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...
Last. Yves Guéguen(PSL Research University)H-Index: 55
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Over the last decades, a large understanding has been gained on the elastic properties of rocks. Rocks are, however, porous materials, which properties depend on both response of the bulk material and of the pores. Because in that case both the applied external pressure and the fluid pressure play a role, different poroelasticity coefficients exist. While theoretical relations exist, measuring precisely those different coefficients remains an experimental challenge. Accounting for the different ...
In situ rock is often saturated with fluid, the presence of which affects both elastic parameters and inelastic deformation processes. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained (long-term), undrained (short-term) and unjacketed (solid matrix) response in hydrostatic, axisymmetric and plane-strain compression. Drained and undrained poroelastic parameters, including bulk modulus, Biot and Skempton coefficients, of Berea sandstone wer...
Abstract Experimental measurements to derive the drained bulk C and the solid bulk C s u compressibility, the poroelastic Biot coefficient α , Skempton coefficient B as well as porosity ϕ were performed under drained, undrained and unjacketed pore pressure conditions. The experiments were conducted for two different kinds of sandstones, Bentheimer and Flechtinger. During all experiments, the confining hydrostatic pressure was continuously increased up to 85 MPa. To measure the undrained pore pre...
#2Herbert F. Wang(UW: University of Wisconsin-Madison)H-Index: 33
Gassmann’s original equation provides a means to relate bulk elastic parameters of a porous material with the compressibility of the pore fluid. The original analysis assumed microhomogeneity and isotropy, which assumed that pore compressibility was equal to grain compressibility. Although subsequent theoretical arguments have shown that Gassmann’s original assumption is violated for most rocks and that pore compressibility need not equal grain compressibility, few experimental studies have comp...
#2Jean Sulem(ENPC: École des ponts ParisTech)H-Index: 34
Abstract For evaluation of the undrained thermo-poro-elastic properties of saturated porous materials in conventional triaxial cells, it is important to take into account the effect of the dead volume of the drainage system. The compressibility and the thermal expansion of the drainage system, along with the dead volume of the fluid filling this system, influence the measured pore pressure and volumetric strain during an undrained thermal or mechanical loading in a triaxial cell. The correction ...
#2Jean Sulem(ENPC: École des ponts ParisTech)H-Index: 34
Temperature increase in saturated porous materials under undrained conditions leads to thermal pressurization of the pore fluid due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. This increase in the pore fluid pressure induces a reduction of the effective mean stress and can lead to shear failure or hydraulic fracturing. The equations governing the phenomenon of thermal pressurization are presented and this phenomenon is studied experime...
The poromechanical behaviour of hardened cement paste under isotropic loading is studied on the basis of an experimental testing program of drained, undrained and unjacketed compression tests. The macroscopic behaviour of the material is described in the framework of the mechanics of porous media. The poroelastic parameters of the material are determined and the effect of stress and pore pressure on them is evaluated. Appropriate effective stress laws which control the evolution of total volume,...
The complete determination of soil water retention curve requires the sample volume to be measured, in order to calculate its void ratio and saturation degree. During drying in the pressure plate apparatus, cracks often appear in the sample altering its deformation and evaporation patterns. Consequently, this causes a significant scatter in the volume measurement when using volume displacement method. This paper proposes a simple method to avoid cracking, by limiting friction and adhesion bounda...
#1James G. Berryman(LLNL: Lawrence Livermore National Laboratory)H-Index: 65
#2Herbert F. Wang(UW: University of Wisconsin-Madison)H-Index: 33
Abstract To account for large-volume low-permeability storage porosity and low-volume high-permeability fracture/crack porosity in oil and gas reservoirs, phenomenological equations for the poroelastic behavior of a double porosity medium have been formulated and the coefficients in these linear equations identified. This generalization from a single porosity model increases the number of independent inertial coefficients from three to six, the number of independent drag coefficients from three ...
Abstract Biot and Willis (1957) performed micromechanical analysis on isotropic poroelastic materials and presented three material constants, the jacketed compressibility, the unjacketed compressibility, and the coefficient of fluid content, to characterize the volumetric deformation. Brown and Korringa (1975) and Rice and Cleary (1976) recast them into a drained bulk modulus K , an unjacketed bulk modulus K s ′ , and an unjacketed pore modulus K s ′ ′ . The constant K s ′ ′ is tied to the stora...
This contribution addresses an experimental study on the poroelastic behavior of a water-saturated limestone. Samples come from Sarvak limestone, a major hydrocarbon-producing reservoir in Iran. Three back-saturated intact specimens were subjected to hydrostatic compression with different boundary pressure conditions. A coherent workflow from testing to data interpretation was established to efficiently deal with possible sources of uncertainty and provide accurate results. Obtained results reve...
Last. Georg Dresen(University of Potsdam)H-Index: 55
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Knowledge of pressure-dependent static and dynamic moduli of porous reservoir rocks is of key importance for evaluating geological setting of a reservoir in geo-energy applications. We examined experimentally the evolution of static and dynamic bulk moduli for porous Bentheim sandstone with increasing confining pressure up to about 190 MPa under dry and water-saturated conditions. The static bulk moduli (Ks) were estimated from stress–volumetric strain curves while dynamic bulk moduli (Kd) were ...
#1Kiseok Kim(UIUC: University of Illinois at Urbana–Champaign)H-Index: 3
#2Roman Y. Makhnenko(UIUC: University of Illinois at Urbana–Champaign)H-Index: 12
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 ...
Abstract Theories of isotropic consolidation for geomaterials with compressible phases require two loading tests: a full-drainage test at constant pore-pressure and a mixture test in which pore-pressure varies. In a no-drainage mixture test, the pore-pressure change falls short of the confining pressure change. In the unjacketed mixture test, the pore-pressure and confining pressure rates are equal. This paper develops a parametric theory that supports extrapolation of unjacketed bulk compressib...
This paper derives an expression for pore pressure coefficient $B in terms of a geomaterial’s mesoscopic properties and jacketed and unjacketed macroscopic compressibilities. The mesoscopic properties include phase compressibilities and pressure distribution ratios. The pressure distribution ratios represent the geomaterial’s meso-heterogeneity, while the difference between the unjacketed bulk compressibility and the solid grain compressibility represents macroscopic effects, such as solid gr...
Last. Joseph F. Labuz(UMN: University of Minnesota)H-Index: 32
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A true triaxial apparatus was designed and fabricated to achieve multi-axial stress states with prismatic specimens. The device, which is a modification of the University of Minnesota plane-strain apparatus, is equipped with piston assemblies that generate the intermediate principal stress. A closed-loop, servo-hydraulic load frame is used to control the major principal stress, while the minor principal stress is developed by fluid pressure. A stress path was developed to perform experiments und...
#1Gang Lei(UPM: King Fahd University of Petroleum and Minerals)H-Index: 11
#2Nai Cao(China University of Petroleum)H-Index: 3
Last. Weiqing Chen(UPM: King Fahd University of Petroleum and Minerals)H-Index: 7
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Over the past decades, many scholars have been studying the pore volume compressibility (PVC) of porous media. However, the fundamental controls on PVC of porous media are not yet definitive. Some scholars suggest a negative correlation between PVC and initial porosity, while others suggest a positive correlation. Motivated by this discrepancy, this paper presents a new analytical model to study the PVC of fractal porous media. The predictions are compared with test results and thereby validated...