Rock-Eval Pyrolysis

Q: What's a Rock- Eval Pyrolysis?

Rock-Eval Pyrolysis adalah analisis geokimia yang memanaskan sampel batuan secara bertahap dalam suasana tanpa oksigen. Hasilnya berupa parameter S1, S2, S3, dan Tmax yang menunjukkan potensi hidrokarbon, jenis kerogen, dan tingkat kematangan termal sebuah batuan induk.

Q: What's S1, S2, and Tmax?

S1 adalah hidrokarbon bebas yang sudah ada di batuan. S2 adalah hidrokarbon yang dihasilkan saat kerogen dipanaskan, sehingga menunjukkan potensi sisa batuan induk. Tmax adalah suhu saat puncak S2 tercapai dan dipakai sebagai indikator kematangan termal.

Q: Does RockEval have to be accompanied by TOC analysis?

Ya, hampir selalu. Hydrogen Index dan Oxygen Index dihitung dengan membagi S2 dan S3 terhadap TOC. Selain itu, hasil Rock-Eval dari sampel dengan TOC sangat rendah kurang andal, sehingga sampel biasanya dipilih dari hasil screening TOC.

Q: How many Tmax indicate the rocks are ripe?

Secara umum, Tmax di bawah 435 °C menandakan batuan belum matang, 435–470 °C berada dalam jendela pembentukan minyak, dan di atas 470 °C sudah memasuki fase gas. Nilai ini sebaiknya dikonfirmasi dengan vitrinite reflectance.

Rock-Eval Pyrolysis measures S1, S2, S3, Tmax, HI, OI, and PI to assess potential, the type of kerogens, and the rigidity of parent rock.

Rock-Eval Pyrolysis Service

Rock-Eval Pyrolysis Warming rock samples gradually without oxygen to measure how much hydrocarbons are already there and that can still be produced by organic materials. From one time analysis, you get a picture The potential, the type of kerogen, and the level of maturity. The mother rocks. BSILAB provides Rock-Eval Pyrolysis as part of a series of geochemical analysis of parent rocks, usually mixed with TOC analysis. Analisis Rock-Eval dikerjakan in-house di laboratorium geokimia BSILAB.

Generated parameters

Parameter	Units	Meaning
S1	mg HC / g rocks	Free hydrocarbons that already exist inside rocks.
S2	mg HC / g rocks	Hydrocarbons are produced from the grazing of the kerogens. — potential size remaining parent rock
S3	mg CO₂/ g rocks	CO₂ organic material. — It deals with the content of kerogen oxygen
Tmax	° C	Temperature at the height of S2 reached — thermal alignment
HI (Hydrogen Index)	mg HC / g TOC	S2 × 100 / TOC — kerogen type marker
OI (Oxygen Index)	mg CO₂/ g TOC	S3 × 100 / TOC
IM (Production Index)	—	S1 / (S1 + S2) — How much hydrocarbons are already formed

Rock-Eval schematic Pirogram S1, S2, and Tmax — Rock-Eval schematic pyrogram: S1 peak, S2, and Tmax.

How to read the RockEval results

1. The potential of hydrocarbons (S2)

S2 (mg HC / g rocks)	Potential
< 2,5	Bad
2,5 – 5	Medium
5 – 10	Good
10 – 20	Very good
> 20	Special

2. Jenis kerogen (HI) — konfirmasi dengan Kerogen typing

HI (mg HC / g TOC)	Kerogen type	Main product
> 600	Type I	Oil (generally acurine / alga)
300 – 600	Type II	Oil (generally ocean)
200 – 300	Type II / III	Oil and gas
50 – 200	Type III	Gas.
< 50	IV Type	Not potentially

3. Stability Level (Tmax and PI)

Stage of maturity	Tmax (° C)	IM
Uncooked (immune)	< 435	< 0,10
Start oil window	435 – 445	0,10 – 0,15
Top of the oil window	445 – 450	0,25 – 0,40
End of oil window	450 – 470	> 0,40
Premature (postmature / gas)	> 470	—

Ambang interpretasi: Peters & Cassa (1994), AAPG Memoir 60. Nilai Tmax dapat dipengaruhi jenis kerogen dan kontaminasi; interpretasi kematangan sebaiknya dikonfirmasi dengan vitrinite reflectance.

Notice: S2 and Tmax samples with TOC are very low (generally < 0.5 wt%) or S2 is very low-tenable. That's why Rock-Eval is almost always run together. TOC analysis, and samples selected from screen TOC results.

BSILAB analysts operate instruments in geochemical labs — BSILAB geochemistry lab, Southern assault.

When is RockEval needed?

Judging by the potential and kind of parent rock in the exploration block evaluation or basin study.
Whether the parent rocks have entered the oil or gas window.
Supports modeling of petroleum and modeling systems.
Filter samples before more expensive analysis like GC-MS biomarker.

How to send samples

Consult — Submit the number and type of sample as well as the purpose of study.
Offers — BSILAB team informs the required sample count, analysis package (TOC + Rock-Eval), cost, and estimate of time.
Sample Delivery fully labeled (well / location, depth, date) with sample list.
Digital report contains all Rock-Eval parameters per sample, ready for HI-Tmax plots and interpretations.

Consult TOC + Rock-Eval packages

The BSILAB team helped determine the number of samples and the order of the most efficient analysis for the study of your parent rocks.

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Questions often asked

What's a Rock- Eval Pyrolysis?

Rock-Eval Pyrolysis is a geochemical analysis that heats up rock samples gradually in an atmosphere without oxygen. The results are S1, S2, S3, and Tmax parameters that indicate the potential for hydrocarbons, the type of kerogen, and the thermal rate of a parent rock.

What's S1, S2, and Tmax?

S1 is a free hydrocarbon that's already on the rocks. S2 is hydrocarbons produced when the kerogen is heated, so it shows the potential of remaining rock master. Tmax is the temperature at the height of S2 reached and used as a thermal coordinates.

Does RockEval have to be accompanied by TOC analysis?

Yeah, almost always. Hydrogen Index and Oxygen Index are calculated by sharing S2 and S3 against TOC.

How many Tmax indicate the rocks are ripe?

In general, Tmax below 435 ° C indicates uncooked rock, 435-470 ° C is in the oil-forming window, and above 470 ° C is already entering the gas phase. This value should be confirmed with vitrinite reflection.

Espiralié, J. dkk. Méthode rapide de caractérisation des roches mères. Revue de I'IFP 32. · Peters, K.E. & Cassa, M.R. (1994). Applied Source Rock Geochemistry. AAPG Memoir 60.