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Collaborating Authors
Seismic processing and interpretation
Macroscopic mechanical properties of fluid-saturated sandstone at variable temperatures
Deng, Wubing (China University of Petroleum (East China), Qingdao National Laboratory for Marine Science and Technology) | Fu, Li-Yun (China University of Petroleum (East China), Qingdao National Laboratory for Marine Science and Technology) | Morozov, Igor B. (University of Saskatchewan) | Wang, Zhiwei (China University of Petroleum (East China), Qingdao National Laboratory for Marine Science and Technology)
ABSTRACT Rocks can be viewed as composites of solid minerals with pores or cracks filled with softer material such as pore fluids, kerogen, bitumen, and other organic matter. The mechanical properties of highly viscous soft phases are highly sensitive to ambient temperatures and lead to temperature-dependent static and dynamic observations with the composite rock. However, the constituents operate by forming some effective (averaged) mechanical properties of the composite rock, and yet these averaged properties are still little known. To reveal such macroscopic temperature-dependent mechanical properties and measure their values in rock samples, a double-porosity model of porous rock with nonlinear viscosity is developed. The model is based on rigorous continuum mechanics with physically meaningful, real-valued, and time- and frequency-independent material properties and elegantly unifies the existing frequency-dependent microscopic squirt flow and mesoscopic wave-induced fluid flow models. The approach is used to accurately model the broad attenuation peaks and Youngโs modulus dispersion observed in previously published laboratory experiments with glycerol-saturated Berea sandstone and invert for its mechanical properties. The observations are explained as mainly due to the temperature-dependent elastic coupling caused by non-Newtonian fluid within microcracks. Several hitherto unknown mechanical properties of the rock are constrained quantitatively: the average porosity of the microcracks, the effective high-pressure bulk modulus of the drained frame, the internal stiffness defect within the rock frame, the solid viscosities associated with bulk and shear deformations, and an exponent of nonlinearity for viscosity. These parameters constitute a Biot-consistent mechanical model of the rock, which can be used to simulate its behavior in arbitrary experimental environments. The rigorous first-principle model can be used in many applications: detailed and physically accurate interpretations of laboratory experiments, numerical wavefield simulations and seismic data inversion, reservoir characterization, geothermal exploration, thermal-enhanced oil recovery, and exploration for deep oil and gas resources in high-temperature environments.
- North America > Canada (0.46)
- North America > United States > West Virginia (0.25)
- North America > United States > Pennsylvania (0.25)
- (2 more...)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.68)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.62)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
Geophysical Research Based on the high and low frequency joint measuring Institute of Shengli Oilfield has introduced low-frequency technique, elastic parameter of sample A and B sandstone measuring equipment since 2012. Through upgrading, are measured at a wide frequency band (2-2000 Hz, 1 MHz) improving and perfecting the low-frequency measuring with different saturating fluids (water, glycerol). The equipment and redesigning the ultrasonic probe, the experimental results show that the higher mobility of technology of simultaneous measurement at high and low porous fluids will cause the frequency band of dispersion frequencies has been realized firstly in China, which occurring in higher frequency. The characteristic frequency effectively solves the problem that separate measurement at band of dispersion is positively correlated with porosity and high and low frequencies cannot guarantee the unified permeability, and negatively correlated with fluid viscosity.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.68)
- Asia > China > Shanxi > Ordos Basin > Changqing Field (0.99)
- Asia > China > Shandong > North China Basin > Shengli Field (0.99)
- Asia > China > Shaanxi > Ordos Basin > Changqing Field (0.99)
- (3 more...)
ABSTRACT The effects of pore fluid and rock structure on the seismic velocity and anisotropy of 3-D printed rock models are studied in the laboratory. We performed fluid substitution experiments on the rock models using water, oil, and glycerol. We printed two models: a solid model (6% porosity, 4% anisotropic) and a fractured model (24% porosity, 26% anisotropic) with penny-shaped horizontal inclusions. When the dry solid model was saturated with the above fluids, compressional velocity increased by 11%โ17% while the shear velocity showed a small decrease 1%โ2% in all directions. For the inclusion model, compressional velocity is increased by 19%โ56%, and the shear velocity decreased by 4%โ13% in all directions. We observed maximum variations in velocity along the symmetry axis which is perpendicular to the orientation of inclusions and the bedding plane. The P-wave anisotropy was reduced significantly (to about 1% for both solid and inclusion model) making both models more isotropic when saturated with glycerol. Using both velocity and anisotropy, we are assisted in distinguishing models saturated with extra heavy oil from water or light oil. Presentation Date: Tuesday, October 16, 2018 Start Time: 1:50:00 PM Location: Poster Station 18 Presentation Type: Poster
Summary Knowledge of dispersion and attenuation in sedimentary rocks is important for understanding variations in seismic properties of reservoirs. These variations are often related to the presence of fluids in the pore space of rocks. In most sedimentary rocks saturated with fluid characterized by low mobility, which can stem either from low intrinsic permeability or from high fluid viscosity, relative motion between pore fluid and a rock skeleton makes a significant impact on acoustic wave attenuation and dispersion of the elastic moduli of rocks at seismic frequencies. But our current understanding of seismic velocity dispersion and attenuation in saturated rocks is limited due to a lack of laboratory data obtained at seismic frequencies. We present the results of the laboratory measurements of elastic and anelastic parameters of dry and glycerol saturated Berea sandstone (71 mD permeability, 19 % porosity) conducted at seismic frequencies. The experiments were performed with a low-frequency laboratory apparatus designed to measure the complex Youngโs moduli and extensional attenuation of rocks at seismic frequencies. The apparatus operates at confining pressures from 0 to 70 MPa and strain amplitudes from 10 to 10. The elastic moduli and extensional attenuation of dry and glycerol-saturated sandstone were measured at a differential pressure of 10 MPa at two temperatures of 23 and 31 C. Peaks of attenuation in the glycerol-saturated sample were found at frequencies of ~0.6 Hz (23C) and ~1.5 Hz (31C). Our analysis shows that the quantitative relationship between the extensional attenuation and the Youngโs modulus measured for the glycerol-saturated sandstone is consistent with the causality principle presented by the Kramers-Kronig relations. Introduction It has been demonstrated (Batzle et al., 2006), that mobility of pore fluids in rocks, which is defined as the ratio of rock permeability to fluid viscosity, ensures fluid pressure deviations amongst the pores when a seismic wave passes. As a result the seismic properties can be significantly influenced by the ability of fluid to move within the pores. For the rocks with low-mobility fluid the pore pressure can be out of equilibrium even at seismic frequencies. However, most laboratory measurements are limited to ultrasonic techniques which operate in the megahertz range. Literature on seismic-frequency laboratory measurements of the acoustic properties of reservoir rocks saturated with fluid having low mobility is relatively sparse. Batzle et al. (2006) studied attenuation and dispersion for water-, brine- and glycerol- saturated sedimentary rocks in the frequency range of 5 Hz to 800 kHz and demonstrated that the Gassmann theory might not be always applicable to the rocks saturated with low-mobility fluids even within the seismic band. Adam and Otheim (2013) measured dry and saturated with liquid CO2 and water low-permeability basalts in the seismic (2-300 Hz) and ultrasonic (~0.8 MHz) frequency ranges at differential pressures of 3.4 to 17.2 MPa and found that the bulk moduli of saturated rocks at frequencies greater than 20 Hz are not consistent with the Gassmann theory. The measurements conducted by Mikhaltsevitch et al. (2014) on dry and water saturated low-permeability (0.7 mD and 1.1 mD) sandstones at differential pressures of 9 and 23 MPa revealed considerable extensional attenuation and dispersion of the bulk moduli in the seismic frequency range. These results demonstrate that for low-permeability rocks the low-frequency limit of acoustic wave dispersion can be below below the seismic frequency range and the Gassmann theory cannot be applied at seismic frequencies.
- North America > United States > West Virginia (0.63)
- North America > United States > Pennsylvania (0.63)
- North America > United States > Ohio (0.63)
- North America > United States > Kentucky (0.63)
ABSTRACT Using two methods, we obtained measurements of elastic moduli for Berea sandstone at exploration seismic frequencies under dry, full, and partial saturation conditions. We refer to one method as indirect, since lower (0.008 โ 0.8 Hz) than seismic frequencies are used, but by controlling fluid (glycerol) viscosity with temperature, the results can be scaled up to higher frequencies (0.1 โ 1000 Hz). The second method involves measuring brine saturated core samples directly at seismic frequencies (5โ50 Hz). The results between the two methods compare well, which validates the indirect methodology and gives more confidence overall to both results. These measurements are of value due to recent interest in the oil industry in low frequency velocity dispersion as a gas indicator. Such measurements, of which relatively few are done at seismic frequencies, can help constrain theoretical models.
- Asia > Middle East (0.29)
- North America > United States > West Virginia (0.25)
- North America > United States > Pennsylvania (0.25)
- (2 more...)
- Geology > Geological Subdiscipline > Geomechanics (0.70)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.62)
ABSTRACT Most thermal heavy oil recovery methods entails changes of pore fluid, pressure and temperature which in turn induce complex changes in the elastic properties of reservoirs that are in general unconsolidated or weakly consolidated porous rocks. In this paper, laboratory measurements of velocities and attenuations under different conditions of temperature and stress were performed on samples of a weakly consolidated reconstituted sandstone saturated with various fluids (air, water and glycerol). The sample investigated is representative of weakly cemented sandstone reservoirs with high porosity and permeability. The experimental results demonstrate the strong impact of the nature of the pore fluid on the compressional and shear wave velocities and attenuations. The influence of temperature and stress are discussed, together with the wave dispersion mechanisms. 1. INTRODUCTION Seismic techniques such as 2D or 3D seismic reflection surveying, sonic well-logging, vertical seismic profiling (VSP), among others, are used in petroleum industry both for reservoir characterization and for production monitoring. The seismic parameters of interest are the intrinsic velocities and attenuations. Many studies have been conducted on changes in wave velocities associated with oil production [1, 2, 3, 4]. The experimental determination of attenuation is more difficult than the measurement of velocities [5, 6], resulting in a very limited amount of available data in this area. Moreover, there is a need of laboratory measurements of the wave velocities and attenuations under various conditions of temperature, pore pressure and fluid saturation so as to determine the changes in rock properties resulting from oil production. The purpose of this paper is to present some data on the dependency of both P-wave and S-wave velocities and attenuations on the pore fluid, the stress and temperature in poorly cemented porous sandstone. To do so, ultrasonic measurements have been carried out. The important effects of the pore fluid viscosity in glycerol-saturated samples and some dispersion mechanisms are discussed. 2. MATERIAL DESCRIPTIONS Cylindrical reconstituted samples are prepared from Fontainebleau sand, composed of mono-crystalline quartz sub-spherical grains [7]. This sand is moderately well sorted with a mean grain size of 250 micrometers (coarse grain). In order to reconstitute the sample, sand is poured into a stainless steel mould and a silicate solution is then circulated through the specimen, precipitating silica at the contacts between grains. After several circulations and oven-drying, the samples exhibit a weak cementation. Samples have a porosity from 37 % to 40 % (deduced from the results of Tomography scanner, Micro Tomography scanner, Purcell tests and from weight measurements) and a high permeability of about 3 to 4.10 mยฒ (3 to 4 D). The Micro Tomography scanner image of the reconstituted sample (Fig. 1) exhibits a poorly consolidated nature. Several clusters of particles are observed, as results of artificial cementation processes. The grains (in white color) are highly angular. In brief, this reconstituted sandstone can be considered as a representative model of sandstone reservoirs with weakly cemented, porous and highly permeable nature. Two types of fluids were used to saturate the samples: water and glycerol.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
Effect of Temperature On Ultrasonic Velocities of Unconsolidated Sandstones Reservoirs During the SAGD Recovery Process
Doan, D.H. (Institut Francais du Petrole) | Nauroy, J.F. (Institut Francais du Petrole, ) | Baroni, A. (Institut Francais du Petrole) | Delage, P. (Ecole des Ponts ParisTech) | Mainguy, M. (TOTAL)
ABSTRACT: The steam assisted gravity drainage (SAGD) has been successfully used to enhance the recovery of heavy oil in Western Canada and Eastern Venezuela basins. Pressure and temperature variations during SAGD operations induce complex changes in the elastic properties of the reservoir rock. To study these changes, measurements of ultrasonic wave velocities were performed on both reconstituted samples and natural oil sands samples. Reconstituted samples were made of Fontainebleau sand with a slight cementation formed by a silicate solution. They have a high porosity (about 37 % to 40 %) and a high permeability (about 10-12 mยฒ). Natural oil sands samples are unconsolidated sandstones extracted from the fluvio-estuarine McMurray Formation in Alberta (Canada). The saturating fluids were heavy oil and glycerol with a strongly temperature dependent viscosity. Tests were carried out at different temperatures (in the range -30ยฐC and 80ยฐC) and at different effective pressures (from 1.2 MPa up to 8 MPa). Experimental results showed that the elastic wave velocities measured are strongly dependent on temperature (mainly through the viscosity) whereas little effect of effective pressure was observed. Velocities decrease with increasing temperature and increase with increasing effective pressure. These effects are mainly due to the variations of the saturating fluids properties. The experimental results were afterwards compared with the Ciz and Shapiro [1] approach, a extension of the poroelastic theory of Biot-Gassmann [2, 3], applied for rock filled with the hightly viscous fluids. 1. INTRODUCTION Vast quantities of heavy oils, estimated to 56.1011 barrels [4] are mainly trapped in unconsolidated sandstone reservoirs in Western Canada and Eastern Venezuela basins. The world's largest deposits are almost entirely located in the province of Alberta, Canada with three major oil sands deposits defined as Athabasca, Cold Lake and Peace River. The SAGD technique combined with horizontal wells has been developed as one of the most effective in-situ process to produce heavy oils. SAGD heats the oil and reduces its viscosity making it mobile and capable to flow towards horizontal lower well by gravity drainage. Steam injection produces changes in the reservoirs, namely changes in temperature, pressures, reservoir porosity, and pore fluid content. These changes obviously affect elastic properties of the rock layers and generate consequently differences on seismic velocities and amplitudes. 4D seismic and other seismic technology can be used to monitor the impact of the changes enumerated above. By comparing maps of seismic attributes at different times the spatial distribution of the heated reservoir zones can be approximately located. Over the past two decades, several measurements of elastic properties of unconsolidated rock reservoir have been published [5, 6, 7, 8, 9, 10, 11]. However, there is still a lack of clear understanding of the effect of the thermal process on the reservoir behavior. Measurements were carried out in natural core samples from some Canadian oil sands reservoirs and also in reconstituted samples saturated with various viscous fluids (heavy oil and glycerol) so as to investigate the effect of changes in viscosity on the elastic properties of saturated rock.
- Research Report > New Finding (0.48)
- Overview (0.34)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > Canada > Alberta > Athabasca Oil Sands > Western Canada Sedimentary Basin > Alberta Basin > McMurray Formation (0.99)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Cold Lake Oil Sands Project > Clearwater Formation (0.98)
- North America > Trinidad and Tobago > North Atlantic Ocean > Eastern Venezuela Basin (0.94)
- (4 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Thermal methods (1.00)
Measurements of shear wave velocity and attenuation as a function of temperature were made in the kilohertz frequency range in sandstones saturated with various liquids. For sandstones partially saturated with glycerol, two attenuation peaks are observed between 80C and 100C; they are attributed to viscous shear relaxation and squirt flow. For fully watersaturated Berea sandstone, the attenuation decreases as the crack density increases. The displacement of the squirt peak, caused by the increase of the central aspect ratio of cracks, is at the origin of this decrease. A simple viscoelastic model, based on the model of OConnell and Budiansky using a ColeCole distribution of cracks, is proposed for calculation of the shear modulus of fluidsaturated rocks. This model interprets the experimental data satisfactorily. The data suggest that the shear attenuation and velocity are controlled by the distribution of crack aspect ratios.
- North America > United States > West Virginia (0.24)
- North America > United States > Pennsylvania (0.24)
- North America > United States > Ohio (0.24)
- North America > United States > Kentucky (0.24)
- Geophysics > Borehole Geophysics (1.00)
- Geophysics > Seismic Surveying > Seismic Processing (0.50)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.36)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (0.88)
Access to, understanding, Introduction and incorporation of the downhole data will provide the A systematic laboratory study was undertaken to evaluate spatially continuous attribute set required to describe the the potential for using seismic imaging to map thermal EOR reservoir and drive the simulation modelat the appropriate fronts in sandstones and in unconsolidated sand reservoirs. This integration must come The study was prompted in part by known effects of steam or hand in hand with closer interdisciplinary communication if gas on wave propagation in consolidated and unconsolidated the geophysicist is to address directly the problems currently rocks, in part by Conoco's successful use of seismic reflection facing the engineer. The geophysicist must clearly understand to image the steam flood at the Street Ranch pilot the requirements of the production department and project (Britton et al., 1982) and in part by anticipated, but provide input as a set of meaningful physical parameters. This paper summarizes results of a series of experiments The 3-D seismic method has emerged as a potentially dealing with the effect of elevated overburden pressure, pore valuable tool in improving the information available to the pressure, temperature, and oil/brine ratio on sonic resonance petroleum engineer. Reservoir samples stratigraphic contexts was presented for different stages in studies include heavy-oil and tar sands from Kern River, the production cycle.
- Geology > Geological Subdiscipline (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.92)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.59)
- Geophysics > Time-Lapse Surveying > Time-Lapse Seismic Surveying (0.40)
- Geophysics > Seismic Surveying > Seismic Processing (0.35)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)