Fractured Core Pressure-Pulse Decay

Status Start Date End Date Locations
Inactive Jun 1, 2019 May 31, 2020 Outside Indiana, Outside Indiana, state, state
Director: Mikey Hannon
Other Researchers: LaBraun Hampton
Funding: Indiana University - Innovation and Commercialization Office
Issue: Natural and drilling-induced fractures are ubiquitous among cylindrical plug samples of shale materials. While approaches exist that recognize the influence of these fractures, few commercial and research laboratories employ them. This leads to notoriously inaccurate estimates of shale permeability, a critical parameter to characterize unconventional oil & gas reservoirs. Even among procedures that recognize fractures, none treat shales as anisotropic materials, despite their permeabilities perpendicular to bedding being lower than those parallel to bedding often by an order of magnitude or more.
Objective: Using equipment to analyze pressure transients from three chambers in contact with shale specimens, this work will develop a technology that accounts for both fracture flow and shale anisotropy with suitable throughput for industrial needs. Implementing this strategy will help to optimize resource-recovery strategies from shale reservoirs, which accounts for roughly 60% (and growing) of nationwide hydrocarbon production. Efforts to this point have proven the concept only through computational analyses. This project, through a series of split-sampling comparisons, will prove it through experimental validation. Once proven, the technology will be marketed to commercial core-analysis laboratories and energy companies for licensing.
Approach: A porous cylindrical sample having known length and diameter and at least one fracture spanning its length is placed in a core holder between an inlet and outlet chamber, each having a known volume. This experimental design resembles the one described in previous works, but in this case a pressure-tap chamber is located at an intermediate location along the length of the sample. These chambers, and the pores in the sample, are initially pressurized to a uniform pressure and temperature. The test begins when the inlet pressure is rapidly increased by a set amount (typically around 5-10%). The entire system is shut in and allowed to reach an equilibrium. Based on the pressure responses in the inlet, outlet, and pressure tap, the sample properties are inferred. These properties include the matrix porosity, matrix directional permeabilities (both parallel and perpendicular to bedding), and the fracture transmissivity.
Products: Previous theoretical and numerical analyses give a promising indication that this technology can be an effective way to estimate matrix and fracture properties simultaneously by testing a fractured sample using this experimental procedure. This proposal will purchase equipment and build a facility on campus to translate the concept to reality and make experimental validations of the technique.
Benefits: Upon completion of this project, researchers at the Indiana Geological and Water Survey will have the capability to estimate fracture transmissivities and matrix directional permeabilities, and the matrix porosities from measurements performed on fractured shale samples. This concept will be proven in reality by comparison with gold-standard benchtop methods, where applicable. At this point, the technology could transfer fairly easily into a service or device that commercial entities, including core laboratories and energy companies, can license from IU and deploy at their facilities.