Transmittance color index (TCI) of amorphous organic matter: New thermal maturity indicator for hydrocarbon source rocks, correlation with mean vitrinite reflectance and thermal alteration index (TAI)

Conference · Fri Sep 01 04:00:00 EDT 1989 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:5630993

Van Gijzel, P ^[1]

---

1. PVG Microscope Technology, Inc., Houston, TX (USA)

A new thermal maturity indicator, the transmittance color index (TCI), is introduced here. The TCI eliminates most limitations of these techniques and is measured on particulate amorphous material, the most abundant type of organic matter in hydrocarbon source rocks of all geologic ages. TCI is obtained from rapid spectral screening of transmittance spectra in tungsten light and is based on the increased curving of these spectra with progressive thermal maturity. TCI shifts from 570 nm for immature material (at an {anti R}{sub 0} of about 0.20%) to about 680 nm ({anti R}{sub 0} = 2.5%) for almost-black kerogen. Thus, TCI covers all zones of thermal maturity. For the same samples, an excellent linear correlation exists between TCI and vitrinite reflectance ({anti R}{sub 0}) and the TAI. Thus, TCI measurements can be converted into equivalent reflectance values (R{sub e}) and plotted with actually measured vitrinite reflectance data in depth vs. maturity diagrams. Examples are given of wells where TCI analysis provides more accurate maturity profiles than conventional techniques do. These include cases where vitrinite is scarce, where formations are older than Upper Silurian, in faulted areas where {anti R}{sub 0} data are conflicting, or when the maturity is locally increased as a result of the occurrence of anhydrites. Although TCI needs further testing, this new technique will probably improve organic petrology.

• OSTI ID: 5630993
• Report Number(s): CONF-8910195--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 73:9
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CARBONACEOUS MATERIALS
GEOLOGIC DEPOSITS
MACERALS
MATERIALS
MATURATION
MINERAL RESOURCES
OPTICAL PROPERTIES
PETROLEUM DEPOSITS
PHYSICAL PROPERTIES
RESOURCES
SOURCE ROCKS
VITRINITE