TOC can be one of the main key indicators when looking at oil and gas plays especially in shale, at Chemostrat we offer TOC analysis using the best sample preparation methods and instrumentation. The key to good TOC analysis is sample preparation and especially the de-carbonation process, without this TOC can vary widely.
Rock Eval pyrolysis
Rock Eval pyrolysis, which is traditionally used to identify the type and maturity of organic matter and to detect petroleum potential in sediments, i.e. source rocks, is now routinely determined on shale resource plays.
The four basic parameters obtained by pyrolysis are:
- S1 = the amount of free hydrocarbons (gas and oil) in the sample.
- S2 = the amount of hydrocarbons generated through thermal cracking of nonvolatile organic matter.
- S3 = the amount of CO2 (in milligrams CO2 per gram of rock) produced during pyrolysis of kerogen.
- Tmax = the temperature at which the maximum release of hydrocarbons from cracking of kerogen occurs during pyrolysis (top of S2 peak).
From these parameters the following variables are calculated:
- HI = hydrogen index (HI = [100 x S2]/TOC).
- OI = oxygen index (OI = [100 x S3]/TOC).
- PI = production index (PI = S1/[S1 + S2]).
- PC = pyrolyzable carbon (PC = 0.083 x [S1 + S2]).
- Maturation estimate of the organic matter.