bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Three-Phase Relative Permeability Isoperms in Heavy Oil/Water/Carbon Dioxide and Heavy Oil/Water/Methane Systems
Authors: Torabi Farshid , Akhlaghinia Manoochehr , Chan Christine
Published: June 2013

Abstract

Three-phase relative permeability data is an Achilles' heel in the field performance prediction of the enhanced heavy oil recovery processes with numerical simulation. Minor inaccuracy could lead to erroneous predictions and, in turn, considerable revenue losses. A technique is proposed to utilize two- and three-phase displacement experiments in order to estimate relative permeability isoperms for a fluid system of heavy oil/water/gas. Three-phase flow zone is determined in a ternary diagram with residual oil and irreducible water saturations obtained from two-phase heavy oil/water displacements experiments. A developed fully implicit three-phase simulator mimics three-phase displacement experiments in the form of gas (carbon dioxide and methane) injection into a consolidated Berea core saturated with heavy oil (1174cP at 28°C) and water. Three-phase relative permeability data corresponds to a saturation path, drawn across the three-phase flow zone, is tuned to match simulated pressure drop, oil and water production with three-phase displacement experiment. Results have indicated, due to high residual oil saturation, a small three-phase flow zone can exist in presence of heavy oils. Although different curvatures have been obtained with relative permeability isoperms of oil, water, and gas phases; however, repeating experinemts with different gases (methane and carbon dioxide) indicates that relative permeability isoperms does not change siginificantly in presence of different gases. Comparison of the proposed procedure with the unsteady state technique indicates that unsteady state technique fails to provide reliable relative permeability data for numerical simulation purposes since it calculates three-phase relative permeability data at saturations out of the three-phase flow zone. In addition, in the case of water, unsteady state technique gives relative permeability values for a short range of water saturations. Proposed technique takes advantage of practicability of displacement experiments to estimate three-phase relative permeabilities it and, also, eliminates uncertainties with unsteady state method such as inaccurate derivative calculations. Although proposed method indirectly estimates three-phase relative permeabilities; sensitivity analysis shows a good margin of confidence with the relative permeability isoperms.
Experimental Investigation of the Effect of Solvent Type and Drainage Height on the Performance of Vapor Extraction (VAPEX) Process in Heavy Oil Systems
Authors: Mohammadpoor Mehdi , Torabi Farshid
Published: June 2013

Available large resources of heavy oil and bitumen in Western Canada are potential future energy sources. Hence, looking for an economically viable, technically feasible, and environmentally friendly heavy oil recovery technique is inevitable.

Although the dramatic decrease in the viscosity of heavy oil with the temperature increase makes the thermal recovery techniques the first choice for these reservoirs, cost associated with generating the required heat, excessive heat loss to the surrounding formations, and large amount of CO2 emitted during these thermal processes are some of major economical and environmental concerns. Solvent-based heavy oil recovery methods have recently gained some attention due to the potential advantages over the thermal processes. It has been found that the viscosity reduction resulted from injecting the appropriate solvent is comparable to that obtained by heating in some cases.

In this paper, the vapor extraction (VAPEX) process is experimentally investigated to examine the effect of injecting different solvents and drainage heights on the heavy oil recovery. For this purpose, two large visual rectangular sand-packed VAPEX models with the heights of 24.5 cm and 47.5 cm and permeability of about 5 ~ 7D were employed. A heavy oil sample with viscosity of 2500 ~ 5500 cP was used to saturate both models. Pure propane, methane, and carbon dioxide where considered as respective solvents and injected in both models under the same operating conditions. The heavy oil production rate and the produced gas-oil ratio where measured periodically during the course of experiments. In addition, the asphaltene content and the visual observation of the gas chamber evolution were monitored.

It was found that the drainage height has a significant impact on the production rate and the ultimate heavy oil recovery. The experiments with smaller drainage height showed higher recovery factor and faster recovery process for similar period of injection-production. Among three different solvents utilized in this study, propane with lower vapor pressure and higher solubility showed more promising results. Additionally, CO2 and methane were used as carrier gases and a series of CO2-based VAPEX process were conducted. Results indicated that CO2-based VAPEX could be used as a means of feasible heavy oil recovery.
Field Trial Results of an Innovative Heavy Oil Production System
Authors: Rushby M. J. , McCann R. , McAleese A.
Published: June 2013

An innovative heavy oil production system has been developed in conjunction with a major operator and has now entered field trials. The system is compatible with cyclic steaming operations, is capable of deployment on jointed or coiled tubing, and fundamentally addresses sand related issues. This paper describes some aspects of the design and qualification of the system, and presents initial feedback from the first field trial.

The system has been developed for heavy oil applications, utilising downhole permanent magnet motor technology and a magnetic torque converter, resulting in both scalability and high operating efficiencies. This dramatically reduces the total power requirements, and the need for expensive surface electrical installations.

A progressive cavity pump is incorporated on bottom, allowing this small diameter system to be set in well bore deviations through to the horizontal. Combined with the ability to run at variable speed and rotate in either direction; sand related failures and workovers are reduced.

This novel configuration reduces both the surface footprint and environmental impact of the well. It also reduces deployment and workover requirements; resulting in fewer and safer operations.

By combining unique technology and a novel configuration a heavy oil system has been developed which reduces total cost of ownership. The system has entered field trials in the San Joaquin Valley fields in California.
Optimal Application Conditions for Steam-Solvent Coinjection
Authors: Keshavarz Mohsen , Okuno Ryosuke , Babadagli Tayfun
Published: June 2013

A limited number of laboratory and field evidences showed that steam-solvent coinjection can lead to a higher oil production rate, higher ultimate oil recovery, and lower steam-oil ratio, compared with steam-only injection. However, a critical question still remains unanswered: Under what circumstances the above mentioned benefits can be obtained when steam and solvent are coinjected? To answer this question requires a detailed knowledge of the mechanisms involved in coinjection and reflection of this knowledge to its numerical simulation. Our earlier studies demonstrated that the determining factors for improved oil production rates are relative positions to the temperature and solvent fronts, the steam and solvent contents of the chamber at its interface with reservoir bitumen, and solvent diluting effects on the mobilized bitumen just ahead of the chamber edge. Then, the key mechanisms for improved oil displacement are solvent propagation, solvent accumulation at the chamber edge, and phase transition.

This paper deals with this unanswered question by deriving a systematic workflow for selecting an optimum solvent and its concentration in coinjection of a single-component solvent with steam. The optimization considers the oil production rate, ultimate oil recovery, and solvent retention in situ. Multiphase behavior of water-hydrocarbon mixtures in the chamber is explained in detail analytically and numerically. The proposed workflow is applied to simulation of the Senlac SAP pilot project to investigate reasons for its success.

Results show that an optimum volatility of solvent can be typically observed in terms of the oil production rate for given operation conditions. This optimum volatility occurs as a result of the balance between two factors affecting the oil mobility along the chamber edge; i.e., reduction of the chamber-edge temperature and superior dilution of oil in coinjection of more volatile solvent with steam. It is possible to maximize oil recovery while minimizing solvent retention in situ by controlling the concentration of a given coinjection solvent. Initiation of coinjection right after achieving the inter-well communication enables the enhancement of oil recovery early in the process. Subsequently, the solvent concentration should be gradually decreased until it becomes zero for the final period of the coinjection. Simulation case studies show the validity of the oil recovery mechanisms described.
Impact of Solvent Loss During Solvent Injection Processes
Authors: Chang Jeannine , Canada Devon , Ivory John , Forshner Ken , Feng Yu
Published: June 2013

Only 5 - 15% of the oil in Lloydminster heavy oil reservoirs is recovered during cold heavy production with sand (CHOPS). Solvent injection processes are being explored as a means of recovering the heavy oil remaining in the reservoir after CHOPS has been completed. Solvent retention becomes a main concern for the process economics. This paper evaluates the relative importance of different solvent retention mechanisms and how solvent can be recovered from the reservoir so that solvent injection processes (e.g. cyclic solvent injection (CSI), Vapor Extraction Process (VAPEX), thermal solvent, and steam-solvent) can be economically viable. In particular, CSI is a promising post-CHOPS follow-up process.

Sources of solvent loss / retention include: Solvent trapped in the reservoir due to surface and interfacial forces including adsorption and capillary pressureSolvent vapor (free gas or trapped bubbles) in porous mediaDissolution in un-recovered oilDissolution in formation water or thief water zonesOther possible sources such as:Lack of confinement of injected fluids; especially important for post-CHOPS reservoirsHydrate formationPrecipitated asphaltenes

Three experiments were performed to estimate solvent losses due to different retention mechanisms. In these experiments, gaseous propane was injected into a sand pack to a pressure of 750 kPag and then depressurized (at an ambient temperature of 21 °C) in 100 kPa steps to 50 kPag. The propane produced at each depressurization step was measured. The sand packs used in the experiments were: Sand pack initially saturated with water ("wet pack")Dry sand packSand pack initially flooded with water and then with dead Husky Edam oil

The experimental results showed that there was significant propane retention in unproduced oil and as solvent gas. However, little propane adsorption occurred on the sand as it had a small surface area due to an insignificant amount of clays being present in the test packs. Solvent adsorption in a reservoir can be significant if there is a considerable amount of clays with a large surface area. It may be particularly high when shale is present.

Propane concentrations in the produced water from the wet pack were similar to literature values. Solvent loss in water was small due to the low pressures involved in the test. However, solvent loss in water will be significant if the solvent dissolves into the formation water at high temperature (for liquid solvent) and/or high pressure especially if there is a significant water source to sweep away the dissolved solvent or the water causes hydrate formation.
Long Term Wellbore Isolation in Corrosive Environments
Authors: Ilesanmi Oluwagbemiga R. , Hilal Bashar , Gill Steve , Leigh Henry , Brandl Andreas , Al Mazrouei Manal , Abdullah Ali , Halim Adam Omar
Published: June 2013

The paper reviews two case histories about successful wellbore isolation with a suitable cementing system for a recent enhanced oil recovery / CO2 project targeting the Thamama B formation of the Bab Far North reservoir in the UAE. The first two wells were vertical observers with zonal isolation required between the Thamama A and B. These wells were expected to exhibit a naturally corrosive environment (e.g. 56, 000 ppm of CO2). To address these challenges, a fit-for-purpose cementing system, suitable for CO2 and other corrosive fluids, was developed and successfully applied. The system was designed to isolate and protect specific Thamama zones and wellbore areas that contained gaseous or liquid corrosive CO2. This cement slurry was developed with a density of 16.7 ppg exhibiting expanding properties after setting to compensate potential shrinkage issues and to improve cement bond. Laboratory test results for the developed cementing system, such as compressive strength development, thickening time, expanding properties after setting, and integrity after long term exposure towards wet CO2, are presented and discussed. Performance requirements for cementing sytems to qualify for CO2 tolerance are elucidated. Finally, the execution in the field and the quality of the cement job was evaluated. All of the special designs exhibited excellent bond log results. The favorable lab test results and the positive case history conclude that the developed cementing system can be a viable solution to provide long term zonal isolation in a wellbore with a corrosive environment.
Modeling In-Situ Combustion in a Heavy Oil Field in Romania
Authors: Ruiz Jorge , Naccache Paul , Priestley Andrew , Glatz Guenther , Crecana Virgil
Published: June 2013

Suplacu de Barcau, a heavy oil field in Romania with more than 2,700 wells and over 50 years of air injection history, is considered one of the world's largest in-situ combustion projects. This paper describes a 3D simulation study of a sector of the field. The sector chosen spans the entire history of the field, from a short period of cold production in the early 1960s to the current production method of cyclic steam stimulation followed by air injection. To date, about 200 wells have been drilled in this sector, which covers approximately 1.1 km2.

We present the different stages of the numerical study and review some of the difficulties involved in modeling in-situ combustion in a large model. We describe how we managed the uncertainties in the reservoir and in the fluid description, and how we overcame limitations in the available data. Kinematic data from laboratory experiments were used as a starting point, and we present details of the simplified kinematic formulation that was needed to improve the numerical performance of the simulation model.

The model is heterogeneous, so there is an uneven propagation of the combustion front. We compare historical production rates with the model predictions and estimate areas of oil that were bypassed due to this heterogeneity and to gravity override.
Analytical Evaluation of Casing Connections for Thermal Well Applications
Authors: Tao Gang , Xie Jueren
Published: June 2013

Thermal well technologies, such as Cyclic Steam Stimulation (CSS) and Steam Assisted Gravity Drainage (SAGD), are widely used for the exploration of heavy oil and oilsands resources. Casing connections are one of the most critical components in thermal wells in terms of the wellbore structural and pressure integrities. High temperature operation of thermal wells inevitably imposes significant axial loads on the casing connections, and as a result, a plastic strain design concept must be used for the casing and connections. In addition, thermal well design should consider the impact of formation shear movement that may be caused by changes in the stress state in the reservoir and overburden formations during thermal operations. To meet the design challenges posed by thermal wells, premium connections are usually preferred over API connections due to generally superior structural capacity and sealability. Rigorous engineering assessments, such as full-scale physical tests and analytical evaluations are often used to assess the performance of premium connections and to identify suitable connection designs for the intended applications. These engineering assessments typically consider the in-situ load conditions specified by operators, or the load cases recommended by industry guidelines, such as the recently released Thermal Well Casing Connection Evaluation Protocol (TWCCEP 2012).

This paper presents approaches and considerations for using Finite Element Analysis (FEA) to conduct the analytical evaluation of casing connections for thermal wells. Such analytical evaluations serve to determine the worst-case specimen configurations (e.g. highest potential for galling or leaking) for full-scale testing programs under the load conditions specified in the Protocol, such as make-up and thermal cycles, as well as for understanding the connection performance under in-situ load cases as specified by operators, such as bending and formation shear. Analysis results provide useful insight into connection performance in terms of structural capacity, leakage resistance and galling potential. To demonstrate the use of the proposed analysis approaches and considerations, an example case with a generic premium connection geometry is analyzed and the results are presented.
Characterizing the Effect of Heat Transfer on Multiphase Flow during the Steam-Assisted Gravity Drainage (SAGD) Process
Authors: Azom Prince N. , Kamp A. M. , Srinivasan S.
Published: June 2013

By solving a 1-D heat equation for single phase flow, Butler et al. (1981, 1985) derived their classical SAGD equation, which has excellent predictive capability at experimental scales but performs poorly at field scales. Several authors have tried to remedy this by accounting for multiphase flow at the steam-bitumen boundary and their efforts have resulted in modified expressions for the oil rate incorporating rate multipliers. The practice of applying rate multipliers, however results in models that seem to vary for each reservoir or experiment. Recently, by making the prior assumption that fluid saturations ahead of the steam chamber vary linearly with temperature, Sharma and Gates (2010) derived a SAGD equation that accounts for multiphase flow ahead of the steam chamber, which performs excellently at field scales but poorly at experimental scales. In this work, we couple the multiphase mass conservation equations with the energy equation and show that the multi-scale, multiphase flow phenomenon associated with SAGD is the classical Marangoni (thermo-capillary) effect which can be characterized by the Marangoni number. At low Marangoni numbers (typical of experimental scales) we get the Butler solution while at high Marangoni numbers (typical of field scales), we approximate the Sharma & Gates solution. We present results from our model in dimensionless space so they can be used as a fast SAGD predictive model within a proxy-based history matching process.
Phase Behavior and Physical Property Modeling for Vapex Solvents: Propane, Carbon Dioxide, and Athabasca Bitumen
Authors: Badamchi-Zadeh Amin , Yarranton Harvey , Maini Brij
Published: June 2013

Employing CO2 as the non-condensable gas in the Vapex process is an attractive option that could provide environmental benefits of CO2 sequestration along with improved Vapex performance. Mixtures of CO2 and a hydrocarbon such as propane allow the solvent to be tailored to different reservoir conditions. To test potential solvent mixtures, the phase behavior and physical properties measurements and modeling are required. We have previously reported on the phase behavior, viscosity and density of the CO2-propane-Athabasca Bitumen systems (Badamchi-Zadeh et al., 2009a,b). These results confirmed the ability of carbon dioxide and propane mixtures to sufficiently reduce Athabasca bitumen viscosity.

In this study, an oil characterization and equation of state model are developed to describe the phase behaviour of mixtures of carbon dioxide, propane, and Athabasca bitumen. The model is tuned to fit the experimental phase behaviour data for binary and ternary mixtures of these components. Solubility data for carbon dioxide and Athabasca bitumen reported by Svrcek and Mehrotra 1982 are also used.

It was found that two parameter cubic equation of state would require a third parameter (i.e. volume-shift) to better predict liquid density. The volume shift parameter was adjusted to improve cubic equation of state calculated liquid density against experimental data. Pederson (1987) viscosity correlation coefficients were modified to improve liquid viscosity prediction for propane, carbon dioxide, and bitumen mixtures.
Investigation of Alkali Resistant Polymer for Improved Heavy Oil Recovery
Authors: Doda Ankit , Kotsuchibashi Yohei , Trivedi Japan J , Narain Ravin
Published: June 2013

Heavy oil reservoirs in western Canada with viscosities ranging from 1,000 cp to 10,000 cp are being exploited using chemical enhanced oil recovery techniques. The most widely used polymer in enhanced oil recovery applications is hydrolyzed polyacrylamide (HPAM). The primary reason for its vast use is its higher viscosity in an aqueous solution and resistance to bio-degradation however is very prone to alkaline conditions as it hydrolyzes very rapidly under such environment.

To overcome this shortfall of conventional HPAM, a new co-polymer P(AAc-st-VP) was synthesized using Acrylic Acid (AA) and N-vinyl-2-pyrrolidinone (NVP) and proper initiator, that can offer stability against alkali. In the research presented herein, currently available conventional HPAM polymers were examined against new synthesized P(AAc-st-VP) co-polymer with improved properties by including different weight percent of N-vinyl-2-pyrrolidinone monomer for use with a focus on highly alkaline environment. Rheological properties were compared in terms of viscosity and elasticity under various NaOH concentrations and aging time, for typical alkali-polymer flood operations. The core flooding experiments of alkali-polymer (AP) flooding was conducted for oil samples collected from a heavy oil reservoir in Alberta. The results were analyzed for tertiary heavy oil recovery performance, residual resistance factor, and residual oil distribution. No significant change in rheological properties of P(AAc-st-VP) co-polymer was observed in presence of alkali even for longer aging times while the conventional HPAM showed much higher viscosity loss, becoming less effective for AP or ASP heavy oil recovery operations. Due to stable rheological characteristic under alkali condition, the new synthesised P(AAc-st-VP) co-polymer showed improved performance over conventional HPAM polymer in terms of injectivity and residual resistance factor. Analysis of the results indicates that AP flooding using P(AAc-st-VP) co-polymer could effectively overcome the drawbacks of conventional HPAM polymer and improve the recovery efficiency for the heavy oil with higher injectivity.
Smart Pad Reservoir Production Machine for Oil Sands SAGD Operations
Authors: Guo Tao , Wang Jingyi , Gates Ian D.
Published: June 2013

The Steam Assisted Gravity Drainage (SAGD) process is widely used in the Athabasca oil sands deposit to recover bitumen. Since the viscosity of bitumen is high at original reservoir conditions, heat is required to lower its viscosity to the point it becomes mobile enough to be recovered under gravity drainage. To heat the reservoir, steam is injected into the formation and thus SAGD is energy intense – on average, the steam-to-oil ratio (SOR) is equal to about 3.5 m3 (expressed as cold water equivalent) of steam injected per m3 of bitumen produced. Given that the fuel used to generate steam is the largest operating cost, the SOR is a key parameter for evaluating the economics of any SAGD project. The target for many SAGD operations is a SOR lower than 2.5 m3/m3. Here, we explore the use of dynamic distributed steam injection within a pad of SAGD wellpairs controlled via a Proportional-Integral-Derivative (PID) feedback controller, a concept we refer to as Smart Pad. The Smart Pad Reservoir Production Machine is designed to dynamically distribute steam injection along multiple well pairs so that over a period of operation, the pad-scale cSOR is dynamically improved as the process evolves. First, a method to condition the PID control gains is described and second, the controller is applied to a multiple well pair SAGD pad in an oil sands reservoir with a top water zone. The results demonstrate that automated control can lead to improvements of the SOR over that of constant pressure. The results show that automated PID control is able to detect the "sweet spots" (oil zones with better geological properties) in the reservoir and dynamically deliver more steam to that region. Meanwhile, it reduces the steam injection towards relatively worse reservoir quality zones, i.e. shale barriers, high permeability channel to the top water zone, to lower the local SOR. In this manner, the PID feedback controller provides an efficient method to recovery bitumen in SAGD operation, especially during the first 7-10 years' operation, where it helps to achieve a relatively low cSOR and maintain a normal level of oil recovery. Also, the PID controller reduces the degree of dependence of SAGD operation on the geological conditions of the reservoir. The algorithm described could be applied to any operating or new SAGD pad.
Enhanced Vapor Extraction through Foamy-oil flow
Authors: Jia Xinfeng , Jiang Tao , Zeng Fanhua , Gu Yongan
Published: June 2013

Hydrocarbon solvent-based enhanced oil recovery techniques, such as vapor extraction (VAPEX) and cyclic solvent injection (CSI), have showed great potential to recover heavy oil reserves. However, VAPEX suffers from low production rates because of the slow mass transfer and inefficient gravity drainage. CSI benefits from solution gas drive and foamy-oil flow; however, solvent gas release would cause the viscosity of the diluted oil to re-increase to slow down the oil flow. In addition, the oil rate of CSI might be uneconomical due to the long no-production injection/soaking period. This paper proposes a new process, named foamy-oil assisted VAPEX, to enhance the heavy oil recovery. This process applies the same production mode as a traditional VAPEX except the model pressure is reduced cyclically to induce foamy-oil flow.

Laboratory experiments are conducted to analyze the new process and compare it with VAPEX under the same well pattern and similar physical conditions. Sandpack permeability is about 5 Darcy. Propane is used to recover a heavy oil sample with a viscosity of 5,875 cP. For VAPEX, model pressure is kept at ~800 kPa. For foamy-oil assisted VAPEX, pressure control in each cycle consists of two periods: a constant pressure period and a pressure reduction period.

Results show that a strong foamy-oil flow can be induced through a pressure drawdown, which forms a foamy-oil zone. The foamy-oil flow pushes the solvent-diluted heavy oil inward the solvent chamber, which not only increases the oil production, but also helps solvent to contact the fresh heavy oil and accelerate the mass-transfer process. In the foamy-oil assisted VAPEX, oil that could not be produced in a traditional VAPEX by the gradititional force could be recovered in the foamy-oil assisted VAPEX process by a foamy-oil flow. Compared with a traditional VAPEX, foamy-oil assisted VAPEX can increase the oil production rate by 68.5 % and the final recover factor by 20.4%.
A Study on Energy Transfer During SADG and Its Effects on Flow Characteristics
Authors: Little L. , Romaniuk N. A. , Feland B. , Vivas F. A. , Babadagli T. , Ozum B.
Published: June 2013

In Alberta, Canada, over 80% of oil sand reserves are suitable for thermal in-situ processes such as the steam assisted gravity drainage (SAGD) process. SAGD recovery is contingent on reducing the viscosity of bitumen, which is immobile at reservoir temperature, to increase its mobility, thus increasing recovery efficiency. Processes based on the co-injection of solvent and steam targeting further reduction of bitumen viscosity have been extensively investigated. These studies generally ignore the potential role of bitumen-water interfacial tension on bitumen mobility and bitumen recovery.

In this study, we propose a new analytical model approach to analyze flow characteristics of injected steam in a bitumen containing reservoir and to clarify the physics of the displacement process during SAGD. The thickness of the chamber front where viscosity reduction occurs is defined for different injection and reservoir conditions and flow patterns are created for different fluid (viscosity and interfacial tension) and reservoir properties (thickness). This model shows how bitumen-water interfacial tension affects bitumen mobility and thereby influences both SAGD displacement efficiency and ultimate bitumen recovery. A composite set of models including the effects of interfacial tension between the bitumen and water in addition to viscosity reduction are developed.

Finally, the observations obtained through analytical model studies are compared against SAGD field observations accumulated over the last two decades. The focus of this comparison is on the advancement rate of the chamber front and its growth characteristics. By understanding the bitumen to water interfacial tension effects, it will be possible to make a better prediction of the relative benefits of solvent or surfactant to accelerate the recovery rate and improve ultimate recovery.
Modeling Thermal and Solvent Injection Techniques as Post-CHOPS Applications Considering Geomechanical and Compositional Effects
Authors: Rangriz-Shokri A. , Babadagli T.
Published: June 2013

Cold Heavy Oil Production with Sand (CHOPS) is considered to be a promising method for heavy-oil recovery from unconsolidated sands, but it offers low recovery factors (~10%). Increasing recovery from such reservoirs should be achieved through post-CHOPS enhanced oil recovery (EOR) applications within an economic framework. Difficulties in modeling CHOPS are mainly due to the representation of wormhole network growth and foamy oil behavior. Also, the co-production of oil and sand simultaneously changes the fundamental reservoir properties including permeability, porosity, and formation compressibility, as well as in-situ stress conditions, making it even more difficult to model post-CHOPS EOR applications.

One of the missing elements in current literature is a representative model capturing the growing nature of the wormhole network and geo-mechanical effects due to production or injection after CHOPS. To this end, in this study, we implemented fractal patterns based on DLA (Diffusion Limited Aggregation) algorithm along with a step-by-step simulation technique using a commercial simulator, coupled with a finite element geo-mechanical module to account for the in-situ stresses induced from overburden and gravity, or fluid injection during EOR processes after CHOPS. A mathematical model was also introduced to populate the wormhole domain based on sand production history, initial in-situ stress conditions, wormhole pattern, its radius and its length.

The suggested approach was first validated using field data from a field in Alberta with fifteen CHOPS producers. Next, the model introduced and tested was used to assess post-CHOPS EOR processes such as thermal, solvent and their hybrid combinations using a black oil and compositional simulator. The latter raised certain difficulties which emerged from embedding the complex wormhole structure into the compositional model and the ways to overcome these difficulties were discussed. Finally, the model generated was used to test steam, solvent and their hybrid applications in the form of cyclic injection stimulation.
Enhancement of phosphorus removal in a low temperature A2/O process by anaerobic phosphorus release of activated sludge
Authors: Li Jianzheng , Jin Yu , Guo Yaqiong , He Junguo
Published: June 2013

An anaerobic phosphorus release tank was introduced to an anaerobic–anoxic–aerobic (A2/O) process treating domestic sewage to enhance the phosphorus removal at low temperature. Phosphorus release of the activated sludge from the second sedimentation tank was evaluated at 14 °C by batch cultures, and the nutrient removal in the modified low temperature A2/O process was further investigated at the same temperature. The results showed that the feasible sludge retention time was 14 h for sequencing batch reaction and 12 h for continuous flow operation. The ratio of raw sewage to activated sludge from the second sedimentation tank was 1:1 in volume to meet the demand of carbon resource for the growth of phosphorus release microbes. The feasible chemical oxygen demand (COD) loading rate of the activated sludge in the phosphorus release tank was 0.015–0.02 g COD/g MLSS (mixed liquor suspended solids) and the nitrate concentration should be less than 5 mg/L. The phosphorus release was doubled when the sludge was blended intermittently and gently. The anaerobic phosphorus release of the activated sludge improved the phosphate removal remarkably, as well as the removal of NH4+-N and total nitrogen (TN) in the modified low temperature A2/O process. The effluent COD, NH4+-N, TN and total phosphorus could meet a stricter discharge standard.
Towards adaptive and integrated management paradigms to meet the challenges of water governance
Authors: Halbe J. , Pahl-Wostl C. , Sendzimir J. , Adamowski J.
Published: June 2013

Integrated Water Resource Management (IWRM) aims at finding practical and sustainable solutions to water resource issues. Research and practice have shown that innovative methods and tools are not sufficient to implement IWRM – the concept needs to also be integrated in prevailing management paradigms and institutions. Water governance science addresses this human dimension by focusing on the analysis of regulatory processes that influence the behavior of actors in water management systems. This paper proposes a new methodology for the integrated analysis of water resources management and governance systems in order to elicit and analyze case-specific management paradigms. It builds on the Management and Transition Framework (MTF) that allows for the examination of structures and processes underlying water management and governance. The new methodology presented in this paper combines participatory modeling and analysis of the governance system by using the MTF to investigate case-specific management paradigms. The linking of participatory modeling and research on complex management and governance systems allows for the transfer of knowledge between scientific, policy, engineering and local communities. In this way, the proposed methodology facilitates assessment and implementation of transformation processes towards IWRM that require also the adoption of adaptive management principles. A case study on flood management in the Tisza River Basin in Hungary is provided to illustrate the application of the proposed methodology.
A novel technique for evaluating foam dynamics in anaerobic digesters
Authors: Park C. , Hermanowicz S. W. , Jolis D.
Published: June 2013

Foaming in anaerobic digesters has severe impacts on process efficiency and operational costs. In this study, we present an experimental method to determine foam behaviour and stability for various foaming solutions. This novel technique measured foam conductivity at different heights along a foam column allowing changes in foam composition to be monitored in time. We analysed foam stability which is primarily dependent on the foam drainage velocity, a quantity that can be determined from forced drainage experiments. The drainage velocity increased in the presence of anaerobic digester sludge, compared to simple surfactant foam. We proposed a new understanding of the effect of sludge particles on the foam stability. Both physical properties (foam physical constant, β) of foam and bubble surface interactions by applying stable and unstable foam in addition of surfactants are also evaluated and discussed.
Adsorption of heavy metals by road deposited solids
Authors: Gunawardana Chandima , Goonetilleke Ashantha , Egodawatta Prasanna
Published: June 2013

The research study discussed in the paper investigated the adsorption/desorption behaviour of heavy metals commonly deposited on urban road surfaces, namely, Zn, Cu, Cr and Pb, for different particle size ranges of solids. The study outcomes, based on field studies and batch experiments, confirmed that road deposited solids particles contain a significantly high amount of vacant charge sites with the potential to adsorb additional heavy metals. Kinetic studies and adsorption experiments indicated that Cr is the most preferred metal element to associate with solids due to the relatively high electronegativity and high charge density of trivalent cation (Cr3+). However, the relatively low availability of Cr in the urban road environment could influence this behaviour. Comparing total adsorbed metals present in solids particles, it was found that Zn has the highest capacity for adsorption to solids. Desorption experiments confirmed that a low concentration of Cu, Cr and Pb in solids was present in water-soluble and exchangeable form, whilst a significant fraction of adsorbed Zn has a high likelihood of being released back into solution. Among heavy metals, Zn is considered to be the most commonly available metal among road surface pollutants.
The effects of anaerobic fermentation on dehydrated sludge
Authors: Lu Haowen , Dai Ruihua , Liu Yan , Song Anan , Liu Xiang
Published: June 2013

Dehydrated sludge with two concentrations of total suspended solids (high: 50 g/L TSS; low: 20 g/L TSS) were studied for 20 d to investigate the effects of anaerobic fermentation on sludge properties. The results showed that the soluble chemical oxygen demand (SCOD) of high-concentration sludge was 16.53 g/L, much higher than that from the low one. The SCOD/total nitrogen ratio of high-concentration sludge varied from 8 to 14.29 g/g, indicating that the sludge could serve as a carbon source for biological denitrification. High-concentration sludge showed a short-chain fatty acid yield of 11.29 g COD/L, much higher than that from low-concentration sludge. The specific resistance of the sludge to filtration (SRF) increased with fermentation time. The quantity of low-speed centrifugation substances (LSCS) was the main factor that influenced the reduction of dehydration. The correlation coefficient between the SRF and protein content in the LSCS layer was significantly positive.
Lower incisor dentoalveolar compensation and symphysis dimensions among Class I and III malocclusion patients with different facial vertical skeletal patterns
Authors: Molina-Berlanga Núria , Llopis-Perez Jaume , Flores-Mir Carlos , Puigdollers Andreu
Published: June 2013

Objective:

To compare lower incisor dentoalveolar compensation and mandible symphysis morphology among Class I and Class III malocclusion patients with different facial vertical skeletal patterns.

Materials and Methods:

Lower incisor extrusion and inclination, as well as buccal (LA) and lingual (LP) cortex depth, and mandibular symphysis height (LH) were measured in 107 lateral cephalometric x-rays of adult patients without prior orthodontic treatment. In addition, malocclusion type (Class I or III) and facial vertical skeletal pattern were considered. Through a principal component analysis (PCA) related variables were reduced. Simple regression equation and multivariate analyses of variance were also used.

Results:

Incisor mandibular plane angle (P < .001) and extrusion (P  =  .03) values showed significant differences between the sagittal malocclusion groups. Variations in the mandibular plane have a negative correlation with LA (Class I P  =  .03 and Class III P  =  .01) and a positive correlation with LH (Class I P  =  .01 and Class III P  =  .02) in both groups. Within the Class III group, there was a negative correlation between the mandibular plane and LP (P  =  .02). PCA showed that the tendency toward a long face causes the symphysis to elongate and narrow. In Class III, alveolar narrowing is also found in normal faces.

Conclusions:

Vertical facial pattern is a significant factor in mandibular symphysis alveolar morphology and lower incisor positioning, both for Class I and Class III patients. Short-faced Class III patients have a widened alveolar bone. However, for long-faced and normal-faced Class III, natural compensation elongates the symphysis and influences lower incisor position.
Musculoskeletal Predictors of Movement Quality for the Forward Step-down Test in Asymptomatic Women
Authors: Park Kyung-Mi , Cynn Heon-Seock , Choung Sung-Dae
Published: June 2013

Study Design

Cross-sectional.

Objective

To investigate the interrater reliability of movement-quality ratings for the forward step-down (FSD) test and to compare hip muscle strength and lower extremity joint range of motion and muscle flexibility among asymptomatic women with different levels of movement quality.

Background

The interrater reliability of the FSD test has not yet been investigated. Additionally, it is not known whether differences in musculoskeletal measures exist among individuals with different levels of movement quality during the FSD test.

Methods

Two physical therapists assessed movement quality during the FSD test in 26 asymptomatic women (mean ± SD age, 22.7 ± 0.9 years). Hip muscle strength and lower extremity joint range of motion and muscle flexibility were also assessed. The interrater reliability of the FSD test was estimated by using the kappa coefficient and percent agreement. Differences in musculoskeletal measures based on movement quality were assessed by independent t tests.

Results

The kappa coefficient and percent agreement for rating the quality of movement on the FSD test were 0.80 (95% confidence interval: 0.57, 1.00) and 85%, respectively. The subjects with moderate movement quality had significantly less strength of the hip abductors, less knee flexion range of motion measured in prone (quadriceps flexibility), and less hip adduction range of motion measured in sidelying (iliotibial band/tensor fascia latae flexibility) compared to those with good movement quality.

Conclusion

There was good agreement for the rating of movement quality during the FSD test, and there were physical attributes that distinguished those with moderate from those with good quality of movement. J Orthop Sports Phys Ther 2013;43(7):504–510. Epub 11 June 2013. doi:10.2519/jospt.2013.4073
Abdominal Muscle Activity During a Standing Long Jump
Authors: Okubo Yu , Kaneoka Koji , Shiina Itsuo , Tatsumura Masaki , Miyakawa Shumpei
Published: June 2013

Study Design

Experimental laboratory study.

Objectives

To measure the activation patterns (onset and magnitude) of the abdominal muscles during a standing long jump using wire and surface electromyography.

Background

Activation patterns of the abdominal muscles, especially the deep muscles such as the transversus abdominis (TrA), have yet to be examined during full-body movements such as jumping.

Methods

Thirteen healthy men participated. Wire electrodes were inserted into the TrA with the guidance of ultrasonography, and surface electrodes were attached to the skin overlying the rectus abdominis (RA) and external oblique (EO). Electromyographic signals and video images were recorded while each subject performed a standing long jump. The jump task was divided into 3 phases: preparation, push-off, and float. For each muscle, activation onset relative to the onset of the RA and normalized muscle activation levels (percent maximum voluntary contraction) were analyzed during each phase. Comparisons between muscles and phases were assessed using 2-way analyses of variance.

Results

The onset times of the TrA and EO relative to the onset of the RA were −.13 ± 0.17 seconds and −.02 ± 0.07 seconds, respectively. Onset of TrA activation was earlier than that of the EO. The activation levels of all 3 muscles were significantly greater during the push-off phase than during the preparation and float phases.

Conclusion

Consistent with previously published trunk-perturbation studies in healthy persons, the TrA was activated prior to the RA and EO. Additionally, the highest muscle activation levels were observed during the push-off phase. J Orthop Sports Phys Ther 2013;43(8):577–582. Epub 11 June 2013. doi:10.2519/jospt.2013.4420
To Awake, Shakespeare of the Night
Authors: Royle Nicholas
Published: June 2013

Royle's text considers the importance of psychoanalysis in the writings of Cixous and Derrida, in particular in terms of Cixous's description of Freud as ‘the Shakespeare of the Night’. An exploration of what Derrida terms ‘thinking analysis’ in Cixous's writing is pursued via readings of Freud and Popper-Lynkeus, Derrida's ‘To Speculate — on Freud’, and telepathic or magical thinking in Shakespeare. It concludes with A Midsummer Night's Dream and with what Royle considers perhaps the most beautiful ‘because’ in Shakespeare.
Cixanalyses — Towards a Reading of Anankè
Authors: Milesi Laurent
Published: June 2013

The first in-depth engagement with and close reading of Anankè, this essay focuses on how Cixous's novel plays with and rewrites psychoanalytic concepts and practices. The critical elaboration of her own ‘cixanalysis’ in this fiction-as-becoming and journey, which reinvents psychoanalysis as it gives free creative rein to woman's desire instead of pathologizing it, unfolds in six related studies: on ‘conduct’ (about autonomy, automobile and behaviour), ‘habit’ (as well as habitation and clothing), staging (about the relation between analysis and the theatrical), transference and/as translation, the interpretation of interpretation (also on telephones), and the shift from drive to drift in Cixous's fictional liberation of woman from destiny and destination.
Flowering date of taxonomic families predicts phenological sensitivity to temperature: Implications for forecasting the effects of climate change on unstudied taxa
Authors: Mazer Susan J. , Travers Steven E. , Cook Benjamin I. , Davies T. Jonathan , Bolmgren Kjell , Kraft Nathan J. B. , Salamin Nicolas , Inouye David W.
Published: June 2013

•Premise of the study:Numerous long‐term studies in seasonal habitats have tracked interannual variation in first flowering date (FFD) in relation to climate, documenting the effect of warming on the FFD of many species. Despite these efforts, long‐term phenological observations are still lacking for many species. If we could forecast responses based on taxonomic affinity, however, then we could leverage existing data to predict the climate‐related phenological shifts of many taxa not yet studied.

•Methods:We examined phenological time series of 1226 species occurrences (1031 unique species in 119 families) across seven sites in North America and England to determine whether family membership (or family mean FFD) predicts the sensitivity of FFD to standardized interannual changes in temperature and precipitation during seasonal periods before flowering and whether families differ significantly in the direction of their phenological shifts.

•Key results:Patterns observed among specieswithinandacrosssites are mirrored among family meansacrosssites; early‐flowering families advance their FFD in response to warming more than late‐flowering families. By contrast, we found no consistent relationships among taxa between mean FFD and sensitivity to precipitation as measured here.

•Conclusions:Family membership can be used to identify taxa of high and low sensitivity to temperature within the seasonal, temperate zone plant communities analyzed here. The high sensitivity of early‐flowering families (and the absence of early‐flowering families not sensitive to temperature) may reflect plasticity in flowering time, which may be adaptive in environments where early‐season conditions are highly variable among years.