Role of diffusion in primary migration of hydrocarbons

Journal Article · Thu Apr 01 04:00:00 EST 1982 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:5568333

Leythaeuser, D; Schaefer, R G; Yukler, A

The following effective diffusion coefficients D(cm/sup 2//sec) were determined for the diffusion of light hydrocarbons through the water-saturated pore space of shales: methane (2.12 x 10/sup -6/), ethane (1.11 x 10/sup -6/), propane (5.55 x 10/sup -7/), iso-butane (3.75 x 10/sup -7/), n-butane (3.01 x 10/sup -7/), n-pentane (1.57 x 10/sup -7/), n-hexane (8.20 x 10/sup -8/), n-heptane (4.31 x 10/sup -8/), and n-decane (6.08 x 10/sup -9/). On the basis of these new data, a deterministic, dynamic model was set up to simulate the diffusive transport of light hydrocarbons (C/sub 1/ to C/sub 10/) from source rocks. For eight documented source-rock units, representing a wide range of geologic conditions (maturities of 0.40 to 1.35% mean vitrinite reflectance; oil- to gas-prone kerogens), the cumulative amounts of hydrocarbons escaping with time were calculated. The origin of hydrocarbon accumulations with high gas-to-oil ratios in low-mature sediments in geologically young basins (early gases and condensates) can be explained by a early phase of primary migration predominantly based on diffusion. Compositional trends among reservoir gases of several multiple-pay gas fields in Louisiana represent evidence for diffusive transport of hydrocarbons. Diffusion of light hydrocarbons in the subsurface can also have economically adverse effects. Large gas accumulations can persist through extended periods of geological time only as dynamic systems reaching some kind of steady-state equilibrium between diffusive loss through the cap rock and continuous replenishment from the source rock. 15 figures, 2 tables.

• Research Organization: Inst. for Petroleum and Organic Geochemistry, Juelich, Germany
• OSTI ID: 5568333
• Journal Information: Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 66:4; ISSN AAPGB
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030300* -- Natural Gas-- Drilling
Production
& Processing
ALKANES
BUTANE
DECANE
DIFFUSION
ECONOMICS
ENGINEERING
ETHANE
FEDERAL REGION VI
GEOLOGIC DEPOSITS
GEOLOGY
HEPTANE
HEXANE
HYDROCARBONS
LOUISIANA
METHANE
MIGRATION
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NATURAL GAS FIELDS
NORTH AMERICA
ORGANIC COMPOUNDS
PENTANE
PETROLEUM GEOLOGY
POROSITY
RESERVOIR ENGINEERING
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
USA