bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer Flood Simulation in a Heavy Oil Field: Offshore Niger-Delta Experience
Authors: Mogbo Obuekwe 
Published: July 2011

Abstract
A simulation case study is described which illustrates the application of polymer flooding to an offshore heavy-oil reservoir within the Niger Delta. This shallow depth offshore reservoir has excellent reservoir quality (up to 39% porosity and 6D in good sands). It has 3 different panels, laminations in sand sequences and contains biodegraded fluid of varying fluid viscosities (2 to 16cp under reservoir conditions). Bubble point is close to reservoir pressure necessitating injection form start of field life to maintain reservoir pressure.
The paper begins by a brief discussion of the mechanics of polymer flooding and its simulation methodology: the effect of water salinity, choke shear degradation and thermal degradation on injectant mixture viscosity is determined from detailed Laboratory studies. Other simulation input parameters like permeability reduction related to adsorption and residual resistance factor are also estimated per facies. All data are implemented as lookup tables in the Polymer option of an available commercial simulator. High injectivity potential (unconsolidated sand dilatance regime) is simulated to ensure that as much polymer as required was injected in High BHP regime without fracturing the reservoir cap rock.
Several full field scale sensitivities were run in an experimental design approach in an effort to optimize the injection strategy and flood pattern for both a water injection case and then the polymer flood case. All producers and injectors are either horizontal wells or deviated wells. The polymer flood effect is recognized and analysed: Best case incremental oil recovery was 7% with earlier polymer injection allowing for greatest incremental recovery. Significant Plateau extension and delayed water breakthrough were noted.
The results show that polymer flooding is economically justified for this field. This paper also discusses how adequate pre-project preparation and pilot-testing brings added value during the life-cycle of Heavy-Oil fields
Case Study: Numerical Simulation of Surfactant Flooding in Low Permeability Oil Field
Authors: Xu Feng , Guo Xiao , Wang Wanbin , Zhang Nan , Jia Sha , Wang Xiaoqin 
Published: July 2011

Abstract
Low permeability reservoir occupies an important position in China’s petroleum industry, as an important oil industry resource over a period of time in future, which helps to increase reserves and production. Surfactant flooding is one of the most effective ways to improve development effect in the low permeability reservoirs, which can reduce the injection pressure and increase injection rate, thereby enhancing oil recovery. Common mechanisms that how the surfactants enhance oil recovery are discussed in the paper. On the basis of assumptions, a seepage model of surfactant flooding was built to describe the complex process. Experiments was done to determine the surfactant’s performance, such as the relationship between surfactant concentration and oil/water interfacial tension, the relationship between surfactant concentration and rock adsorbance, and the relationship between surfactant concentration and water viscosity. Take the Yanchang low permeability reservoir for example, where the study of surfactant flooding is conducted after the optimal water injection plan to evaluate the effect of different surfactant concentration on the development results in the low permeability reservoir. The simulation results show that surfactant flooding has the role of enhancing oil recovery, and that the optimal surfactant concentration is 2%, which can enhance oil recovery by the percentage of 0.22.
Sustainable Surfactants in Enhanced Oil Recovery
Authors: Santa Monika , Alvarez-Jürgenson Gabriela , Busch Stefan , Birnbrich Paul , Spindler Christian , Brodt Gregor 
Published: July 2011

Abstract
Alkyl polyglucosides (APGs) are recognised as sustainable surfactants based on natural raw materials. They exhibit a low ecotoxicity profile and are therefore already used in different oil field applications. In this paper it is shown that APGs have superior solubility properties in high salinity environments. The interfacial tension of crude/brine systems can be significantly lowered even in high salinity brines. The performance of APGs can be improved by optimising the hydrophobic as well as the hydrophilic part of the surfactant. In contrast to standard surfactants used in EOR applications the performance of APGs is not reduced under elevated temperature or high salinity conditions. Their performance is not influenced by typical salinity and temperature gradients as can occur in the reservoir. Moreover, microemulsions can be formed even under high salinity and elevated temperature if APGs are used together with co-solvents.
Increasing Cold Lake Recovery by Adapting Steamflood Principles to a Bitumen Reservoir
Authors: Stark Shane D. 
Published: July 2011

Abstract
The Cold Lake project, located in Alberta, Canada, is the world’s largest heavy oil in situ thermal development, with production of about 24,000 m3/d (150 kB/d) of oil from more than 4500 wells. In 2009, Cold Lake produced its one billionth barrel (160 million m3) of heavy oil.
The world class Cold Lake hydrocarbon resource is characterized as a bitumen deposit, featuring in situ viscosities in excess of 100,000 mPa-s. Early depletion plans envisioned a thermal recovery process similar to the steamflood technologies employed to recover heavy oil in California’s San Joaquin Valley. The order of magnitude difference between Cold Lake and California in-situ viscosities, however, severely limits steam injectivity below fracture pressure, necessitating the development of a Cold Lake specific cyclic steam stimulation (CSS) process throughout the 1980s.
Continual process optimization combined with infill drilling has resulted in a progressive increase in expected bitumen recovery from 13% to greater than 40% of effective bitumen in place (EBIP). A multi-disciplinary reservoir management effort conducted over the last several years has provided the view that Cold Lake recovery levels may potentially be increased to over 65% by adapting steamflood principles to mature CSS areas of the reservoir: reservoir simulation was used to define the steamflood opportunity’s technical and economic viabilityan extensive selection process based on several criteria was used to select an appropriate field trial locationtrial plans were reviewed with experts with California steamflood experiencea Cold Lake steamflood field trail was designed, implemented and successfully operated for three years
As cyclic process efficiency declines due to lack of steam confinement, steamflood technologies become an attractive recovery scheme in mature Cold Lake reservoir by capitalizing on large scale inter-well communication while focusing on gravity drainage: trial results to date are encouraging and in agreement with performance predictionssuccess to date has benefited from the evaluation of prior trails at Cold Lake, review of global steamflood analogs and extensive reservoir simulation efforts prior to field trial design and implementationsteam confinement is a significant but manageable operational challenge
What Has Been Learned From A Hundred MEOR Applications
Authors: Zahner R. L. , Tapper S. J. , Marcotte B. W. , Govreau B. R. 
Published: July 2011

AbstractUsing a breakthrough process, which does not require microbes to be injected, over one hundred Microbial Enhanced Oil Recovery (MEOR) applications have been conducted since 2007 in producing oil and water injection wells in the United States and Canada. On average, these applications increased oil production by 127% with an 89% success rate. This paper reviews the MEOR process, reviews the results of the first one hundred plus applications and shares what has been learned from this work.Observations and conclusions include the following: Screening reservoirs is critical to success. Identifying reservoirs where appropriate microbes are present and oil is movable is the key.MEOR can be applied to a wide range of oil gravities. MEOR has been successfully applied to reservoirs with oil gravity as high as 41° and as low as 16° API.When bacteria growth is appropriately controlled, reservoir plugging or formation damage is no longer a risk.Microbes reside in extreme conditions and can be manipulated to perform valuable in-situ "work." MEOR has been applied successfully at reservoir temperatures as high as 200°F and salinities as high as 140,000 ppm TDS.MEOR can be successfully applied in dual-porosity reservoirs.A side benefit of applying MEOR is that it can reduce reservoir souring.An oil response is not always seen when treating producing wells.The application of MEOR can be applied to many more reservoirs than originally thought with little downside risk. This review of more than a hundred MEOR applications expands the types of reservoirs where MEOR can be successfully applied. Low risk and economically attractive treatments can be accomplished when appropriate scientific analysis and laboratory screening is performed prior to treatments.
Assessing the EOR Potential of the United States
Authors: Mohan Hitesh , Biglarbigi Khosrow , Carolus Marshall , Van Wagener Dana 
Published: July 2011

Abstract
With the conventional decline in oil production from wells in the United States, additional sources of crude oil are required. One option supported by high oil prices is the application of enhanced oil recovery and advanced secondary recovery technologies to the currently producing wells. The U.S. onshore lower 48 crude oil in-place resource are vast. The question is how much of the oil can be produced using currently available technologies.
In order to answer that question, a detailed analysis was conducted in which the potential technical and economic production was estimated for several commonly used technologies. These include EOR technologies such as carbon dioxide flooding, polymer flooding, and steam flooding, as well as a variety of advanced secondary recovery technologies.
This analysis was conducted using screening and analytic tools which identify the recovery processes which are applicable to each reservoir in the onshore lower 48 and estimate the technical production from each reservoir. In addition, a newly developed economic model was used to estimate the technical and economic production which could be realized. The results, data and opinions presented in this paper are those of the authors and not the companies with which they currently work.
This paper describes the screening criteria which were used to determine the applicable technologies. The paper also describes the analytical tools used to estimate the technical and economic production for each of the assessed technologies. Finally, the paper details the production levels which could be realized under a variety of technical and economic scenarios.
Recovering Heavy Oil from a Middle East Carbonate Reservoir: EOR Potential, Screening, Challenges, Uncertainties and Risk Management Measures
Authors: Choudhary Muhammad A. , Wani Mohamad R. , Mahmeed Ali , Al-Rashidi Hussain , Redha Mohammad 
Published: July 2011

Abstract
Heavy oil carbonate reservoirs of the giant Wafra field located in the Kuwait - Saudi Arabia Divided Zone hold huge resource of heavy oil in 3 reservoirs, namely 1st Eocene, 2nd Eocene, and Maastrichtian. More than 50 years of primary production from these high porosity, moderate permeability carbonates has recovered less than 5% of this volume and the ultimate recovery is not expected to exceed 10%. Suitable EOR technology is needed to unlock these huge resources. In absence of any commercial analogs, application of EOR technology carries enormous risk in terms of technical viability, reserves recovery and resources commitment. Proper understanding of the reservoir and optimization of EOR technology are essential to mitigate these risks to a manageable level.
This paper will discuss the process used to mitigate the risks of EOR application in the 2nd Eocene reservoir. Production in this reservoir is from dolomitized carbonates associated with anhydrite. Ultimate recovery from primary production is estimated about 12%. Low primary recovery in this highly porous and moderate permeability reservoir is attributed to oil gravity, viscosity and drive mechanism. Detailed screening study to select suitable EOR processes suggested the suitability of both waterflood and steamflood for this reservoir. The study indicated the opportunity to recover up to 20% with waterflood and 40% with steamflood. Economic Modeling work indicates similar NPV for both processes but higher profitability in water flood case due to substantially lower capital requirement. Both projects have serious challenges due to reservoir nature, uncertainty in reservoir characterization, non-availability of fresh water, lack of proven technology for processing produced water for steam generation, disposal of excess produced water, fuel for steam generation, and safe environment for workers, public and wild life. These challenges make the EOR projects very high risk ventures in the areas of oil recovery, return on investment, and health, safety and environment (HSE). These risks are being managed through extensive G&G and simulation studies, exhaustive screening work and properly designed pilot projects. Two pilot projects, steamflood and waterflood, are under implementation to resolve the number of uncertainties and manage associated risks in the high reward EOR process for this reservoir.
This paper will share the work flow (reservoir to economic modeling) for planning, designing and evaluation of pilot projects and innovative technology being utilized to manage risks of EOR in carbonate reservoirs. Success in mitigation of such risks will help industry to enhance sustainable and economic energy resource for future.
Polymer Flooding Design and Optimization Under Uncertainty
Authors: AlSofi Abdulkareem M. , Blunt Martin J. 
Published: July 2011

Abstract
We use a streamline-based simulator that accurately captures non-Newtonian rheology and controls numerical dispersion to investigate polymer flooding design. First, we develop and test a parallel design algorithm to optimize polymer floods with respect to net present value in terms of slug size, polymer concentration and initiation; in which simulations are ran simultaneously and the results are combined through scaling of optimal slug size. In terms of optimal strategies, the optimization results illustrate that polymer-flooding design – with respect to concentration, slug size, and initiation – is more intuitive than earlier expected. It is always beneficial to start polymer flooding as soon as possible preferably before any waterflooding. The optimal slug size is close to being continuous. The optimal concentration is generally high and represents a balance between mobility gains and injectivity losses. Second, we quantify the impact of uncertainty on both the design and profitability of polymer flooding. This serves as a guide to associated data acquisition efforts, where pre-polymer flooding initiation, efforts can be focused on reducing uncertainties of high impact factors thereby increasing the probability of success. The same methods can be applied to other augmented waterfloods, such as low salinity flooding.
Riemann Integral of Functions from R into Real Normed Space
Authors: Miyajima Keiichi , Kato Takahiro , Shidama Yasunari 
Published: July 2011

Riemann Integral of Functions from R into Real Normed Space
In this article, we define the Riemann integral on functions from R into real normed space and prove the linearity of this operator. As a result, the Riemann integration can be applied to a wider range of functions. The proof method follows the [16].
Linear Transformations of Euclidean Topological Spaces
Authors: Pąk Karol 
Published: July 2011

Linear Transformations of Euclidean Topological Spaces
We introduce linear transformations of Euclidean topological spaces given by a transformation matrix. Next, we prove selected properties and basic arithmetic operations on these linear transformations. Finally, we show that a linear transformation given by an invertible matrix is a homeomorphism.
Simulation of bonding effects in HRTEM images of light element materials
Authors: Kurasch Simon , Meyer Jannik C , Künzel Daniela , Groß Axel , Kaiser Ute 
Published: July 2011

The accuracy of multislice high-resolution transmission electron microscopy (HRTEM) simulation can be improved by calculating the scattering potential using density functional theory (DFT) Gemming, T.; Möbus, G.; Exner, M.; Ernst, F.; Rühle, M. J. Microsc. 1998, 190, 89–98. doi:10.1046/j.1365-2818.1998.3110863.xDeng, B.; Marks, L. D. Acta Crystallogr., Sect. A 2006, 62, 208–216. doi:10.1107/S010876730601004X. This approach accounts for the fact that electrons in the specimen are redistributed according to their local chemical environment. This influences the scattering process and alters the absolute and relative contrast in the final image. For light element materials with well defined geometry, such as graphene and hexagonal boron nitride monolayers, the DFT based simulation scheme turned out to be necessary to prevent misinterpretation of weak signals, such as the identification of nitrogen substitutions in a graphene network. Furthermore, this implies that the HRTEM image does not only contain structural information (atom positions and atomic numbers). Instead, information on the electron charge distribution can be gained in addition.In order to produce meaningful results, the new input parameters need to be chosen carefully. Here we present details of the simulation process and discuss the influence of the main parameters on the final result. Furthermore we apply the simulation scheme to three model systems: A single atom boron and a single atom oxygen substitution in graphene and an oxygen adatom on graphene.
NKT Cell Ligand Recognition Logic: Molecular Basis for a Synaptic Duet and Transmission of Inflammatory Effectors
Authors: Joyce Sebastian , Girardi Enrico , Zajonc Dirk M. 
Published: July 2011

AbstractNKT cells that express the semi-invariant TCR are innate-like lymphocytes whose functions are regulated by self and foreign glycolipid ligands presented by the Ag-presenting, MHC class I-like molecule CD1d. Activation of NKT cells in vivo results in rapid release of copious amounts of effector cytokines and chemokines with which they regulate innate and adaptive immune responses to pathogens, certain types of cancers, and self-antigens. The nature of CD1d-restricted ligands, the manner in which they are recognized, and the unique effector functions of NKT cells suggest an immunoregulatory role for this T cell subset. Their ability to respond fast and our ability to steer NKT cell cytokine response to altered lipid ligands make them an important target for vaccine design and immunotherapies against autoimmune diseases. This review summarizes our current understanding of CD1d-restricted ligand recognition by NKT cells and how these innate-like lymphocytes regulate inflammation.
Progesterone Promotes Differentiation of Human Cord Blood Fetal T Cells into T Regulatory Cells but Suppresses Their Differentiation into Th17 Cells
Authors: Lee Jee H. , Ulrich Benjamin , Cho Jungyoon , Park Jeongho , Kim Chang H. 
Published: July 2011

Abstract
Progesterone, a key female sex hormone with pleiotropic functions in maintenance of pregnancy, has profound effects on regulation of immune responses. We report in this work a novel function of progesterone in regulation of naive cord blood (CB) fetal T cell differentiation into key T regulatory cell (Treg) subsets. Progesterone drives allogeneic activation-induced differentiation of CB naive, but not adult peripheral blood, T cells into immune-suppressive Tregs, many of which express FoxP3. Compared with those induced in the absence of progesterone, the FoxP3+ T cells induced in the presence of progesterone highly expressed memory T cell markers. In this regard, the Treg compartment in progesterone-rich CB is enriched with memory-type FoxP3+ T cells. Moreover, CB APCs were more efficient than their peripheral blood counterparts in inducing FoxP3+ T cells. Another related function of progesterone that we discovered was to suppress the differentiation of CB CD4+ T cells into inflammation-associated Th17 cells. Progesterone enhanced activation of STAT5 in response to IL-2, whereas it decreased STAT3 activation in response to IL-6, which is in line with the selective activity of progesterone in generation of Tregs versus Th17 cells. Additionally, progesterone has a suppressive function on the expression of the IL-6 receptor by T cells. The results identified a novel role of progesterone in regulation of fetal T cell differentiation for promotion of immune tolerance.
Cutting Edge: HLA-DO Impairs the Incorporation of HLA-DM into Exosomes
Authors: Xiu Fangming , Côté Marie-Hélène , Bourgeois-Daigneault Marie-Claude , Brunet Alexandre , Gauvreau Marie-Élaine , Shaw Andrew , Thibodeau Jacques 
Published: July 2011

Abstract
In multivesicular bodies, HLA-DM (DM) assists the loading of antigenic peptides on classical MHC class II molecules such as HLA-DR. In cells expressing HLA-DO (DO), DM is redistributed from the internal vesicles to the limiting membrane of these organelles. This suggests that DO might reduce DM incorporation into exosomes, which are shed upon fusion of multivesicular bodies with the plasma membrane. To test this hypothesis, we used the 721.45 B lymphoblastoid cell line and different HeLa cell transfectants. We demonstrate that the poor recovery of DM in exosomes as compared with HLA-DR is not the mere reflection of differences in protein expression. Indeed, we found that DO contributes to the inefficient transfer of DM to exosomes. This negative regulation requires an intact di-leucine endosomal sorting motif in the cytoplasmic tail of HLA-DOβ. These results demonstrate that canonical sorting signals and protein–protein interactions modulate the selection of MHC protein cargos.