Poroelasticity During Fluid Injection in Confined Geological Reservoirs: Incorporating Effects of Seal-Rock Stiffness

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 184-197 ◽  
Author(s):  
K. Atefi Monfared ◽  
L.. Rothenburg
Keyword(s):  
Diffusion Constant ◽  
Vertical Component ◽  
Analytical Description ◽  
Pressure Change ◽  
Fluid Injection ◽  
Winkler Model ◽  
Realistic Assessment ◽  
Strain Components ◽  
Vertical Restraint ◽  
Fully Coupled

Summary This paper presents a new poroelastic solution to describe the time-dependent response of a confined geological reservoir to fluid injection through a fully penetrating vertical well treated as a point source. Unlike previous studies, vertical-confinement effects of seal rocks are incorporated in the solution. To facilitate analytical description of a fully coupled poroelastic behavior within the reservoir, the stiffness of surrounding rocks is described by the Winkler model, simplifying the response of seal rocks in the direction perpendicular to the reservoir plane. Analytical expressions are obtained for axisymmetric stress and strain components in the reservoir and for the vertical reaction stress. The latter is essential for evaluation of integrity of seal rocks during injection. Solutions are also obtained for the magnitude and location of the maximum-induced radial displacement as a function of time during injection. The effects of poroelastic coupling are articulated through the equivalent diffusion constant of the reservoir-seal rocks system. The latter is expressed through traditional poroelastic parameters as well as the relative stiffness of reservoir and seal rocks. The Winkler modulus of seal rocks, which is involved in all analytical relationships presented in this paper, is empirically linked to elastic characteristics of surrounding strata by comparing their response with the same pressure change in the reservoir according to the ideally elastic and Winkler models. The derived solutions are compared with previous studies, and verified against fully coupled numerical simulations. A comprehensive sensitivity analysis is conducted to assess the effects of the stiffness of the confining strata on the response of a uniform reservoir to injection. The vertical component of stress and the radial and vertical displacements are found to be substantially sensitive to the magnitude of the vertical restraint. The findings note the significance of incorporating seal-rock characteristics to attain a realistic assessment of the geomechanics of injection, specifically in formations with lower elastic moduli.

scholarly journals Fully Coupled Well Models for Fluid Injection and Production

2013 ◽  
Vol 37 ◽  
pp. 3960-3970 ◽  
Author(s):  
M.D. White ◽  
D.H. Bacon ◽  
S.K. White ◽  
Z.F. Zhang
Keyword(s):  
Fluid Injection ◽  
Fully Coupled ◽  
Well Models

Terrestrial spectroscopy following the Rat Island earthquake

1966 ◽  
Vol 56 (6) ◽  
pp. 1269-1288
Author(s):  
Ali A. Nowroozi
Keyword(s):  
Cross Correlation ◽  
Vertical Component ◽  
Order Number ◽  
The Earth ◽  
Spectral Peaks ◽  
Component Strain ◽  
Strain Components ◽  
Components Analysis ◽  
Shearing Strain ◽  
Spheroidal Oscillations

Abstract Fourier analysis of the four-component strain recordings at Ogdensburg, New Jersey, after the Rat Island earthquake of February 4, 1965, has yielded spectra of the earth oscillations. Three horizontal components were used to calculate synthetic longitudinal, transverse, and shearing strain components. Analysis of the different components or their combinations yielded spectra of the torsional and spheroidal oscillations. The spectral peaks corresponding to l = 3 through l = 24 were resolved and were significantly above the 95 per cent confidence level. The novelty of this analysis is the appearance of 9 first overtones and 8 second overtones of the spheroidal oscillations from cross-correlation of two sections of the vertical component of the strain recording. The observed periods are compared to theoretical periods of four earth models: M1 of Landisman; R1 of Dorman; Jeffreys-Bullen B; and Gutenberg-Bullen A. The M1 and R1 models gave the most satisfactory agreement with the observations of the fundamental modes, whereas the Jeffreys-Bullen B model had a better agreement with the observations of the overtones than other models considered. Assuming the azimuthal order number, m, of the source as a combination of m = 0, m = 1, and m = 2, the variations of the spectral amplitudes at Ogdensburg indicated that the main contributing component of the azimuthal order number of the source was not only zero, but it was 1 for the modes corresponding to l = 2,4,7,9,12, and 2 for the modes corresponding to l = 3, 5,6,8,10, and 13.

scholarly journals On the effective stress law for rock-on-rock frictional sliding, and fault slip triggered by means of fluid injection

2017 ◽  
Vol 375 (2103) ◽  
pp. 20160001 ◽  
Author(s):  
Ernest Rutter ◽  
Abigail Hackston
Keyword(s):  
Effective Stress ◽  
Fault Plane ◽  
Fluid Pressure ◽  
Pressure Change ◽  
Fault Slip ◽  
Fluid Injection ◽  
Rock Matrix ◽  
Seismogenic Fault ◽  
Planar Surfaces ◽  
Seismic Moment Release

Fluid injection into rocks is increasingly used for energy extraction and for fluid wastes disposal, and can trigger/induce small- to medium-scale seismicity. Fluctuations in pore fluid pressure may also be associated with natural seismicity. The energy release in anthropogenically induced seismicity is sensitive to amount and pressure of fluid injected, through the way that seismic moment release is related to slipped area, and is strongly affected by the hydraulic conductance of the faulted rock mass. Bearing in mind the scaling issues that apply, fluid injection-driven fault motion can be studied on laboratory-sized samples. Here, we investigate both stable and unstable induced fault slip on pre-cut planar surfaces in Darley Dale and Pennant sandstones, with or without granular gouge. They display contrasting permeabilities, differing by a factor of 10 5 , but mineralogies are broadly comparable. In permeable Darley Dale sandstone, fluid can access the fault plane through the rock matrix and the effective stress law is followed closely. Pore pressure change shifts the whole Mohr circle laterally. In tight Pennant sandstone, fluid only injects into the fault plane itself; stress state in the rock matrix is unaffected. Sudden access by overpressured fluid to the fault plane via hydrofracture causes seismogenic fault slips. This article is part of the themed issue ‘Faulting, friction and weakening: from slow to fast motion’.

scholarly journals Numerical simulation of fluid injection in faulted and fractured rocks based on a fully-coupled hydro-mechanical model

2021 ◽  
Author(s):  
Lei Qinghua ◽  
Chin-Fu Tsang
Keyword(s):  
Fractured Rocks ◽  
Network Connectivity ◽  
Fracture Network ◽  
Elastic Response ◽  
Fluid Injection ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Stress Dependent ◽  
Strong Control ◽  
Fully Coupled

<p>We present a fully-coupled hydro-mechanical simulation of fluid injection-induced activation of pre-existing discontinuities, propagation of new damages, development of seismic activities, and alteration of network connectivity in naturally faulted and fractured rocks, which are represented using the discrete fracture network approach. We use the finite element method to compute the multiphysical fields including stress, strain, damage, displacement, and pressure by solving governing and constitutive equations of coupled solid and fluid domains. Essential hydro-mechanical coupling mechanisms are honoured such as pore pressure-induced shear slip of natural discontinuities, poro-elastic response of rock matrix, and stress-dependent permeability/storativity of both fractures and rocks. We use the numerical model developed to investigate the hydro-mechanical behaviour of deeply buried fractured rocks and fault zones in response to high-pressure fluid injection, with a specific focus on the system either below or above the percolation threshold. We observe a strong control of fracture network connectivity on the damage emergence, seismicity occurrence and connectivity change in the rock mass subject to hydraulic stimulation. We highlight the strong poro-elastic effect that tends to drive heterogeneous connectivity evolution of fracture systems during fluid injection. The results of our research and insights obtained have important implications for injection-related geoengineering activities such as the development of enhanced geothermal systems and extraction of hydrocarbon resources.</p>

Quantitative Analysis Of X-Ray Images From Geological Materials

1990 ◽  
Vol 48 (2) ◽  
pp. 244-245
Author(s):  
J. M. Paque ◽  
R. Browning ◽  
P. L. King ◽  
P. Pianetta
Keyword(s):  
Quantitative Analysis ◽  
Bulk Composition ◽  
Principal Component ◽  
Analytical Description ◽  
Bulk Sample ◽  
Geological Samples ◽  
X Ray ◽  
Software And Hardware ◽  
And Storage ◽  
Insight Into

Geological samples typically contain many minerals (phases) with multiple element compositions. A complete analytical description should give the number of phases present, the volume occupied by each phase in the bulk sample, the average and range of composition of each phase, and the bulk composition of the sample. A practical approach to providing such a complete description is from quantitative analysis of multi-elemental x-ray images.With the advances in recent years in the speed and storage capabilities of laboratory computers, large quantities of data can be efficiently manipulated. Commercial software and hardware presently available allow simultaneous collection of multiple x-ray images from a sample (up to 16 for the Kevex Delta system). Thus, high resolution x-ray images of the majority of the detectable elements in a sample can be collected. The use of statistical techniques, including principal component analysis (PCA), can provide insight into mineral phase composition and the distribution of minerals within a sample.

Heart Rate Signal Decomposition

2000 ◽  
Vol 39 (02) ◽  
pp. 200-203
Author(s):  
H. Mizuta ◽  
K. Yana
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressure Change ◽  
Normal Subjects ◽  
Signal Decomposition ◽  
Large Individual ◽  
Heart Rate Fluctuations ◽  
Type Pattern ◽  
Signal Cancellation ◽  
Pressure Changes

Abstract:This paper proposes a method for decomposing heart rate fluctuations into background, respiratory and blood pressure oriented fluctuations. A signal cancellation scheme using the adaptive RLS algorithm has been introduced for canceling respiration and blood pressure oriented changes in the heart rate fluctuations. The computer simulation confirmed the validity of the proposed method. Then, heart rate fluctuations, instantaneous lung volume and blood pressure changes are simultaneously recorded from eight normal subjects aged 20-24 years. It was shown that after signal decomposition, the power spectrum of the heart rate showed a consistent monotonic 1/fa type pattern. The proposed method enables a clear interpretation of heart rate spectrum removing uncertain large individual variations due to the respiration and blood pressure change.

Stress Analysis of Tire Sections

1996 ◽  
Vol 24 (4) ◽  
pp. 349-366 ◽  
Author(s):  
T-M. Wang ◽  
I. M. Daniel ◽  
K. Huang
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Stress Analysis ◽  
Strain Analysis ◽  
Experimental Stress ◽  
Inflation Pressure ◽  
Substantial Agreement ◽  
Finite Element Stress Analysis ◽  
Strain Components ◽  
Fringe Patterns

Abstract An experimental stress-strain analysis by means of the Moiré method was conducted in the area of the tread and belt regions of tire sections. A special loading fixture was designed to support the tire section and load it in a manner simulating service loading and allowing for Moiré measurements. The specimen was loaded by imposing a uniform fixed deflection on the tread surface and increasing the internal pressure in steps. Moiré fringe patterns were recorded and analyzed to obtain strain components at various locations of interest. Maximum strains in the range of 1–7% were determined for an effective inflation pressure of 690 kPa (100 psi). These results were in substantial agreement with results obtained by a finite element stress analysis.

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