Experimental Modeling of Primary Migration in a Layered, Brittle Analogue System

30 Pages Posted: 21 Apr 2022

See all articles by James Johnson

James Johnson

affiliation not provided to SSRN

Maya Kobchenko

affiliation not provided to SSRN

Andrew Johnson

affiliation not provided to SSRN

Nazmul Haque Mondol

University of Oslo - Department of Geosciences

Francois Renard

University of Oslo

Abstract

A quasi-2D Hele-Shaw cell was built to study microfracture nucleation, growth, and network formation during internal fluid production. Fluid is slowly produced into a low permeability solid, which leads to local fluid pressure increase that controls the nucleation of microfractures that grow and then connect to create flow pathways. This process occurs in various geological systems, including primary migration of hydrocarbons in source rocks, the expulsion of water during dehydration of clay-rich sediments in sedimentary basins or serpentinite rocks in subduction zones, and the transport of magmatic melts. Our system consists of a transparent, brittle gelatin material mixed with yeast and sugar. The consumption of sugar by yeast leads to CO 2 formation, resulting in microfracture nucleation and growth. We varied three parameters, (1) anisotropy (i.e., number of layers), (2) lateral sealing, and (3) rate of fluid production. We tracked fluid movement through the opening and closing of microfractures within the system. Microfracture nucleation density is similar in a layered system to previous studies (0.45 microfracture per cm 2 ). However, we observed that lateral confinement (0.31 microfracture per cm 2 ) and rate of expulsion (0.99 microfracture per cm 2 ) affect nucleation density and the geometrical characteristics of the microfracture network. The size, extent, and geometry of the microfracture network are dependent on all three parameters investigated, where lateral confinement and a higher rate of expulsion result in greater microfracture network connectivity. Layers control the angle of intersection between microfractures. Furthermore, layering and sealing have an impact on fracture topology. Results also show that the microfracture pattern significantly influences the fluid expulsion rate. Our results have direct applications to understanding how fluid migration occurs in low-permeability rocks through the development of a connected microfracture network produced by internal fluid generation.

Keywords: Primary migrationMicrofracturesFluid expulsionOrganic-rich shaleRock analogue

Suggested Citation

Johnson, James and Kobchenko, Maya and Johnson, Andrew and Mondol, Nazmul Haque and Renard, Francois, Experimental Modeling of Primary Migration in a Layered, Brittle Analogue System. Available at SSRN: https://ssrn.com/abstract=4089599 or http://dx.doi.org/10.2139/ssrn.4089599

James Johnson (Contact Author)

affiliation not provided to SSRN ( email )

No Address Available

Maya Kobchenko

affiliation not provided to SSRN ( email )

No Address Available

Andrew Johnson

affiliation not provided to SSRN ( email )

No Address Available

Nazmul Haque Mondol

University of Oslo - Department of Geosciences ( email )

P.O. Box 1047
Oslo, 0316
Norway

Francois Renard

University of Oslo ( email )

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