Proper characterization of the mechanical and flow properties of participating rock formations is crucial for subsurface geo-energy projects, including hydrocarbon extraction, geologic carbon storage, and enhanced geothermal systems. Application of mechanical and hydraulic pressures changes the porosity of rock and modifies flow paths. For low-permeable or “tight” rock that mainly contains nanoscale pores and serves as the confining layer for underground storage operations, a significant change in permeability may occur due to a small change in porosity. The pore volume changes in nanoporous geomaterials are extremely difficult to measure directly, but can be assessed from the knowledge of the hydro-mechanical response. Experimental methods to measure the stress-dependent permeability and poroelastic parameters of fluid-saturated tight rock are introduced. Eau Claire shale, Opalinus clay (claystone), and Charcoal granite are selected as representative materials for tight rock and their pore structure and material properties are carefully investigated. The porosity–permeability relationship for tight rock is established by adopting a power-law dependence with the exponent value in the range of 15–17, thus being significantly larger than that for a porous reservoir rock. Consequently, even small perturbations of porosity can cause orders of magnitude changes in permeability possessing a risk on the sealing capacity of the tight formations.
#1Raphael Schulz(FAU: University of Erlangen-Nuremberg)H-Index: 5
#2Nadja Ray(FAU: University of Erlangen-Nuremberg)H-Index: 9
Last. Peter Knabner(FAU: University of Erlangen-Nuremberg)H-Index: 28
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Various processes such as heterogeneous reactions or biofilm growth alter a porous medium’s underlying geometric structure. This significantly affects its hydrodynamic parameters, in particular the medium’s effective permeability. An accurate, quantitative description of the permeability is, however, essential for predictive flow and transport modeling. Well-established relations such as the Kozeny–Carman equation or power law approaches including fitting parameters relate the porous medium’s po...
#1Faruk Civan(OU: University of Oklahoma)H-Index: 38
The stress dependency of the porosity and permeability of porous rocks is described theoretically by representing the preferential flow paths in heterogeneous porous rocks by a bundle of tortuous cylindrical elastic tubes. A Lame-type equation is applied to relate the radial displacement of the internal wall of the cylindrical elastic tubes and the porosity to the variation of the pore fluid pressure. The variation of the permeability of porous rocks by effective stress is determined by incorpor...
This work investigates the interplay of gas transport in the microcracks and matrix of shale using He and \(\hbox {CO}_2\) via transient upstream pressure-pulse-decay experiments. The microcracks are natural in the sense no laboratory pretreatment created them. A novel setup of the pressure-pulse-decay experiment was used to determine the storage and flow capacities simultaneously. Experimentally, the pressure signals are used to define time-dependent pore volume partitioning between the microcr...
Pressure decline caused by the extraction of oil from deep sedimentary layers depends on the pore modulus Kpp, a poroelastic parameter that characterizes the effect of pressure change on pore volum...
Geologic carbon storage is considered as a requisite to effectively mitigate climate change, so large amounts of carbon dioxide (CO2) are expected to be injected in sedimentary saline formations. CO2 injection leads to the creation of acidic solution when it dissolves into the resident brine, which can react with reservoir rock, especially carbonates. We numerically investigated the behavior of reservoir-caprock system where CO2 injection-induced changes in the hydraulic and geomechanical proper...
Ubiquitous observations of channelised fluid flow in the form of pipes or chimney-like features in sedimentary sequences provide strong evidence for significant transient permeability-generation in the subsurface. Understanding the mechanisms and dynamics for spontaneous flow localisation into fluid conductive chimneys is vital for natural fluid migration and anthropogenic fluid and gas operations, and in waste sequestration. Yet no model exists that can predict how, when, or where these conduit...
Velocity profiles originated by a pump as turbine (PAT) were measured using an ultrasonic doppler velocimetry (UDV). PAT behavior is influenced by the velocity data. The effect of the rotational speed and the associated flow velocity variations were investigated. This research focuses, particularly, on the velocity profiles achieved for different rotational speeds and discharge values along the impeller since that is where the available hydraulic power is transformed into the mechanical power. C...
Abstract Hydrogen is being regarded as a primary vector in the energy transition process towards a less polluted planet. The tremendous and increasing energy demands necessitate finding large-scale storage techniques. Underground salt caverns seem to be promising. Nevertheless, the fast solicitations (thermal and mechanical) of these caverns, to reply to the fast demands, imply damage to the ambient rock salt. There is a general scientific ambiguity about the transport mechanisms taking place in...