bluuebunny/crossref_metadata_2025 huggingface dataset:
Practical Implementation of Knowledge-Based Approaches for SAGD Production Analysis
Authors: Ma Zhiwei , Leung Juliana Y. , Zanon Stefan D. , Dzurman Peter J.
Published: June 2014

Quantitative appraisal of different operating areas and assessment of uncertainty due to reservoir heterogeneities are crucial elements in optimization of production and development strategies in oil sands operations. Although detailed compositional simulators are available for recovery performance evaluation for SAGD, the simulation process is usually deterministic and computationally demanding, and it not quite practical for real-time decision-making and forecasting. Data mining and machine learning algorithms provide efficient modeling alternatives, particularly when the underlying physical relationships between system variables are highly complex, non-linear, and possibly uncertain.

In this study, a comprehensive training set encompassing SAGD field data compiled from numerous publicly-available sources is studied. Exploratory data analysis is carried out to interpret and extract relevant attributes describing characteristics associated with reservoir heterogeneities and operating constraints. Because of their ease of implementation and computational efficiency, knowledge-based techniques including artificial neural networks (ANN) are employed to facilitate SAGD production performance prediction. Predicting (input) variables including porosity, net-to-gross ratio, saturation, gross pay, normalized shale barrier thickness and distance to well pair, and initial production rate are formulated. Measures such as cumulative production over discrete time intervals are considered as prediction (output) variables. Data records that are comprised of both input and output variables are assembled; the network is trained using the data set to identify all significant patterns and relationships that exist between the input and the output variables. The model is subsequently validated using a cross-verification procedure, during which records that have been excluded at the training stage are presented to the model.

This paper demonstrates that knowledge-based techniques can be implemented in a practical manner to analyze large amount of competitor data efficiently. The approach can be integrated directly into most existing reservoir management routines. It can also be readily updated when new information has become available. Given that robust reservoir management and real-time decision-making are major challenges faced by the industry, the data-driven models presented in this paper has great potential to be applied in other recovery projects such as solvent-aided steam injection.
Wellbore modeling and design of Nozzle-Based Inflow Control Device (ICD) for SAGD wells
Authors: Shad Saeed , Majdi Yazdi Mehdi
Published: June 2014

Production of bitumen from heavy oil reservoirs is a complex process due to high oil viscosity and heterogeneity of reservoirs. Steam assisted gravity drainage (SAGD) process have been applied to Western Canadian bitumen reservoirs as a feasible and technically effective process to produce heavy oil and bitumen. Considering cost associated with SAGD process and complexity involved in this recovery method, it is vital to optimize design and operation of SAGD to achieve the maximum return. Horizontal wells have become an indispensable component of SAGD process. Therefore, optimizing and improving their design will have significant impact on SAGD recovery method. Despite the fact that horizontal wells improve reservoir access, they suffer from high frictional pressure loss due to their long lengths. In addition, combination of limited control points on horizontal wells (toe and heal) and reservoir quality variation along the well and in the reservoir, poses significant challenges in well control and production optimization. One solution for such issues is the use of Inflow control devices (ICD). ICD's equalize and balance the pressure drop in the wellbore by shortening the flow paths, choking back the steam, and changing pressure potential to velocity potential and provide us with better well control.

In this paper, a SAGD well pair with eccentric dual tubing completion is numerically modeled. The numerical modeling consists of a history matching step that is followed by five years of production forecast. The base case is compared with several scenarios with nozzle ICD's installed on the producer well. The simulation cases with ICD include different nozzle sizes and various compartmentalization schemes along the wellbore. The results show how ICD's can improve well performance and increase efficiency of the SAGD process.

With the sensitivity analysis done using numerical simulation results, the optimum number of ICD's and nozzle size is proposed based on several screening criteria such as low SOR, steam chamber uniformity, high steam chamber temperature, low subcool, and low steam production.

This study reveals the advantages of ICD-equipped wells over the conventional dual-tubing and slotted liner completions for SAGD operation. The improved well performance, increased bitumen production, and longevity of the wells will compensate for additional cost of ICD installation in a short period of time.
Advances in Electrical Heating Technology for Heavy Oil Production
Authors: Sandberg Chet , Thomas Keith , Hale Arthur
Published: June 2014

Electrical downhole heating has been used for many years for flow assurance and now is being adapted for reservoir stimulation, viscosity reduction and "in situ" conversion of heavy oil. This paper starts with a short review of flow assurance applications in Alaska and Canada as described in SPE-165323-MS. It then reviews the current and developing technology and some of the heat transfer parameters for use of high voltage high power electrical heaters in a number of types of applications. In the past heater voltages have been limited to below 600 volts for mineral insulated cable heaters. Significant material and processing advances have now permitted operation at 4160 volts. This has a number of operational advantages in providing longer length heater capabilities and less parasitic heating loss in the overburden. MI cable production technology is now available to fabricate MI cable heaters that can produce 1600 meters lengths without external splices. The thermal heat transfer from the well casing to the reservoir is usually the limiting factor on the amount of energy that can be transferred from the electrical heater to the formation. Both constant power and constant temperature heaters are explained with the emphasis on in operation reliability of each type of heater. The paper concludes with an economic analysis of the opportunity provided by a high voltage MI cable heater system in a horizontal well.
Numerical Thermal Simulation and Optimization of Hybrid CSS/SAGD Process in Long Lake with Lean Zones
Authors: Xu Jinze , Chen Zhangxin , Yu Yanguo , Cao Jili
Published: June 2014

Cyclic steam stimulation (CSS) and steam-assisted gravity drainage (SAGD) are successful commercial methods for enhanced oil recovery (EOR) used in Canada. Although SAGD exhibits higher oil recovery than CSS, it is more sensitive to reservoir heterogeneities such as top water and lean zones. In most cases, these baffles cause channeling in steam injection operations, thus leading to a high steam-oil ratio (SOR) and low injectivity. Therefore, recovering bitumen by using SAGD in a pilot well pad with such baffles in Long Lake has been a considerable challenge. To overcome the aforementioned issues, a hybrid process that combines CSS and SAGD (hybrid CSS/SAGD) is investigated in this study. Hybrid CSS/SAGD takes advantage of the benefits of both methods. During this process, all SAGD wells operate as cyclic injection/production wells. When the wells are shut in for a soak period, the injectivity of SAGD is highly improved. Simultaneously, the producer can also function as a heat source. After good conductivity is achieved between the injector and the producer, oil recovery is improved significantly.

This study aims to construct a hybrid CSS/SAGD simulation model for the Long Lake pilot well pad. The simulation is based on a well-defined 3D geostatistical model. By strictly controlling detailed lithological facies, lean zones and top water zones are accurately described in the geological model. These baffles are mainly located in the upper-middle portion of the McMurray Formation. By adjusting relative permeability curves, a SAGD model with a ten-year production history (beginning in April 2003) is history matched well. Based on this model, we then run hybrid CSS/SAGD simulations by changing well constraints from April 2003 with a submodel of well pair 1. Both wells in the well pair 1 operate as producers and injectors. The simulation results show that CSS-SAGD exhibits higher oil recovery and lower SOR than SAGD alone. Moreover, sensitivity analysis on preheating pressure is performed. Based on the net present value, we optimize the steam injection pressure and steam injection rate to establish criteria for each parameter for the pilot well pad.
The Successful Application of Automated Managed Pressure Drilling (MPD) To Protect Caprock Integrity by Narrow Margin Drilling in SAGD wells
Authors: Osayande Nadine , Mammadov Elvin , Sephton Sheldon , Boucher Vincent
Published: June 2014

The Canadian SAGD (Steam Assisted Gravity Drainage) industry continues to grow with more wells being drilled in Alberta that cannot be mined. Drilling issues addressing low reservoir pressure, tight well spacing, highly pressurized steam injection, cap rock integrity and tight drilling windows are currently some of the challenges that are being faced today.

As the industry looks for a way to improve and mitigate both drilling and environmental issues, this paper presents a drilling solution on applying an automated MPD (Managed Pressure Drilling) technique proven to identify and react to the actual wellbore pressures. This can detect and control any gain and losses within liters, while still having the ability to maintain a CBHP (Constant bottom hole Pressure) while drilling through tight windows.

This document demonstrates the successful application of advanced automated MPD technologies on Suncor's Dover well close to Fort McMurray, Alberta and will also elaborate on recommended operational procedures, equipment set up and to process flow diagrams along with the analyzed graphical data. The results demonstrated a successful re-drill of a producer well within an over pressured reservoir induced by steam injection, by using near water density mud weights, minimizing mud losses, preventing any steam or bitumen intrusion by monitoring return density to surface while maintaining bottom hole pressure within a narrow operating window.
Multi-stage Cleaning for Routine Core Analysis in Heavy Oil-bearing Carbonates, Campos Basin, Brazil
Authors: Borre Mai K. , Coffey Brian P.
Published: June 2014

Reservoir characterization of carbonate pore systems with both movable and non-movable phases of hydrocarbon (HC) was improved by use of a modified, multi-stage core cleaning procedure. Analyses were completed on core plugs collected from a 60 m carbonate-dominated core with highly variable depositional textures and pore networks. Rock fabrics included grain-dominated carbonates of variable size and sorting, framework-supported carbonates with finer interstitial matrix, and mixed carbonate-siliciclastic sands with a higher degree of grain sorting.

A modified workflow for sample cleaning was developed in collaboration with Weatherford Laboratories. The multi-stage workflow describes more accurately in-situ reservoir quality in reservoirs with heavy HC fractions, and it is applicable to carbonate and siliciclastic reservoirs. For this study, samples were first cleaned with a lighter solvent to remove only movable fluids from pore networks. Following measurement of effective porosity and permeability, the samples then were cleaned by standard solvents to remove all soluble fluids. After final cleaning, total porosity and permeability was measured.

When cleaned for movable fluids only, core plug porosity is comparable with NMR wireline data that estimate porosity related to movable fluid phases. The standard cleaning workflow yielded total porosity that resembled more conventional log-derived total porosity from density and neutron porosity log data. The difference in the permeability measured between these two cleaning methods often varied by an order of magnitude.

This cleaning methodology resulted in a more accurate depiction of reservoir quality and improved validation of wireline log data. When integrated with other datasets to better document the controls on reservoir quality and porosity distribution, these results provided valuable insight into the differentiation between in-place and recoverable hydrocarbons in this heavy oil-dominated petroleum system.
Improvement of Sweep Efficiency of Miscible Displacement Processes in Heterogeneous Porous Media
Authors: Sajjadi M. , Azaiez J.
Published: June 2014

The viscous fingering phenomenon in displacement processes develops due to higher mobility of the injected fluid compared to that of the inhabitant fluid. It causes early breakthrough of the injected fluid and results in reduced sweep efficiency of the process. In addition to viscous fingering, heterogeneity of the porous medium can be a source of instability in displacement processes which has significant interactions with the viscous forces. The coupling between viscous fingering and heterogeneity induced channeling has been deemed to enhance the instabilities by increasing the growth rate of fingers formed inside the high permeable channels. This conclusion is questioned by the present work which investigates the effect of the injection velocity, diffusion coefficient, and width of the layers in a layered medium, on the coupling between the two named sources of instability. Numerical simulations and quantitative analysis of the instabilities show that the flow in heterogeneous media goes through four different regimes (initial diffusion, channeling, lateral dispersion, and viscous fingering) each dominated by a different flow mechanism that results in different growth rates of fingers. Based on these characterizations a method is suggested to design the process with an optimum injection rate such that the coupling between viscous fingering and heterogeneity attenuates the instability and results in improved sweep efficiency. Finding the optimum displacement parameters and improving the efficiency of the process helps to reduce the amount of solvent to be injected in the medium and therefore decreases the environmental effects of the recovery process.
Gasflooding-Assisted Cyclic Solvent Injection (GA-CSI) for Enhancing Heavy Oil Recovery
Authors: Jia Xinfeng , Zeng Fanhua , Gu Yongan
Published: June 2014

Cyclic solvent injection (CSI) process takes advantage of solution-gas drive and foamy oil flow for the oil production. However, it suffers from the solvent liberation during the production period. This results in an increased viscosity of the oil and its mobility loss. 0How to recover the partially diluted heavy oil becomes a key challenge for a CSI process. This paper first experimentally studies the conventional CSI processes with a one-well configuration, in which the solvent injector is alternately used the oil producer, and a two-well configuration, in which the solvent injector and oil producer are placed horizontally apart. It is found that during the one-well CSI test, some foamy oil that remains in the solvent chamber at the end of the production period of a previous cycle is pushed back by the injected solvent during the injection period of the next cycle. Such a back-and-forth movement of oil is not observed in the two-well CSI test. In addition, it is found that the oil saturation and oil relative permeability inside the solvent chamber are increased due to the foamy oil flow during the production period. Based on this fact, a new process, namely gasflooding-assisted cyclic solvent injection (GA-CSI), is proposed to enhance the performance of the CSI process. In this new process, a gasflooding slug is applied after the pressure depletion process to produce the partially diluted foamy oil in the solvent chamber. Results show that the GA-CSI process can increase the oil production rate by over 3 times, in comparison with the conventional CSI process.
Hybrid Thermal-Chemical Processes (HTCP) for Heavy-Oil and Oil-Sand Recovery
Authors: Taghavifar M. , Fortenberry R. , De Rouffignac E. , Sepehrnoori K. , Pope G. A.
Published: June 2014

For many shaley thin oil deposits, steam injection is not feasible. A hybrid process that involves moderate reservoir heating and chemical enhanced oil recovery is proposed, in which the same set of horizontal wells is used for injection of both energy and fluids. Simulations based on realistic Peace River field data were performed to investigate the performance of the proposed hybrid thermal-chemical process. Economic feasibility was established by optimization of the process.
Phase Behaviour Study of Butane / Athabasca Bitumen Mixtures Applicable for Thermal and Hybrid Solvent Recovery Processes
Authors: Nourozieh Hossein , Kariznovi Mohammad , Abedi Jalal
Published: June 2014

World production of heavy and extra-heavy oils has increased as the production of conventional crudes decline. However, the conventional oil recovery methods cannot effectively recover the heavy oil due to their high viscosities. The steam and/or solvent-based recovery processes can be considered as an efficient method for recovery of these resources. The performance of these techniques depends on the amount of solvent dissolved in the crude and the variation of oil viscosity with temperature. Thus, full understanding of the quantitative effects of the solvent on heavy oil viscosity and phase behaviours are crucial for feasibility studies, design and prediction of field-scale processes.

Phase behaviour study of bitumen diluted with heavy hydrocarbon solvents such as propane and butane have gained less attention in recent years. These solvents, as good candidates for recently developed recovery methods such as Expanding Solvent Steam-Assisted Gravity Drainage (ES-SAGD), would provide promising oil production rates. The aim of this research, thus, is the development of an understanding of the phase behaviour of butane / Athabasca bitumen systems. It deals with both vapor-liquid and liquid-liquid phase equilibriums over wide range of temperatures (up to 200°C) approaching the conditions of in situ steam processes and pressures up to 8 MPa.

Experimental results indicated that the vapor-liquid and liquid-liquid equilibrium formed over the studied temperature and pressure ranges. In the case of vapor-liquid equilibrium, the dissolved butane in bitumen leads to a significant oil viscosity reduction. The effect was higher at lower temperature and higher pressure. For liquid-liquid equilibrium, butane extracted light components from oil and formed a butane-enriched phase while the heavier constitutes such as asphaltene separated as second heavy liquid phase. Finally, the measured solubility and density data were adequately modeled with Peng-Robinson equation of state.
Asphaltene Precipitation Inhibitors and Phase Behaviour Control for Bitumen Recovery by Solvent Injection
Authors: Yakubov M. R. , Yakubova S. G. , Borisov D. N. , Romanov G. V. , Arbuzov A. E. , Yakubson K. I.
Published: June 2014

In situ bitumen recovery directly depends on the reduction of bitumen viscosity. Solvent injection is an alternative to thermal bitumen recovery by steam injection. Injection of solvents containing n-alkanes like butane, propane and naphtha may lead to asphaltene precipitation and deposition in the porous media and a possible negative effect on the ultimate oil recovery. Addition of an asphaltene inhibitor (stabilizer) to solvents is a way to prevent asphaltene precipitation and deposition in a reservoir. Efficiency of an asphaltene inhibitor depends on the characteristics of the inhibitor and bitumen properties.In addition to aromatic hydrocarbons, various natural and synthetic polar heteroatom species can be used as asphaltene inhibitors. Results of the study show that deasphalted bitumen is an effective asphaltene inhibitor and it is of the same strength as environmentally hazardous aromatic hydrocarbons. Resins prevent asphaltene precipitation and are similar to expensive synthetic inhibitors. Addition of less than 8 vol. % of resins to low boiling point n-alkanes provides total asphaltene stabilizationin the process of bitumen recovery. When n-alkanes are used as solvents, it is important to know the amount of precipitated asphaltenes in the reservoir. To obtain such data, an experimental study has been conducted to simulate bitumen recovery. A specially designed experimental set-up was used in the study. The experiments allowed a set of chemical additives to be selected to improve colloidal stability of asphaltenes in bitumen.
Nanoparticle Stablized CO2 in Water Foam for Mobility Control in Enhanced Oil Recovery via Microfluidic Method
Authors: Nguyen Phong , Fadaei Hossein , Sinton David
Published: June 2014

Nanoparticle stabilized CO2 in water foam can overcome the low stability challenges facing surfactant foams in reservoir conditions. Foams are effective in mobility control against viscous fingering during gas injection in enhanced oil recovery. This study presents a microfluidic approach to image and quantify the stability of foam at pore scale and the dynamics of the oil recovery process during water flooding, CO2 gas flooding, and nanoparticle foam flooding. In addition to chip scale flooding visualization, micro-scale imaging reveals the mechanisms of the viscous fingering in gas flooding and the high sweep efficiency of foam; micro-emulsion size and distribution in gas and foam flooding. Coated silica nanoparticle CO2 foam is significantly more stable than sodium dodecyl sulfate (SDS) foam at both pore scale and bulk foam. Nanoparticle foam can improve oil recovery an additional 17% IOIP after water flooding, this is 10% IOIP more efficient than CO2 gas flooding as a result of high sweep efficiency and increase in effective viscosity.
Results of Field Operation of a Distributed Flux Burner in a Heater Treater in a Northern Canada Heavy Oil Field; Thermal Performance and Firetube Life
Authors: Bartz David , Gotterba James
Published: June 2014

Horizontal heater treaters are commonly used to separate oil/water emulsions from enhanced oil recovery in heavy oil reservoirs. Conventional burners used in these heaters can cause hot spots that result in coking of the viscous emulsion on the outer surface of the firetube. This coking layer acts as an insulator and results in high tube wall temperatures, leading to an early failure of the firetube. The problem may be exacerbated when using polymer injection in the recovery fluid due to increased viscosity of the fluid and thermal breakdown of the polymer which creates a thicker insulating layer along the firetube.

To prevent this coking and tube-failure process, an all radiant, distributed flux burner distributes the heat over a much larger area with a very uniform flame shape compared to a conventional burner. The distributed flux burner has a porous ceramic cylindrical surface that provides surface-stabilized premixed combustion, such that combustion characteristics at every point along the cylindrical burner surface are nearly identical. This significantly reduces peak heat flux surrounding the combustion zone, reducing likelihood of hot spots and potential for coking compared to conventional burners. At the same time, more heat is distributed further down the length of the firetube, increasing heat transfer in the rear section of the heater and improving its overall performance and efficiency. Firetube life is increased because of the lower peak wall temperatures, and because less heat is needed to achieve the required process throughput and water cut.

In this follow up paper to SPE 166261-MS presented in October 2013, key operating data is provided from a recent burner retrofit of a horizontal heater treater at the Canadian oil sands field in northern Canada. The retrofit was completed in a two day effort. Operating data presented includes heater firing rate and tube wall temperatures over time. Based on the recent field data, thermal analysis, and measurements made in lab tests, the distributed flux burner is compared to a conventional burner with respect to thermal efficiency, process throughput, oil/water separation performance, and tube wall temperatures.
Development of Electrical Joule's Heating Simulation for Heavy Oil Reservoirs
Authors: Lashgari Hamid R. , Delshad Mojdeh , Sepehrnoori Kamy , de Rouffignac Eric
Published: June 2014

In the electrical joule's heating process, the reservoirs are heated in situ by electrical energy to reduce the viscosity. In principle, electrical current passes through the reservoir fluids due mostly to the electrical conductivity of saturated fluids such as saline water. The flow of electrical current through the reservoir leads the heat in the reservoir and thereby drastically reduces the oil viscosity.

In this process, electrical current can flow between electrical potential sources (wells) and generate the joule's heat. Therefore, the regions around the electrodes in (or around) the wells are extremely heated. Because the wells act as line sources for the electrical potential, greater heating takes place near the wellbore causing possible vaporization of water in that region. Since steam has very low electrical conductivity, it can reduce the efficiency of this process significantly. In this process electrical conductivity plays a very important role. In order to increase efficiency of this type of heating process, the presence of optimum saline water saturation is an essential design factor.

In order to simulate a challenging multiphysics problem, we use three Maxwell classical electromagnetism equations. These equations are simplified and assumed for low frequency to obtain the conservation of electrical current equation and Ohm's law. The conservation of electrical current and Ohm's law are implemented using a finite difference method in a four phase chemical flooding reservoir simulator (UTCHEM). The joule's heating rate due to electrical current is calculated and added as an energy source to the energy balance equation.

A typical reservoir model is built and constant electrical potential with alternating current (AC) is applied to this model to study the efficiency of the electrical joule's heating process in the presence of water saturated fracture and evaluate this efficiency at, above, and/or below the water boiling point. Results illustrate that water saturation in the presence of fracture and electrical conductivity of saturated rock have an important effect on the joule's heating process. In this paper, we show that since, steam is a non-conductive electrical phase, this process should be designed to keep the temperature below the boiling point by circulating water. This can prevent the evaporation leading to an increase in the process efficiency.

Electrical conductivity of water can also be easily increased by injecting high salinity water into the reservoir and increasing the amount of heat substantially. This is highly beneficial and the main advantage of the electrical joule's heating process that can obtain high recovery in comparison to other thermal recovery methods. In this paper the understanding of the influence of saline water and steam forming is a key finding in order to economically optimize the process to unlock heavy oil reservoirs.
SAGD Vacuum Insulated Tubing vs. Bare Tubing – Concentric and Eccentric Configurations: A Comparative Thermal Computational Fluid Dynamics Study
Authors: Karra Shashank , Chudiak Mike , Sinha Apoorv , Greg Boser
Published: June 2014

In a typical injector string in SAGD operation, steam is injected through tubing placed inside a casing. Heat losses through the string and casing can result in lower quality steam being injected into the formation, and hence reduce the productivity of a SAGD operation. An ideal SAGD operation would be one where no heat losses happen inside the tubing and all the latent heat is released inside the formation to heat up the heavy oil. Several methods have been used to reduce heat losses in the injector tubing. One of the methods is the usage of a vacuum insulated tubing (VIT) placed inside the casing. VIT consists of specially manufactured tubing with a getter coating to maintain vacuum between ID and the OD of the tube. This helps in preventing heat losses compared to normal bare steel tubing.

In an effort to demonstrate the benefits of VIT compared to bare tubing injector string, a comparative 3D Computational Fluid Dynamics (CFD) study was carried out. The objective of the study is to provide a comparison of heat loss in both VIT and bare tubing concentric and eccentric configurations. The simulation accounts for frictional and heat losses throughout the tubing and most importantly, condensation of steam inside the tubing as result of heat loss. The consideration of condensation inside the tubing is a critical component of the simulation as it in turn affects the heat loss through the tubing. The other significant aspect of the study is the consideration of eccentric and concentric placement of tubing string inside the casing and its effect on heat loss. This study uses an Euler-Euler Multiphase flow based approach which accounts for the fluid-fluid interactions such as drag, turbulent dispersion etc. between steam and water inside the tubing. The thermal phase change model in ANSYS CFD accounts for the condensation of steam into water.

The computed results successfully demonstrate the benefits of vacuum insulated tubing over bare tubing in maintaining steam quality in the vertical section of the wellbore. Also, the study shows reduction in steam quality for eccentric position of the bare tubing compared to concentric position. Most importantly this study demonstrates the capability of CFD to solve industrial scale complex problems and provide engineers with an insight into some of the challenging physics associated with a SAGD operation in the field.
Steam-Surfactant-Foam Modeling in Heavy Oil Reservoirs
Authors: Lashgari Hamid R. , Lotfollahi Mohammad , Delshad Mojdeh , Sepehrnoori Kamy , de Rouffignac Eric
Published: June 2014

Steam foam is a hybrid and novel method of the thermal and chemical flooding to improve the sweep efficiency of steam for producing heavy crude oils. Steam injection is a mature process to substantially reduce the oil viscosity in heavy oil reservoirs to increase its mobility. Steam flooding is an unstable displacement since the gravity of steam causes poor vertical sweep efficiency due to the gravity override in thick high permeability pay zones and poor areal sweep efficiency in high permeability channels with high connectivity. On the other hand foam reduces the mobility of steam by stabilizing the liquid lamellae that cause some or all of the steam to exist as a discontinuous phase. Therefore, foam plugs large pores to divert the flow into the low permeability zones and controls gravity override. Foam increases the pressure gradient slightly in the steam swept regions and leads to heating oil more efficiently when steam diverts into the cold unswept regions. Furthermore, surfactant mobilizes the high viscous oil by emulsification and reduction of interfacial tension. The synergy of steam, surfactant, and foam has the potential to greatly improve the recovery of heavy oil reservoirs.

Based on a literature survey, steam foam injection has been conducted in both laboratory corefloods and few field pilots. On the other hand, existing numerical simulators have not been able to capture the mechanisms involved in such a process. In this paper, we present the development and implementation of a new robust steam formulation in a four phase chemical flooding reservoir simulator (UTCHEM) to model and understand the contribution of each mechanism such as viscosity reduction, emulsification, and foam for mobility control. Results illustrate that the steam foam process controls the mobility of steam to avoid incomplete vertical sweep due to gravity segregation. Formation of the emulsion phase by condensing steam along with the presence of water leads to an increase in the emulsion viscosity and thereby decreases water production. The presence of surfactant and emulsification of oil either as water in oil or oil in water emulsions can also impact the displacement and propagation of viscous oil.

The mechanistic understanding of steam foam process and improvement of the heat transfer compared to conventional steam flooding is a key finding in this research to optimize the technology that unlocks heavy oil reservoirs with favorable economics.
Modeling the Diffusion Controlled Swelling and Determination of Molecular Diffusion Coefficient in Propane-Bitumen System Using a Front Tracking Moving Boundary Technique
Authors: Etminan S. Reza , Maini Brij B. , Chen Zhangxin John
Published: June 2014

Accurate estimation of molecular diffusion coefficient is necessary for the design and modeling of solvent-assisted recovery techniques for exploitation of heavy oil and bitumen resources. Several studies on molecular diffusion measurement have been conducted using various pure gaseous solvents but there are very few diffusivity measurements available for the propane-bitumen system. The scarcity of these data is due to the complexities arising in the modeling of dissolution of propane in bitumen. These include high solubility of propane in bitumen and subsequently, dramatic volume change of the diluted oil, drastic reduction of bitumen viscosity during dilution and the possibility of asphaltene precipitation.

In this work, a rigorous numerical model is developed to model the diffusivity of propane in bitumen based on real data. This model accounts for bitumen solution density change (swelling) as a result of dilution. A front-tracking moving boundary algorithm and numerical procedure is proposed which accounts for volume change of each grid at each time step. Those grids which experience diffusive flux, change sizes based on non-ideal mixing data available from measurement of solution density versus concentration. Finally, the Levenberg-Marquartd method was applied to estimate the propane diffusion coefficient based on laboratory measured gas-oil interface movement. A constant-pressure diffusion measurement experimental technique was used to measure mass of gas dissolved and solution height change in a propane-bitumen diffusion experiment at 413.7kPa (60 psia) and 827 kPa (120 psia) both in 24°C.

The experimental results show that the "no-swelling" simplifying assumption often used in diffusion measurement modeling studies, cannot be generalized to all gaseous solvents because based on our experiments, the bitumen solution volume can be increased by 50% due to propane dissolution. The estimated diffusion coefficient is compared with the results of other mathematical techniques available in the literature. It is shown that the no-swelling simplifying assumption used in unidirectional modeling of gas diffusion in bitumen leads to estimation of erroneous parameters when propane is the gas and oil density and oil volume change is neglected.
Contribution of Geomechanics in Evaluation of Heat Transfer Mechanisms at Mobile Zone of SAGD and ES-SAGD
Authors: Shokri A. Rangriz , Hosseini B. Koohmareh
Published: June 2014

Efficient recovery of heavy oil and bitumen in western Canada has widely been applied with thermal-based processes. The well-known Steam-Assisted Gravity Drainage (SAGD) takes advantage of the strong dependency of bitumen viscosity on temperature ranging from 10 to 250 °C. The latent heat of injected steam is released as the steam chamber develops and causes the bitumen to mobilize and drain under the effect of gravity toward the production well. Co-injection of solvent with steam (ES-SAGD) may help to reduce the oleic phase viscosity adjacent to chamber edge by offsetting the temperature reduction effect.

While many researchers are currently tackling the optimal operational conditions from a fluid property point of view (pressure, solvent fraction, etc.), less attention was paid to the impact of heat transfer due to incorporation of geomechanics into occurring physics. Such simplifications in analyzing the real processes physics would result in neglecting of the convection flow of heat along with conduction. Considering the dramatic changes in temperature at the chamber edge, the induced thermal geomechanical responses would lead to a faster fluid movement. The fluid mobility at the edge of chamber would even increase more, mainly because of temperature-dependant heat capacity of water, changes in absolute and relative permeabilities, and possible wettability alteration. If a multi-component solvent is used (ES-SAGD), the assessment of production performance would get more complicated due to the different condensation dynamics of light versus heavy components and the possible gas-blanket effect caused by the co-injected solvent.

In this study, the geomechanical changes due to pressure and temperature effects were considered at the steam chamber, for both SAGD and ES-SAGD scenarios. The thermo-poro-elasticity concept, with elastic constitutive rock behaviour, was chosen for geomechanical study. The primary impacts of geomechanics on the physics of ES-SAGD were rock and fluid alterations, and changes in petrophysical properties (porosity and absolute permeability). Assuming a potential change in rock and fluid interaction due to geomechanics, the same analysis was conducted for a multi-component solvent with different condensation profiles. It was shown how the use of solvent will adversely affect the induced thermal geomechanics contribution. The findings of this paper can be used as a guideline for further experimental studies on the effect of geomechanics in thermal-based recovery processes.
Extending the Role of Compliance: Competent Teams Drive Confident Operations
Authors: Coward Brian Andrew
Published: June 2014

Competence is a word that is used increasingly across process industries and is becoming a core part of legislation in much of the world. Standards and directives such as IEC61508, EU Offshore Safety Directive 2013/30/EU, or indeed the UK Health and Safety Executive's “Managing Competence For Safety-Related Systems” all refer to the requirement to be able to document and assess competence. IEC 61508, Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems (E/E/PE, or E/E/PES) requires that “All persons involved in any overall, E/E/PES or software safety lifecycle activity, including management activities, should have the appropriate training, technical knowledge, experience and qualifications relevant to the specific duties they have to perform.” In addition, it crucially requires that competence be “documented and assessed.”

Competence is developed through many routes – on-the-job training, Original Equipment Manufacturer (OEM) training, formal classroom learning, external classroom courses, through the use of Operator Training Simulators (OTS) or by simply doing a job for many years. What is becoming harder for many companies now though is the ability to map people to competencies, to demonstrably track their staff against these competence requirements and, with the departure of senior people due to retirement, to be able to create the role models for competence profiles so that seamless replacement of staff can happen.

This paper will work through the steps of defining competence, how a competence development and management plan is created and how compliance to the current varying legislation can create more confident operations.
Refinery wastewater degradation with Titanium dioxide, Zinc oxide, and Hydrogen peroxide in a photocatalytic reactor
Authors: Khan Wasi Z. , Najeeb Imad , Tuiyebayeva Madina , Makhteyeva Zhibek
Published: June 2014

This paper presents the photocatalytic degradation of real refinery wastewater from National Refinery Limited (NRL) in Karachi, Pakistan, using TiO2, ZnO, and H2O2. The pretreatment of the refinery effluent was carried out on site and pretreated samples were tested at 32-37 °C in a stirrer bath reactor by using Ultra-Violet photo oxidation process. The degradation of wastewater was measured as a change in initial Chemical Oxygen Demand (COD) and with time. Optimal conditions were obtained for catalyst type, and pH. The titanium dioxide proved to be very effective catalysts in photocatalytic degradation of real refnery wastewater. The maximum degradation achieved was 40.68% by using TiO2 at 37 °C and pH of 4, within 120 minutes of irradiations. When TiO2 was combined with H2O2 the degradation decreased to 25.35%. A higher reaction rate was found for Titanium dioxide. The results indicate that for real refinery wastewater, TiO2 is comparatively more effective than ZnO and H2O2. This study proves that real refinery wastewater reacts differently than synthetic refinery wastewater, oil field produced water or oil water industrial effluent.
Efficient Production Optimization With Flow-Network Models
Authors: Lerlertpakdee Pongsathorn , Jafarpour Behnam , Gildin Eduardo
Published: June 2014

Automating model calibration and production optimization is computationally demanding because of the intensive multiphase-flow-simulation runs that are needed to predict the response of real reservoirs under proposed changes in model inputs. Fast surrogate models have been proposed to speed up reservoir-response predictions without compromising accuracy. Surrogate models either are derived by preserving the physics of the involved processes (e.g., mass balance) to provide reliable long-range predictions or are developed solely on the basis of statistical input/output relations, in which case they can only provide short-range predictions because of the absence of the physical processes that govern the long-term behavior of the reservoir. We present an alternative approach that combines the advantages of both statistics-based and physics-based methods by reducing the flow predictions in complex 3D models to a 1D flow-network model. The existing injection/production wells in the original model form the nodes or vertices of the flow network. Each pair of wells (nodes) in the flow network is connected by use of a 1D numerical simulation model, resulting in a connected network of 1D grid-based simulation models. The coupling between the individual 1D flow models is enforced at the nodes where network edges intersect. The proposed flow-network model provides a useful and fast tool for characterizing interwell connectivity, estimating drainage volume between each pair of wells, and predicting reservoir production over an extended period of time for optimization purposes. The parameters of the flow-network model are estimated by a robust training approach to ensure that the network model reproduces the response of the full model under a wide range of development strategies. This step helps the network model to preserve its predictive power during optimization iterations when alternative development strategies are proposed and evaluated to find the solution. We demonstrate the effectiveness and applicability of the proposed flow-network model by use of two-phase waterflooding experiments.
Experimental Study on the Compressibility of Gelled Crude Oil
Authors: Gang Liu , Lei Chen , Guozhong Zhang , Zhongliang Chen , Yingpeng Hao , Pingsheng Dong , Junfeng Liu
Published: June 2014

The compressibility of gelled crude oil is crucial for the restart behavior of a pipeline. However, only a few reports have been published in this field. In this paper, experiments were conducted for the compressibility of waxy crude oil at temperatures lower than pour point. Results show that the compressibility of gelled crude oil is much higher than that of the liquid oil at temperatures above pour point. The compressibility characteristic curve of gelled crude oil is obtained in this research, which shows that the compressibility of gelled crude oil will gradually decrease during the compression process until the gel structure is completely destroyed and the void space is compacted.
Produced Water Management: An Example of a Regulatory Gap
Authors: Khalilpour R..
Published: June 2014

The current Oil-in-Water (OiW) regulations, measuring only dispersed oil and grease content, have been practiced for long time without any significant improvement. This is whilst the major hazardous portion of produced water falls in dissolved components. Although, in recent years numerous technologies have been commercialized for online measurement and treatment of the entire components of produced water, the regulations have not been updated, except for some limited regions.

Given the international awareness of sustainability and the move towards zero discharge, it seems that the environmental authorities have delayed in upgrading their current unsustainable "oil-and-grease" regulations with more accurate ones. It is recommendable to the prospective field developers/operators to take into account the dissolved components of produced water and consider the economic consequences of adopting tertiary produced water polishing technologies.
New Hybrid Drill Bit with Innovative Technology Improves Drilling Efficiency in Challenging Jordanian Drilling Project
Authors: Ismail Ahmed , Moustafa Waleed
Published: June 2014

Major operator is drilling in an exploratory field, located in East Jordan, targeting sandstone reservoir approximately 2,600 m below the surface. Historically, the operator drilled these underbalanced wells with conventional roller-cone and polycrystalline diamond compact (PDC) bits. The drilling project included a 26-in. hole through a tough and highly interbedded formation of mudstone, sandstone and siltstone down to depth of 1,350 m. Inconsistent drilling performance of PDC bits resulted in short run intervals with poor dull conditions. The roller-cone bits also inconsistently drilled the entire interval, achieving slow penetration rates with short runs.

horough in-depth engineering analysis of all available data including rock strength, bit dull, bottomhole assembly, drilling parameters and downhole vibrations, identified the possible root causes for this poor performance and led to a new 26-in. hybrid bit design to overcome the drilling challenges and improve the overall drilling efficiency.

The 26-in. hybrid bit technology with combined elements of PDC bits and tungsten carbide inserts (TCI) was deployed. This combination overcame the drilling challenges in this application and achieved all the operator objectives by drilling the entire 26-in. hole in one run, replacing three bits used to drill the same interval in the offset well, saving five rig days over the planned AFE drilling days.

This paper provides a detailed description of the operational challenges in this application. It then introduces the concept of the new hybrid bit design and provides recommendations based on the performance achieved. After a description of the implementation and operation execution of drilling 26-in. hole in this challenging application, the paper concludes with a discussion of the benefits and value added to the operator by the deployment of this new design approach, highlighting the reduction in number of trips for bit changes.