bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laboratory Investigations of CO2 Near-miscible Application in Arbuckle Reservoir
Authors: Bui L. H. , Tsau J. S. , Willhite G. P. 
Published: July 2010

Abstract
Carbon dioxide (CO2) is a proven enhanced oil recovery technology. However, many reservoirs are located at shallow depths or geologic conditions such that CO2 can not be injected at pressures above the MMP. CO2 injection is usually not considered as an enhanced oil recovery process in these reservoirs. When CO2 is injected below the MMP, displacement efficiency decreases as a result of the loss of miscibility. Near miscible displacement has sometimes been referred to as the process occurring between immiscible and miscible pressures, but has never been clearly defined. This paper describes laboratory study of CO2 near miscible displacement in an Arbuckle reservoir in Kansas.
Phase behavior studies between CO2 and Arbuckle crude oil were carried out to define near miscible conditions at reservoir conditions. Swelling/extraction tests combined with slim-tube experiments were interpreted to identify the mass transfer mechanisms at near miscible condition. A phase behavior model was developed to match PVT data and MMP in the slim-tube experiment. Good agreement was obtained between simulated and observed data from slim-tube experiments. Core flooding tests were conducted to evaluate oil recovery at near miscible condition at which pressure varies from 1350 psi (MMP) to 1150 psi. Recovery of over 50% of the waterflood residual oil saturation was observed when CO2 was used to displace Arbuckle oil from Berea, Baker dolomite and Arbuckle dolomite cores.
At near miscible conditions, extraction appears to be the primary mechanism for mass transfer between hydrocarbon components and CO2. However, the reduction of oil viscosity by a factor of five occurred when CO2 dissolved in the oil. This suggests that some of the additional oil recovery may be attributed to reduction of the mobility ratio between CO2 and resident oil.
Deep Conformance Control by a Novel Thermally Activated Particle System to Improve Sweep Efficiency in Mature Waterfloods of the San Jorge Basin
Authors: Mustoni J. L. , Norman C. A. , Denyer P. 
Published: July 2010

Abstract
This paper shows the results of the six pilot applications of a novel thermally activated particle system in mature water floods operated by Pan American Energy, at the San Jorge Basin (SJB), Argentina. These were injected between 2006 and 2008 and after up to three years of response, the evaluation is presented with notes on the well and reservoir character, treatment application and observed responses including incremental oil recovery. Field logistics, candidate selection, treatment design, operational aspects and pre and post application monitoring will also be described in detail.
SJB's water floods are characterized by low recovery efficiency due to an adverse mobility ratio as well as spatial reservoir rock anisotropy. This heterogeneity is typical of fluvial systems with high rock property contrasts inside the same channel body. A permeability contrast of 5 to 1 between the center and the edge of the channel is very typical. Therefore, injected water preferentially flows along the center of the channel, becomes a "thief zone", and breaks through to the producers prematurely, leaving behind unswept oil not contacted by the injection water.
In the last decade, many conformance trials failed to improve recovery efficiency. The main reasons for this failure were the utilization of an inappropriate chemical and / or ineffective placement of the application. However, since that time, this new particle technology has shown successful results by blocking thief zones deep in the reservoir. This blocking creates a new pressure gradient that promotes the diversion of injected water toward zones with high oil saturation. A confirmed success rate of around 80 percent seen in these pilots, with no apparent technical failures, has paved the way for a widespread deployment of the technology. In conclusion, the paper discusses treatment selection criteria for field scale application and feasibility for optimization.
The Use of Non-Intrusive Ultrasonic Intelligent Sensors for Corrosion and Erosion Monitoring
Authors: Instanes Geir , Toppe Mads , Kristiansen Sindre Halse , Nagy Peter B. 
Published: July 2010

Abstract
Corrosion and erosion detection and monitoring are essential prognostic means of preserving material integrity and reducing the life-cycle cost of industrial infrastructure, ships, aircraft, ground vehicles, pipelines, oil installations, etc. Spatially dynamic pipeline monitoring systems have to necessarily face extremely hostile conditions of operation including surface roughness, fluid loading issues, temperature variations, and a host of other factors that make development of a robust wall thickness assessment tool a challenging task. This paper describes the working of Corrosion-Erosion Monitor (CEM) - an online, real-time path based thickness assessment tool that deploys a set of transducers over a given pipe area, and utilizes a dispersion based principle to assess wall thickness loss. This instrument was developed keeping the needs of the oil, gas and petrochemical industry in mind, both upstream and downstream, but because it essentially monitors reductions in wall loss, it can find applications in many other industries. Experimental work and field trials provide very promising results pertaining to the functionality of the CEM system, and some of these results have been discussed in this paper. The CEM can be used as a permanent installation or as a relocatable instrument, a result of the development of so called "dry contact" transducers. It is installed on the outer pipe wall to produce real- time pipe wall thickness information, not as a spot measurement, but as a unique average path wall thickness.
Modeling and Assessment of Wettability Alteration Processes in Fractured Carbonates using Dual Porosity and Discrete Fracture Approaches
Authors: Farhadinia M. A. , Delshad M. 
Published: July 2010

AbstractNaturally fractured reservoirs (NFR) with significant oil reserves consist of highly conductive fractures and low permeable matrix media. The matrix rock is usually oil or mixed wet and cause a large amount of the oil remain stagnant after primary and secondary oil recovery processes. Recent laboratory studies have revealed that the injection of chemicals such as surfactant and alkali can change the wettability of the matrix to more water wet and help to mobilize and produce the remaining oil from matrix. Despite numerous publications on successful laboratory experiments, research on simulation and accurate modeling of the process is still very scarce. This paper focuses on the mechanistic modeling of the wettability alteration by chemical injection in NFRs using dual porosity MINC (multiple interacting continua) method.Oil recovery from NFRs is a large target in the oil industry but requires new technologies including more advanced simulation tools to produce it cost effectively. Applications of the new technologies require numerical simulators capable of modeling the interaction between fractures and matrix in transport of the injected and produced materials. Inclusion of the wettability alteration due to surfactant injection in dual porosity model allows for the extension of the laboratory results to the field scale. This work opens up an area to mechanistic simulation of the oil recovery from NFRs in field scale using dual porosity multiple interacting continua, MINC, method.We present the wettability alteration model in NFR carbonates using surfactants with a dual porosity model including matrix subgrid capabilities. The model is tested against both published fractured block experiment and a discrete fracture model. The impact on oil recovery of key process parameters such as surfactant concentration and phase behavior, injection/production rate, fracture-matrix permeability ratios, fracture intensity and initial water saturation are investigated.To the best of our knowledge this is the first time that wettability alteration is coupled with a dual porosity model to estimate the oil recovery from NFRs. Both advantages and limitations of the dual porosity and discrete fracture in the context of wettability modification with chemicals are discussed to provide guidelines and insights for future research.
History Matching of a Realistic Stochastic Fault Model Using Fractal Geometry and the Gradual Deformation Method
Authors: Verscheure Marius , Fourno André , Chilès Jean-Paul 
Published: July 2010

Abstract
Subseismic faults, which strongly influence the hydrodynamic behavior of fractured reservoirs, are inadequately handled in most studies. First, simulation methods were developed to generate fractured models respecting geological observations and static data. Then, history matching methods were introduced to make these models consistent with dynamic data too. However, these fracture models were too simple to accurately describe geology. In this work, we go one step further and develop a methodology to calibrate a realistic stochastic fault model to both static and dynamic data.
We first propose a fractal methodology to generate the faults. The model parameters (length distribution, clustering properties, and orientation) are derived from the analysis of the seismic faults. A stochastic algorithm is used to randomly draw 3D object based sub-seismic fault realizations. Then, these realizations are constrained to the faults identified from seismic. This results in geologically consistent static fault models.
The fracture network is then discretized on a dual porosity simulation grid. Equivalent flow parameters are computed using an analytical method, which makes it possible to account for large-scale fractures. Last, full field simulations are performed using a commercial multiphase flow simulator.
Then, we introduce a method to gradually change the locations of faults while preserving geological consistency. The changes in locations are driven from a reduced number of parameters. During the history-matching process, these parameters are gradually perturbed to compel the initial fault model to reproduce as well as possible the hydrodynamic data collected on the field. As the resulting fault displacement is continuous, common optimization algorithms can be used.
The potential of the methodology is stressed from a 3D case study. A sub-seismic fault network is generated and constrained to seismic faults. Equivalent parameters are computed on a complex CPG grid. Then, the model is calibrated to water-cut levels and well pressures by varying fault locations.
Modeling Formation Damage and Wettability Alteration Induced by Asphaltene Precipitation and Their Effects on Percolation Performances During Oil Production
Authors: Ju Binshan , Qin Jishun , Chen Xinglong , Fan Tailiang , Wu Yushu 
Published: July 2010

AbstractAsphaltene, which exists in crude oil, is a high molecular weight, polar component. It is widely believed that asphaltene may precipitate and plug pores of reservoir rock and induce wettability alteration for the changes in oil composition, reservoir pressure and temperature. Therefore, alphaltene precipitation in the pores of oil formation definitely leads to formation damage and wettability alteration. The mechanisms caused asphaltene precipitation have been researched in labs and the key factors to effect the precipitation have been well understood, but prediction for its quantitative damages for oil formation, wettability alteration and their effects on percolation performance are still uncertain. In this work, a mathematical model considering asphaltene precipitation and wettability alteration is presented and an oil field scaled numerical simulator is developed to predict for asphaltene precipitation problems in the development of oil field. The simulation results show that the porosity and permeability in the vicinity of production wellbore decrease dramatically for asphaltene precipitation. The water-cut increases for the increase in the effective permeability of oil phase and the decrease in the effective permeability of water for the wettability alteration induced by asphaltene deposition onto the pore surfaces.
Mechanisms for High Displacement Efficiency of Low-Temperature CO2 Floods
Authors: Okuno R. , Johns R. T. , Sepehrnoori K. 
Published: July 2010

Abstract
CO2 floods at temperatures typically below 120°F can involve complex phase behavior, where a third CO2-rich liquid (L2) phase coexists with the oleic (L1) and gaseous (V) phases. Results of slim-tube measurements in the literature show that an oil displacement by CO2 can achieve high displacement efficiency of more than 90% when three hydrocarbon-phases coexist during the displacement. However, the mechanism for the high displacement efficiency is uncertain because the complex interaction of phase behavior with flow during the displacement is not fully understood.
In this paper, we present the first detailed study of three-phase behavior predictions and displacement efficiency for low-temperature CO2 floods. Four-component EOS models are initially used to investigate systematically the effects of pressure, temperature, and oil properties on development of three-phase regions and displacement efficiency. Multicomponent oil displacements by CO2 are then considered. We use a compositional reservoir simulator capable of robust three-phase equilibrium calculations.
Results show that high displacement efficiency of low-temperature CO2 floods is a consequence of both condensing and vaporizing behavior. The L2 phase serves as a buffer between the immiscible V and L1 phases within the three-phase region. Components in the L1 phase first transfer efficiently to the L2 phase near a lower critical endpoint (LCEP). These oil components then transfer to the V phase near an upper critical endpoint (UCEP) at the trailing edge of the three-phase region. The CEPs are defined where two of the three coexisting phases merge in the presence of the other immiscible phase. Unlike two-phase displacements, condensation and vaporization of intermediate components occur simultaneously within the three-phase region. The simultaneous condensing/vaporizing behavior involving the CEPs is also confirmed for simulations of several west Texas oil displacements. Quaternary fluid models can predict qualitatively the complex displacements because four is the minimum number of components to develop CEP behavior in composition space at a fixed temperature and pressure.
Single-Well Simulation Study of Foam EOR in Gas-Cap Oil of the Naturally-Fractured Cantarell Field
Authors: Abbaszadeh Maghsood , Rodriguez-de la Garza Fernando , Yuan Chengwu , Pope Gary A. 
Published: July 2010

Abstract
This paper presents results of a simulation study to investigate foam-assisted chemical EOR surfactants that target recovery of oil from the vast volumes of bypassed oil in the tight and oil-wet matrix in the gas cap of the naturally fractured Akal field of Cantarell complex. First, gravity drainage in a 1D column of stacked matrix blocks of Akal gas cap is simulated with both fine-scale single-porosity and coarse-scale dual-continuum media under the conditions of capillary continuity and discontinuity. This establishes that a combined dual-porosity and dual-permeability coarse scheme is appropriate as the representative modeling method. Next, 2D cylindrical and 3D Cartesian single-well models with fluid and rock properties of Akal field are constructed and aqueous solutions of foaming and EOR-surfactants are co-injected in the nitrogen gas stream through vertical or limited-entry side-tracked horizontal wells. Simulation approaches are developed that formulate the impact of foam on fluid flow within fractures, wettability alteration and subsequent imbibition of EOR surfactant solutions into matrix for accelerated gravity induced EOR of matrix oil. Sensitivity studies with respect to foam quality, foam strength, processes of wettability alteration and ultra-low tension EOR and well geometry configurations are conducted. Use of horizontal injector and producer help better confine the released oil within the testing interval and aid in assessing the efficiency of foam-EOR method for gas cap matrix oil.
How to Get the Best Out of Hydrophobically Associative Polymers for IOR? New experimental Insights
Authors: Guillaume Dupuis , David Rousseau , René Tabary , Bruno Grassl 
Published: July 2010

AbstractThe specific molecular structure of Hydrophobically Modified Water Soluble Polymers (HMWSP, also called hydrophobically associative polymers) gives them both superior thickening and surface adsorption abilities as compared to classical Water Soluble Polymers (WSP) and makes them attractive for both polymer flooding and well treatment operations (water shutoff, conformance control). However, their strong adsorption can obviously impair their injectivity and, conversely, the shear-sensitivity of their gels can be detrimental to well treatments. Determining for which IOR application HMWSP are best suited remains therefore difficult. The aim of this work was to bring new insights regarding the interaction mechanisms between HMWSP and rock matrix and their consequences concerning their propagation in reservoirs.A consistent set of HMWSP with sulfonated polyacrylamide backbones and alkyl hydrophobic side-chains together with an equivalent WSP were synthesized and fully characterized. HMWSP and WSP solutions were then injected in model granular packs. As expected, with HMWSP, high resistance factors (or mobility reductions, Rm) were observed. Yet, no core-plugging occurred, since stabilization trends in the Rm curves and no loss of viscosity in the effluents were observed. A first significant outcome concerns the specificities of the Rm curves during HMWSP injections. Rm increases took place in two steps: the first corresponded to the propagation of the viscous front, as observed with WSP, whereas the second was markedly delayed, occurring several pore volumes after the breakthrough. This result is not compatible with the classical picture of multilayers adsorption of HMWSP, but suggests that injectivity is controlled by the sole adsorption of minority polymeric species. This hypothesis was confirmed by re-injecting the collected effluents into fresh cores: no second-step Rm increases were observed.Brine injections in HMWSP treated cores revealed high residual resistance factors (or irreversible permeability reductions, Rk) which can be attributed to the presence of thick polymer adsorbed layers on the pore surface. Nevertheless, Rk values strongly decreased when increasing the brine flow rate. This second significant outcome shows that the adsorbed layers thickness is shear-controlled.These new results should lead to proposing new adapted filtration and injection procedures for HMWSP, aimed in particular at improving their injectivity.
Transport and Retention of Aqueous Dispersions of Paramagnetic Nanoparticles in Reservoir Rocks
Authors: Yu H. , Kotsmar C. , Yoon K. Y. , Ingram D. R. , Johnston K. P. , Bryant S. L. , Huh C. 
Published: July 2010

Abstract
Paramagnetic nanoparticles have potential applications for enhanced oil recovery (by imposing an external field to control the behavior of injected fluids) and especially for evaluating oil saturations and other properties of an EOR target formation (by imposing a magnetic field near the wellbore after injecting fluid and measuring the response). However, the first requirement for these applications is the ability to place the particles a desired distance from the injection well. This means the particles should exhibit little retention in sedimentary rock and minimal formation damage. The ability to predict and control the degree of retention will be valuable for designing field trials and applications of such particles.
We evaluate the transport of surface-treated paramagnetic iron-oxide nanoparticles in sedimentary rocks by injecting aqueous dispersions of the particles into core plugs of different lithologies. The nanoparticle loading ranges from concentrated (10 wt %) to dilute (0.1 wt %). The dispersions are prepared with a range of ionic strengths and pH. Several different surface treatments yield stable dispersions of these particles, but provide very different transport characteristics. Effluent concentration histories are measured for particles that undergo little retention. The results are interpreted in terms of surface charges, zeta potential, and van der Waals interaction between particles and rock.
Our experiments indicate paramagnetic nanoparticles stabilized with small negatively-charged citrate ligands can significantly reduce retention in sedimentary rocks and incur little reduction in permeability. Little retention (&lt;5 % of particles injected over several pore volumes) can be achieved even at very large injected concentration (10 wt %). Citrate-stabilized dispersions were stable even at high salinity (3 wt% NaCl) and the citrate provided electrostatic repulsion between particles and the negatively-charged sandstone and carbonate lithologies tested here. On the other hand polyvinylpyrrolidone (PVP), tetramethylammonium hydroxide (TMAOH) and oleic acid bilayer coatings also stabilized particle dispersions, but the attraction between polymer and rock surface led to high or near-total retention of injected particles.
Analytical Formulae for In-Situ Combustion
Authors: Mailybaev A. A. , Bruining J. , Marchesin D. 
Published: July 2010

Abstract
There is a renewed interest in using combustion to recover difficult oil. In spite of numerous experimental, numerical and analytical studies, the mechanisms for incomplete fuel combustion or oxygen consumption are not fully understood. Incomplete fuel combustion or oxygen consumption are indicators of sub-optimal process conditions and hazardous oxygen breakthrough in the production wells. This paper shows that these features emerge in a relatively simple 1-D model, where air is injected in a porous medium filled with inert gas, water and an oil mixture consisting of precoke, medium and light oil. Precoke is a component that is dissolved in the oil, but has essentially the same composition as coke. At high temperatures, precoke is converted to coke, which participates in high-temperature oxidation. At high temperatures, medium oil components are cracked releasing gaseous oil. Light oil components and water are vaporized. The model possesses an analytical solution, which was obtained by a method introduced by Zeldovich. This method entails that reaction can only occur in a very small temperature range, due to the highly non-linear nature of the Arrhenius factor. For a temperature below this range the reaction rate is too slow and for temperatures above this range the reacton rate is so fast that either the fuel or oxygen concentrations become zero. The model results show that there are two combustion regimes in which coke or oxygen is partially consumed. In one regime the reaction zone moves in front of the heat wave, whereas in the other regime the order of the waves is reversed. There are also two combustion regimes in which the coke and oxygen are completely consumed. Also here the reaction zone can move in front or at the back of the heat wave. Each combustion regime is described by a sequence of waves; we derive formulae for parameters in these waves. We analyse our formulae for typical in-situ combustion data and compare the results with numerical simulation.