Chromatographic Migration: A Model for Geochemical Migration from the Reservoir to the Soil

Paul B. Trost

Migration of petroleum hydrocarbons, from their reservoir source to the earth' s surface in short geologic times of tens to hundreds of years, is proposed to occur on a molecular level along mineral grain boundaries by chromatographic methods. Near vertical ascent is controlled by three vectors: (1) electrotelluric potential caused by electrotelluric currents, (2) centrifugal force and (3) capillary force.

An excellent correlation between the common laboratory techniques of chromatography and geochemical migration of petroleum hydrocarbons through the earth's crust can be demonstrated as shown below.

Paper/thin layer chromatography utilizes silica gel, clays, calcium carbonate or aluminum oxide/salt water as the solid phase for organic and inorganic transport and separation. These same minerals are commonly present in the earth's crust to act as the solid phase. Paper/thin layer chromatography utilizes acetic acid, formic acid, phenols and alcohols in water as the mobile phase (solvents) to solubilize organic mixtures. These same solvents are commonly present in petroleum reservoirs and their associated water. Paper/thin layer chromatographic separation of hydrocarbons above an oil/gas reservoir has been well documented.

Advancement and interpretation of the scientific and theoretical basis of surface geochemical exploration can be achieved based on the well known and quantifiable techniques of paper and thin layer chromatography.

Transport on a molecular basis avoids two major problems of: (1) migration by large diameter micro bubbles and (2) necessity of intersecting microfractures to achieve near vertical ascent.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995