AnchorRTF32343230323a204368617074RTF32343230323a204368617074Source Rock (SR) Analyzer:
User Guide

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Introduction

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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\]\[Agreed DJH\]_Erik DJH][DH1] 

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 [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 I’m leaving this for you guys to work on together. (To complete 31 December 2017.) \\ \\

Method Overview

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.

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• T_max = 400°–430°C: immature organic matter
• T_max = 435°–450°C: mature or oil zone
• T_max > 450°C: overmature zone

S3 Parameter

Wiki MarkupS3 (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 CO{~}2~ ₂ 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 <span style="color: #000d94"><strong><em>Oxygen Index (OI) Parameter</em></strong></span>\].

S4 Parameter

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Oxygen Index (OI) Parameter].

S4 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 ´ TOC – [0.83 ´ (S1 + S2)]; RC = S4/10

TOC Parameter

Wiki MarkupTOC 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

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=

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PC

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+

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RC

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TOC

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=

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[k

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´ (S1

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+

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S2)

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]/10

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+

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S4/10

Where PC = Pyrolyzed Carbon, RC = Residual Carbon, k = .83 (an average carbon content of hydrocarbons by atomic weight).

Hydrogen Index (HI) Parameter

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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

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Oxygen Index (OI) Parameter

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

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• PI < 0.2: immature rocks
• PI = 0.3–0.4: typical for samples in the petroleum window
• PI > 0.5: may indicate proximity of migrated hydrocarbons or trapped petroleum

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• PI

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• =

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• [S1/(S1

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• +

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• S2)

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• ]

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• ´ 100

S1/TOC Parameter

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:

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Evaluation requires assessment of possible contamination by drilling fluid additives and regional geochemistry of sediments.

S1

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´ 100/TOC

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Apparatus, Reagents, & Materials

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SRA Hardware

The SRA system consists of the following main components (Figure 1):

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• Autosampler
• Main control unit: oven and detector temperature control units and gas flow controllers
• Infrared (IR) section : CO/CO₂ detectors

• Combustion with gas separation and FID (pedestal, oven, and conversion FID)

  Figure 1: The four main components of the SRA

  Figure 2. SRA Sample Preparation Tools.

  
  

  Laboratory Equipment

• Cahn analytical balance (Analytical Balance User Guide)
• SRA
• Laboratory apparatus for sample preparation

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• Standard material (99986)
• Weatherford Standard 533 (PWDR3998091)

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Instrument Calibration

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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.

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Sample Preparation

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:

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1. Obtain freeze-dried bulk sample.
2. Crush sample by hand or use an electric mill to roughly crush samples.
3. Homogenize sample using a mortar and pestle. Note: Inadequate homogenization will cause high standard deviation in the data.

Weighing Samples

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See Quality Assurance/Quality Control for sample amounts and explanation of sample codes.

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1. Wipe sample filler, spatula, and forceps
2. Log into the balance system for Cahn electrobalance
3. Click Test Options, enter a value from 200 – 300 (depending on sea-state), then click Save/Exit.
4. Place weighing paper on both balance pans, close the door, and click Tare and Start on the balance software main screen.
5. Once the measurement is completed and the value is acceptable, click Get Mass at the bottom of the Dual Balance Plot area.
6. Place sample on the weighing paper in the left pan and click Weigh and Start on the screen.
7. Once the measurement is completed and value is acceptable, click Get Mass.
8. Place weighed sample material in a crucible using sample filler.
9. Select SRANL from the Analysis drop-down list, enter the text ID in the Text ID field and click Assign.
10. Highlight the appropriate sample from the search list and click Assign.
11. Enter the number of the crucible holder in the Container Number field.
12. Click Save at the bottom left of the screen to save mass with a measurement code to LIMS. Enter the mass in the log book.

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Sample Analysis

Sample analysis workflow is as follows:

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• Prepare the instrument (see Preparing the SRA Instrument).
• Set up software for sequence acquisition (see Setting up the Software).
• Acquire samples (see Running Samples).

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Preparing the Instrument

SRA Instrument

The SRA goes through an intense warm-up for at least six hours before operation. Perform the following steps to prepare for sample acquisition

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1. Open H₂, He, and air gas lines. Note: Verify gas gauge pressures using the gas flow meter.
2. Turn on the SRA.
3. Turn on the PC.
4. Double-click the TStationAcq.exe shortcut icon on the desktop to open the software Main Menu (Figure 3).
5. Check gas flow rates by removing the instrument panel covering the FID castle (Figure 7). Gas flow rates can be manipulated by rotating the valves on the rear of the instrument IR Section.
   1. Disconnect each gas line individually. Verify the hydrogen flow rate is ~65 mL/min, and the air flow rate is ~300 mL/min with a flowmeter. Use a Swagelock fitting to connect the flowmeter line with the instrument. Reconnect the gas line.
   2. Disconnect the gas line at the base of the oven pedestal (Figure 8) and connect to the flow meter. Navigate to Configuration>General and verify the helium flowrate is 100 mL/min and the oxidation air flowrate is 250 mL/min by selecting the gas radio buttons (Figure 6). Reconnect the gas line.
6. Zero and calibrate the CO/CO₂ detectors. This step should only be performed after the instrument has had ample time to warm up and clean, moisture-free helium has been circulating through the pedestal for at least 5 minutes.
   1. Open the IRCal program and click the play button (Figure 10).
   2. Calibrate the zero point of the IR sensor by clicking the lock icon (to activate the calibration buttons) and clicking Zero. The readings should be between 0-200 ppm before zeroing.
   3. Disconnect the fitting at the base of the drierite moisture trap located on the left side of the instrument and connect the 1% carbon monoxide gas standard bottle to the line entering the instrument (Figure 9).
   4. After 3-4 minutes the readings should stabilize. Click Calib and the reading should revert to 10000 ppm (1% wt). Click the lock icon to deactivate the zero and calib buttons.

   5. 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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      Figure 7: Hydrogen and air supply lines to the FID

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      Figure 8: Sample pedestal and gas line for purge gas (helium) and oxidation air

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      Figure 9: Setup of the IR cell calibration

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      Figure 10: IR Calibration screen

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      Setting up the Software

      Prepare the software for data acquisition as follows:

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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).

Editing the Sequence Editing the Sequence Table

A sequence table represents an analytical batch (see Qua Anchor_Hlt488379137_Hlt488379137lity 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):

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• Data File name (one for each sample to be run). Examples:
• Calibration blank: BLANK
• Calibration standard: 88695, 533
• Calibration verification standard: STDCHK
• Unknown samples: textID = LIMS text ID
• Sample ID: must be identical to the Text ID.
• Method
• C#: container number (must match autosampler place number
• Sample Weight: (mg)
• Acq Type: acquisition type
• BLK = Calibration blank
• STD = Calibration standard
• TPH = Unknown samples or QA/QC control samples

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Figure 13. SRA > Sequence Editor > Sequence Table.
Edit the sequence table as follows:

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1. Click Sequence Editor on the Main Menu (Figure 3).
2. Fill in the Data File, Sample ID, Method, C# (container number), Sample Weight, and Acq Type (blank - BLK, calibration – STD and unknown samples – TPH), fields using the logbook as the reference.
3. Click Save As and give the sequence a new name.

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Running Samples

To analyze samples, fill in the Acquisition Setup screen and confirm sample information on the Analysis screen.

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1. Click Next to open the Analysis screen (Figure 15).
2. Click Info at the bottom right to open detail information and confirm the information for the first sample.

3. Click Start Sequence above the sample window to start the run.

   Figure 14. SRA > Acquisition.

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   Figure 15. Analysis Screen.

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   Analyzing results

   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.
   

   Figure 16:

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   Figure 16: TStationProc program menu with sample raw file loaded

   Figure 17: TStationProc detailed overview

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   Quality Assurance/Quality Control

   Analytical Batch (Sequence)

   An analytical batch is referred to as a Sequence in this User Guide. Each sequence can contain the following samples:

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• Calibration blank (CB): A crucible containing no material and included as the first sample of any sequence
• Calibration standard (CS): ~90-100 mg of standard material run immediately after the calibration blank, and used to calibrate the instrument signals to known values
• QA/QC standard (CV) : A standard run as a sampler which allows the user to monitor instrument accuracy and precision. Calibration verification is conducted for each batch of 10 samples:
• QA/QC blank: An empty crucible analyzed as a sample
• Unknown sample(s) (TPH): ~90-100 mg of freezed-dried, powdered sample material

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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.

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LIMS Integration

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

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Health, Safety, & Environment

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