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Results
New Paradigm in the Understanding of In Situ Combustion: The Nature of the Fuel and the Important Role of Vapor Phase Combustion
Gutiérrez, Dubert (AnBound Energy Inc.) | Mallory, Don (University of Calgary) | Moore, Gord (University of Calgary) | Mehta, Raj (University of Calgary) | Ursenbach, Matt (University of Calgary) | Bernal, Andrea (AnBound Energy Inc.)
Abstract Historically, the air injection literature has stated that the main fuel for the in situ combustion (ISC) process is the carbon-rich, solid-like residue resulting from distillation, oxidation, and thermal cracking of the residual oil near the combustion front, commonly referred to as "coke". At first glance, that assumption may appear sound, since many combustion tube tests reveal a "coke bank" at the point of termination of the combustion front. However, when one examines both the laboratory results from tests conducted on various oils at reservoir conditions, and historical field data from different sources, the conclusion may be different than what has been assumed. For instance, combustion tube tests performed on light oils rarely display any significant sign of coke deposition, which would make them poor candidates for air injection; nevertheless, they have been some of the most successful ISC projects. It is proposed that the main fuel consumed by the ISC process may not be the solid-like residue, but light hydrocarbon fractions that experience combustion reactions in the gas phase. This vapor fuel forms as a result of oxidative and thermal cracking of the original and oxidized oil fractions. An analysis of different oxidation experiments performed on oil samples ranging from 6.5 to 38.8°API, at reservoir pressures, indicates that this behavior is consistent across this wide density spectrum, even in the absence of coke. While coke will form as a result of the low temperature oxidation of heavy oil fractions, and while thermal cracking of those fractions on the pathway to coke may produce vapor components which may themselves burn, the coke itself is not likely the main fuel for the process, particularly for lighter oils. This paper presents a new theory regarding the nature and formation of the main fuel utilized by the ISC process. It discusses the fundamental concepts associated with the proposed theory, and it summarizes the experimental laboratory evidence and the field evidence which support the concept. This new theory does still share much common ground with the current understanding of the ISC process, but with a twist. The new insights result from the analysis of laboratory tests performed on lighter oils at reservoir pressures; data which was not available at the time that the original ISC concepts were developed. This material suggests a complete change to one of the most important paradigms related to the ISC process, which is the nature and source of the fuel. This affects the way we understand the process, but provides a unified and consistent theory, which is important for the modelling efforts and overall development of a technology that has the potential to unlock many reserves from conventional and unconventional reservoirs.
- North America > United States (1.00)
- Europe (1.00)
- North America > Canada > Alberta (0.94)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (0.90)
- Geology > Geological Subdiscipline (0.67)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.94)
- North America > United States > Nebraska > Sloss Field (0.99)
- North America > Canada > Alberta > Athabasca Oil Sands > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- North America > United States > South Dakota > Williston Basin > Buffalo Field > Red River Formation (0.94)
- North America > United States > North Dakota > Medicine Pole Hills Field (0.94)
Abstract The wettability alteration is the most prominent mechanism for a favorable effect of low salinity water flooding in enhanced oil recovery. It has been accepted that the surface charge at crude oil/brine and rock/brine interfaces significantly influences the interaction of the crude oil with rock surface and thus wettability changes. In this study, the interface characteristics were coupled with a solute transport model to simulate low salinity waterflooding in carbonate and sandstone reservoirs. The ionic transport and two- phase flow of oil and water equations were solved and coupled with IPhreeqc for geochemical calculations. The dissolution and precipitation of minerals were considered thorough thermodynamic equilibrium reactions in IPhreeqc. In addition, a triple layer surface complexation model was employed in IPhreeqc to predict electrokinetic properties of crude oil/brine and rock/brine interfaces. The wettability alteration was calculated based the adsorbed polar components of crude oil on minerals’ surface, which changes the relative permeability. The coupled model able to predict the spatiotemporal variation of ionic profiles, surface and zeta potentials, dissolution and precipitation of minerals, total disjoining pressure, and wettability index in addition to oil recovery for the injection of brines. The validity of the coupled model results was tested against PHREEQC in a single-phase flow without the presence of oil. Moreover, the modelling results were compared with the published experimental data for a single-phase flow in carbonate cores. A very good agreement between experimental data and modelling results was obtained. Furthermore, the coupled model was applied to predict ionic concentration, pH profile, and oil recovery in both carbonate and sandstone cores and verified with experimental data. The modelling results reproduce well the experimental data, suggesting that model captures the geochemical and interface reactions. Finally, the coupled model can be used to optimize brine composition for improved oil recovery in carbonate and sandstone reservoirs.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline (1.00)
Abstract Conventional in-situ upgrading techniques use electric heaters to heat oil shale. However, the efficiency of electrical heating method is very slow which requires preheating more than a year. Most conventional heating technologies focused on converting the oil shale, not shale oil reservoirs. The shale oil matrix is very tight and the pore scale is in micro to nano-meter. In this paper, it has been attempted to inject air into hydraulically fractured horizontal wells to create in-situ combustion of shale oil in ultra-low permeability formations. Heat is introduced into the formation through multistage fractured horizontal wells, which enhances the contact area of exposed kerogen. The main focus of this paper is to evaluate the technical feasibility of recovering shale oil resources by air injection. It involves the application of hydraulic fracturing technology to enhance the kerogen exposure to oxygen. Heat flows from the fracture into shale oil formation, gradually converting the solid kerogen into mobile oil and gas, which can be produced via fractures to the production wells.
- Asia > China > Xinjiang Uyghur Autonomous Region > Junggar Basin > Lucaogou Formation (0.99)
- Asia > Russia > West Siberian Basin > Bazhenov Formation (0.98)
- Europe > United Kingdom > North Sea > Central North Sea > South Viking Graben > Block 9/28a > Crawford Field (0.93)
Abstract Clays are known to act as a catalyst during the in-situ combustion (ISC) process. This work investigates the role of clay in reaction kinetics of a bitumen sample. Several Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC) experiments were conducted on a Canadian bitumen and its saturates, aromatics, resins, and asphaltenes (SARA) fractions in the presence and absence of a clay (kaolinite and illite) mixture. The role of each fraction in ISC reactions was investigated at low temperature oxidation (LTO) and high temperature oxidation (HTO) regions by calculating the total activation energy and the heat of combustion. The activation energy calculations were based on the Arrhenius approximation and the heat of reaction was estimated by a simple integration of the DSC curve below the standard zero heat generation line. Accordingly, we have observed that saturates act like ignitors and their ignition characteristics are enhanced in the presence of clay. Bitumen oxidation in LTO region requires more heat for asphaltenes only in the absence of clay. In the presence of clays, bitumen oxidation in LTO region requires more heat for the mutual interaction of resins with asphaltenes. The required heat for the bitumen oxidation and combustion in HTO region is reduced due to contribution of mainly saturates fraction in the presence of clays. The generated heat (heat of combustion) is increased both in LTO and HTO regions for clay presence case. This is mainly due to the mutual interaction of aromatics fraction with resins fraction in LTO region and the mutual interaction of aromatics fraction with saturates fraction in HTO region. It has also been found that bitumen sample contains emulsified water, which reduces the combustion process performance.
- North America > United States > Texas (0.69)
- North America > Canada > Alberta (0.46)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.78)
- North America > United States > Kansas > Iola Field (0.99)
- North America > Canada > Alberta > Athabasca Oil Sands > Western Canada Sedimentary Basin > Alberta Basin (0.99)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery (1.00)
- Facilities Design, Construction and Operation > Unconventional Production Facilities > Oil sand/shale/bitumen (1.00)
Numerical Simulation of Crossed-Linked Polymer Injection in Dina Cretaceous Field: A Real Field Case Study
Izadi, Mehdi (Ecopetrol SA) | Jimenez, Jaime Alberto (Ecopetrol SA) | Zapata, Jose Francisco (Ecopetrol SA) | Felipe Castillo, Andres (Ecopetrol) | Pinto, John (Ecopetrol SA) | Vicente, Sebastian (Ecopetrol SA)
Abstract The main objective of this work is to shed light on the mechanism of modeling crossed-linked polymer (CLP) technology, by incorporating real field pilot injection and production data in the Dina Cretaceous field located in the Upper Magdalena Valley (UMV) Basin in Colombia. The paper will highlight why original simulation model predictions differ from the actual observed field data and the predictability of numerical simulation of CEOR process would be discussed and presented. Despite successful application and positive field results in the literature, the propagation of CLP system in porous media has been challenged with conflicting opinions and reports and still remains debatable and uncertain. This paper will use recent experimental laboratory data in conjunction with actual field data to properly explain the possible mechanism of CLP and offer practical modeling techniques to capture experimental and field data. Therefore a modeling methodology was developed and used to model the field data, this method is based on previous modeling mechanisms with incorporating a new grid-based residual resistance factor (RRF) and pore throat sizes. The model requires a proper understanding of rock typing and populate the permeability distribution based on pore throat sizes. The new modeling mechanism was able to reasonably predict the pilot performance in some of the offset producers. To model delayed viscosification and adsorption of the CLP process, two approaches has been evaluated and used in the original simulation model, the use of multiple regions and chemical reaction. The chemical reaction rate is tuned to calibrate laboratory data and to model the delayed viscosification and RRF. However recent laboratory experiments explained the possible mechanisms of CLP formation through intra-molecular crosslinking and intra-inter-molecular crosslinking. In conclusion, because of extensive and numerous laboratory experiments and the conduct of field pilot results, proposed numerical modeling demonstrate the complexity of modeling the CLP system and offers a practical solution to the field applications.
- South America > Colombia (0.68)
- Europe > United Kingdom > North Sea > Central North Sea (0.45)
- North America > United States > Oklahoma (0.29)
- South America > Colombia > Huila Department > Dina Field (0.99)
- North America > United States > Oklahoma > Anadarko Basin > North Burbank Field (0.99)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Yian Formation (0.99)
- (2 more...)
Improvements on Modelling Wettability Alteration by Engineered Water Injection: Geochemical Pore-Scale Approach
Bordeaux Rego, Fabio (The University of Texas at Austin) | Mehrabi, Mehran (The University of Texas at Austin) | Sanaei, Alireza (The University of Texas at Austin) | Sepehrnoori, Kamy (The University of Texas at Austin)
Abstract Several laboratory experiments demonstrated that different water compositions cause rocks to change from oil- to water-wet state. Although it is a consensus that wettability alteration is the main recovery mechanism, modeling the underlying mechanism is still a major challenge. Our main goal is to improve and validate a physically based model to predict contact angles from zeta-potential measurements. We propose a new mass-action formulation for surface complexation model (SCM) that includes the energy interaction effect between two close surfaces (PS). Currently, most SCMs consider rock and oil as isolated surfaces (IS). Thus, we hypothesize that, as rock and oil surface approach each other, PS model produce a better description of electrostatic distribution. Additionally, we develop a method of determining SCM equilibrium constants to fit several zeta-potential measurements for different ion concentrations (Na, Ca, Mg, SO4 and H). Finally, we estimate contact angles using disjoining pressure calculations and compare them with ones reported in the literature. From a SCM set of reactions available in the literature, we validate the developed IS model against PHREEQC (a reference simulator for geochemical reactions). For the PS case, the system of equations’ solution is very close to IS approach when the interaction between surfaces are negligible (wide spacing between surfaces). Regarding zeta-potential prediction for calcite-brine system, we argue that Na might not be an indifferent ion as suggested previously. Our simulation results indicate that, besides the renowned potential-determining ions, sodium adsorption on calcite can play an important role in electrostatic interactions, switching surface charge polarity. Thus, we only achieve a successful fit of zeta-potential measurements when Na is considered in the SCM reactions. Finally, contact angle estimation using the PS model and disjoining pressure theory provide good predictions of seven different cases reported in the literature. We validate our method on a total of 66 and 163 contact angle and zeta-potential measurements, respectively. The present work is a novel approach to represent how electrostatic interactions among rock, brine and oil modify the rock surface charge and the rock wetting state.
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.47)
- Geology > Mineral > Carbonate Mineral > Calcite (0.47)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.40)
- North America > United States > Arkansas > Magazine Field (0.89)
- Europe > United Kingdom > England > London Basin (0.89)
Geochemical Modeling of Wormhole Propagation During Carbonate Acidizing with Consideration of Fractures
Wei, Wan (The University of Texas at Austin) | Yu, Wei (The University of Texas at Austin) | Chen, Youguang (The University of Texas at Austin) | Sepehrnoori, Kamy (The University of Texas at Austin)
Abstract Matrix acidizing is a widely-used stimulation treatment performed below the fracture pressure of the formation. The purpose of acidizing is to improve or restore the formation permeability through rock dissolution. Natural fractures exist in approximately 50% of carbonate reservoirs worldwide (Jo Garland et al. 2018). In this paper, a two-scale continuum model is implemented in UTCOMP (a 3D compositional reservoir simulator) with consideration of fractures using EDFM (Embedded Discrete Fracture Model). The model is also coupled with IPhreeqc (an open- source geochemical program) to calculate reactions occurring among minerals and geochemical species in the aqueous phase. In the coupled model, the two-scale continuum model describes convection and dispersion while IPhreeqc is responsible for the dissolution calculation both in the matrix and on the fracture surface. We validated the simulation model by comparing with the analytical solution. We used two methods for reaction calculation; in the first method we assumed a simple first-order reaction between acid and mineral; in the second method the UTCOMP-IPhreeqc coupled model is used to calculate complex reactions among geochemical species and different mineral compositions. Consistent results were obtained between the simple-reaction model and the UTCOMP- IPhreeqc coupled model by tuning the reaction calculation in the IPhreeqc database. On this basis, we investigated the effects of fractures on acidizing efficiency and wormhole propagation. It is found that for homogeneous matrix with existence of fractures, wormhole in the matrix is generated along the fracture. For heterogeneous matrix, the initiation of the wormhole is dependent on the permeability distribution in the matrix, but wormhole propagation after the initiation is dependent on the position of the nearest fracture tip and the fracture orientation. As a high- conductivity flow path, fracture retards wormhole propagation in the matrix by attracting most acid. As acid dissolves the minerals on the fracture surface, the fracture conductivity is increased and the fluid leak-off into the matrix is reduced. For a vertical fracture with a smaller height compared with the matrix thickness, wormhole propagation is slowed down for the entire matrix. For the first time, it is possible to simulate formations with hydraulic fractures or natural fractures during acidizing, with consideration of geochemical reactions among aqueous phase and different rock compositions. The presented model improves our understanding in acidizing optimization.
- North America > United States > Texas (0.69)
- North America > United States > Oklahoma (0.46)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.94)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (21 more...)
Abstract Hydrochloric acid is commonly used in acid fracturing. Given that the interaction between acid and rock affects multiphase flow behaviors, it’s important to thoroughly understand the relevant phenomena. Darcy–Brinkman–Stokes (DBS) method is most effective to describe the matrix–fracture system among the proposed models. The objective of this study is to analyze the impact of acid–rock interaction on multiphase flow behavior, by developing a pore–scale numerical model applying DBS method. The new pore–scale model is developed based on OpenFOAM, which is an open source platform for the prototyping of diverse flow mechanisms. The developed simulation model describes the fully–coupled mass balance equation and the chemical reaction of carbonate acidization in an advection–diffusion regime. Volume of Fluid (VOF) method is employed to track liquid and gas phase interface on fixed Eulerian grids. Here, penalization method is applied to describe the wettability condition on immersed boundaries. To compute the numerical solutions of discretized equations, finite volume method is applied, where the equations of saturation, concentration, and diffusion are solved successively, and momentum equation is solved by using Pressure–Implicit with Splitting of Operators (PISO) method, respectively. The simulation results computed by this numerical model have been validated by experimental results. Different injection velocities and the second Damkohler numbers have been simulated to investigate their effects on the evolving porosity and rock surface area. The newly developed pore–scale model in this research provides the fundamental knowledge of physical–and–chemical phenomena of acid–rock interaction and their impact on acid transport. The modelling results describing mineral aci dization will help us to implement an effective fracturing project while reducing environment impacts.
- Geology > Mineral (0.72)
- Geology > Rock Type > Sedimentary Rock (0.46)
Thermo-Sensitive Nanogels for Targeted Tracer Release in Push and Pull Operations
Panneer Selvam, Arun Kumar (National IOR Center of Norway, University of Stavanger, Institute of Energy Technology) | Ould Metidji, Mahmoud (National IOR Center of Norway, Institute of Energy Technology) | Silva, Mario (National IOR Center of Norway, Institute of Energy Technology) | Krivokapic, Alexander (Institute of Energy Technology) | Bjørnstad, Tor (National IOR Center of Norway, Institute of Energy Technology)
Abstract The single-well chemical tracer test (SWCTT) is widely used in the determination of residual oil saturation (SOR) in the near-well region. SWCTTs typically require large amounts of chemicals and some days of well shut-down. In the present paper, we propose using thermo-sensitive nanogel carriers for targeted release of tracers for SWCTTs. This approach has the potential to significantly reduce the time and amount of chemicals required by a SWCTT. The targeted tracer release method was inspired by previously developed drug delivery applications using stimuli-sensitive nano-capsules. Nanoparticles loaded with medical cargo were synthesised to target specific sites. The release of the active principles would then be triggered by an in-situ (temperature, pH) or ex-situ (magnetic field, light) stimuli. A novative approach to address the current limitation of classical SWCTT is based on the biomedical background. It consists in using a poly-N-isopropylacrylamide (pNIPAm) based nanogel, known for its thermo-sensitive nature, to ensure the in-situ delivery of tracer molecules. This effect is explored as a mechanism to both load and release the tracers for a SWCTT. PNIPAm nanogels or hydrogels are highly hydrophilic, cross-linked polymeric networks. When the temperature of the solution is increased above the lower critical solution temperature (LCST) of PNIPAm molecule, the capsules exhibit a reversible collapse effect, causing the release of the tracer molecules. The hydrodynamic diameters of capsules were measured using Dynamic Light Scattering (DLS) and were found to be 195 nm at 25 °C and 73 nm at 45 °C. The nanogels exhibit a reduction in volume to 8 times when the temperature is increased from 25 °C to 45 °C. This change in volume acts as a lock-in mechanism once the tracer is loaded and open-up to release loaded tracers. The study of the encapsulation and release of tracer compounds was achieved using passive and partitioning tracers loaded into the structures. The capsules showed a significant tracer loading efficiency. For studying the release rate and mechanism, increase in temperature was used to trigger the release of tracers. Although the SWCTTs are the most used tracer tests by the oil industry, their development have been relatively slow since it was originally introduced in 1973 (Deans 1971). The present study aims at presenting a novel approach on how nanotechnology can be used to reduce the large amounts of chemicals and time required by classical SWCTTs. Concepts and results about the synthesis of the nano-carriers, loading and releasing of the tracers are presented and discussed.
- Europe (0.70)
- North America > United States > Oklahoma > Beaver County (0.24)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.70)
Abstract Previously proposed models of wettability change have not been tied to the chemistry that controls wettability but instead were driven by simplistic criteria such as salinity level or concentration of an adsorbed species. Such models do not adequately predict the impact of brine compositional change and therefore cannot be used to optimize brine composition. In this work, after testing proposed models in the literature on sandstones and carbonates, we propose a mechanistic surface-complexation-based model that quantitatively describes observations for ionically treated waterfloods. To the best of our knowledge this is the first surface-complexation-based model that fully describes ionic compositional dependence observed in ionically treated waterfloods in both sandstones and carbonates. We model wettability change by directly linking wettability to brine chemistry using detailed colloidal science. Brine has charged ions that interact with polar acidic/basic components at the oil-water interface and rock surface and therefore oil/brine and rock/brine interfaces are charged and exert both Van der Waals and electrostatic forces on each other. If the net result of the forces is repulsive, the thin water film between the two interfaces is stable (i.e., the rock is water-wet) otherwise, the thin water film is unstable and the rock becomes oil-wet. Based on Hirasaki (1991), we describe a ratio of electrostatic force to Van der Waals force with a dimensionless group, called "stability number," where rock wettability is water-wet for values greater than one and oil-wet for values less than one. For sandstones, the zeta potentials of oil/brine and rock/brine interfaces become more negative/less positive by diluting or softening the brine and/or increasing pH. Similarly, for carbonates, dilution and/or sulfate enrichment of brine makes surface potentials more negative. Such brine modification can therefore be used to improve oil recovery. We implemented the improved wettability change model in a comprehensive coupled reservoir simulator, UTCOMP-IPhreeqc, in which oil/brine and rock/brine zeta potentials are modeled using the IPhreeqc surface complexation module. We take into the account total acid number (TAN) and total base number (TBN) for the oil/brine interface and we use rock surface reactions for brine/rock surface potential modeling. Surface potentials obtained from the geochemical model are used to calculate the dimensionless group controlling wettability change, which is dynamically modeled in the transport simulator. The model is validated in sandstones and carbonates by simulating an inter-well test, and several corefloods and imbibition tests reported in the literature. For sandstones, we model Kozaki (2012) and BP's Endicott trial. For simple dilution in carbonates we model experiments by Shehata et al. (2014) and Yousef et al. (2010). For enrichment with sulfate we model Zhang and Austad (2006) and for increasing total ionic strength via sodium chloride enrichment, Fathi et al. (2010a).
- Asia > Middle East (0.67)
- North America > United States > Texas (0.28)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline (1.00)