--> Temporal evolution of reservoir permeability in fault damage zones: An experimental approach

AAPG Foundation 2019 Grants-in-Aid Projects

Datapages, Inc.Print this page

Temporal evolution of reservoir permeability in fault damage zones: An experimental approach

Abstract

I aim to characterize time dependent mechanical healing of fault damage zone materials to study the temporal evolution of fracture permeability after fault reactivation and its impacts on reservoir productivity. In this study, I will conduct viscoelastic creep experiments on rocks collected at different distances from the fault core to study how creep can cause production decline. The Chelungpu fault system is ideal to study such spatiotemporal evolution of crustal permeability, not only because Taiwan Chelungpu-fault Drilling Project (TCDP) acquired good quality continuous cores, but also because the predominant lithology in the area comprises of sandstone and shale, which are most frequently encountered in unconventional reservoirs. Additionally, TCDP boreholes encounter three large reverse faults at different stages of the seismic cycle and its damage zones, providing a wide spectrum of damage zone materials in discrete phases of formation and healing. To overcome the challenge of preparing perfectly flat parallel cylindrical specimens out of damage zone rocks, I will design a new platen to test TCDP core samples in its indigenous form. Moreover, I will conduct Micro Computed Tomography and Scanning Electron Microscopy of the samples before and after the experiments to investigate healing. I have budgeted (in the proposal) P and S wave transducers to continuously monitor fracture evolution because a strong recovery in elastic wave velocity acts as a proxy of fracture recovery. Damage induced elastic anisotropy during interseismic tectonic loading and coseismic slip heals after earthquakes (Passelegue et al. 2018). Therefore, even if damage zones are regions of high permeability (Hennings et al. 2012), characterizing healing is essential to study long term well performance.