Mechanics of Secondary Hydrocarbon Migration and Entrapment

Tim T. Schowalter ²

Search and Discovery Article #40002 (1999)

² Kirkwood Oil and Gas, Casper, Wyoming 82602.

Table of Contents

ABSTRACT

INTRODUCTION

MECHANICS OF SECONDARY HYDROCARBON MIGRATION AND ENTRAPMENT

Driving Forces in Secondary Migration

Effects of Hydrodynamics on Driving Forces

Resistant Forces to Secondary Migration

Interfacial Tension

Wettability

Radius of Pore Throats

Mercury Capillary Pressure Tests

Displacement Pressures

Laboratory Tests of Displacement Pressure

Test Results

Capillary Properties of Drill Cuttings

Conversion of Mercury Data to Hydrocarbon-Water Data

Calculations of Hydrocarbon Column Heights

Sample Calculation

Seal Capacity

Quantitative Hydrocarbon Show Interpretation

MIGRATION AND ENTRAPMENT MODEL

Differential Entrapment

 

Schematic cross-sections related to migration and entrapment

Buoyant force in reservoir, static conditions (Fig. 1)

Effects of hydrodynamics on pressure-depth plot (Fig. 7)

Effects of hydrodynamics on buoyant force in oil reservoir (Fig. 8)

Distribution of fluids in reservoir, with capillary curve (Fig. 14)

Seal capacity in structure (Fig. 24)

Buoyant force in structural trap (Fig. 25)

Buoyant force in stratigraphic trap (Fig. 26)

Downdip limit of production in stratigraphic trap (Fig. 27)

Capillary properties in zoned reservoir (Fig. 29)

Downdip limit of oil accumulation from near-miss show (Fig. 30)

Shows in oil-water transition zone (Fig. 31)

Migration path (Fig. 32)

Structural differential entrapment (Fig. 34)

Stratigraphic differential entrapment (Fig. 35)

Capillary-pressure curves related to migration and entrapment

Mercury (Fig. 13)

Mercury vs. distribution of fluids in oil reservoir (Fig. 14)

Curve with plateau (Fig. 15)

Curve with no plateau (Fig. 16)

Breakthrough saturations (Fig. 17)

Interbedded sand and shale (Fig. 19)

Sandstone (Fig. 20)

Chalk (Fig. 21)

Pecos sandstone (Fig. 22)

Sandstone and clay-filled sandstone (Fig. 24)

Facies A vs. Facies B (Fig. 25)

Zoned reservoir (Fig. 26)

Nomographs related to migration and entrapment

Density of formation water (Fig. 2)

Oil Density in subsurface (Fig. 3)

Pressure/temperature vs. gas molecular weight (Fig. 4)

Compressibility vs. temperature/pressure (Fig. 5)

Reservoir density of gas condensate (Fig. 6)

Seal capacity vs. hydrodynamics (Fig. 9)

Oil-water interfacial tension vs. temperature (Fig. 11)

Methane-water interfacial tension vs. temperature/pressure (Fig. 12)

Mercury-air to hydrocarbons-water conversion (Fig. 23)

CONCLUSIONS

REFERENCES

 

Acknowledgments:

This paper is based on work done at Shell Development Research in Houston during 1972-74. I thank Shell Development Co. for permission to publish this paper. Special thanks are extended to Bob Purcell, Higby Williams, Paul Hess, and Ben Swanson for their help in formulating and carrying out the project, and to my supervisors, Larry Meckel and Garland Spaight, with credit for some of the figures to R. E. Tenny and John Howell.

Copyright 1994 American Association of Petroleum Geologists