmax temperatures vary with the temperature programming rate and are useful for approximating kinetic values. Tmax is a calibrated temperature and does not represent the true (absolute) temperature.
Maturation of organic matter can be estimated by the Tmax range:
S3 (milligrams of organic carbon dioxide per gram of rock) is produced during pyrolysis of kerogen and is organic carbon dioxide evolved during low-temperature pyrolysis (<390°C). It may be affected by the decomposition of inorganic matrix particularly due to weathering or mineral matrix interaction. S3 is measured via the CO2 detector on the SRA. Generally, S3 values >200 are anomalously high, possibly due to high concentrations of carbonates that break down at temperatures <390°C and may or may not be valid. S3 is an indication of the amount of oxygen in the kerogen and is used to calculate the oxygen index [see Oxygen Index (OI) Parameter].
S4 (milligrams of carbon per gram of rock) is obtained from oxidizing (at 600°C) the organic matter remaining in the sample after pyrolysis (residual carbon). Using this value, TOC is determined by adding the residual organic carbon to the pyrolyzed organic carbon. It is measured using a combination of the CO and CO2 detectors. Because the instrument automatically combines convertible carbon (pyrolyzed carbon) with the residual carbon (RC) and reports TOC to actually determine the S4 value, it is necessary to subtract the convertible carbon from the TOC.
S4 = 10 x TOC – [0.83 x (S1 + S2)]; RC = S4/10
TOC is the weight percent of carbon (unit weight of carbon per unit weight of whole rock). TOC is composed of convertible fraction, which represents the hydrocarbon already generated (S1) and the potential to generate hydrocarbons (S2). The residual fraction (S4) has no potential to generate hydrocarbons.
TOC = PC + RC
TOC = [k x (S1 + S2)]/10 + S4/10
Where PC = Pyrolyzed Carbon, RC = Residual Carbon, k = .83 (an average carbon content of hydrocarbons by atomic weight).
HI is the normalized hydrocarbon content of a rock sample. Kerogen type information is derived from this value as follows:
HI decreases as the sample matures. HI may be lowered by weathering or mineral matrix interactions, which cause reduction in the S2 value. Marine organisms and algae, in general, are composed of lipid- and protein-rich organic matter, where the ratio of H to C is higher than in the carbohydrate-rich constituents of land plants. HI typically ranges from ~100 to 600 in geological samples. High HI values (>400) indicate large proportions of well-preserved algal and microbial organic matter.
HI = (S2 * 100)/TOC
OI is the normalized oxygen content of a rock sample. Type III kerogens generally have higher OI than either Type I or II kerogens. However, the hydrogen content is the principal discriminating factor for oil or gas potential. OI may be increased by weathering or mineral matrix interactions, which elevate the S3 value. If TOC is <0.50 wt%, OI may be meaningless (Espitalié, 1982). OI correlates with the ratio of O to C, which is high for polysaccharide-rich remains of land plants and inert organic material encountered as background in marine sediments. OI values range from near 0 to ~150. High OI values (>100) are an indicator of continental organic matter or immature organic matter from all sources.
OI = (S3 ¿ 100)/TOC
PI is indicative of the conversion of kerogen into free hydrocarbons or, in a general sense, the transformation ratio. PI increases with increasing thermal maturation in the absence of expulsion. Anomalies may be due to differences in organic facies or migration into or expulsion out of a sediment sample. PI values indicate the following:
PI = [S1/(S1 + S2)] x 100
The ratio of free hydrocarbons (S1) to TOC may be used to identify source or reservoir rocks. The S1 determination yields lighter hydrocarbons, which are usually lost during solvent evaporation.. This parameter can be evaluated as follows:
Evaluation requires assessment of possible contamination by drilling fluid additives and regional geochemistry of sediments.
S1 x 100/TOC
The SRA system consists of the following main components (Figure 1):
Combustion with gas separation and FID (pedestal, oven, and conversion FID)
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Compressed gases
Every time the instrument is powered on, the SRA must be calibrated (standard run as a 'calibration' type. After this initial calibration, and if no other changes are made to the instrument, a only a blank and a standard check need to be measured to verify calibration. Allow the instrument to stabilize for 3 hrs before performing a calibration.
Sediments and sedimentary rock samples logged into the LIMS system as SRANL are analyzed by SRA. During sample preparation, keep in mind that sample container numbers must correlate with autosampler place numbers. Sample preparation includes the following steps:
Text ID (parent) | Text ID (child) | Mass | Container number | LIMS code | SRA code |
Blank | 1 | BLK | |||
STD99986 | OTHR137987 | 90.00 | 2 | QAQCSTD | STD |
OTHR2764599 | OTHR346972 | 92.00 | 3 | UNK | TPH |
OTHR2765092 | OTHR130746 | 92.36 | 4 | UNK | TPH |
CV2-99986 | OTHR427034 | 92.05 | 10 | QAQCCV | TPH |
See Quality Assurance/Quality Control for sample amounts and explanation of sample codes.
Sample analysis workflow is as follows:
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The SRA goes through an intense warm-up for at least six hours before operation. Perform the following steps to prepare for sample acquisition
Reconnect the moisture trap, then perform steps a-e again to calibrate the IR cell for carbon dioxide after residual carbon monoxide has been purged from the IR cell (~5 mins).
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Data files are saved into the expedition-specific data folder with respect to each sequence .
The method does not need to be edited for regular onboard measurements (i.e., safety monitoring) except for the standard information. The Technician will edit the fields in the Standard tab (Figure 12) if the standard material changes. In that case, one blank, one standard, and one known sample (house standard) must be measured to confirm calibration (see Quality Assurance/Quality Control).
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A sequence table represents an analytical batch (see Quality Assurance/Quality Control for information about batches and calibration). The sequence file is an archive file that is updated with respect to each run. After each batch, the sequence table is saved into the expedition-specific data folder. A typical sequence table contains the following (see Figure 9):
Figure 13. SRA > Sequence Editor > Sequence Table.
Edit the sequence table as follows:
To analyze samples, fill in the Acquisition Setup screen and confirm sample information on the Analysis screen.
Click Start Sequence above the sample window to start the run.
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The sequence results may be viewed individually by opening up the RAW files stored in the data directory with the TStationProc program. A graphical display of the oven temperature, FID, CO2, and CO data streams is presented. Typically, trends in these data will appear similar to those for Weatherford Standard 533 as shown in Figure 16. Additional measurement parameters may be viewed by clicking the Details button (Figure 17). This information may be exported from TStationProc or reprocessed by navigating to File>Export or File>Reprocess Sequence, respectively.
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Analyte | Standard 999986 | Standard 533 |
S1 (mg HC/g) | 0.16 ± 0.08 (50%) | 0.76 ± 0.19 (25%) |
S2 (mg HC/g) | 8.41 ± 1.26 (15%) | 12.21 ± 1.83 (15%) |
S3 (mg CO2/g) | 0.39 ± 0.10 (15%) | 1.42 ± 0.36 (25%) |
S4 (mg C/g) | 23.99 | 29.3 |
Tmax (°C) | 418 ± 5 | 418 ± 5 |
TOC (wt%) | 3.11 | 3.78 |
Precision of analysis is determined by calculating the relative standard deviation of replicate samples.
Accuracy is determined by running a calibration verification (CV) with every batch or every 10 samples, and calculating the percent difference of measured values from known values.
Results are stored in the LIMS database associated with an analysis code and an analysis component, component value, and component unit. Analysis codes and their components, definitions, and units are listed below. Use Spreadsheet Uploader to transfer data from a Sequence Report to LIMS. Complete fields in Spreadsheet Uploader with the following parameters: Analysis: SRANL, Instrument: SRA, Display Flag: T, and the rest according to the table below.
Table 1: LIMS components and units
Analysis | Component Name | Definition | Unit | LIMS Unit |
SRANL | HI | Hydrogen index (S2 x 100/TOC) | mg HC/g TOC | NONE |
OI | Oxygen index (S3 x 100/TOC) | mg CO2/g TOC | NONE | |
PC | Pyrolysis carbon (0.83 x [S1 + S2]/10) | mg HC/g rock | MG_PER_G | |
PI | Production index ([S1/(S1 + S2)] x 100) | — | NONE | |
S1 | HC vaporize < 330°C (free oil) | mg HC/g rock | MGHC_P_GC | |
S2 | HC vaporize > 330°C (kerogen) | mg HC/g rock | MGHC_P_GC | |
S3 | Carbon dioxide evolved | mg CO2/g rock | MGHC_P_GC | |
S4 | Residual carbon | mg HC/g rock | MGHC_P_GC | |
mass | Sample mass | Mg | MILLIGRAMS | |
tmax | Maximum S2 (peak) temperature | °C | CELSIUS | |
toc | Total organic carbon | wt% | PCT_WEIGHT |
All Technicians must adhere to the complete required safety protocols operating the SRA instrument.
Although there's a component list in the LIMS Integration section, it is not all of the components either created by the LIMS or the uploader. The list below describes all of them.
ANALYSIS | TABLE | NAME | ABOUT TEXT |
SRANL | SAMPLE | Exp | Exp: expedition number |
SRANL | SAMPLE | Site | Site: site number |
SRANL | SAMPLE | Hole | Hole: hole number |
SRANL | SAMPLE | Core | Core: core number |
SRANL | SAMPLE | Type | Type: type indicates the coring tool used to recover the core (typical types are F, H, R, X). |
SRANL | SAMPLE | Sect | Sect: section number |
SRANL | SAMPLE | A/W | A/W: archive (A) or working (W) section half. |
SRANL | SAMPLE | text_id | Text_ID: automatically generated database identifier for a sample, also carried on the printed labels. This identifier is guaranteed to be unique across all samples. |
SRANL | SAMPLE | sample_number | Sample Number: automatically generated database identifier for a sample. This is the primary key of the SAMPLE table. |
SRANL | SAMPLE | label_id | Label identifier: automatically generated, human readable name for a sample that is printed on labels. This name is not guaranteed unique across all samples. |
SRANL | SAMPLE | sample_name | Sample name: short name that may be specified for a sample. You can use an advanced filter to narrow your search by this parameter. |
SRANL | SAMPLE | x_sample_state | Sample state: Single-character identifier always set to "W" for samples; standards can vary. |
SRANL | SAMPLE | x_project | Project: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises |
SRANL | SAMPLE | x_capt_loc | Captured location: "captured location," this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2 |
SRANL | SAMPLE | location | Location: location that sample was taken; this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2 |
SRANL | SAMPLE | x_sampling_tool | Sampling tool: sampling tool used to take the sample (e.g., syringe, spatula) |
SRANL | SAMPLE | changed_by | Changed by: username of account used to make a change to a sample record |
SRANL | SAMPLE | changed_on | Changed on: date/time stamp for change made to a sample record |
SRANL | SAMPLE | sample_type | Sample type: type of sample from a predefined list (e.g., HOLE, CORE, LIQ) |
SRANL | SAMPLE | x_offset | Offset (m): top offset of sample from top of parent sample, expressed in meters. |
SRANL | SAMPLE | x_offset_cm | Offset (cm): top offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset, converted to cm) |
SRANL | SAMPLE | x_bottom_offset_cm | Bottom offset (cm): bottom offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset + length, converted to cm) |
SRANL | SAMPLE | x_diameter | Diameter (cm): diameter of sample, usually applied only to CORE, SECT, SHLF, and WRND samples; however this field is null on both Exp. 390 and 393, so it is no longer populated by Sample Master |
SRANL | SAMPLE | x_orig_len | Original length (m): field for the original length of a sample; not always (or reliably) populated |
SRANL | SAMPLE | x_length | Length (m): field for the length of a sample [as entered upon creation] |
SRANL | SAMPLE | x_length_cm | Length (cm): field for the length of a sample. This is a calculated field (length, converted to cm). |
SRANL | SAMPLE | status | Status: single-character code for the current status of a sample (e.g., active, canceled) |
SRANL | SAMPLE | old_status | Old status: single-character code for the previous status of a sample; used by the LIME program to restore a canceled sample |
SRANL | SAMPLE | original_sample | Original sample: field tying a sample below the CORE level to its parent HOLE sample |
SRANL | SAMPLE | parent_sample | Parent sample: the sample from which this sample was taken (e.g., for PWDR samples, this might be a SHLF or possibly another PWDR) |
SRANL | SAMPLE | standard | Standard: T/F field to differentiate between samples (standard=F) and QAQC standards (standard=T) |
SRANL | SAMPLE | login_by | Login by: username of account used to create the sample (can be the LIMS itself [e.g., SHLFs created when a SECT is created]) |
SRANL | SAMPLE | login_date | Login date: creation date of the sample |
SRANL | SAMPLE | legacy | Legacy flag: T/F indicator for when a sample is from a previous expedition and is locked/uneditable on this expedition |
SRANL | TEST | test changed_on | TEST changed on: date/time stamp for a change to a test record. |
SRANL | TEST | test status | TEST status: single-character code for the current status of a test (e.g., active, in process, canceled) |
SRANL | TEST | test old_status | TEST old status: single-character code for the previous status of a test; used by the LIME program to restore a canceled test |
SRANL | TEST | test test_number | TEST test number: automatically generated database identifier for a test record. This is the primary key of the TEST table. |
SRANL | TEST | test date_received | TEST date received: date/time stamp for the creation of the test record. |
SRANL | TEST | test instrument | TEST instrument [instrument group]: field that describes the instrument group (most often this applies to loggers with multiple sensors); often obscure (e.g., user_input) |
SRANL | TEST | test analysis | TEST analysis: analysis code associated with this test (foreign key to the ANALYSIS table) |
SRANL | TEST | test x_project | TEST project: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises |
SRANL | TEST | test sample_number | TEST sample number: the sample_number of the sample to which this test record is attached; a foreign key to the SAMPLE table |
SRANL | CALCULATED | Top depth CSF-A (m) | Top depth CSF-A (m): position of observation expressed relative to the top of the hole. |
SRANL | CALCULATED | Bottom depth CSF-A (m) | Bottom depth CSF-A (m): position of observation expressed relative to the top of the hole. |
SRANL | CALCULATED | Top depth CSF-B (m) | Top 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. |
SRANL | CALCULATED | Bottom depth CSF-B (m) | Bottom 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. |
SRANL | RESULT | HI | RESULT hydrogen index (HI): 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. |
SRANL | RESULT | OI | RESULT oxygen index (OI): normalized oxygen content of a rock sample (S3 x 100/TOC). High OI values (>100) indicate continental or immature organic matter. |
SRANL | RESULT | PC (mg/g) | RESULT 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]. |
SRANL | RESULT | PI | RESULT production index (PI): indicates conversion of kerogen into free hydrocarbons and increases with increasing thermal maturation ([S1/(S1 + S2)] x 100). |
SRANL | RESULT | S1 (mg HC/g C) | RESULT 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. |
SRANL | RESULT | S2 (mg HC/g C) | RESULT 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. |
SRANL | RESULT | S3 (mg HC/g C) | RESULT 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. |
SRANL | RESULT | container_number | RESULT container number: number of the container/autosampler position for this sample |
SRANL | RESULT | csv_asman_id | RESULT csv file ASMAN_ID: serial number of ASMAN record for the CSV data file |
SRANL | RESULT | csv_filename | RESULT spreadsheet uploader filename: file name of the CSV data file |
SRANL | RESULT | pdf_asman_id | RESULT image file ASMAN_ID: serial number of ASMAN record for the image file (for the thermogram); may be in PDF, PNG, or other image format |
SRANL | RESULT | pdf_filename | RESULT image filename: file name of the image file (for the thermogram); may be in PDF, PNG, or other image format |
SRANL | RESULT | raw_asman_id | RESULT raw data ASMAN_ID: serial number of ASMAN record for the raw data file (binary format) |
SRANL | RESULT | raw_filename | RESULT raw data filename: file name of the raw data file (binary format) |
SRANL | RESULT | sr_mass (mg) | RESULT sample mass (mg): mass of the sample for this run |
SRANL | RESULT | ssup_asman_id | RESULT spreadsheet uploader ASMAN_ID: serial number of ASMAN record for the spreadsheet uploader file |
SRANL | RESULT | ssup_filename | RESULT spreadsheet uploader filename: file name of spreadsheet uploader file |
SRANL | RESULT | tmax (°C) | RESULT Tmax (deg. 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. |
SRANL | RESULT | toc (wt%) | RESULT total organic carbon (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%). |
SRANL | SAMPLE | sample description | SAMPLE comment: contents of the SAMPLE.description field, usually shown on reports as "Sample comments" |
SRANL | TEST | test test_comment | TEST comment: contents of the TEST.comment field, usually shown on reports as "Test comments" |
SRANL | RESULT | result comments | RESULT comment: contents of a result parameter with name = "comment," usually shown on reports as "Result comments" |
SRA User Guide: 29th September 2022