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Carlos Torres-verdín - One of the best experts on this subject based on the ideXlab platform.

  • Depth variation of wettability alteration during oil-base Mud-Filtrate invasion and corresponding effects on resistivity logs
    Journal of Petroleum Science and Engineering, 2016
    Co-Authors: Rohollah Abdollah-pour, Kamy Sepehrnoori, Carlos Torres-verdín, Zoha Nasizadeh
    Abstract:

    Abstract Resistivity logs acquired in hydrocarbon-bearing formations invaded by oil-base Mud (OBM) often indicate abnormally high values of mobile water saturation. It is not possible to explain such abnormally high values of water saturation with saturation-height analysis. The common explanation invokes rock wettability alterations due to surfactants included in oil-base Mud-Filtrate (OBMF). A quantitative study is needed to explain whether the interaction of OBMF surfactants with water-wetted grains can cause a sufficiently large increase in mobile water saturation in the near-wellbore region to affect resistivity logs. In this paper, we use a near wellbore simulator to model the processes of Mud-Filtrate invasion and ensuing wettability alteration once emulsifiers included in OBMF make contact with grain surfaces. We assume a wettability alteration model in which the degree and type of alteration are governed by the pore-volume concentration of emulsifier in OBMF within the invaded formation. Results indicate surfactants included in OBMF may change the rock's surface wettability from a water-wet to a neutral or oil-wet condition. This behavior causes a fraction of the originally residual pore volume of connate water to become moveable. The radial displacement of movable water by OBMF can give rise to an annulus of water bank, which in turn causes the resistivity annulus. We perform simulations of OBMF invasion into oil and gas saturated formations. Simulated apparent resistivity logs across layers which exhibited shallow invasion showed a reverse OBM effect where deep resistivity was larger than shallow resistivity.

  • 2004, Assessment of in-situ hydrocarbon saturation in the presence of deep invasion and highly saline connate water
    2015
    Co-Authors: Carlos Torres-verdín, Mojdeh Delshad, Bovan K George, Farid Zouioueche, Richard Sigal, Barbara Anderson
    Abstract:

    The drilling of wells with heavy Mud causes large over-balance pressures, resulting in deep invasion of Mud Filtrate into porous and permeable layers. In the past, the effect of Mud-Filtrate invasion on induction logs has been studie

  • QUANTIFYING WETTABILITY ALTERATION DURING OIL-BASE Mud-Filtrate INVASION AND CORRESPONDING EFFECTS ON RESISTIVITY LOGS
    2011
    Co-Authors: Rohollah A. Pour, Carlos Torres-verdín, Kamy Sepehrnoori
    Abstract:

    Resistivity logs acquired in hydrocarbon-bearing formations invaded by oil-base Mud (OBM) often indicate abnormally high values of mobile water saturation. It is not possible to explain such abnormally high values of water saturation with saturation-height analysis. The common explanation invokes rock wettability alterations due to surfactants included in oilbase Mud-Filtrate (OBMF). A quantitative study is needed to explain whether interaction of OBMF surfactants with water-wetted grains can cause a sufficiently large increase in mobile water saturation in the near-wellbore region. We develop a new equation-of-state compositional simulator for near-wellbore applications. The simulator models the processes of Mud-Filtrate invasion and ensuing wettability alterations once emulsifiers included in OBMF make contact with grain surfaces. We assume a wettability alteration model in which the degree and type of alteration are governed by the porevolume concentration of emulsifier in OBMF within the invaded formation. Sensitivity analyses on different Mudcake properties quantify the effect of each Mudcake property on the radial distributions of water saturation and electrical resistivity resulting from invasion. Simulation results confirm that irreducible water saturation decreases as grain surfaces make contact with OBMF emulsifiers. The reduction of irreducible water saturation causes a portion of connate water to become mobile, with the percentage of additional movable water depending on both type of Mud-Filtrate and degree of wettability alteration. It is found that additional movable water saturation released by wettability alteration can give rise to a radial annulus of abnormally low electrical resistivity. This behavior is consistent with observations made of apparent resistivity logs acquired in OBMF invaded formations. Numerically simulated radial distributions of electrical resistivity also explain the separation of apparent resistivity logs often observed in hydrocarbon-saturated formations invaded with OBM. Comparison of radial profiles of electrical resistivity simulated for various rock types confirms that dynamic petrophysical properties of invaded formations can have a significant effect on the degree of wettability alteration due to OBMF.

  • Estimation of Dry-Rock Elastic Moduli Based on the Simulation of Mud-Filtrate Invasion Effects on Borehole Acoustic Logs
    SPE Reservoir Evaluation & Engineering, 2009
    Co-Authors: Tobiloluwa B. Odumosu, Carlos Torres-verdín, Jesús M. Salazar, Benjamin Voss, Gong Li Wang
    Abstract:

    Summary Reliable estimates of dry-rock elastic properties are critical to the accurate interpretation of the seismic response of hydrocarbon reservoirs. We describe a new method for estimating elastic moduli of rocks in-situ based on the simulation of Mud-Filtrate invasion effects on resistivity and acoustic logs. Simulations of Mud-Filtrate invasion account for the dynamic process of fluid displacement and mixing between Mud-Filtrate and hydrocarbons. The calculated spatial distributions of electrical resistivity are matched against resistivity logs by adjusting the underlying petrophysical properties. We then perform Biot-Gassmann fluid substitution on the 2D spatial distributions of fluid saturation with initial estimates of dry-bulk (kdry) modulus and shear rigidity (µdry) and a constraint of Poisson's ratio (?d) typical of the formation. This process generates 2D spatial distributions of compressional and shear-wave velocities and density. Subsequently, sonic waveforms are simulated to calculate shear-wave slowness. Initial estimates of the dry-bulk modulus are progressively adjusted using a modified Gregory-Pickett (1963) solution of Biot's (1956) equation to estimate a shear rigidity that converges to the well-log value of shear-wave slowness. The constraint on dynamic Poisson's ratio is then removed and a refined estimate of the dry-bulk modulus is obtained by both simulating the acoustic log (monopole) and matching the log-derived compressional-wave slowness. This technique leads to reliable estimates of dry-bulk moduli and shear rigidity that compare well to laboratory core measurements. Resulting dry-rock elastic properties can be used to calculate seismic compressional-wave and shear-wave velocities devoid of Mud-Filtrate invasion effects for further seismic-driven reservoir-characterization studies.

  • Modeling Mud-Filtrate Invasion Effects on Resistivity Logs to Estimate Permeability of Vuggy and Fractured Carbonate Formations
    All Days, 2009
    Co-Authors: Luis Javier Miranda, Carlos Torres-verdín, F. Jerry Lucia
    Abstract:

    Abstract We develop and validate a new method to diagnose and estimate secondary porosity and absolute permeability of fractured and vuggy carbonate formations based on the numerical simulation of the process of Mud-Filtrate invasion. The method includes the geological characterization of core laboratory data and their integration with well logs and fluid production measurements. We apply the new method to the interpretation of data acquired in a carbonate reservoir in the Barinas-Apure Basin in southwest Venezuela. The latter reservoir behaves as a triple-porosity petrophysical system which exhibits intercrystalline, intra-crystalline, moldic, vuggy (connected and non-connected) and fractured porosity, all embedded in a tight matrix. Rock-core data and wellbore resistivity images indicate that vugs are the mayor component of secondary porosity while fractures and interconnected vugs account for most of the permeability. The initial phase of our interpretation method consists of integrating core measurements with conventional and nonconventional well logs to calculate static and dynamic petrophysical properties via standard carbonate evaluation procedures. Starting with the calculated petrophysical properties, we simulate the process of invasion with both water- and oil-base Muds. Resulting spatial distributions of water saturation and salt concentration in the near-borehole region give rise to spatial distributions of electrical resistivity which are used to numerically simulate laterolog and induction apparent resistivity logs. If the input values of porosity and permeability are not correct, the simulation of Mud-Filtrate invasion will result in a poor match of resistivity logs. In such cases, we update porosity and permeability until securing a good match between measurements and simulations. This procedure was tested on several key wells with and without core measurements, wellbore resistivity images, and well-testing measurements. We conclusively find that our final estimates of porosity and permeability are in good agreement with the properties of the global petrophysical system. Differences between porosity and permeability before and after simulation of the process of invasion are reliable indicators of presence and influence of vugs and/or fractures in the displacement of hydrocarbons by Mud Filtrate. Introduction Permeability estimation is one of the most important steps of reservoir characterization. Even though there are reliable methods to estimate porosity and fluid saturation, reliable permeability estimation is difficult, especially in carbonate reservoirs. In heterogeneous reservoirs with variable rock composition and petrophysical properties, integration of core measurements and well logs is necessary to predict petrophysical properties in zones with no or scarce core samples. In this study, we estimate permeability via numerical simulation of the process of Mud-Filtrate invasion that takes place in complex reservoirs with a triple-porosity system (Fig. 1). In so doing, we numerically simulate dual-laterolog and array-induction resistivity logs to validate the estimation of petrophysical properties. Our method includes the geological characterization of core measurements as well as integration of well logs and production data.

Kamy Sepehrnoori - One of the best experts on this subject based on the ideXlab platform.

  • Depth variation of wettability alteration during oil-base Mud-Filtrate invasion and corresponding effects on resistivity logs
    Journal of Petroleum Science and Engineering, 2016
    Co-Authors: Rohollah Abdollah-pour, Kamy Sepehrnoori, Carlos Torres-verdín, Zoha Nasizadeh
    Abstract:

    Abstract Resistivity logs acquired in hydrocarbon-bearing formations invaded by oil-base Mud (OBM) often indicate abnormally high values of mobile water saturation. It is not possible to explain such abnormally high values of water saturation with saturation-height analysis. The common explanation invokes rock wettability alterations due to surfactants included in oil-base Mud-Filtrate (OBMF). A quantitative study is needed to explain whether the interaction of OBMF surfactants with water-wetted grains can cause a sufficiently large increase in mobile water saturation in the near-wellbore region to affect resistivity logs. In this paper, we use a near wellbore simulator to model the processes of Mud-Filtrate invasion and ensuing wettability alteration once emulsifiers included in OBMF make contact with grain surfaces. We assume a wettability alteration model in which the degree and type of alteration are governed by the pore-volume concentration of emulsifier in OBMF within the invaded formation. Results indicate surfactants included in OBMF may change the rock's surface wettability from a water-wet to a neutral or oil-wet condition. This behavior causes a fraction of the originally residual pore volume of connate water to become moveable. The radial displacement of movable water by OBMF can give rise to an annulus of water bank, which in turn causes the resistivity annulus. We perform simulations of OBMF invasion into oil and gas saturated formations. Simulated apparent resistivity logs across layers which exhibited shallow invasion showed a reverse OBM effect where deep resistivity was larger than shallow resistivity.

  • QUANTIFYING WETTABILITY ALTERATION DURING OIL-BASE Mud-Filtrate INVASION AND CORRESPONDING EFFECTS ON RESISTIVITY LOGS
    2011
    Co-Authors: Rohollah A. Pour, Carlos Torres-verdín, Kamy Sepehrnoori
    Abstract:

    Resistivity logs acquired in hydrocarbon-bearing formations invaded by oil-base Mud (OBM) often indicate abnormally high values of mobile water saturation. It is not possible to explain such abnormally high values of water saturation with saturation-height analysis. The common explanation invokes rock wettability alterations due to surfactants included in oilbase Mud-Filtrate (OBMF). A quantitative study is needed to explain whether interaction of OBMF surfactants with water-wetted grains can cause a sufficiently large increase in mobile water saturation in the near-wellbore region. We develop a new equation-of-state compositional simulator for near-wellbore applications. The simulator models the processes of Mud-Filtrate invasion and ensuing wettability alterations once emulsifiers included in OBMF make contact with grain surfaces. We assume a wettability alteration model in which the degree and type of alteration are governed by the porevolume concentration of emulsifier in OBMF within the invaded formation. Sensitivity analyses on different Mudcake properties quantify the effect of each Mudcake property on the radial distributions of water saturation and electrical resistivity resulting from invasion. Simulation results confirm that irreducible water saturation decreases as grain surfaces make contact with OBMF emulsifiers. The reduction of irreducible water saturation causes a portion of connate water to become mobile, with the percentage of additional movable water depending on both type of Mud-Filtrate and degree of wettability alteration. It is found that additional movable water saturation released by wettability alteration can give rise to a radial annulus of abnormally low electrical resistivity. This behavior is consistent with observations made of apparent resistivity logs acquired in OBMF invaded formations. Numerically simulated radial distributions of electrical resistivity also explain the separation of apparent resistivity logs often observed in hydrocarbon-saturated formations invaded with OBM. Comparison of radial profiles of electrical resistivity simulated for various rock types confirms that dynamic petrophysical properties of invaded formations can have a significant effect on the degree of wettability alteration due to OBMF.

  • prediction of formation tester fluid sample quality in highly deviated wells
    Petrophysics, 2009
    Co-Authors: Renzo Angeles, Carlos Torresverdin, Kamy Sepehrnoori, Mayank Malik
    Abstract:

    Fluid samples acquired with formation testers are often contaminated with Mud Filtrate. In some cases, it may take hours or even days to achieve acceptable levels of Mud-Filtrate contamination, thereby rendering the fluid-sampling operation undesirable for either economical or safety considerations. We apply 3D numerical algorithms to simulate formation-tester measurements acquired in highly-deviated wells using standard and focused-sampling probes. Because this approach is not restricted to the assumption of single-phase flow nor does it neglect presence of spatially asymmetric Mud-Filtrate invasion, numerical simulation enables the quantitative appraisal of realistic tool and formation properties under a wide range of deviation angles. Sensitivity studies consider the effects of permeability anisotropy, capillary pressure, gravity segregation, radius of Mud-Filtrate invasion, fluid viscosity, fluid density, probe diameter, and pumpout rate for oil- and dry-gas-bearing rock formations. Moreover, comparisons are made between sampling operations performed in wells drilled with water-based (WBM) and oil-based (OBM) Mud. We also appraise the performance of recently-introduced focused fluid-sampling probes for the rapid acquisition of low-contamination fluid samples in highly-deviated wells. Our study indicates that gravity is detrimental to production cleanup times and it also affects focused-sampling probes which, at specific ratios between sample and guard assemblies, achieve cleaner samples than conventional probes. For the cases considered in this paper, the larger the angle of deviation (with respect to the vertical axis), the longer it takes to achieve oil breakthrough. Finally, gravity-segregated invaded formations strongly affect fluid sampling predictions, hence enforcing our notion that a numerical approach, such as the one implemented in this paper, is necessary to accurately predict production cleanup times in high-angle wells.

  • Comparison of Wireline Formation-Tester Sampling with Focused and Conventional Probes in the Presence of Oil-Base Mud-Filtrate Invasion
    2009
    Co-Authors: Mayank Malik, Birol Dindoruk, Kamy Sepehrnoori, Hani Elshahawi, Carlos Torres-verdín, Richard Jackson, Peter Weinheber, Oliver C. Mullins, Mohamed Hashem
    Abstract:

    In the course of fluid sampling, varying concentrations of oil base Mud (OBM) will lead to variations of fluid properties such as viscosity, density, and gas-oil ratio (GOR). A focused probe can be useful in reducing OBM contamination by diverting flow into different channels without compromising fluid pumpout time. However, it is important to properly quantify the relative performance of focused and conventional probes for a wide range of field conditions. The objective of this paper is to appraise the performance of different probes under the same simulated field conditions and for a comprehensive set of petrophysical and fluid properties. Results indicate that sample quality generally improves when the flow is split between the guard and sample probes, but the specific amount of improvement depends on probe geometry, fluid composition, and formation properties. Permeability anisotropy, presence of a flow boundary, and lack of Mud-Filtrate invasion can help to improve sample quality. In addition, fluid cleanup can be accelerated by altering both the probe design and the flow-rate ratio between the sample and guard fluid streams, thereby leading to increased pressure differential between the sample and guard areas and enhancing the "coning" of the Mud-Filtrate invasion front.

  • Effects of Petrophysical Properties on Array-Induction Measurements Acquired in the Presence of Oil-Base Mud-Filtrate Invasion
    Petrophysics, 2008
    Co-Authors: Mayank Malik, Carlos Torres-verdín, Jesús M. Salazar, Gong Li Wang, Hee Jae Lee, Kamy Sepehrnoori
    Abstract:

    We quantify the influence of petrophysical properties on array-induction resistivity measurements acquired in the presence of oil-base Mud (OBM) Filtrate invasion. To simulate OBM-Filtrate invasion, we consider a simple two-component formulation for the oil phase (OBM and reservoir oil) wherein the components are first-contact miscible. Simulations also include the presence of irreducible, capillary-bound, and movable water. The dynamic process of OBM invasion causes the component concentrations to vary with space and time. In addition, the relative mobility ofthe oil phase varies during the process of invasion given that oil viscosity and oil density are both dependent on component concentrations. This behavior in turn conditions the spatial distribution of electrical resistivity and, consequently, the borehole array-induction measurements. We use an implicit pressure, explicit concentration (IMPEC) reservoir simulator with a two-component formulation to reproduce the invasion process in axial-symmetric rock formations penetrated by a vertical well. Simulations of the process of OBM-Filtrate invasion yield two-dimensional spatial distributions of water and oil saturation that are transformed into spatial distributions of electrical resistivity using Waxman-Smits' saturation-resistivity equations. Subsequently, we simulate array-induction measurements with a numerical mode-matching method. Simulation of induction measurements in the presence of OBM are compared against the corresponding measurements acquired in the presence of water-base Mud (WBM) using field measurements from a deepwater Gulf-of-Mexico reservoir. Sensitivity analyses are conducted to quantify the effect of OBM-Filtrate invasion on array-induction logs, including different values of formation porosity-permeability, movable water zone, capillary pressure, relative permeability, Mud-Filtrate invasion rates, and fluid viscosity. In addition, we quantify the effect of changes of rock wettability due to OBM invasion on field measurements. Our study indicates that relative permeability, capillary pressure, and flow rate of invasion control the radial length of invasion of OBM and, consequently, the values and relative separation of apparent resistivity curves. Porous rock formations saturated with movable water entail smooth radial distributions of water saturation which, in turn, result in deep (1.5 ft - 2 ft) radial invasion profiles and relatively large separation of apparent resistivity curves. By contrast, null or marginal separation of apparent resistivity curves occurs when the invaded rock is at irreducible water saturation.

Mayank Malik - One of the best experts on this subject based on the ideXlab platform.

  • prediction of formation tester fluid sample quality in highly deviated wells
    Petrophysics, 2009
    Co-Authors: Renzo Angeles, Carlos Torresverdin, Kamy Sepehrnoori, Mayank Malik
    Abstract:

    Fluid samples acquired with formation testers are often contaminated with Mud Filtrate. In some cases, it may take hours or even days to achieve acceptable levels of Mud-Filtrate contamination, thereby rendering the fluid-sampling operation undesirable for either economical or safety considerations. We apply 3D numerical algorithms to simulate formation-tester measurements acquired in highly-deviated wells using standard and focused-sampling probes. Because this approach is not restricted to the assumption of single-phase flow nor does it neglect presence of spatially asymmetric Mud-Filtrate invasion, numerical simulation enables the quantitative appraisal of realistic tool and formation properties under a wide range of deviation angles. Sensitivity studies consider the effects of permeability anisotropy, capillary pressure, gravity segregation, radius of Mud-Filtrate invasion, fluid viscosity, fluid density, probe diameter, and pumpout rate for oil- and dry-gas-bearing rock formations. Moreover, comparisons are made between sampling operations performed in wells drilled with water-based (WBM) and oil-based (OBM) Mud. We also appraise the performance of recently-introduced focused fluid-sampling probes for the rapid acquisition of low-contamination fluid samples in highly-deviated wells. Our study indicates that gravity is detrimental to production cleanup times and it also affects focused-sampling probes which, at specific ratios between sample and guard assemblies, achieve cleaner samples than conventional probes. For the cases considered in this paper, the larger the angle of deviation (with respect to the vertical axis), the longer it takes to achieve oil breakthrough. Finally, gravity-segregated invaded formations strongly affect fluid sampling predictions, hence enforcing our notion that a numerical approach, such as the one implemented in this paper, is necessary to accurately predict production cleanup times in high-angle wells.

  • Comparison of Wireline Formation-Tester Sampling with Focused and Conventional Probes in the Presence of Oil-Base Mud-Filtrate Invasion
    2009
    Co-Authors: Mayank Malik, Birol Dindoruk, Kamy Sepehrnoori, Hani Elshahawi, Carlos Torres-verdín, Richard Jackson, Peter Weinheber, Oliver C. Mullins, Mohamed Hashem
    Abstract:

    In the course of fluid sampling, varying concentrations of oil base Mud (OBM) will lead to variations of fluid properties such as viscosity, density, and gas-oil ratio (GOR). A focused probe can be useful in reducing OBM contamination by diverting flow into different channels without compromising fluid pumpout time. However, it is important to properly quantify the relative performance of focused and conventional probes for a wide range of field conditions. The objective of this paper is to appraise the performance of different probes under the same simulated field conditions and for a comprehensive set of petrophysical and fluid properties. Results indicate that sample quality generally improves when the flow is split between the guard and sample probes, but the specific amount of improvement depends on probe geometry, fluid composition, and formation properties. Permeability anisotropy, presence of a flow boundary, and lack of Mud-Filtrate invasion can help to improve sample quality. In addition, fluid cleanup can be accelerated by altering both the probe design and the flow-rate ratio between the sample and guard fluid streams, thereby leading to increased pressure differential between the sample and guard areas and enhancing the "coning" of the Mud-Filtrate invasion front.

  • Effects of Petrophysical Properties on Array-Induction Measurements Acquired in the Presence of Oil-Base Mud-Filtrate Invasion
    Petrophysics, 2008
    Co-Authors: Mayank Malik, Carlos Torres-verdín, Jesús M. Salazar, Gong Li Wang, Hee Jae Lee, Kamy Sepehrnoori
    Abstract:

    We quantify the influence of petrophysical properties on array-induction resistivity measurements acquired in the presence of oil-base Mud (OBM) Filtrate invasion. To simulate OBM-Filtrate invasion, we consider a simple two-component formulation for the oil phase (OBM and reservoir oil) wherein the components are first-contact miscible. Simulations also include the presence of irreducible, capillary-bound, and movable water. The dynamic process of OBM invasion causes the component concentrations to vary with space and time. In addition, the relative mobility ofthe oil phase varies during the process of invasion given that oil viscosity and oil density are both dependent on component concentrations. This behavior in turn conditions the spatial distribution of electrical resistivity and, consequently, the borehole array-induction measurements. We use an implicit pressure, explicit concentration (IMPEC) reservoir simulator with a two-component formulation to reproduce the invasion process in axial-symmetric rock formations penetrated by a vertical well. Simulations of the process of OBM-Filtrate invasion yield two-dimensional spatial distributions of water and oil saturation that are transformed into spatial distributions of electrical resistivity using Waxman-Smits' saturation-resistivity equations. Subsequently, we simulate array-induction measurements with a numerical mode-matching method. Simulation of induction measurements in the presence of OBM are compared against the corresponding measurements acquired in the presence of water-base Mud (WBM) using field measurements from a deepwater Gulf-of-Mexico reservoir. Sensitivity analyses are conducted to quantify the effect of OBM-Filtrate invasion on array-induction logs, including different values of formation porosity-permeability, movable water zone, capillary pressure, relative permeability, Mud-Filtrate invasion rates, and fluid viscosity. In addition, we quantify the effect of changes of rock wettability due to OBM invasion on field measurements. Our study indicates that relative permeability, capillary pressure, and flow rate of invasion control the radial length of invasion of OBM and, consequently, the values and relative separation of apparent resistivity curves. Porous rock formations saturated with movable water entail smooth radial distributions of water saturation which, in turn, result in deep (1.5 ft - 2 ft) radial invasion profiles and relatively large separation of apparent resistivity curves. By contrast, null or marginal separation of apparent resistivity curves occurs when the invaded rock is at irreducible water saturation.

  • History matching and sensitivity analysis of probe-type formation-tester measurements acquired in the presence of oil-base Mud-Filtrate invasion
    Petrophysics, 2007
    Co-Authors: Mayank Malik, Birol Dindoruk, Kamy Sepehrnoori, Hani Elshahawi, Carlos Torres-verdín, Mohamed Naguib Hashem
    Abstract:

    The acquisition of contamination-free fluid samples in hydrocarbon reservoirs drilled with oil-base Mud (OBM) is challenging due to the presence of multiple fluid phases as well as partial-to-complete miscibility between reservoir fluids and OBM. Throughout the sampling process, varying concentrations of OBM contained in the sampled fluid will lead to changes in observed (apparent) fluid properties. Similarly, sand-face transient pressure measurements are affected by OBM invasion as the invasion process itself modifies both fluid viscosity and fluid density in the near-wellbore region due to mixing between different hydrocarbon components. We use a commercial adaptive-implicit compositional numerical simulator to model the Filtrate cleanup process during fluid sampling and to compare the predicted pressure and apparent fluid properties at the sand-face against observed field measurements. A history-matching approach is used to estimate formation permeability and permeability anisotropy. We apply the proposed workflow to three sets of field measurements of sink probe pressure, observation probe pressure, gas-oil ratio (GOR), and flow rate acquired with a formation tester in light-oil formations. Since the formation is invaded with oil-base Mud Filtrate that is assumed free of gas, GOR can be used to discriminate between fluids. We use a dimensionless fluid contamination function to relate transient GOR measurements to sample fluid quality. The successful comparison of simulations to field measurements helps us to diagnose and quantify adverse data-acquisition conditions such as plugging and noisy transient data. It is found that numerical simulations are a reliable way to verify the internal consistency of the transient measurements of flow rate, pressure, and GOR in the presence of biasing acquisition problems. We perform sensitivity analyses to identify the dominant governing parameters such as formation properties, formation-tester flow rates, relative permeability, and radial extent of Mud-Filtrate invasion, on transient measurements of sand-face pressure and sampled fluid contamination. Our observation is that transient pressure, GOR, and density variations are sensitive to both the radial extent of Mud-Filtrate invasion and the rate of fluid cleanup. If the radial length of invasion is large, the total pumped volume must be increased in order to retrieve representative fluid samples. This can be achieved either by increasing the duration of the test, using higher rates of fluid withdrawal, or both.

  • Field Examples Of History Matching Of Formation Tester Measurements Acquired In The Presence Of Oilbase Mud-Filtrate Invasion
    2007
    Co-Authors: Mayank Malik, Birol Dindoruk, Kamy Sepehrnoori, Hani Elshahawi, Carlos Torres-verdín, Mohamed Hashem
    Abstract:

    The acquisition of fluid samples in hydrocarbon reservoirs drilled with oil-base Mud (OBM) is challenging due to both presence of multiple phases as well as partial-to-complete miscibility between reservoir fluids and OBM. Throughout the sampling process, varying concentrations of OBM will lead to changes in observed (apparent) fluid properties. Similarly, sand-face transient pressure measurements are affected by OBM as the invasion process itself modifies both fluid viscosity and fluid density in the near-wellbore region due to mixing between different hydrocarbon components. We use a commercial adaptive-implicit compositional method to simulate the Filtrate cleanup process during fluid sampling and compare the predicted pressure and apparent fluid properties at the sand-face against observed field measurements. A history matching approach is used to estimate formation permeability and permeability anisotropy. We apply the proposed workflow to three sets of transient field measurements of sink probe pressure, observation probe pressure, gas-oil ratio (GOR), and flow rate acquired with a formation tester in light-oil formations. Since the formation is invaded by oil-base Mud Filtrate, GOR can be used to diagnose types of fluids. We use a dimensionless fluid contamination function to relate transient GOR measurements to sample fluid quality. The successful comparison to field measurements validates our simulation model and helps us to diagnose and quantify adverse data-acquisition conditions such as plugging and noisy data. We perform sensitivity analyses to identify the dominant governing parameters such as formation properties, formation tester flow rates, relative permeability, and radial length of Mud-Filtrate invasion, on transient measurements of sand-face pressure and fluid contamination function. Our observation is that transient pressure, GOR, and density variations are sensitive to both the radial length of Mud-Filtrate invasion and the rate of fluid cleanup. If the radial length of invasion is large, then the total pumped volume must be increased in order to retrieve representative fluid samples. This can de achieved either by increasing the duration of the test, using higher rates of fluid withdrawal, or both.

Robert G. Bryant - One of the best experts on this subject based on the ideXlab platform.

  • multi dimensional nuclear magnetic resonance characterizations of dynamics and saturations of brine crude oil Mud Filtrate mixtures confined in rocks the role of asphaltene
    Energy & Fuels, 2014
    Co-Authors: Lyès Benamsili, Gerald Hamon, Jean-pierre Korb, Brice Bouyssiere, Honggang Zhou, Alain Louisjoseph, Robert G. Bryant
    Abstract:

    We propose multi-dimensional one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) techniques for probing quantitatively the different saturations and dynamics of brine/crude oil/Mud Filtrate mixtures confined in a rock system that could be used potentially down-hole. The rock samples and petroleum fluids have been characterized by standard petrophysical techniques. Electron spin resonance (ESR) quantitatively measured levels of the paramagnetic vanadyl ions VO2+ and organic radicals trapped in the used crude oils with and without asphaltene. Size-exclusion microchromatography with a high-resolution inductively coupled plasma–mass spectrometric detection technique has demonstrated the trapping of metalloporphyrine (MP) by asphaltene nanoaggregates. These two latter techniques have shown that around 2/3 of VO2+ is trapped in MP embedded within asphaltene nanoaggregates, while 1/3 stayed in the bulk. Standard gas chromatography (GC) and gel permeation chromatography (GPC) have exten...

  • Multi-dimensional Nuclear Magnetic Resonance Characterizations of Dynamics and Saturations of Brine/Crude Oil/Mud Filtrate Mixtures Confined in Rocks: The Role of Asphaltene
    Energy and Fuels, 2014
    Co-Authors: Lyès Benamsili, Gerald Hamon, Jean-pierre Korb, Alain Louis-joseph, Brice Bouyssiere, Honggang Zhou, Robert G. Bryant
    Abstract:

    We propose multi-dimensional one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) techniques for probing quantitatively the different saturations and dynamics of brine/crude oil/Mud Filtrate mixtures confined in a rock system that could be used potentially down-hole. The rock samples and petroleum fluids have been characterized by standard petrophysical techniques. Electron spin resonance (ESR) quantitatively measured levels of the paramagnetic vanadyl ions VO2+ and organic radicals trapped in the used crude oils with and without asphaltene. Size-exclusion microchromatography with a high-resolution inductively coupled plasma–mass spectrometric detection technique has demonstrated the trapping of metalloporphyrine (MP) by asphaltene nanoaggregates. These two latter techniques have shown that around 2/3 of VO2+ is trapped in MP embedded within asphaltene nanoaggregates, while 1/3 stayed in the bulk. Standard gas chromatography (GC) and gel permeation chromatography (GPC) have extended the sensitivity to the range of the chain length distribution. We employed 2D NMR D–T2 experiments for different in situ successive rock saturations in monophasic, biphasic, and triphasic conditions. The D–T2 experiments of imbibition drainage of petroleum fluids on a sandstone rock have also been performed for different temperatures and pressures. In all of the multiphasic cases, the characteristic features of the D–T2 spectrum allow for probing the individual saturations and wettability of each confined fluid in the mixture. Finally, the anomalous relationship D ∝ √T2 previously observed has been confirmed at low T2 values for bulk and confined crude oils in the presence of asphaltene. On the basis of a theoretical relaxation treatment, we propose an interpretation of this relationship with a nonlinear scaling T2 → √T2 affecting mainly the local dynamics of the long hydrocarbon chains. The leveling off, D ≈ Cte, of this relationship for large T2 values is new and explained in terms of surface dynamics of the short hydrocarbon chains on asphaltene nanoaggregates. This result is consistent with the bilogarithmic frequency dependence of the nuclear magnetic relaxation dispersion (NMRD) profiles observed for the same crude oil in the presence of asphaltene.

  • Multi-dimensional Nuclear Magnetic Resonance Characterizations of Dynamics and Saturations of Brine/Crude Oil/Mud Filtrate Mixtures Confined in Rocks: The Role of Asphaltene
    Energy & Fuels, 2013
    Co-Authors: Lyès Benamsili, Gerald Hamon, Jean-pierre Korb, Alain Louis-joseph, Brice Bouyssiere, Honggang Zhou, Robert G. Bryant
    Abstract:

    We propose multi-dimensional one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) techniques for probing quantitatively the different saturations and dynamics of brine/crude oil/Mud Filtrate mixtures confined in a rock system that could be used potentially down-hole. The rock samples and petroleum fluids have been characterized by standard petrophysical techniques. Electron spin resonance (ESR) quantitatively measured levels of the paramagnetic vanadyl ions VO2+ and organic radicals trapped in the used crude oils with and without asphaltene. Size-exclusion microchromatography with a high-resolution inductively coupled plasma–mass spectrometric detection technique has demonstrated the trapping of metalloporphyrine (MP) by asphaltene nanoaggregates. These two latter techniques have shown that around 2/3 of VO2+ is trapped in MP embedded within asphaltene nanoaggregates, while 1/3 stayed in the bulk. Standard gas chromatography (GC) and gel permeation chromatography (GPC) have exten...

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  • Rock quality assessment using the effect of Mud-Filtrate invasion on conflicting borehole resistivity measurements
    GEOPHYSICS, 2012
    Co-Authors: Jesús M. Salazar, A. Jeff Martin
    Abstract:

    ABSTRACTUnexpected borehole measurements are often inaccurately interpreted due to limited knowledge of the formation, particularly in tight-gas unconventional reservoirs. A novel method was applied to determine reservoir quality and the reliability of borehole array-induction resistivity measurements in a tight gas sandstone reservoir. Four exploration wells drilled with synthetic oil-based Mud showed conflicting resistivity profiles. The discovery well showed a conductive invasion profile, but the appraisal wells showed resistive profiles. Simulation of oil-based Mud-Filtrate invasion was coupled with forward simulation and inversion of array-induction resistivity measurements to determine the difference in such resistivity profiles. Laboratory measurements on rock core and fluid samples were used to calibrate a log-based petrophysical model that was necessary to simulate the physics of fluid-flow Mud-Filtrate invasion. The dynamic process of invasion was simulated with a multicomponent formulation for ...

  • Estimation of Dry-Rock Elastic Moduli Based on the Simulation of Mud-Filtrate Invasion Effects on Borehole Acoustic Logs
    SPE Reservoir Evaluation & Engineering, 2009
    Co-Authors: Tobiloluwa B. Odumosu, Carlos Torres-verdín, Jesús M. Salazar, Benjamin Voss, Gong Li Wang
    Abstract:

    Summary Reliable estimates of dry-rock elastic properties are critical to the accurate interpretation of the seismic response of hydrocarbon reservoirs. We describe a new method for estimating elastic moduli of rocks in-situ based on the simulation of Mud-Filtrate invasion effects on resistivity and acoustic logs. Simulations of Mud-Filtrate invasion account for the dynamic process of fluid displacement and mixing between Mud-Filtrate and hydrocarbons. The calculated spatial distributions of electrical resistivity are matched against resistivity logs by adjusting the underlying petrophysical properties. We then perform Biot-Gassmann fluid substitution on the 2D spatial distributions of fluid saturation with initial estimates of dry-bulk (kdry) modulus and shear rigidity (µdry) and a constraint of Poisson's ratio (?d) typical of the formation. This process generates 2D spatial distributions of compressional and shear-wave velocities and density. Subsequently, sonic waveforms are simulated to calculate shear-wave slowness. Initial estimates of the dry-bulk modulus are progressively adjusted using a modified Gregory-Pickett (1963) solution of Biot's (1956) equation to estimate a shear rigidity that converges to the well-log value of shear-wave slowness. The constraint on dynamic Poisson's ratio is then removed and a refined estimate of the dry-bulk modulus is obtained by both simulating the acoustic log (monopole) and matching the log-derived compressional-wave slowness. This technique leads to reliable estimates of dry-bulk moduli and shear rigidity that compare well to laboratory core measurements. Resulting dry-rock elastic properties can be used to calculate seismic compressional-wave and shear-wave velocities devoid of Mud-Filtrate invasion effects for further seismic-driven reservoir-characterization studies.

  • quantitative comparison of processes of oil and water based Mud Filtrate invasion and corresponding effects on borehole resistivity measurements
    Geophysics, 2009
    Co-Authors: Jesús M. Salazar, Carlos Torresverdin
    Abstract:

    Some laboratory and qualitative studies have documented the influence of water-based Mud(WBM)-Filtrate invasion on borehole resistivity measurements. Negligible work, however, has been devoted to studying the effects of oil-based Mud(OBM)-Filtrate invasion on well logs and the corresponding impact on the estimation of petrophysical properties. We quantitatively compare the effects of WBM- and OBM-Filtrate invasion on borehole resistivity measurements. We simulate the process of Mud-Filtrate invasion into a porous and permeable rock formation assuming 1D radial distributions of fluid saturation and fluid properties while other petrophysical properties remain constant. To simulate the process of Mud-Filtrate invasion, we calculate a time-dependent flow rate of OBM-Filtrate invasion by adapting the available formulation of the physics of WBM-Filtrate invasion. This approach includes the dynamically coupled effects of Mud-cake growth and multiphase Filtrate invasion. Simulations are performed with a commercia...

  • Effects of Petrophysical Properties on Array-Induction Measurements Acquired in the Presence of Oil-Base Mud-Filtrate Invasion
    Petrophysics, 2008
    Co-Authors: Mayank Malik, Carlos Torres-verdín, Jesús M. Salazar, Gong Li Wang, Hee Jae Lee, Kamy Sepehrnoori
    Abstract:

    We quantify the influence of petrophysical properties on array-induction resistivity measurements acquired in the presence of oil-base Mud (OBM) Filtrate invasion. To simulate OBM-Filtrate invasion, we consider a simple two-component formulation for the oil phase (OBM and reservoir oil) wherein the components are first-contact miscible. Simulations also include the presence of irreducible, capillary-bound, and movable water. The dynamic process of OBM invasion causes the component concentrations to vary with space and time. In addition, the relative mobility ofthe oil phase varies during the process of invasion given that oil viscosity and oil density are both dependent on component concentrations. This behavior in turn conditions the spatial distribution of electrical resistivity and, consequently, the borehole array-induction measurements. We use an implicit pressure, explicit concentration (IMPEC) reservoir simulator with a two-component formulation to reproduce the invasion process in axial-symmetric rock formations penetrated by a vertical well. Simulations of the process of OBM-Filtrate invasion yield two-dimensional spatial distributions of water and oil saturation that are transformed into spatial distributions of electrical resistivity using Waxman-Smits' saturation-resistivity equations. Subsequently, we simulate array-induction measurements with a numerical mode-matching method. Simulation of induction measurements in the presence of OBM are compared against the corresponding measurements acquired in the presence of water-base Mud (WBM) using field measurements from a deepwater Gulf-of-Mexico reservoir. Sensitivity analyses are conducted to quantify the effect of OBM-Filtrate invasion on array-induction logs, including different values of formation porosity-permeability, movable water zone, capillary pressure, relative permeability, Mud-Filtrate invasion rates, and fluid viscosity. In addition, we quantify the effect of changes of rock wettability due to OBM invasion on field measurements. Our study indicates that relative permeability, capillary pressure, and flow rate of invasion control the radial length of invasion of OBM and, consequently, the values and relative separation of apparent resistivity curves. Porous rock formations saturated with movable water entail smooth radial distributions of water saturation which, in turn, result in deep (1.5 ft - 2 ft) radial invasion profiles and relatively large separation of apparent resistivity curves. By contrast, null or marginal separation of apparent resistivity curves occurs when the invaded rock is at irreducible water saturation.

  • Estimation of Dry-Rock Elastic Moduli Based on the Simulation of Mud-Filtrate Invasion Effects on Borehole Acoustic Logs
    All Days, 2007
    Co-Authors: Tobiloluwa B. Odumosu, Carlos Torres-verdín, Jesús M. Salazar, Benjamin Voss, Gong Li Wang
    Abstract:

    This paper (SPE 109879) was accepted for presentation at the SPE Annual Technical Conference and Exhibition, Anaheim, California, USA, 11–14 November 2007, and revised for publication. Original manuscript received for review 30 July 2007. Revised manuscript received for review 27 January 2009. Paper peer approved 26 April 2009. Summary Reliable estimates of dry-rock elastic properties are critical to the accurate interpretation of the seismic response of hydrocarbon reservoirs. We describe a new method for estimating elastic moduli of rocks in-situ based on the simulation of Mud-Filtrate invasion effects on resistivity and acoustic logs. Simulations of Mud-Filtrate invasion account for the dynamic process of fluid displacement and mixing between Mud-Filtrate and hydrocarbons. The calculated spatial distributions of electrical resistivity are matched against resistivity logs by adjusting the underlying petrophysical properties. We then perform Biot-Gassmann fluid substitution on the 2D spatial distributions of fluid saturation with initial estimates of dry-bulk (kdry) modulus and shear rigidity ( dry) and a constraint of Poisson’s ratio ( d) typical of the formation. This process generates 2D spatial distributions of compressional and shear-wave velocities and density. Subsequently, sonic waveforms are simulated to calculate shear-wave slowness. Initial estimates of the dry-bulk modulus are progressively adjusted using a modified Gregory-Pickett (1963) solution of Biot’s (1956) equation to estimate a shear rigidity that converges to the well-log value of shearwave slowness. The constraint on dynamic Poisson’s ratio is then removed and a refined estimate of the dry-bulk modulus is obtained by both simulating the acoustic log (monopole) and matching the log-derived compressional-wave slowness. This technique leads to reliable estimates of dry-bulk moduli and shear rigidity that compare well to laboratory core measurements. Resulting dry-rock elastic properties can be used to calculate seismic compressional-wave and shear-wave velocities devoid of Mud-Filtrate invasion effects for further seismic-driven reservoir-characterization studies.