Guidelines for type II-S kerogens in basin modeling: Organic sulfur content of kerogens and crude oils

Conference · Wed Sep 01 00:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6917858

Orr, W L ^[1]; McCulloh, T H ^[2]

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1. Mobil Exploration and Production Technical Center, Dallas, TX (United States)
2. Mobil Exploration and Production Services, Dallas, TX (United States)

Kerogens rich in organically bound sulfur (type II-S or high sulfur) generate oil at lower thermal exposure than more familiar type II kerogens. Initial oils have high sulfur content (3-6 wt. %), low API gravities (10-20[degrees] API), and are expelled at low kerogen maturities (R[sub o] [approximately] 0.3-0.4). Oil quality improves significantly as kerogen maturity increases such that oils from the two kerogen types are virtually indistiguishable when oil gravity exceeds about 35[degrees] API. Different kinetic parameters characterize oil generation from type II and type II-S kerogens. Depending on which kinetic model is selected, results of quantitative basin modeling are very different, especially in timing of oil generation and significant expulsion. Geochemical criteria for selecting between type II and type II-S kerogens for basin modeling are (a) the atomic S[sub org]/C ratio of the source kerogen; (b) the atomic S[sub org]/C ratio of the asphaltene fraction of oils, oil-stained rocks, and tar seeps; and (c) the relationship between %S and API gravity for crude oils. Geological criteria for predicting which kerogen type(s) may be influential in a particular depocenter can result from thoughtful analysis of the depositional environment and lithology of the known or presumed source rock. Dysoxic or anoxic bottom waters beneath highly productive near-surface waters, and environments with limited terrigenous sediment input, are the favored settings for formation of type II-S kerogens. Worldwide, the occurrence of high-sulfur kerogen should be considered wherever potential source rocks are in thick carbonate, marl, diatomaceous, or evaporitic sequences. A global survey suggests that major fraction of the world's crudes originated from high-sulfur kerogens.

• OSTI ID: 6917858
• Report Number(s): CONF-9310237-; CODEN: AABUD2
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:9; Conference: American Association of Petroleum Geologists (AAPG) mid-continent section meeting, Amarillo, TX (United States), 10-12 Oct 1993; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
KEROGEN
MATURATION
SULFUR CONTENT
PETROLEUM
QUALITATIVE CHEMICAL ANALYSIS
SEDIMENTARY BASINS
GEOLOGIC MODELS
API GRAVITY
GEOCHEMISTRY
LITHOLOGY
SEEPS
SOURCE ROCKS
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMICAL ANALYSIS
CHEMISTRY
DENSITY
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC STRUCTURES
GEOLOGY
MATERIALS
MATTER
ORGANIC MATTER
PETROLOGY
PHYSICAL PROPERTIES
020200* - Petroleum- Reserves
Geology
& Exploration