Publications
186 results found
Muggeridge AH, Smalley PC, 2008, A diagnostic toolkit to detect compartmentalization using time-scales for reservoir mixing, Pages: 1699-1709
Unidentified reservoir compartmentalization through faulting or depositional heterogeneity can have a profound, usually adverse, effect on oil or gas recovery. Thus it is vital to characterize reservoir compartmentalization as early as possible in field life, ideally during appraisal. One signature of compartmentalization is the detection of variable fluid properties (e.g. pressure, fluid contacts, oil or water composition) in different parts of the reservoir. Such spatial variations arise during the burial, structural and filling history of the reservoir, and gradually equilibrate through time. However such spatial variations may persist simply because sufficient time has not yet elapsed for that property to equilibrate, potentially leading to false-positive diagnoses (variations are present but relate to insufficient mixing times, not compartmentalization). In other cases, mixing can occur so rapidly that fluid variations have already mixed, leading to potential false-negative diagnoses (variations not present because mixing has occurred quickly in spite of compartmentalization that will affect the production timescale). It is thus vital to incorporate an understanding of reservoir mixing timescales into the early diagnosis of compartmentalization. This paper provides simple analytic expressions for estimating the time taken for tilted contacts and spatial pressure or compositional variations to return to their equilibrium distribution, as a function of reservoir thickness, length, porosity, permeability, fluid viscosity, density and compressibility. These form a simple and practical diagnostic toolkit. Use of this toolkit reveals many cases where lateral compositional variations do not indicate compartmentalization but result from incomplete mixing due to very slow molecular diffusion. In contrast, pressure may equilibrate across a micro-Darcy, permeability fault in 100,000 years, so uniform pressure does not necessarily guarantee good reservoir communication on
Alkindi A, Muggeridge A, Al-Wahaibi Y, 2008, The influence of diffusion and dispersion on heavy oil recovery by VAPEX, Pages: 486-497
Heavy oil recovery by VAPEX appears to be a promising IOR technique as it uses less energy than SAGD and, if CO2 is injected, can also provide a means of disposing of excess CO2 in the subsurface. Nonetheless field application of this process has been limited due to concerns that favourable laboratory recoveries may not scale up to the field. In particular previous laboratory studies of VAPEX in porous media have obtained significantly higher production rates than predicted either by analytic models derived from Hele-Shaw experiments or numerical simulations. The discrepancy between experiment and models has been explained by assuming greater mixing between vapour and oil than would be expected from molecular diffusion. Justifications for this increase include convective dispersion, an increased surface area due to the formation of oil films on sand grains, imbibition of oil into those films and a greater dependence on drainage height. Convective dispersion seems to be the most plausible mechanism. This paper investigates the role of convective dispersion on oil recovery by VAPEX using a combination of well characterized laboratory experiments and numerical simulation. A first contact miscible fluid system was used so that all mechanisms contributing to increased-mixing apart from convective dispersion were eliminated. Longitudinal and transverse dispersion coefficients were measured experimentally as a function of flow-rate and viscosity ratio. Vapex drainage experiments were then performed over a range of injection rates. The laboratory measurements of oil drainage rate were compared with those predicted by the Butler-Mokrys analytical model and numerical simulation using either molecular diffusion or convective dispersion. Using measured convective dispersion improved prediction of oil drainage rate by 50%. The numerical model was then used to investigate the impact of rate (through viscous to gravity ratio and Peclet number), well separation and reservoir geomet
Carmine L, Aristodemou E, Pain C, et al., 2008, Inversion of time-dependent nuclear well-logging data using neural networks, Geophysical Prospecting, Vol: 56, Pages: 115-140, ISSN: 0016-8025
The purpose of this work was to investigate a new and fast inversion methodology for the prediction of subsurface formation properties such as porosity, salinity and oil saturation, using time-dependent nuclear well logging data. Although the ultimate aim is to apply the technique to real-field data, an initial investigation as described in this paper, was first required; this has been carried out using simulation results from the time-dependent radiation transport problem within a borehole. Simulated neutron and gamma-ray fluxes at two sodium iodide (NaI) detectors, one near and one far from a pulsed neutron source emitting at similar to 14 MeV, were used for the investigation. A total of 67 energy groups from the BUGLE96 cross section library together with 567 property combinations were employed for the original flux response generation, achieved by solving numerically the time-dependent Boltzmann radiation transport equation in its even parity form. Material property combinations (scenarios) and their correspondent teaching outputs (flux response at detectors) are used to train the Artificial Neural Networks (ANNs) and test data is used to assess the accuracy of the ANNs. The trained networks are then used to produce a surrogate model of the expensive, in terms of computational time and resources, forward model with which a simple inversion method is applied to calculate material properties from the time evolution of flux responses at the two detectors. The inversion technique uses a fast surrogate model comprising 8026 artificial neural networks, which consist of an input layer with three input units (neurons) for porosity, salinity and oil saturation; and two hidden layers and one output neuron representing the scalar photon or neutron flux prediction at the detector. This is the first time this technique has been applied to invert pulsed neutron logging tool information and the results produced are very promising. The next step in the procedure is to apply th
Al-Wahaibi YM, Muggeridge AH, Grattoni CA, 2007, Experimental and numerical studies of gas/oil multicontact miscible displacements in homogeneous and crossbedded porous media, 2005 SPE Reservoir Simulation Symposium, Publisher: SOC PETROLEUM ENG, Pages: 62-76, ISSN: 1086-055X
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- Citations: 16
Al-Wahaibi YM, Grattoni CA, Muggeridge AH, 2007, Physical properties (density, viscosity, surface tension, interfacial tension, and contact angle) of the system isopropyl alcohol plus cyclohexene plus water, JOURNAL OF CHEMICAL AND ENGINEERING DATA, Vol: 52, Pages: 548-552, ISSN: 0021-9568
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- Citations: 6
Yang C, Frattoni CA, Muggeridge AH, et al., 2007, Flow of water trough channels filled with in elastically-deformable polymer gels
A mathematical model is developed for the flow of water through a channel impregnated with a polymer gel. The model uses a Brinkman equation along with an experimentally-observed velocity-dependent permeability. Numerical and approximate analytical solutions are given. When combined with a mathematical analysis of oil flow through polymer gels, which is currently underway, these results should help to understand the mechanism of disproportionate permeability reduction, which is the basis of successful polymer gel treatments for water control.
Al-Wahalbi YM, Grattoni CA, Muggeridge AH, 2006, Drainage and imbibition relative permeabilities at near miscible conditions, JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING, Vol: 53, Pages: 239-253, ISSN: 0920-4105
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- Citations: 21
Al-Wahaibi YM, Muggeridge AH, Grattoni CA, 2006, Gas/oil nonequilibrium in multicontact miscible displacements within homogeneous porous media, Pages: 610-631
Compositional simulation is usually used to predict the performance of multi-contact miscible (MCM) recovery schemes. One key assumption in most such simulations is that of instantaneous compositional equilibrium is achieved between phases in each grid block. This is despite the fact that most grid blocks are tens of metres long and at least a metre thick. This paper investigates the non-equilibrium observed in series of multi-contact miscible displacements performed in the laboratory. For simplicity a two-phase, three-component (IPA/water/cyclohexene) liquid system that exhibits an upper critical point at ambient conditions was used. Both vaporising and condensing drives were performed in well-characterised homogenous glass-bead packs. The use of analogue fluids and bead-packs enabled visualisation of the displacements as well as the usual measurements of effluent composition against time and recovery. Non-equilibrium was observed in the effluent from both the condensing and vaporising experiments. This increased with flow-rate but appeared to be independent of the permeability and the length of the bead-pack. Further experiments investigating the influence of gravity on vertical displacements indicated that non-equilibrium may also be a function of the viscous to gravity ratio. Detailed simulation using a commercial compositional simulator was unable to predict this non-equilibrium unless the results were tuned to the experimental observed effluent profiles using alpha factors. This is despite the fact that all PVT data, relative permeabilities and other pack properties were taken directly from experiments. However good match was obtained from a layered model with the permeability distribution obtained from a unit mobility ratio miscible displacement in the same pack. These results are consistent with physical dispersion being the underlying cause of the non-equilibrium. Viscous fingering is discounted due to the low mobility ratio (∼2) of the displacements. C
Al-Shuraiqi H, Muggeridge A, Grattoni CA, 2005, Numerical and experimental investigation into the mechanisms of first contact miscible simultaneous and slug WAG injection, Pages: 304-311
Miscible Water-Alternate-Gas (WAG) injection is currently being performed in many fields around the world and a large number of numerical studies, investigating both simultaneous and slug injection including the effects of slug sizes, gravity and heterogeneity, have been carried out in the past. However there are few laboratory studies to support the numerical work and to understand the interactions between injected fluids during WAG injection. In this paper we investigate the effects of WAG ratio and slug size on WAG recovery efficiency both experimentally (using well-characterised packs) and numerically (using detailed simulation). The use of bead-packs rather than cores enabled us to observe and video-record the fluid interactions during each experiment, as well as the effluent profiles and recovery as a function of time. Thus, all the input data to the simulator were determined directly from the experiment, and there was no need for any history matching. The results are compared with previous experimental studies on simultaneous WAG injection reported by Al-Shuraiqi et al.] We show that for simultaneous injection there exists an optimal WAG ratio that is close to the ratio predicted by the method proposed by Stalkup2. Although the simulator produces good predictions at the optimum WAG ratio, it cannot predict recovery or effluent profiles at higher or lower WAG ratios and viscous fingering is not suppressed to the extent observed in earlier numerical studies reported by Christie3. We also observe that it is not possible to achieve true simultaneous flow of water and gas. Instead the fluids tend to follow segregated paths. We also found that, for slug injection, recovery increases as slug size decreases, approaching that of simultaneous injection at a slug size of 5% PV. The breakdown of the miscible slug does not adversely affect recovery. However stabilization of the miscible fingering is observed as slug size increases, which is not predicted by the simulator.
Al-Wahaibi YM, Muggeridge AH, Grattoni CA, 2005, The effect of cross-bedding laminations on the efficiency of gas/oil multi-contact miscible displacements
A series of well-characterized laboratory experiments in a two-dimensional, cross-bedded beadpack were carried out. A two-phase three-component (isopropyl alcohol (IPA)/water/cyclohexene) liquid system, that exhibits an upper critical point at ambient conditions, was used as the fluid model. The produced oil and gas in the experiments were not to be in compositional equilibrium. This was observed both in homogeneous and heterogeneous packs. As a result the oil recoveries and gas cut predicted by compositional simulation for multi-contact miscible (MCM) displacements in laminated media differed significantly from the experimental results, although an excellent match was obtained for the first contact miscible (FCM) and immiscible displacements. Although the simulator was able to predict the saturation distributions, recovery curves, and gas cuts for the FCM and immiscible displacements in the cross-bedded model with great accuracy, it over-predicted equilibrium oil recovery by as much as 11% for the condensing drive and 12% for the vaporizing drive. This is an abstract of a paper presented at the SPE Europe/EAGE Annual Conference (Madrid, Spain 6/13-16/2005).
Jackson MD, Yoshida S, Muggeridge AH, et al., 2005, Three-dimensional reservoir characterization and flow simulation of heterolithic tidal sandstones, AAPG BULLETIN, Vol: 89, Pages: 507-528, ISSN: 0149-1423
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- Citations: 66
Mahani H, Muggeridge AH, 2005, Improved coarse grid generation using vorticity, Pages: 1787-1794
This paper describes the use of vorticity to optimize the generation of coarse simulation grids from finely gridded geological models, thereby reducing (or removing) the need for two phase upscaling. Vorticity has been used in the simulation of flow in porous media since de Josselin de Jong1 first discussed it in 1960. However this is the first time, to our knowledge, that it has been used in the area of upscaling. Vorticity maps are generated from simulations of single-phase flow in the finely gridded geological model of interest. A coarse simulation grid is then derived which is more refined in areas of high vorticity and coarser in areas of low vorticity. The method is demonstrated for simple, layered and lens heterogeneities as well as Model 1 from the SPE Comparative Study in Upscaling2. Good matches between fine and coarse grid simulations of waterflooding are obtained, compared with using a conventionally generated coarse grid model. Copyright 2005, Society of Petroleum Engineers.
Al-Wahaibi YM, Muggeridge AM, Grattoni CA, 2005, The effect of cross-bedding laminations on the efficiency of gas/oil multi-contact miscible displacements, Pages: 825-848
Many oil fields produce from fluvial sands where cross bedding lamination is one of the most common type of small-scale heterogeneity. To our knowledge, there are no published studies on the effects of cross-bedding laminations on multi-contact miscible (MCM) displacement processes and how they might alter the development of miscibility during oil recovery by gas displacement. This work aims to remedy this deficiency. A particular objective was to quantify the accuracy of compositional simulation when modelling sub-miscible displacements in these systems. A series of well-characterized laboratory experiments in a two-dimensional, cross-bedded beadpack were carried out. A two-phase three-component (IPA/water/cyclohexene) liquid system, that exhibits an upper critical point at ambient conditions, was used as the fluid model. First contact miscible (FCM), immiscible and MCM displacement experiments were performed in the model laminated media. They were then simulated using a commercial compositional simulator with a single set of EOS parameters and without using history matching (the relative permeabilities as a function of IFT were obtained independently from displacement experiments in homogeneous packs). The produced oil and gas in the experiments were found not to be in compositional equilibrium. This was observed both in homogeneous and heterogeneous packs. As a result the oil recoveries and gas cut predicted by compositional simulation for MCM displacements in laminated media differed significantly from the experimental results, although an excellent match was obtained for the FCM and immiscible displacements. The use of alpha factors, derived from MCM experiments in a homogeneous pack gave a much-improved prediction of experimental results for both condensing and vaporizing gas drives in both homogeneous and cross-bedded porous media. Copyright 2005, Society of Petroleum Engineers.
Muggeridge AM, Jackson MD, Agbehi O, et al., 2005, Quantifying bypassed oil in the vicinity of discontinuous shales during gravity dominated flow, Pages: 903-913
Gravity-stable, miscible gas injection is a common oil recovery technique throughout the world. In homogeneous environments recovery efficiencies may be more than 90%. However the influence of heterogeneity on the sweep efficiency in these recovery schemes is not well understood. For example most clastic reservoirs contain 'discontinuous' shales that cannot be correlated between wells. Several numerical studies have suggested that these may cause significant bypassing of oil during waterflooding or gas injection. However flow experiments and detailed simulation of viscous dominated displacements, without gravity, indicate that very little oil is bypassed1. In this paper, we investigate flow patterns around discontinuous shales during vertical, gravity-influenced miscible gas injection in well-characterised bead-pack experiments at three flow-rates corresponding to unstable, partly stable and completely stable flow regimes. We examine the volume of oil bypassed and whether viscous fingering is reduced by gravity or altered by the presence of a discontinuous shale. The results are compared to the predictions of detailed simulation. We find that, during miscible displacements, an isolated shale causes negligible bypassing. However, during adverse mobility ratio displacements, the simulation program erroneously predicts significant bypassing of oil both upstream and downstream of the shale at high and intermediate flow-rates. Copyright 2005, Society of Petroleum Engineers.
Al-Wahaibi YM, Muggeridge AH, Grattoni CA, 2005, Experimental and numerical studies of gas/oil multicontact miscible displacements in homogeneous porous media, Pages: 127-142
Both vaporizing and condensing miscible gas floods are being conducted in a large number of reservoirs worldwide. The performance of these gas floods is usually determined via a combination of laboratory analysis and compositional simulation. However the ability of numerical simulation to correctly predict the progress of a multi-contact miscible displacement has not been fully verified. This paper investigates the physical processes occurring during multi-contact miscible displacement the ability of the Coats correlation to model the changes in gas-oil relative permeabilities with interfacial tension (IFT) and the associated inaccuracies in predicted oil recovery the importance of gas/oil disequilibrium on the prediction of oil recovery and gas-oil ratio These objectives are achieved by using a commercial compositional simulator to predict the behaviour of multi-contact miscible (MCM) floods in well-characterised, bead-pack experiments. Both condensing and vaporizing drives are investigated using a ternary liquid system that exhibits an upper critical point at ambient conditions. Relative permeabilities as a function of IFT were obtained independently from displacement experiments. Glass bead-packs permitted the visualisation of the displacements whilst the effluent profiles in terms of composition and phase volume versus time were measured using a calibration with refractive index of the fluids. efficient with about 90% of the oil in place recovered at one pore volume injected. Compared to immiscible displacements, breakthrough and total recoveries were increased by 8% and 20% respectively. However, in both condensing and vaporising drives, the compositional simulation (that assumes equilibrium conditions) over-predicted oil recovery. Further simulations identified that these errors are due to inaccuracies in Coats' correlation describing the behaviour of relative permeabilities as miscibility is approached and/or the fact that the produced fluids were not in comp
Muggeridge A, Abacioglu Y, England W, et al., 2005, The rate of pressure dissipation from abnormally pressured compartments, AAPG BULLETIN, Vol: 89, Pages: 61-80, ISSN: 0149-1423
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- Citations: 27
Muggeridge A, Abacioglu Y, England W, et al., 2004, Dissipation of anomalous pressures in the subsurface, JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 109, ISSN: 2169-9313
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- Citations: 10
Smalley C, England W A, Muggeridge A, et al., 2004, Rates of Reservoir Fluid Mixing: Implications for Interpretation of Fluid Data, Understanding Petroleum Reservoirs: Towards an Integrated Reservoir Engineering, Editors: Cubitt M, England A, Larter R, England, Publisher: Geological Society, ISBN: 9781862391680
Bijeljic B, Muggeridge AH, Blunt MJ, 2004, Pore-scale modeling of longitudinal dispersion, WATER RESOURCES RESEARCH, Vol: 40, ISSN: 0043-1397
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- Citations: 156
Al-Mahrooqi SH, Grattoni CA, Muggeridge AH, et al., 2004, Pore-scale modelling of NMR relaxation for the characterization of wettability, 8th international symposium on reservoir wettability, Houston, Texas
Jackson MD, Muggeridge AH, Yoshida S, et al., 2003, Upscaling permeability measurements within complex heterolithic tidal sandstones, MATHEMATICAL GEOLOGY, Vol: 35, Pages: 499-520, ISSN: 0882-8121
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- Citations: 44
Bijeljic B, Muggeridge AH, Blunt MJ, 2003, Multicomponent mass transfer across water films during hydrocarbon gas injection, CHEMICAL ENGINEERING SCIENCE, Vol: 58, Pages: 2377-2388, ISSN: 0009-2509
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- Citations: 27
Hastings JJ, Muggeridge AH, Blunt MJ, 2003, A new streamline method for evaluating uncertainty in small-scale, two-phase flow properties, SPE JOURNAL, Vol: 8, Pages: 32-40, ISSN: 1086-055X
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- Citations: 1
Al-Shuraiqi HS, Muggeridge AH, Grattoni CA, 2003, Laboratory investigation of first contact miscible WAG displacement: the effects of Wag radio and flow rate (SPE 84894), Richardson, Texas, SPE international improved oil recovery conference, Kuala Lumpur, Malaysia, 20 - 21 October 2003, Publisher: SPE International
Yang CH, Grattoni CA, Muggeridge AH, et al., 2002, Flow of water through channels filled with deformable polymer gels, JOURNAL OF COLLOID AND INTERFACE SCIENCE, Vol: 250, Pages: 466-470, ISSN: 0021-9797
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- Citations: 16
Bijeljic BR, Muggeridge AH, Blunt MJ, 2002, Effect of Composition on Waterblocking for Multicomponent Gasfloods, Pages: 3125-3135
During tertiary miscible gas injection direct contact, between gas and oil can be prevented by water surrounding residual oil. The principal aim of our study is to assess the importance of this waterblocking phenomenon in multicomponent gas injection. We study this process using a multicomponent porescale model. Light components in the gas dissolve in the water and diffuse through the water to reach the oil. This causes the oil to swell. Eventually the oil swells sufficiently to contact the gas directly. However, components in the oil can diffuse into the gas, causing the oil to shrink and preventing the contact. We apply our model to a variety of first-contact and multiple-contact miscible gas/oil systems from published field studies. Due to the low solubility of hydrocarbons in water, oil swelling and shrinkage can prevent direct contact for many days to years. We show that increasing the miscibility of injected gas, by, for instance, moving from a multi-contact miscible to a first-contact miscible displacement increases the time taken to achieve direct gas/oil contact. This leads to an extended two-phase region in the reservoir, even for a thermodynamically miscible gas flood.
Coll C, Muggeridge A, Jing XD, 2002, A new method to upscale heterogeneous reservoirs for a range of force regimes, Soft computing for reservoir characterization and modeling, Editors: Wong, Nikravesh, Aminzadeh, Wong, Nikravesh, Aminzadeh, Heidelberg, Publisher: Physica-Verlag, Pages: 218-240, ISBN: 9783790814217
Bijeljic B, Muggeridge A, Blunt M, 2002, Effect of composition on waterblocking for multicomponent gasfloods, SPE annual technical conference and exhibition, San Antonio, Texas, 29 September - 2 October 2002
Muggeridge AH, Jackson MD, Al-Mahrooqi SH, et al., 2002, Quantifying bypassed oil in the vicinity of discontinuous shales (SPE 77487), Richardson, Texas, SPE annual conference and exhibition, San Antonio, Texas, 29 September - 2 October 2002, Publisher: Society of Petroleum Engineers
Coll C, Muggeridge A, Jing XD, 2002, Regional upscaling: a new method to upscale heterogeneous reservoirs for a range of force regimes, Studies in Fuzziness and Soft Computing, Vol: 80, Pages: 419-464, ISSN: 1434-9922
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