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C. H. Cheng - One of the best experts on this subject based on the ideXlab platform.
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ACOUSTIC WAVEFORM LOGGING- ADVANCES IN THEORY AND APPLICATION
2016Co-Authors: F L. Paiilet, C. H. Cheng, W. D. PenningtonAbstract:Full-waveform acoustic logging has made significant advances in both theory and applic cation in recent years, and these advances have greatly increased the capability of log analysts to measure the physical properties of Formations. Advances in theory provide the analytical tools required to understand the properties of measured seismic waves, and to relate those properties to such quantities as shear and compressional velocity and attenuation, and primary and fracture porosity and Permeability of potential reservoir rocks. The theory demonstrates that all parts of recorded waveforms are related to various modes of propagation, even in the case of dipole and quadrupole source logging. However, the theory also indicates that these mode properties can be used to design velocity and attenuation picking schemes, and shows how source frequency spectra can be selected to optimize results in specific applications. Synthetic microseismogram com-putations are an effective tool in waveform interpretation theory; they demonstrate how shear arrival picks and mode attenuation can be used to compute shear velocity and intrinsic attenuation, and Formation Permeability for monopole, dipole and quadrupole sources. Array processing of multi-receiver data offers the opportunity to apply even more sophisticated analysis techniques. Synthetic microseismogram data is used to illus-trate the application of the maximum-likelihood method, semblance cross-correlation, and Prony's method analysis techniques to determine seismic velocities and attenua-8 Paillet et al. tions. The interpretation of acoustic waveform logs is illustrated by reviews of various practical applications, including synthetic seismogram generation, lithology determina-tion, estimation of geomechanical properties in situ, Permeability estimation, and design of hydraulic fracture operations
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2016Co-Authors: Xiao Ming Tang, C. H. ChengAbstract:This paper describes a fast algorithm for estimating Formation Permeability from Stone-ley wave logs. The procedure uses a simplified Biot-Rosenbaum model formulation. The input to the inversion is the Stoneley wave spectral amplitudes at each depth and re-ceiver, the borehole fluid properties (velocity and density), the borehole caliper log, the Formation density and porosity (from log data), and the compressional and shear velocities for the interval of interest. The model uses the borehole caliper and elastic properties to compute the Stoneley wave excitation (that is, predicted amplitude with-out Permeability effects) as a function of frequency, and the porosity and Permeability to compute the fluid flow amplitude reduction. This method also uses a reference depth of known Permeability and compares amplitude variations at other depths relative to the reference depth. The Permeability value obtained from the inversion represents the best fit over all receivers and all relevant frequencies. A processing example is shown to demonstrate the ability of this technique to extract Formation Permeability from Stoneley wave logs
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STONELEY WAVE PROPAGATION IN HETEROGENEOUS PERMEABLE POROUS FormationS
2016Co-Authors: Xiaomin Zhao, M N Toksoz, C. H. ChengAbstract:The propagation of borehole Stoneley waves is strongly correlated with Permeability of the Formation. Previous studies primarily focused on the situation where the per-meability is homogeneously distributed in the Formation. In many in-situ situations, however, the Permeability distribution of the Formation is heterogeneous, due to effects such as a damaged zone around the borehole, random variation of the Formation perme-ability, and layering, etc. This study investigates the effects of Formation Permeability heterogeneity on Stoneley wave propagation. Using the theory of dynamic Permeability and a finite difference technique in cylindrical coordinates, dynamic pore fluid flow in an arbitrarily heterogeneous porous medium surrounding the borehole is modeled. The effects of the flow on the borehole Stoneley waves are calculated. The calculations were performed on various types of Permeability heterogeneities. For a Formation having ran-dom Permeability variation with various heterogeneity scale lengths (smaller than the scale of the borehole), the Stoneley wave attenuation and dispersion are only slightly higher than those calculated with a constant Permeability (mean value of the random distributions). For a Formation with Permeability linearly increasing or decreasing away from the borehole, the Stoneley wave behaviors are also similar to those calculated with a constant Permeability. Significant effects are found for a damaged zone case where the zone has much higher Permeability than the virgin Formation. The attenuation exhibits a peak and the Stoneley wave velocity is significantly decreased in the frequency range from 0 to 3 kHz. These features, if measured from the data, can be used as a diagnostic of the borehole condition. 44 Zhao et al
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EFFECTS OF A BOREHOLE ENVIRONMENT AND RESIDUAL HYDROCARBON ON STONELEY WAVE AMPLITUDE AND REFLECTIVITY
2016Co-Authors: Guo Tao, C. H. ChengAbstract:In recent years, borehole Stoneley wave amplitude and reflectivity have been used for estimating Formation Permeability based on the strong correlation between Stoneley wave attenuation, reflectivity and Formation fluid conductivity. There are other factors, however, that may cause substantial Stoneley attenuation and reflection in a borehole environment. To make better use of Stoneley measurements for Formation Permeability estimation, it is desirable to identify and quantify those causes of Stoneley attenuation and reflection that do not directly result from Formation Permeability. In this study, a simplified Biot-Rosenbaum model developed by Tang et at. (1991) is adopted to sys-tematically model Stoneley attenuation and reflection in various borehole environments and Formation configurations. By changing pore fluid, Formation porosity, lithology, bed boundaries and thickness in the modeling, the sensitivity of Stoneley wave propa-gation to these conditions are quantitatively assessed. It is found that the presence of a light hydrocarbon in the Formation, especially a natural gas residual in the immediate vicinity of the borehole wall, even with only 5 % contained in pore fluid, may also cause substantial Stoneley attenuation and reflection. This phenomenon, on the other hand, can be used to evaluate a nonfractured, low Permeability gas reservoir when combined with shear wave velocity data. For the full gas-saturated zone, Stoneley wave reflection may be observed even when the Permeability is as low as a few milliDarcies. Com-pared to the effects of pore fluid, the effects due to lithology contrasts at the boundaries and the changes of nonfracture porosity are insignificant in the cases studied here. For a residual gas-bearing zone of moderate Permeability, Stoneley wave attenuation and reflection may be observed if the zone is thicker than 0.5 meter
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fast inversion of Formation Permeability from stoneley wave logs using a simplified biot rosenbaum model
Geophysics, 1996Co-Authors: Xiao Ming Tang, C. H. ChengAbstract:This paper describes a fast algorithm for estimating Formation Permeability from Stoneley wave logs. The procedure uses a simplified Biot-Rosenbaum model formulation. The input to the inversion is the Stoneley-wave spectral amplitudes at each receiver position, the bore-hole fluid properties (velocity and density), the borehole caliper log, the Formation density and porosity (from log data), and the compressional and shear velocities for the interval of interest. The model uses the borehole caliper and elastic properties to compute the Stoneley wave excitation (that is, predicted amplitude without Permeability effects) as a function of frequency, and the porosity and Permeability to compute the fluid flow amplitude reduction. This method also uses a reference depth of known Permeability and compares amplitude variations at other depths relative to the reference depth. The Permeability value obtained from the inversion represents the best fit over all receivers and all relevant frequencies. A processing example is shown to demonstrate the ability of this technique to extract Formation Permeability from Stoneley wave logs.
Curtis M. Oldenburg - One of the best experts on this subject based on the ideXlab platform.
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joule thomson cooling due to co2 injection into natural gas reservoirs
Energy Conversion and Management, 2007Co-Authors: Curtis M. OldenburgAbstract:Depleted natural gas reservoirs are a promising target for Carbon Sequestration with Enhanced Gas Recovery (CSEGR). The focus of this study is on evaluating the importance of Joule-Thomson cooling during CO2 injection into depleted natural gas reservoirs. Joule-Thomson cooling is the adiabatic cooling that accompanies the expansion of a real gas. If Joule-Thomson cooling were extreme, injectivity and Formation Permeability could be altered by the freezing of residual water, Formation of hydrates, and fracturing due to thermal stresses. The TOUGH2/EOS7C module for CO2-CH4-H2O mixtures is used as the simulation analysis tool. For verification of EOS7C, the classic Joule-Thomson expansion experiment is modeled for pure CO2 resulting
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joule thomson cooling due to co2 injection into natural gas reservoirs
Lawrence Berkeley National Laboratory, 2006Co-Authors: Curtis M. OldenburgAbstract:Depleted natural gas reservoirs are a promising target for Carbon Sequestration with Enhanced Gas Recovery (CSEGR). The focus of this study is on evaluating the importance of Joule-Thomson cooling during CO2 injection into depleted natural gas reservoirs. Joule-Thomson cooling is the adiabatic cooling that accompanies the expansion of a real gas. If Joule-Thomson cooling were extreme, injectivity and Formation Permeability could be altered by the freezing of residual water, Formation of hydrates, and fracturing due to thermal stresses. The TOUGH2/EOS7C module for CO2-CH4-H2O mixtures is used as the simulation analysis tool. For verification of EOS7C, the classic Joule-Thomson expansion experiment is modeled for pure CO2 resulting in Joule-Thomson coefficients in agreement with standard references to within 5-7 percent. For demonstration purposes, CO2 injection at constant pressure and with a large pressure drop (~;50 bars) is presented in order to show that cooling by more than 20oC can occur by this effect. Two more-realistic constant-rate injection cases show that for typical systems in the Sacramento Valley, California, the Joule-Thomson cooling effect is minimal. This simulation study shows that for constant-rate injections into high-Permeability reservoirs, the Joule-Thomson cooling effect is not expected to create significant problems for CSEGR.
Xiaomin Zhao - One of the best experts on this subject based on the ideXlab platform.
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STONELEY WAVE PROPAGATION IN HETEROGENEOUS PERMEABLE POROUS FormationS
2016Co-Authors: Xiaomin Zhao, M N Toksoz, C. H. ChengAbstract:The propagation of borehole Stoneley waves is strongly correlated with Permeability of the Formation. Previous studies primarily focused on the situation where the per-meability is homogeneously distributed in the Formation. In many in-situ situations, however, the Permeability distribution of the Formation is heterogeneous, due to effects such as a damaged zone around the borehole, random variation of the Formation perme-ability, and layering, etc. This study investigates the effects of Formation Permeability heterogeneity on Stoneley wave propagation. Using the theory of dynamic Permeability and a finite difference technique in cylindrical coordinates, dynamic pore fluid flow in an arbitrarily heterogeneous porous medium surrounding the borehole is modeled. The effects of the flow on the borehole Stoneley waves are calculated. The calculations were performed on various types of Permeability heterogeneities. For a Formation having ran-dom Permeability variation with various heterogeneity scale lengths (smaller than the scale of the borehole), the Stoneley wave attenuation and dispersion are only slightly higher than those calculated with a constant Permeability (mean value of the random distributions). For a Formation with Permeability linearly increasing or decreasing away from the borehole, the Stoneley wave behaviors are also similar to those calculated with a constant Permeability. Significant effects are found for a damaged zone case where the zone has much higher Permeability than the virgin Formation. The attenuation exhibits a peak and the Stoneley wave velocity is significantly decreased in the frequency range from 0 to 3 kHz. These features, if measured from the data, can be used as a diagnostic of the borehole condition. 44 Zhao et al
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stoneley wave propagation across borehole Permeability heterogeneities
Seg Technical Program Expanded Abstracts, 1994Co-Authors: Xiaomin Zhao, M N Toksoz, C. H. ChengAbstract:An important application of borehole acoustic logging is the determination of Formation Permeability using Stoneley waves. Heterogeneous permeable structures, such as fractures, sand-shale sequences, etc., are commonly encountered in acoustic logging. The purpose of this study is to investigate the effects of the Permeability heterogeneities on the borehole Stoneley wave propagation, We have studied the effects of Formation Permeability heterogeneities on the Stoneley wave propagation when the heterogeneity changes in radial and azimuthal directions (Zhao et aL, 1993). To further study the problem of acoustic logging in heterogeneous porous Formations, we study the case where the Formation Permeability varies in the borehole axial and radial directions. This is a very important problem because vertical heterogeneity variations are commonly encountered in acoustic logging applications. Using the finite difference approach, such heterogeneities as random heterogeneous Permeability variations, multiple fracture zones, permeable (sand) non-permeable (shale) sequences, can be readily modeled, and the results are presented. Our numerical simulation results show that the continuous Permeability variations in the Formation have only minimal effects on the Stoneley wave propagation. Whereas the discontinuous variation (e.g., permeable sand and non-permeable shale sequences) can have significant effeces on the Stoneley wave propagation. However, when the Stoneley wavelength is considerably large compared to the scale of heterogeneity variations, the Stoneley wave is sensitive only to the overall fluid transmissivity of the Formation heterogeneity, To demonstrate the effects of heterogeneity on the Stoneley wave propagation. an experimental data set (Winkler et aI., 1989) has been modeled using a randomly layered Permeability model. The heterogeneous Permeability model results agree with the data very well, while the data disagree with the results from homogeneous Permeability models. The numerical technique for calculating Stoneley wave propagation across Permeability heterogeneities has been applied to interpret the acoustic logging data across a heeerogeneous fraceure zone (paillet. 1984). The modeling technique, in conjunction with a variable Permeability model, successfully explains the non-symmetric patterns of the Stoneley wave attenuation and reileceion at the top and bottom of the fracture
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stoneley wave propagation in heterogeneous permeable porous Formations
Seg Technical Program Expanded Abstracts, 1993Co-Authors: Xiaomin Zhao, M N Toksoz, C. H. ChengAbstract:The propagation of borehole Stoneley waves is strongly correlated with Permeability of the Formation. Previous studies primarily focused on the situation where the Permeability is homogeneously distributed in the Formation. In many in-situ situations, however, the Permeability distribution of the Formation is heterogeneous, due to effects such as a damaged zone around the borehole, random variation of the Formation Permeability, and layering, etc. This study investigates the effects of Formation Permeability heterogeneity on Stoneley wave propagation. Using the theory of dynamic Permeability and a finite difference technique in cylindrical coordinates, dynamic pore fluid flow in an arbitrarily heterogeneous porous medium surrounding the borehole is modeled. The effects of the flow on the borehole Stoneley waves are calculated. The calculations were performed on various types of Permeability heterogeneities. For a Formation having random Permeability variation with various heterogeneity scale lengths (smaller than the scale of the borehole), the Stoneley wave attenuation and dispersion are only slightly higher than those calculated with a constant Permeability (mean value of the random distributions). For a Formation with Permeability linearly increasing or decreasing away from the borehole, the Stoneley wave behaviors are also similar to those calculated with a constant Permeability. Significant effects are found for a damaged zone case where the zone has much higher Permeability than the virgin Formation. The attenuation exhibits a peak and the Stoneley wave velocity is significantly decreased in the frequency range from 0 to 3 kHz. These features, if measured from the data, can be used as a diagnostic of the borehole condition.
Carlos Torresverdin - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation of oil base mud contamination in condensates from cleanup to sample quality
Journal of Natural Gas Science and Engineering, 2010Co-Authors: Mayank Malik, Birol Dindoruk, Hani Elshahawi, Carlos TorresverdinAbstract:Abstract Formation Testers are widely used to determine pore pressure, estimate Formation Permeability, and detect reservoir connectivity through pressure transient testing after the onset of invasion. Mud filtrate invasion takes place in reservoirs penetrated by a well that is hydraulically overbalanced by mud circulation, or due to capillary forces. In water-base muds (WBM), the invading mud is immiscible with respect to the Formation hydrocarbons. Therefore, water can be physically separated from the in-situ hydrocarbons leading to the best estimates of the in-situ PVT properties and thereby Formation properties. Oil-base muds (OBM) are partially to completely miscible with the reservoir hydrocarbons, and so OBM contamination causes alteration of fluid properties which becomes even more critical for condensates when changes in fluid viscosity, density, and relative Permeability occur. Due to the complexity of partial miscibility with gases and gas condensates, limited work has been done to simulate invasion by OBM. The goals of our work were to: 1. Determine conditions to obtain better samples. 2. Quantify the errors in numerical cleaning methods necessary for obtaining in-situ fluid compositions and properties. 3. Investigate the physics of the clean-up process. 4. Investigate the feasibility of tracers for monitoring contamination. Our results show that for condensates and lean gases, quantifying OBM contamination in terms of the live/bulk fluid alone can be misleading. For such fluids, contamination in the stock tank oil is just as critical as that of the bulk fluid because only the former predicts the errors in saturation pressures and CGR numbers observed in laboratory analyses. Lean fluids can take extremely long times to completely clean up during a Formation test or even during a well test. For those fluids, it is more essential than ever to clearly define the primary objectives of the sampling program and to decide which answers are most critical.
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the influence of water base mud properties and petrophysical parameters on mudcake growth filtrate invasion and Formation pressure
Petrophysics, 2005Co-Authors: Carlos Torresverdin, Mark A ProettAbstract:The work described in this paper models the complete invasion process quantitatively with a finite-difference invasion simulator that includes the dynamically coupled effects of mudcake growth and multiphase, immiscible filtrate invasion. A fully coupled mudcake growth model is assumed and the flow rate of filtrate invasion is determined from both mud parameters and rock Formation properties. Specific parametric representations of the assumed invasion model are based on previously published laboratory experiments on mudcake buildup. As part of the numerical validation of the simulator, we reproduced available experimental data and obtained very good agreements. The influence of several mud and petrophysical parameters on both mudcake growth and filtrate invasion is quantified with a sensitivity analysis. These parameters include mudcake Permeability, mudcake porosity, mud solid content, relative Permeability, capillary pressure, Formation Permeability, cross flow between adjacent layers, and gravity segregation. Our simulations reveal the physical character of invasion profiles taking place under realistic petrophysical conditions. Results also characterize Formation pressure changes and pressure supercharging observed during wireline Formation testing.
Lionel Esteban - One of the best experts on this subject based on the ideXlab platform.
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impact of diagenesis on reservoir quality in a sedimentary geothermal play a case study in the cooper basin south australia
Basin Research, 2016Co-Authors: Antoine Dillinger, Ludovic Ricard, Cameron Huddlestoneholmes, Lionel EstebanAbstract:Geothermal resources hosted within sedimentary basins with high natural Permeability have been targeted for the production of energy in Australia. The Hutton Sandstone (Cooper-Eromanga Basin) – a prolific oil and gas producer known to have good reservoir quality and high reservoir volume – was recently tested for its geothermal potential in the Cooper Region. However, recent exploratory drilling did not produce the anticipated flow rates, raising the question of the impact of diagenesis on the reservoir quality of this sedimentary Formation. The combined characterization of the petrology, diagenesis and petrophysical properties of the Hutton Sandstone at Celsius-1 and other surrounding wells indicates variable reservoir properties in the Cooper Region. This integrated study demonstrates that low Formation Permeability occurs at geothermal target depth and explains the negligible flow rates obtained at Celsius-1. These low permeabilities are the results of the preservation of widespread detrital clayey matrix and the extensive occurrence of authigenic kaolinite, illite and silica cements at the top and base of the Hutton Sandstone. This aspect is confirmed by NMR T2 transversal relaxation time becoming shorter at similar depths. Petrography analysis also reveals that sandstones are affected by diagenetic processes of the eogenetic and mesogenetic phases. However, the Hutton Sandstone at Celsius-1 is presently at pressure-temperature conditions that are below the mesogenetic conditions, which suggests a late episode of uplift and cooling from maximum palaeotemperatures.
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experimental evaluation of reservoir quality in mesozoic Formations of the perth basin western australia by using a laboratory low field nuclear magnetic resonance
Marine and Petroleum Geology, 2014Co-Authors: Antoine Dillinger, Lionel EstebanAbstract:Abstract Accurate porosity and Permeability evaluation of rock Formations is critical to estimate the quality and resource potential of a reservoir. In addition to directly measure the porosity and pore size distribution, low field Nuclear Magnetic Resonance (NMR) is able to measure the effective porosity and estimate the in-situ Formation Permeability, though its robustness is arguable and requires calibrations on cores with specific lithologies. The Mesozoic Formations of the central Perth Basin (Western Australia) host hot sedimentary aquifers and recently became key targets for geothermal heat extraction. A collection of cores was retrieved from three wells intersecting these units. The characterisation of their flow properties complements the current evaluation of the Perth Basin by adding new data on effective porosity, pore size distribution, pore geometry and calibration of predictive models for the Permeability according to a comprehensive facies classification scheme. This study highlights the consistency of the NMR approach when compared to conventional helium injection method. Most favourable lithologies for well production correspond to very coarse to fine sandstones of fluvial channel fill with porosities >15% and permeabilities >>1 mD. Similarly, these facies exhibit (i) the highest effective porosities, (ii) the highest pore space to pore throat ratio, and (iii) the lowest contribution of clay bound water. These aspects confirm the importance of clay occurrence in the assessment of the flow efficiency of a Formation. The Yarragadee Formation presents the best reservoir quality regarding its porosity and Permeability, even though high discrepancies occur locally owing to the great variability of lithofacies encountered. The scattered values observed for the Lesueur Sandstone are likely to be due to the basin architecture and fault system which generate different mechanical compaction and secondary cementation. Given an adequate facies analysis, the NMR method represents a powerful tool to estimate the flow efficiency of a reservoir.