bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Dimensional Magnetic Resonance Study of Synthetic Oil Sands
Authors: Jones M.. , Taylor S. E. , Zeng H.. 
Published: June 2014

Abstract
Understanding oil sand structure and recovery processes at the laboratory scale is important for generating accurate models to predict performance ‘in the field’. Magnetic resonance imaging and nuclear magnetic resonance (NMR) are powerful nondestructive, non-invasive tools that have been shown to be ideal for characterizing porous materials. Previous work using NMR to investigate heavy oil and bitumen sands has primarily focused on one-dimensional relaxation analysis. Whilst the spectra produced are sensitive to the confining geometry and fluid types, there is often overlap between relaxation peaks from different fluids with similar relaxation times. These peaks are often difficult to separate accurately. We present a 20 MHz, 1H NMR two-dimensional correlation spectroscopy study of a range of synthetic oil sands systematically prepared with varying compositions of bitumen, water, sand and clay.
These two-dimensional experiments couple nuclear spin relaxation or self-diffusion in one time period with relaxation or self-diffusion occurring during a subsequent time period. This results in the acquisition of proton population distributions as a function of longitudinal (T1) relaxation time and transverse (T2) relaxation time. This allows further, more accurate, discrimination of the fluids and their different physical environments within in the oil sands. The results can also potentially lead to improved wettability and viscosity analyses of heavy oils in-situ.
The results from the synthetic samples are then applied to natural core samples.
Analysis of In-Situ Combustion Performance in Heterogeneous Media
Authors: Hascakir Berna , Kovscek Anthony R. 
Published: June 2014

Abstract
Potential candidates for in-situ combustion (ISC) are screened in the laboratory by one-dimensional combustion tube runs or reaction kinetics experiments, or, ideally, a combination of both. While one-dimensional experiments are conducted at average reservoir conditions, reservoir heterogeneities may have an impact on the amount of fuel formed and, consequently, the amount of heat generated. Therefore, prior to field applications of any potential candidates, it is essential to understand the upper and lower limits of the reservoir rock and fluid properties, and how ISC functions within those limits. In this study, the effect of varying connate water saturation, initial oil saturation, clay content, permeability, and porosity are investigated with one-dimensional combustion tube experiments on different heavy crudes (8-20 °API) with asphaltene content ranging from 10 to 18 wt% for different reservoir rocks including carbonates and sandstone. Process dynamics for good and poor ISC candidates are discussed in terms of effluent gas composition, temperature profiles and histories, total experiment time, oil recovery, behavior of fluid (oil, water, steam, and gas) front movements, and the level of oil upgrading at different reservoir conditions. Fuel consumption along with air requirements are analyzed for each experiment analytically. For good ISC candidates as identified by laboratory screening, the reservoir conditions that may lead to poor ISC field performance are estimated. It is observed that the reactivity of reservoir rocks at elevated temperatures (in the presence of oxygen) and the initial oil saturation are two important parameters that influence the fate of ISC. The findings considerably advance our understanding of field-scale ISC through the evaluation and interpretation of experimental data for different reservoir conditions.
How Does the Incorporation of Engineering Knowledge Using Fuzzy Logic during History Matching Impact Reservoir Performance Prediction?
Authors: Mirzabozorg Arash , Nghiem Long , Chen Zhangxin , Yang Chaodong , Li Heng 
Published: June 2014

Abstract
Population-based optimization algorithms are shown to be excellent candidates for improving the speed and solution diversity of history matching and optimization workflows, based on their successful track records for solving real-world problems.
The incorporation of reservoir engineering knowledge within these workflows, however, has been somewhat neglected. In particular, there is a lack of capability for guiding the optimization algorithms to specific regions of the search space. In a previous study, we introduced a framework for helping reservoir engineers incorporate their knowledge into history matching and optimization frameworks, by coupling a rule-based fuzzy system with a population-based sampling method.
The question is how the use of this type of information in history matching affects the performance of the reservoir study during the prediction stage. This paper investigates the effect that the incorporation of reservoir engineering knowledge during the history matching of the Teal South model production data has on reservoir performance in the prediction stage.
Two scenarios are considered. In Case I, we augment the history matching with reservoir engineering knowledge and then produce a forecast. In Case II, production data is history matched using differential evolution (DE), without fuzzy-logic-based engineering knowledge, then a forecast is produced
The results show that incorporating engineering knowledge of the reservoir under study during the history matching process can significantly reduce the uncertainty in the forecast, compared with the case where unrealistic parameter value ranges are used.
Physical and Numerical Modeling of Capillarity and Aqueous Phase Saturation Effects on the Rate of Solvent Mass Transfer in Boundary Layer in Heavy Oil Reservoirs
Authors: Ahmadloo F. , Asghari K. , Henni A. , Freitag N. 
Published: June 2014

Abstract
Solvent injection has emerged as a recovery technique in low pressure and shallow heavy oil reservoirs in cold systems or in combination with steam in steam-based thermal processes. The performance of solvent-based processes strongly depends on the rate of mass transfer in the boundary layer on the edge of solvent and/or steam chamber. Therefore, understanding of the mass transfer phenomena is required for realistic prediction of the performance of solvent-based or solvent-assisted processes. This study was designed to investigate the capillarity and aqueous phase saturation effects on the rate of mass transfer occurring in the boundary layer on the edge of the solvent chamber. In this study, a new experimental approach was designed and developed to eliminate any disturbance in the boundary layer to experimentally simulate the gravity drainage process in vapor extraction process at two different drainage heights. The porous media and oil-solvent characteristics required for history matching study were determined by measuring the capillary pressure and pore size distribution of sand packs, as well as conducting a complete phase behavior study to determine the properties of the oil-solvent system in a wide range of solvent concentrations. Total number of 12 experiments was conducted in three different sandpacks with different pore size distributions, but similar range of permeabilities (i.e., 5.1-6.5 D) to investigate the effect of capillary forces on the mass transfer phenomena.
Conducted analytical and numerical modeling showed that the effective diffusion coefficient was in the range of 4.91×10-8-1.10×10-5 cm2/s. In absence of immobile water saturation, effective diffusion coefficient was in the range of 4.91×10-8-7.89×10-6 cm2/s. In presence of immobile of aqueous phase saturation, the effective diffusion coefficient varied between 2.96×10-6 and 1.10×10-5 cm2/s. The comparison between the calculated effective diffusion coefficients and reported molecular diffusion in literature by different researchers confirmed that the velocity-dependent term in convective dispersion does not play a major role at higher capillarities in heavy oil systems, i.e., lower permeability range compared to other studies (i.e., &gt;100 D). This study highlights the need for selection of a realistic mass transfer coefficient for the simulation of the performance of the solvent injection processes.
Gas Recharging Process Study in Heavy Oil Reservoirs
Authors: Zhang Jihong , Kantzas Apostolos 
Published: June 2014

Abstract
With the increase of demand for crude oil, heavy oil production becomes an increasingly important crude source for the energy industry. Non-thermal recovery methods, as a supplementary technique, hold the key for exploitation of these depleted or nearly depleted thin heavy oil reservoirs1. This paper focuses on gas recharging processes study for post-cold heavy oil production.
Although there is a diverse research effort on improving oil recovery ongoing for years, most of the experiments to date were conducted using small-scale core samples. It is always difficult at the laboratory level to conduct experiments at real representative field conditions, but larger - scale experiment can provide more realistic conditions15 compared to the reservoir scale. This is very helpful in understanding the prevailing mechanisms which may occur in the reservoir. To the best of our knowledge, the longest cores2-14 which have ever been used in the past are two 18m in length cores (glass beads and sand packed separately) tested by Goodarzi and Kantzas3,5 and Shi and Kantzas4.
This study involves three post-cold heavy oil production processes: CH4 recharging and depletion, CO2 and C3H8 huff-puff, and C3H8 flood. To generate data that is a step closer to reservoir scale, the two 18m long cores mentioned above and one 1.5m sand-packed core were used for testing. The mechanisms of each process were investigated. NMR and GC techniques were applied to help better understand production mechanisms. CT-scan was also used as the tool to monitor the core saturations before and after each process on 1.5m core. Density profiles as a function of core length were investigated. An attempt was made to use the results from short-core tests to explain the long-core results. The effects of core length and permeability on oil recovery were also compared and discussed. Multiple parameters were monitored and analyzed, such as pressure and temperature variations along the core, injected and produced gas composition, produced oil viscosity and water cut, core density before and after each process etc.
Long-Term Calcium Phosphate Cement for In-Situ Combustion Project
Authors: Mac Fuenmayor , Diego Orozco , Hollman Nieto , Javier Urdaneta , Alberto Gomez , Brothers Lance , Herman Pedrosa 
Published: June 2014

Abstract
The increasing demand for energy has increased the need for production of hydrocarbon. As a result, operators have exploited more difficult reservoirs (e.g., deeper wells, remote areas, mature depleted fields, and heavy oil reservoirs). Traditional methods are not sufficient for producing heavy oil; therefore, over time, enhanced recovery methods have been researched and developed.
In-situ combustion (ISC) is the oldest thermal-recovery technique. It has been used for more than nine decades for many successful projects. This method is basically the injection of an oxidizing gas (air- or oxygen-enriched air) to generate heat by burning a portion of resilient oil. Most of the oil is driven toward the producers using a combination of gasdrive, steam, and waterdrive.
High temperatures and the presence of corrosive gases involved during the ISC process can present significant challenges during well isolation.
Phosphate cement is a unique system capable of resisting corrosive attack, maintaining low permeability at high temperatures, and resisting the attack of carbonic acid.
One of the primary challenges was developing a special phosphate cement slurry capable of setting at low temperatures to minimize the waiting on cement (WOC) as well as developing properties sufficient for resisting future stresses. A special sodium aluminate thixotropic additive was used for the first time to react chemically with the pH of this special cement system to develop a quick and high compressive strength.
More than nine wells have been cemented with this system in Colombia with good results. These wells have been subjected to different stresses (production, steam injection, and ISC). This paper presents the successful application of advanced non-Portland cement slurry within the Quifa heavy oil reservoir in Colombia utilizing an ISC enhanced recovery method
Hybrid High Build Rate RSS Improves Challenging Directional Control in a Soft Abrasive Drilling Environment in Oman Drilling Operation
Authors: Al Bardisi Tareq , Akhmetov Roustam , Sanderson Martin , Adly Essam , Escamilla Barton , Andreasen Greg , Noureldin Ali , Al Habsy Hilal 
Published: June 2014

Abstract
A heavy oil field, located in south-central Oman with unconsolidated sandstone reservoirs represents many drilling challenges. Past drilling with conventional mud motors in the field was associated with many drilling risks, including poor wellbore quality, difficulty steering, inadequate hole cleaning, and differential sticking. These risks resulted in extra correction trips, lost-in-hole bottomhole assemblies, sidetracking, and redrilling entire sections.
The field's current development plan is based on the factory drilling concept, which is driven by the number of wells that are required to be delivered in a given year. This requirement places a great amount of importance on drilling time. The average time from spud to spud in the field is 8 to 9 days; any additional trips have a large impact on the total number of wells delivered. In addition, due to the nature of the heavy oil sandstone reservoir, steam injection is required to enhance oil recovery. It is therefore critical to place the lateral hole section of the well in the center of the target corridor to avoid early breakthrough. To compound this, the fluvial nature of the reservoir, tight surface location constraints, and shallow reservoir true vertical depths (TVDs) have added to directional complexity.
To address the main technical challenges of directional assurance and greater drilling efficiency, the operator and service company explored alternative ways of drilling the 8.5-in. reservoir hole section, and this hole section was be the focus of our analysis.
The learning curve experienced in finding an answer for the technical challenges of directional control and drilling efficiency can be broken down to four distinct phases: Phase 1 in 2008: Conventional motorPhase 2 in 2009: Introduction of point the bit rotary steerable system (RSS)Phase 3 in 2012: Introduction of high dogleg severity (DLS) rotary steerable system (RSS), a hybrid design (i.e., push-the-bit and point-the-bit system)Phase 4 in 2013: Enhance drilling efficiency
Extensive data gathering and log analysis provided a better understanding of the main issues and ultimately led to the root cause. The analysis provided a clear solution, which was that a high-build-rate-capable RSS was needed to overcome the directional tendencies and deliver the planned well trajectory to the final total depth (TD) in one run to reduce the average well time.
Using Multiple Objective Optimization for SAGD Simulation Numerical Tuning
Authors: Li Heng , Yang Chaodong , Mirzabozorg Arash , Fedutenko Eugene , Nghiem Long 
Published: June 2014

Abstract
Numerical tuning has shown to be an effective approach to improve computational performance of simulation models, especially complex large-scaled ones. One purpose of numerical tuning is to find a set of numerical parameters that make the simulation run faster with less material balance error. However, in many cases, these two objectives are conflicting with each other. The most common way to tackle this problem is to create an aggregated global objective function, which is the weighted average of the two objectives, and then try to optimize it using a single objective optimizer. In this study, Multiple Objective Particle Swarm Optimizer (MO-PSO) is applied to conduct numerical tuning on a sub-model of a real field SAGD case study. MO-PSO tries to reduce the simulation run time, and the material balance error simultaneously. The results obtained by MO-PSO are compared with that of single objective particle swarm optimizer (SO-PSO). Results showed that MO-PSO is much more effective and efficient in finding Pareto front compared with SO-PSO. MO-PSO eliminates the usage of any weighting factor, which makes it much easier to set up and avoid biased searching results. In addition, MO-PSO converges to optimal solutions much faster than SO-PSO for this study. SO-PSO with well-defined aggregated weighted global objective function can also find a good Pareto front, but inappropriate weighting factors in the aggregated global objective may lead to biased solutions.
Research on the Effect of Non-condensable Gas and Viscosity Reducer for Better SAGD Performance
Authors: Lu Chuan , Liu Huiqing , Liu Qian , Lu Keqin , Wang Limei 
Published: June 2014

Abstract
Steam Assisted Gravity Drainage (SAGD) is widely used as an in-situ technology to recover heavy oil and bitumen. But due to serious heat losses, large energy requirements and enormous CO2 emissions, pure SAGD may not be sufficiently efficient to allow economical production.
The main objective of addition of viscosity reducer is to couple viscosity reduction capability of heat and surfactant. It strengthens the formation of emulsions of O/W type that have much lower viscosity than the oil from which they are formed, and enhances oil production under the same amount of steam to make the thermal process more profitable. With regard to the non-condensable gas, its distribution and movement is essential for the expansion of the steam chamber.
In this paper, the performances of a set of selected viscosity reducers under high temperatures are firstly evaluated. Then based on a high temperature and high pressure two-dimension physical model, different injection processes are conducted to study the separate and combined effect of nitrogen and viscosity reducer on the vertical and horizontal expansion rates of steam chamber. The results show that the injection of nitrogen helps the steam chamber expand more quickly in the horizontal direction. And the combination of viscosity reducer and nitrogen makes the steam chamber expand more quickly than the pure SAGD and Nitrogen-SAGD processes. The following sand pack physical models are conducted to further investigate the mechanisms of viscosity reducer and nitrogen in porous media, such as the steam profile correction relying on the blocking capacity of emulsions, heat loss reduction and the combination effect of gas expansion and viscosity reducer on the displacement of residual oil. In addition, numerical simulations are conducted to demonstrate the feasibility of SAGD assisted by viscosity reducer and nitrogen in Du 84 ultra-heavy oil reservoir. Besides optimizing operation parameters, such as nitrogen steam ratio, effective nitrogen injection volume, interval time between viscosity reducer injection and nitrogen injection, the study results show the effect of this technology on the improvement of thermal oil recovery.
In summary, this study is beneficial for the application of viscosity reducer and nitrogen in the process of SAGD.
An Integrated Approach to Building History-Matched Geomodels to Understand Complex Long Lake Oil Sands Reservoirs, Part 1: Geomodeling
Authors: Zhang Xingquan Kevin , Feizabadi Seyed Ali , Yang Peter 
Published: June 2014

AbstractAt the Nexen Long Lake in situ steam-assisted gravity drainage (SAGD) oil sands recovery project, the bitumen-saturated reservoir is in the Lower Cretaceous McMurray Formation. The main depositional environment in the reservoir unit is fluvial-estuarine meandering channels. Stacked channel deposition exhibits a high degree of variability both vertically and laterally over short distances and depositional complexity occurs at many scales. Many papers have been written on characterizing oil sands deposition geologically or geostatistically. However, complete characterization cannot be achieved at all scales due to the degree of complexity.Building a history-matched geomodel can be very time consuming and very challenging in complex reservoirs such as in Long Lake, where the Quaternary (Gregoire) Channel, collapse features, top gas and top water, lean zones, as well as shale barriers and baffles, contribute to the complexity. This paper presents a practical geological modeling approach used at Nexen to quantify uncertainties of reservoir properties. This approach has been validated by history matching and prediction. The solution is based on the integration of all available geology, geophysics, petrophysics, reservoir engineering, and production information. Using the proposed solution, the number of modeling iterations and the time required to achieve the desired objectives of history matching and prediction have been significantly reduced.
The Role of Water Soluble Species in Bitumen Recovery from Oil Sands
Authors: Swiech Weronika M , Taylor Spencer E , Zeng Huang 
Published: June 2014

Abstract
It has been considered that water soluble species can influence the recovery of bitumen by having an effect on parameters such as wettability or surface charge, thereby altering interactions between oil sand components.
This work considers interactions occurring between representative water soluble acid species and their potential effect on bitumen recovery. It considers the characterization of oil sands components in terms of physicochemical and dielectric properties. Dielectric properties arise from electronic and atomic polarization or dipole, ionic or dielectric relaxation mechanisms. Organic compounds present in the water in the natural environment and also considered to be in oil sand reservoirs are functionalized with chemical groups that undergo chemical processes dependent on the physical conditions of the environment.
The study focusses on a combination of artificially prepared systems analyzed using a variety of techniques, including dielectric spectroscopy, UV-Vis spectrophotometry, sedimentation analysis and adsorption isotherms. Dielectric measurements were undertaken on a range of artificially prepared samples analyzed at moderately low frequencies (10-2 to 107 Hz), which, in the first part of this study, revealed strong, regular dependencies on the composition of the systems, enabling effects of adsorbed species to be discerned. These results revealed information on the properties of a range of compounds naturally present in the oil sand or induced during processing. Colloid and interfacial properties were probed through conductivity, surface tension and zeta potential measurements. With reference to the literature and the new results, an attempt has been made to propose the mechanism representing the interactions between the water soluble compounds and other components present in oil sands such as solids and bitumen, which influence not only heavy oil recovery but also produced water treatment.