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Introduction In the Chapter 5 we considered the case in which transported material did not influence the fluid flow. Now we consider the situation in which at least two distinct fluids are present in the porous medium and the presence or... more
Introduction In the Chapter 5 we considered the case in which transported material did not influence the fluid flow. Now we consider the situation in which at least two distinct fluids are present in the porous medium and the presence or absence of one of the fluids will have a significant impact on the flow of the other. In Chapter 2 we discussed the governing equations for the flow of such immiscible fluids, so we will limit our remarks to the key features of such flow. One restriction maintained in this chapter is that the mass transfer between fluid phases is negligible. Such a restriction is not necessary for the adoption of trajectory-based methods, but simply serves to limit the complexity of our treatment. Governing equations for two-phase flow A classic example of the type of immiscible fluid flow that we have in mind is the movement of oil and water within a porous material. In fact, this example illustrates some of the most important characteristics of multiphase fluid flow within a solid containing connected pore space. For example, it is often the case that the molecules of one fluid will have an affinity for the molecules of the solid matrix. This fluid tends to adhere to the solid surface of the pores, or to wet the solid. We will denote the saturation of this ‘wetting’ phase by S w . The other fluid, simply referred to as the ‘non-wetting’ phase, has less attraction for the solid and tends to occupy the central regions of the pores. The saturation of the non-wetting phase is denoted by S n . Since the pore volume of the medium is completely occupied by some combination of the two fluids, the saturations must sum to unity S w + S n = 1. The differential affinity for the solid has another consequence, leading to surface tension and curvature in the boundary separating the two fluids. The result is greater pressure in the non-wetting fluid relative to the pressure in the wetting fluid. This pressure difference is termed the capillary pressure, p c , and is most frequently assumed to be a unique function of the fluid saturation: The capillary pressure curve p c (S w ) is an important aspect of multiphase fluid flow and a key constitutive equation. However, the difference in capillary pressure is often much smaller than the average fluid pressure.
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Streamline Simulation: Theory and Practice presents a systematic exposition of current streamline simulation technology—its foundations, historical precedents, applications, field studies, and limitations. This textbook emphasizes the... more
Streamline Simulation: Theory and Practice presents a systematic exposition of current streamline simulation technology—its foundations, historical precedents, applications, field studies, and limitations. This textbook emphasizes the unique features of streamline technology that in many ways complement conventional finite-difference simulation. The book should appeal to a broad audience in petroleum engineering and hydrogeology; it has been designed for use by undergraduate and graduate students, current practitioners, educators, and researchers. Included in the book is a CD-ROM with a working streamline simulator and exercises to provide the reader with hands-on experience with the technology.
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Subsurface sequestration of CO2 has received attention from the global scientific community in response to climate change concerns due to higher concentrations of CO2 in the atmosphere. Mathematical models have thus been developed to aid... more
Subsurface sequestration of CO2 has received attention from the global scientific community in response to climate change concerns due to higher concentrations of CO2 in the atmosphere. Mathematical models have thus been developed to aid the understanding of multiphase flow of CO2 and trapping mechanisms during subsurface sequestration. Solutions to these models have ranged from analytical, semi-analytical and numerical methods, each having its merits and limitations in terms of underlying physics, computational speed and accuracy. We present a streamline-based method for modeling CO2 transport in saline aquifers which leverages sub-grid resolution capabilities of streamlines in capturing small- and large-scale heterogeneity effects during CO2 injection. Our approach is based on an iterative IMPES scheme and accounts for the physical processes characteristic of CO2 injection in saline aquifers. These include compressibility, gravity, capillarity, mutual solubility, precipitation and...
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This paper describes a novel streamline-based rate allocation approach to maximize oil recovery from polymerfloods and its application to an ongoing polymerflood in the Mangala field, India which is one of the largest polymerfloods in the... more
This paper describes a novel streamline-based rate allocation approach to maximize oil recovery from polymerfloods and its application to an ongoing polymerflood in the Mangala field, India which is one of the largest polymerfloods in the world. With over 130 injectors and producers, the field-scale optimization is challenging because of the long simulation times, operational constraints at the well, group and field level and changing field conditions.The FM-1 unit which is the main producing zone of the Mangala field comprises of multi-layered single storied fluvial channel sands of thickness ranging 3-10m with excellent flow characteristics. The gross thickness of FM-1 is about 90m. The sand is under a five-spot pattern polymerflood with a well spacing of aproximately 200m. A finite difference simulator is used for modeling the polymerflood performance with all relevant physics (mobility control, adsorption, residual resistance factor, polymer rheology/shear thinning, inaccessible...
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We present a novel and efficient approach to integrate frequent time lapse (4D) seismic data into high resolution reservoir models based on seismic onset times, defined as the calendar time when the seismic attribute crosses a... more
We present a novel and efficient approach to integrate frequent time lapse (4D) seismic data into high resolution reservoir models based on seismic onset times, defined as the calendar time when the seismic attribute crosses a pre-specified threshold value at a given location. Our approach reduces multiple time- lapse seismic survey data into a single map of onset times, leading to substantial data reduction for history matching while capturing all relevant information regarding fluid flow in the reservoir. Hence, the proposed approach is particularly well suited when frequent seismic surveys are available using permanently embedded sensors.Our history matching workflow consists of two stages: global and local. At the global stage of history matching, large-scale features such as regional permeabilities, pore volumes, temperature and fluid saturations are adjusted to match seismic and bottomhole pressure data using a Pareto-based multiobjective history matching workflow. Rather than...
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We present a probabilistic approach for integrating multiple data into subsurface flow models. Our approach is based on a Bayesian framework whereby we exhaustively sample the multi-dimensional posterior distribution to define a Pareto... more
We present a probabilistic approach for integrating multiple data into subsurface flow models. Our approach is based on a Bayesian framework whereby we exhaustively sample the multi-dimensional posterior distribution to define a Pareto front which represents the trade-off between multiple objectives during history matching. These objectives can be matching of water-cut, GOR, BHP and time-lapse seismic data. For field applications, these objectives do not necessarily move in tandem because of measurement errors and also interpretative nature of the seismic data. Our proposed method is built on a Differential Evolution Markov Chain Monte Carlo (DEMC) algorithm in which multiple Markov Chains are run in parallel. First, a dominance relationship is established amongst multiple models. This is followed by construction of the posterior distribution based on a hypervolume measure. A unique aspect of our method is the proposal selection which is based on a random walk on two arbitrarily sel...
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Summary We discuss two inverse approaches to construction of fracture-flow models and their application in characterizing a fractured limestone formation. The first approach creates "equivalent discontinuum" models that... more
Summary We discuss two inverse approaches to construction of fracture-flow models and their application in characterizing a fractured limestone formation. The first approach creates "equivalent discontinuum" models that conceptualize the fracture system as a partially filled lattice of conductors that are locally connected or disconnected to reproduce the observed hydrologic behavior. An alternative approach— i.e., "variable aperture lattice" models—represent the fracture system as a fully filled network composed of conductors of varying apertures or hydraulic conductivities. The fracture apertures are sampled from a specified distribution, usually log-normal, which is consistent with field data. The spatial arrangement of apertures is altered through inverse modeling to fit the available hydrologic data, such as transient pressure and/or tracer data. Unlike traditional discrete fracture-network approaches that rely on fracture geometry to reproduce flow and tran...
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SUMMARYOur limited knowledge of the relationship between changes in the state of an aquifer or reservoir and the corresponding changes in the elastic moduli, that is the rock physics model, hampers the effective use of time-lapse seismic... more
SUMMARYOur limited knowledge of the relationship between changes in the state of an aquifer or reservoir and the corresponding changes in the elastic moduli, that is the rock physics model, hampers the effective use of time-lapse seismic observations for estimating flow properties within the Earth. A central problem is the complicated dependence of the magnitude of time-lapse changes on the saturation, pressure, and temperature changes within an aquifer or reservoir. We describe an inversion methodology for reservoir characterization that uses onset times, the calendar time of the change in seismic attributes, rather than the magnitude of the changes. We find that onset times are much less sensitive than magnitudes to the rock physics model used to relate time-lapse observations to changes in saturation, temperature and fluid pressure. We apply the inversion scheme to observations from daily monitoring of enhanced oil recovery at the Peace River field in Canada. An array of 1492 bur...
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A series of earthquakes was recorded along a mapped fault system near Azle, Texas in 2013. To identify the mechanism of seismicity, coupled fluid flow and geomechanical simulation is carried out to model fluid injection/production and the... more
A series of earthquakes was recorded along a mapped fault system near Azle, Texas in 2013. To identify the mechanism of seismicity, coupled fluid flow and geomechanical simulation is carried out to model fluid injection/production and the potential onset of seismicity. Sensitivity studies for a broad range of reservoir and geomechanical parameters are performed and the calibrated models are used to identify controlling mechanisms for seismicity in the Azle area, North Texas and its relationship to hydrocarbon production and fluid injection in the vicinity. Geologic, production/injection, and seismicity data are gathered to build a detailed simulation model with coupled fluid flow and geomechanics. Geomechanical simulation results are used to calculate cumulative seismic moment magnitude. Sensitivity analyses for injection well head pressure and earthquake data are performed over a range of reservoir and geomechanical parameters. Influential parameters are selected to perform a paret...
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A series of earthquakes was recorded along a mapped fault system near Azle, Texas in 2013. To identify the mechanism of seismicity, coupled fluid flow and geomechanical simulation is carried out to model fluid injection/production and the... more
A series of earthquakes was recorded along a mapped fault system near Azle, Texas in 2013. To identify the mechanism of seismicity, coupled fluid flow and geomechanical simulation is carried out to model fluid injection/production and the potential onset of seismicity. Sensitivity studies for a broad range of reservoir and geomechanical parameters are performed and the calibrated models are used to identify controlling mechanisms for seismicity in the Azle area, North Texas and its relationship to hydrocarbon production and fluid injection in the vicinity. Geologic, production/injection, and seismicity data are gathered to build a detailed simulation model with coupled fluid flow and geomechanics. Geomechanical simulation results are used to calculate cumulative seismic moment magnitude. Sensitivity analyses for injection well head pressure and earthquake data are performed over a range of reservoir and geomechanical parameters. Influential parameters are selected to perform a paret...
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We have performed a site specific study of the mechanics of induced seismicity in the Azle area, North Texas, using a coupled 3-D fluid flow and poroelastic simulation model, extending from the overburden into the crystalline basement.... more
We have performed a site specific study of the mechanics of induced seismicity in the Azle area, North Texas, using a coupled 3-D fluid flow and poroelastic simulation model, extending from the overburden into the crystalline basement. The distinguishing feature of this study is that we account for the combined impact of water disposal injection and gas and water production on the pore pressure and stress distribution in this area. The model is calibrated using observed injection well head pressures and the location, timing, and magnitude of seismic events. We utilized a stochastic multi-objective optimization approach to obtain estimated ranges of fluid flow and poroelastic parameters, calibrated to the pressure, rate and seismic event data. Mechanisms for induced seismicity were examined using these calibrated models. The calibrated models show no fluid movement or pressure increase in the crystalline basement, although there is plastic strain accumulation for the weaker elements ...
Research Interests: Geology and Geophysics
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Downhole temperature measurements is one of the solutions to understand downhole flow conditions, especially in complex well/reservoir domains such as multi-stage fractured horizontal wells. In the past, models and methodologies have been... more
Downhole temperature measurements is one of the solutions to understand downhole flow conditions, especially in complex well/reservoir domains such as multi-stage fractured horizontal wells. In the past, models and methodologies have been developed for fracture diagnosis for multiple-stage fractured horizontal wells. They are based on either semi-analytical approach for simplicity or reservoir simulation for generality. The challenges are that semi-analytical models are not robust enough to describe complex fracture systems, while numerical simulation is computationally expensive and impractical for routine inversion. To develop a comprehensive approach to translate temperature to flow profile, we adopted Fast Marching Method in simulating both heat transfer and velocity/pressure field in the domain of interest (heterogeneous reservoir with multiple fractured horizontal wells). Fast Marching Method (FMM) is a relatively new approach which is efficient in front tracking. Previous stu...
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ABSTRACT Novel heterogeneity parameterization for groundwater model calibrationParameterization dependence upon grid connectivity information aloneAdaptive multiscale parameter estimation balancing model and data resolution
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Flow simulation of multimillion grid cell models with hundreds of wells and decades long production history can be extremely time-consuming. This often limits the applicability of assisted history matching techniques. A pragmatic solution... more
Flow simulation of multimillion grid cell models with hundreds of wells and decades long production history can be extremely time-consuming. This often limits the applicability of assisted history matching techniques. A pragmatic solution to this problem is grid coarsening which is now embedded in many commercial reservoir simulators. Instead of up-scaling geological models in external packages, grid cells are automatically amalgamated within the simulator while preserving flux distribution and reducing the total number of active cells. The resulting speedup can be significant, often only at small loss of accuracy. Both characteristics are essential elements of any inversion technique in a multimillion grid cell environment. For water-flood history matching, we have utilized a commercial finite-volume simulator and the streamline-based generalized travel time inversion whereby water-cut behavior is matched by adjusting inter-well permeabilities. To apply the assisted history matchin...
Unconventional reservoirs are characterized by sufficiently low permeabilities so that the pressure depletion from a producing well may not propagate far from the well during the life of a development. This is in contrast to conventional... more
Unconventional reservoirs are characterized by sufficiently low permeabilities so that the pressure depletion from a producing well may not propagate far from the well during the life of a development. This is in contrast to conventional plays where the pressure transients may probe the entire reservoir in weeks to months. The concept of depth of investigation and its application to unconventional reservoirs provide the understanding necessary to describe and optimize the interaction between complex multi-stage fractured wells, reservoir heterogeneity, drainage volumes, pressure depletion, well rates, and the estimated ultimate recovery. Previous studies have performed unconventional reservoir analysis using more conventional reservoir simulation techniques. High resolution local PEBI grids and global corner point grids have been used to represent complex fracture geometry and conductivity and estimate subsequent well performance. However, these techniques do not provide the more ge...
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Copyright 2008, Society of Petroleum Engineers This paper was prepared for presentation at the 2008 SPE/DOE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA, 1923 April 2008. This paper was selected for presentation by an SPE... more
Copyright 2008, Society of Petroleum Engineers This paper was prepared for presentation at the 2008 SPE/DOE Improved Oil Recovery Symposium held in Tulsa, Oklahoma, USA, 1923 April 2008. This paper was selected for presentation by an SPE program committee ...
Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE Annual Technical Conference and Exhibition held in New Orleans, Louisiana, USA, 47 October 2009. This paper was selected for... more
Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE Annual Technical Conference and Exhibition held in New Orleans, Louisiana, USA, 47 October 2009. This paper was selected for presentation by an SPE program ...
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The work of Akhil Datta-Gupta and Yalchin Efendiev is partially supported by DOE (DE-FG03-00ER15034), NSF CMG 0724704, and KAUST award number KUS-C1-016-04.
Integrating dynamic data into high resolution reservoir models is a crucial aspect of any optimal reservoir development and management strategy. In this regard, pressure data provides several advantages. First, pressure transient tests... more
Integrating dynamic data into high resolution reservoir models is a crucial aspect of any optimal reservoir development and management strategy. In this regard, pressure data provides several advantages. First, pressure transient tests are easier and less expensive to carry out in the field. Second, pressure responses can be obtained early in the field life compared to watercut or tracer data. Finally, the pressure perturbations travel much faster compared to tracer or water front, resulting in quicker response in the field. This makes interference tests much more appealing compared to tracer tests which may require months to see a field response. However, the computation cost and localized nature of pressure sensitivities pose difficulties in history matching transient pressure data with a finite difference model. Also, pressure tests from multiple wells are difficult to analyze because of superposition of pressure responses. We propose a fast and robust approach to integrating tra...
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Summary Predicting permeability from well logs typically involves classification of the well-log response into relatively homogeneous subgroups based on electrofacies, Lithofacies, or hydraulic flow units (HFUs). The electrofacies-based... more
Summary Predicting permeability from well logs typically involves classification of the well-log response into relatively homogeneous subgroups based on electrofacies, Lithofacies, or hydraulic flow units (HFUs). The electrofacies-based classification involves identifying clusters in the well-log response that reflect "similar" minerals and lithofacies within the logged interval. This statistical procedure is straightforward and inexpensive. However, identification of lithofacies and HFUs relies on core-data analysis and can be expensive and time-consuming. To date, no systematic study has been performed to investigate the relative merits of the three methods in terms of their ability to predict permeability in uncored wells. The purpose of this paper is three-fold. First, we examine the interrelationship between the three approaches using a powerful and yet intuitive statistical tool called "classification-tree analysis." The tree-based method is an exploratory ...
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Summary The ensemble Kalman filter (EnKF) has gained increased popularity for history matching and continuous reservoir-model updating. It is a sequential Monte Carlo approach that works with an ensemble of reservoir models. Specifically,... more
Summary The ensemble Kalman filter (EnKF) has gained increased popularity for history matching and continuous reservoir-model updating. It is a sequential Monte Carlo approach that works with an ensemble of reservoir models. Specifically, the method uses cross covariance between measurements and model parameters estimated from the ensemble. For practical field applications, the ensemble size needs to be kept small for computational efficiency. However, this leads to poor approximations of the cross covariance and can cause loss of geologic realism from unrealistic model updates outside the region of the data influence and/or loss of variance leading to ensemble collapse. A common approach to remedy the situation is to limit the influence of the data through covariance localization. In this paper, we show that for three-phase-flow conditions, the region of covariance localization strongly depends on the underlying flow dynamics as well as on the particular data type that is being ass...
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Summary Field-scale rate optimization problems often involve highly complex reservoir models, production-and-facilities related constraints, and a large number of unknowns. These factors make optimal reservoir management through rate- and... more
Summary Field-scale rate optimization problems often involve highly complex reservoir models, production-and-facilities related constraints, and a large number of unknowns. These factors make optimal reservoir management through rate- and flood-front control difficult without efficient optimization tools. Some aspects of the optimization problem have been studied before mainly using an optimal control theory. However, the applications to date have been rather limited to small problems because of the computation time and the complexities associated with the formulation and solution of adjoint equations. Field-scale rate optimization for maximizing waterflood sweep efficiency under realistic field conditions has remained largely unexplored. This paper proposes a practical and efficient approach for computing optimal injection and production rates, thereby managing the waterflood front to maximize sweep efficiency and delaying the arrival time to minimize water cycling. Our work relies...
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Summary We present a streamline-based approach for estimating relative permeabilities from production data. The streamline approach offers two principal advantages. First, we can analytically compute the sensitivity of the production... more
Summary We present a streamline-based approach for estimating relative permeabilities from production data. The streamline approach offers two principal advantages. First, we can analytically compute the sensitivity of the production response with respect to relative permeability parameters. The approach is extremely fast and requires a single streamline simulation run. Second, we can exploit the analogy between streamlines and seismic ray tracing to develop a formalism for efficient inversion of production data. For relative permeability representations we have used the commonly used power functions and also a more flexible representation through the use of B-splines. The relative advantages of these representations are examined through inversions of water-cut data from a nine-spot pattern. Finally, we address the underlying challenges associated with the simultaneous estimation of absolute and relative permeabilities from production data. We systematically investigate the nonuniqu...
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... the model, all levels of detail or all parameters are evaluated simultaneously using a regularization term that effectively promotes the removal of redundant parameters, as implied by available observations, from the estimation... more
... the model, all levels of detail or all parameters are evaluated simultaneously using a regularization term that effectively promotes the removal of redundant parameters, as implied by available observations, from the estimation problem ( [Jafarpour et al., 2010] , [Li and Jafarpour ...
Research Interests: Forecasting, Model Updating, Low Frequency, Level Of Detail (LOD), Heterogeneity, and 15 morePermeability, Spatial Scale, Discrete Cosine Transform, Inverse Problem, Inversion, Local minima, Petroleum science, Flow Regime, Waste minimisation, Spatial resolution, Parameterization, Large Scale, Low Resolution, Minimization, and Frequency Domain
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Abstract 3-D streamlines provide an effective tool for reservoir management because of their ability to display reservoir flow and well connections in a physically intuitive manner. Streamlines have been extensively used to investigate... more
Abstract 3-D streamlines provide an effective tool for reservoir management because of their ability to display reservoir flow and well connections in a physically intuitive manner. Streamlines have been extensively used to investigate the interaction between heterogeneity and well patterns and also for rate allocation and pattern balancing. More recently, streamlines have been used in conjunction with constrained optimization techniques for improving waterflood performance via rate control. Field scale rate optimization problems, however, involve highly complex reservoir models, production and facilities constraints and a large number of unknowns, making them inaccessible for routine waterflood management. In this paper we provide a simple and easy to use workflow for waterflood rate optimization using streamline-based flood efficiency maps that display the flux and time of flight distribution amongst producing wells. We demonstrate the use of flood efficiency map to optimize the injection/production rates to maximize waterflood sweep efficiency by equalizing the average time of flight (TOF) amongst the producing wells in regional basis. Our optimization approach is extremely efficient because it relies on simple analytic calculations to compute weighting factors for injection and production rates to minimize the TOF variance amongst producing wells. Because the approach does not rely on formal and complex optimization tools, it is particularly well-suited for large-scale field application. Also, the approach can be used with both streamline and finite difference simulators. For finite-difference simulations, the streamlines and time of flight are derived from the flux field generated by the simulator. Multiple examples are presented to support the robustness and efficiency of the proposed waterflood management scheme. These include 2D synthetic examples for validation and a 3D field application.
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Abstract Current practice of well placement in tight gas reservoirs generally involves the use of empirical correlations based on reservoir properties and analysis of past production histories and/or pressure maps from flow simulation. No... more
Abstract Current practice of well placement in tight gas reservoirs generally involves the use of empirical correlations based on reservoir properties and analysis of past production histories and/or pressure maps from flow simulation. No rigorous procedure is available to compute well drainage volumes in the presence of heterogeneity controlled by the distribution and orientation of natural fractures. The situation is complicated by the routine use of complex wells in tight gas reservoirs and the presence of multistage hydraulic fractures. The computation of drainage volume will be critical to our understanding of the interaction between existing wells, potential infill locations and the estimated ultimate recovery (EUR) computations. We propose a rigorous approach for well drainage volume calculations in tight gas reservoirs based on the flux field derived from dual porosity finite-difference simulation and demonstrate its application to optimize well placement. Our approach relies on a high frequency asymptotic solution of the diffusivity equation and emulates the propagation of a ‘pressure front’ along gas streamlines. The proposed approach is a generalization of the radius of drainage concept in well test analysis ( Lee, 1982 ). The method allows us not only to compute rigorously the well drainage volumes as a function of time but also examine the potential impact of infill wells on the drainage volumes of existing producers. Using these results, we present a systematic approach to optimize well placement to maximize the EUR. We demonstrate the power and utility of our method using both synthetic and field applications. The synthetic example is used to validate our approach by establishing consistency between the drainage volume calculations from streamlines and the EUR computations based on detailed finite-difference simulations. We also present comparison of our approach with analytic drainage volume calculations for simplified cases. Finally, we present a field example whereby we utilize the streamline-based drainage volumes to identify depleted sands and generate a reservoir ‘depletion capacity’ map to optimize infill well placement based on the undepleted and undrained regions. The field application clearly demonstrates a systematic approach to optimal well placement in tight gas reservoirs.
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We have developed an efficient approach of petroleum reservoir model calibration that integrates 4D seismic surveys together with well-production data. The approach is particularly well-suited for the calibration of high-resolution... more
We have developed an efficient approach of petroleum reservoir model calibration that integrates 4D seismic surveys together with well-production data. The approach is particularly well-suited for the calibration of high-resolution reservoir properties (permeability) because the field-scale seismic data are areally dense, whereas the production data are effectively averaged over interwell spacing. The joint calibration procedure is performed using streamline-based sensitivities derived from finite-difference flow simulation. The inverted seismic data (i.e., changes in elastic impedance or fluid saturations) are distributed as a 3D high-resolution grid cell property. The sensitivities of the seismic and production surveillance data to perturbations in absolute permeability at individual grid cells are efficiently computed via semianalytical streamline techniques. We generalize previous formulations of streamline-based seismic inversion to incorporate realistic field situations such a...
Research Interests: Geology and Geophysics
Abstract Experience has shown that fractures and faults within a given array are not all equally conductive or well-connected. To investigate new techniques for locating conductive fracture flow paths, a series of high resolution (1 to 10... more
Abstract Experience has shown that fractures and faults within a given array are not all equally conductive or well-connected. To investigate new techniques for locating conductive fracture flow paths, a series of high resolution (1 to 10 kHz) crosswell and single well seismic surveys and interference tests were conducted in a shallow five spot well array penetrating a fractured limestone formation. Two inverse approaches for constructing fracture flow models were applied to the interference test data. Both approaches successfully reproduced the transient pressure behaviour at the pumping and observation wells and indicated a preferential fracture flow path between two wells aligned in an east-northeast direction, the dominant direction of fracturing mapped in the area. Crosswell and single well seismic experiments were performed before and after air injection designed to displace water from the fracture flow path and increase seismic visibility. The crosswell experiments showed that replacement of water with gas produces significant changes in the seismic signal. The single well reflection surveys were able to precisely locate the position of the fracture flow path. This location was confirmed by core from a slant well which intersected a single open fracture at the targeted depth.
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Summary We propose a simple, cost-effective approach to obtaining permeability estimates in heterogeneous carbonate reservoirs using commonly available well logs. Our approach follows a two-step procedure. First, we classify the well-log... more
Summary We propose a simple, cost-effective approach to obtaining permeability estimates in heterogeneous carbonate reservoirs using commonly available well logs. Our approach follows a two-step procedure. First, we classify the well-log data into electrofacies types. ...
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Summary We present a streamline-based approach for estimating relative permeabilities from production data. The streamline approach offers two principal advantages. First, we can analytically compute the sensitivity of the production... more
Summary We present a streamline-based approach for estimating relative permeabilities from production data. The streamline approach offers two principal advantages. First, we can analytically compute the sensitivity of the production response with respect to relative ...
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We exploit an analogy between streamlines and seismic ray tracing to develop an efficient formalism for integrating dynamic data into high-resolution reservoir models. Utilizing concepts from asymptotic ray theory in seismic and diffusive... more
We exploit an analogy between streamlines and seismic ray tracing to develop an efficient formalism for integrating dynamic data into high-resolution reservoir models. Utilizing concepts from asymptotic ray theory in seismic and diffusive electromagnetic ...