Fluid escape pipe formation in the Levant Basin

This project includes a study of the numerous FEPs that are widespread in the Levant Basin as it offers an excellent natural dataset for analyzing the formation of FEPs. The basin stratigraphy consists of a c. 2 km
thick sheet of impermeable rock salt that overlies a c. 3 km thick succession of mudstone and sandstone layers (Cartwright et al., 2020). Sandstone units form the gas-hosting reservoirs which are vertically sealed
by mudstone and salt. Levant FEPs vent gas from these sandstones (Oppo et al., 2020) and so penetrate through kilometers of impermeable mudstone and salt. In the north-eastern margin of the basin, 3D
seismic data reveals that pipes have been forming from 12 fixed positions over the past two million years. However, due to the westward flow of viscous salt, existing conduits are deformed and shifted, such that
a new vertical pipe must form for each event every c. 10 kyr. The end result is 12 trails of pipes recording each event through geologic time since the local salt topography also enables relative dating of each event
(Oppo et al., 2020, Evans et al., 2020).

Aims & Objectives
To understand the mechanisms underlying FEP formation, I require an accurate physical model that is consistent with the available data at all spatial and temporal scales. I propose to divide the project into
three sub-projects:
1. Basin and reservoir-scale pressure evolution.
2. Mechanics of individual pipe events.
3. Coupled model for the Levant basin.
This line of enquiry naturally leads each component conceptually to the next and builds on the knowledge obtained from the previous one. The first part is concerned with the source of overpressure in the Levant
basin and how it leads to FEP formation. For example, is it NE-SW tectonic compression or marginal uplift causing overpressure and subsequent pipe formation? How is this overpressure transferred to the source
reservoir of each pipe? Is the pressure model consistent with the pipe trail data? With a broad understanding of the large-scale mechanisms, the second objective is the fracture mechanics
of pipe events. The foundational questions to be answered here include: at what pressure will a fracture initiate/heal? How do fractures propagate and interact to form a pipe? Is the role of gas (or buoyancy)
important?
Finally, with the combined knowledge from the preceding two parts, these models can be combined into a coupled model for the evolution of the Levant basin across geologic time. This will provide a refined,
cohesive and multi-scale explanation for the occurrence of fluid escape pipes in the Levant basin. As this area of research is integral to carbon dioxide storage risk assessment, this work can be useful to projects
such as the Sleipner field. Some specific questions regarding this application include: Is FEP formation likely during industrial processes and if so, what must CO2 injection operators do to avoid FEP formation? How
can we better identify and characterize existing pipes from seismic data?