Using Rock-Eval S4Tpeak as thermal maturity proxy for shales.
IR@CIMFR: CSIR-Central Institute of Mining and Fuel Research, Dhanbad
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| Title |
Using Rock-Eval S4Tpeak as thermal maturity proxy for shales.
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| Creator |
Hazra, Bodhisatwa
Singh, Deependra Pratap Chakraborty, Prasenjeet Singh, Pradeep K Sahu, Santi Gopal Adak, Ashis K. |
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| Subject |
Rock Testing
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| Description |
The Rock-Eval pyrolysis-stage derived parameters such as free hydrocarbons (S1), heavier pyrolysis-hydrocarbons (S2), pyrolyzable carbon (PC) and pyrolysis Tmax (from S2 curve) have received considerable interest for source-rock screening and thermal maturity assessment. On the other hand, the Rock-Eval oxidation-stage S4CO2 curve, which gives the amount of residual carbon (RC), only recently has received some interest. While the pyrolysis-stage S2 temperature-peak (Tmax) is conventionally used as a maturity proxy, in this work we show that the temperature-peak of S4CO2 curve (S4Tmax) can also be used as a thermal maturity proxy for shales. For overmature and low-TOC shale samples, showing asymmetric S2 shape and concomitantly producing doubtful Tmax, the S4 curves showed symmetric nature and consequently the S4Tmax was observed to be a reliable thermal maturity estimate. While the S4Tmax clearly resolved immature and overmature shales, for the early mature and peak mature shales the S4Tmax showed overlapping values. S4Tmax of pre-pyrolyzed and pyrolyzed masses showed good positive correlation with differential scanning calorimetry temperature-peak (DSCTpeak), and consequently indicated its applicability as a thermal maturity proxy. When early mature pre-pyrolyzed samples were directly analyzed using the Rock-Eval oxidation stage, the S4 curves showed formation of two sub-peaks, and consequently the Tmax was observed to decrease. It is recommended that analysts and interpreters should thoroughly cross-check S2 curves before reporting data, and in case of asymmetric or unreliable S2 curves, the S4Tmax can be used as a maturity proxy.
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| Date |
2021-05-21
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| Type |
Article
PeerReviewed |
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| Identifier |
Hazra, Bodhisatwa and Singh, Deependra Pratap and Chakraborty, Prasenjeet and Singh, Pradeep K and Sahu, Santi Gopal and Adak, Ashis K. (2021) Using Rock-Eval S4Tpeak as thermal maturity proxy for shales. Marine and Petroleum Geology, 127.
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| Relation |
http://cimfr.csircentral.net/2389/
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