How to share underground reservoirs

TL;DR

This paper explores how to effectively share underground reservoirs by analyzing the fractal geometry of boundary lines formed during simultaneous fluid invasion, revealing complex structures and critical phenomena.

Contribution

It introduces a novel geometric framework for understanding resource sharing in porous media through fractal boundary analysis and critical point characterization.

Findings

The boundary lines form a fractal set with a dimension of approximately 1.69.

The spanning thread has a fractal dimension of about 1.55.

Loop size distribution follows a power law, indicating scale invariance.

Abstract

Many resources, such as oil, gas, or water, are extracted from porous soils and their exploration is often shared among different companies or nations. We show that the effective shares can be obtained by invading the porous medium simultaneously with various fluids. Partitioning a volume in two parts requires one division surface while the simultaneous boundary between three parts consists of lines. We identify and characterize these lines, showing that they form a fractal set consisting of a single thread spanning the medium and a surrounding cloud of loops. While the spanning thread has fractal dimension ${1.55\pm0.03}$, the set of all lines has dimension ${1.69\pm0.02}$. The size distribution of the loops follows a power law and the evolution of the set of lines exhibits a tricritical point described by a crossover with a negative dimension at criticality.