bluuebunny/crossref_metadata_2025 huggingface dataset:
The cannabinoid receptors agonist WIN55212-2 inhibits macrophageal differentiation and alters expression and phosphorylation of cell cycle control proteins
Authors: Paulsen Katrin , Tauber Svantje , Timm Johanna , Goelz Nadine , Dumrese Claudia , Stolzing Alexandra , Hass Ralf , Ullrich Oliver
Published: December 2011

In this study we investigated if and how cannabinoid receptor stimulation regulates macrophageal differentiation, which is one of the key steps in the immune effector reaction. For that reason, we used a well established differentiation model system of human U937 myelocytic leukemia cells that differentiate along the monocyte/macrophage lineage upon stimulation with the phorbol ester PMA. Constant cannabinoid receptor (CB) stimulation was performed using WIN55212-2, a potent synthetic CB agonist. We found that WIN55212-2 inhibited CB1/2-receptor-dependent PMA-induced differentiation of human myelocytic U937 cells into the macrophageal phenotype, which was associated with impaired vimentin, ICAM-1 and CD11b expression. In the presence of WIN55212-2, cdc2 protein and mRNA expression was progressively enhanced and Tyr-15-phosporylation of cdc2 was reduced in differentiating U937 cells. Additionally, p21Waf1/Cip1expression was up-regulated. PMA-induced apoptosis was not enhanced by WIN55212-2 and differentiation-associated c-jun expression was not altered. In conclusion, we suppose that WIN55212-2-induced signals interferes with cell-cycle-arrest-signaling in differentiating myelocytic cells and thus inhibits macrophageal differentiation. Thus, it is possible that the cannabinoid system is able to influence one of the key steps in the immune effector function, the monocytic-macrophageal differentiation by alteration of cell cycle control proteins cdc2 and p21, and is therefore representing a promising option for therapeutic intervention in exacerbated immune reactions.
Antiviral activity of four types of bioflavonoid against dengue virus type-2
Authors: Zandi Keivan , Teoh Boon-Teong , Sam Sing-Sin , Wong Pooi-Fong , Mustafa Mohd Rais , AbuBakar Sazaly
Published: December 2011

Background

Dengue is a major mosquito-borne disease currently with no effective antiviral or vaccine available. Effort to find antivirals for it has focused on bioflavonoids, a plant-derived polyphenolic compounds with many potential health benefits. In the present study, antiviral activity of four types of bioflavonoid against dengue virus type -2 (DENV-2) in Vero cell was evaluated. Anti-dengue activity of these compounds was determined at different stages of DENV-2 infection and replication cycle. DENV replication was measured by Foci Forming Unit Reduction Assay (FFURA) and quantitative RT-PCR. Selectivity Index value (SI) was determined as the ratio of cytotoxic concentration 50 (CC50) to inhibitory concentration 50 (IC50) for each compound.

Results

The half maximal inhibitory concentration (IC50) of quercetin against dengue virus was 35.7 μg mL-1 when it was used after virus adsorption to the cells. The IC50 decreased to 28.9 μg mL-1 when the cells were treated continuously for 5 h before virus infection and up to 4 days post-infection. The SI values for quercetin were 7.07 and 8.74 μg mL-1, respectively, the highest compared to all bioflavonoids studied. Naringin only exhibited anti-adsorption effects against DENV-2 with IC50 = 168.2 μg mL-1 and its related SI was 1.3. Daidzein showed a weak anti-dengue activity with IC50 = 142.6 μg mL-1 when the DENV-2 infected cells were treated after virus adsorption. The SI value for this compound was 1.03. Hesperetin did not exhibit any antiviral activity against DENV-2. The findings obtained from Foci Forming Unit Reduction Assay (FFURA) were corroborated by findings of the qRT-PCR assays. Quercetin and daidzein (50 μg mL-1) reduced DENV-2 RNA levels by 67% and 25%, respectively. There was no significant inhibition of DENV-2 RNA levels with naringin and hesperetin.

Conclusion

Results from the study suggest that only quercetin demonstrated significant anti-DENV-2 inhibitory activities. Other bioflavonoids, including daidzein, naringin and hesperetin showed minimal to no significant inhibition of DENV-2 virus replication. These findings, together with those previously reported suggest that select group of bioflavonoids including quercetin and fisetin, exhibited significant inhibitory activities against dengue virus. This group of flavonoids, flavonol, could be investigated further to discover the common mechanisms of inhibition of dengue virus replication.
Partners in crime: the TGFβ and MAPK pathways in cancer progression
Authors: Chapnick Douglas A , Warner Lisa , Bernet Jennifer , Rao Timsi , Liu Xuedong
Published: December 2011

The TGFβ and Ras-MAPK pathways play critical roles in cell development and cell cycle regulation, as well as in tumor formation and metastasis. In the absence of cellular transformation, these pathways operate in opposition to one another, where TGFβ maintains an undifferentiated cell state and suppresses proliferation, while Ras-MAPK pathways promote proliferation, survival and differentiation. However, in colorectal and pancreatic cancers, the opposing pathways' mechanisms are simultaneously activated in order to promote cancer progression and metastasis. Here, we highlight the roles of the TGFβ and Ras-MAPK pathways in normal and malignant states, and provide an explanation for how the concomitant activation of these pathways drives tumor biology. Finally, we survey potential therapeutic targets in these pathways.
Remote Monitoring and Diagnosis System of Rolling Mill Based on CORBA and SOAP/Web Service Technology
Authors: Li Gongfa , Kong Jianyi , Jiang Guozhang , Xie Liangxi , Xiao Han , Wu Zehao , Xu Siqiang
Published: December 2011

A detailed solution to the remote monitoring and diagnosis system for a rolling mill is introduced. The hardware and software structure of remote monitoring and diagnosis system is presented. The structure of the system is made up of four subsystems, namely online monitoring subsystem, data servo subsystem, database service subsystem and www server subsystem. Software module of system includes seven parts, namely online monitoring module, data query module, fault information query module, trend analysis module, diagnosis analysis module, engineer station module and eigenvalue query module. The system adopts B/S model and integrates CORBA technology with SOAP/Web Service technology. It makes dynamic display and traversing for a great deal of on-line data and Firewall traversal possible. It has run a long time that proves that the system interface is friendly and easy to use. It has better security, good portability, expandability and stability. It can judge the running-condition of a rolling mill in real time.
Study on the Clearance of Automotive Hub-Bearings
Authors: Luo Yuanxin , Wang Yongqing , Yan Xingchun
Published: December 2011

The hub-bearing assembly is one of the fundamental components of modern vehicles. A bad hub-bearing can cause phantom noises or ghost vibrations at sporadic points during the drive. In this paper, effects on the clearance of the bearing are investigated by both the analytical method and the Finite Element Method (FEM). It is found that the assembly process, the initial setting clearance, the rotating speed, the thermo-expansion contribute to the clearance of automotive hub bearing. The fundamental study is the basis for analyzing the dynamic performance and noise of the bearing. Also, it can be extended to optimize the assembly process.
Investigation on Critical Speed and Vibration Mode of High Speed Grinder
Authors: Li C. H. , Liu Z. R. , Zhou Y. , Ding Y. C.
Published: December 2011

The influences of the grinder spindle's major structural parameters on its vibration mode were investigated. Based on the transfer-matrix method and taking into consideration the gyroscopic couple, the shear, the variable cross-section and other influential factors, a dynamic model was established for the multi-disk rotor of the rotor-bearing system of the grinder spindle. The critical speeds of first three orders, the modes of variation and other dynamic characteristic parameters of the grinder spindle were programmed and calculated. The influences of the axial pre-tightening force of the bearing, the span of the fulcrum bearing as well as the changes in the front and rear overhangs on the critical speed of the rotor-bearing system on the grinder spindle and their pattern of changes were analyzed. The results showed that the working speed of the spindle system is much lower than the primary critical speed and can therefore stay away the resonance range effectively.
Vibration Signal Processing for Gear Fault Diagnosis Based on Empirical Mode Decomposition and Nonlinear Blind Source Separation
Authors: Jiang Yu , Qin Li , Zhang Yuelei , Wu Jingping
Published: December 2011

Gear failures happen frequently in the gear mechanisms, and an unexpected serious gear fault may cause severe damage on the machinery. Hence, precise gear fault detection at the early stage is imperative to ensure the normal operation of the machinery. Independent component analysis (ICA) has been paid more and more attention for its powerful ability of separating the useful vibration source from the multi-sensor observations to enhance the fault feature extraction. This is the so called blind source separation (BSS) procedure. However, the popular ICA model may suffer from two limitations. One is the linear mixture assumption, and the other is the lack of sensor channels. Up to now, only limited research considered the nonlinear ICA model in the field of mechanic fault diagnosis, and techniques for the situation where the number of sensor channels is less than the number of independent sources for gear defect detection are scarce. In order to extract the useful source involved with the gear fault characteristics in single-channel vibration signal processing, this work presents a new method based on the empirical mode decomposition (EMD) and nonlinear ICA. The EMD was firstly employed to decompose the vibration signal into a number of intrinsic mode functions (IMFs), and then these IMFs were taken as the multi-channel observations. The post-nonlinear (PNL) ICA model based on the radial basis function (RBF) neural network was applied to the nonlinear BSS procedure on the IMFs. The experimental vibration data acquired from the gear fault test-bed were processed for the validation of the proposed method. The nonlinear ICA method has been compared with the linear ICA and non-ICA based approaches. The analysis results show that the sensitive characteristics of the gear meshing vibration can be separated from the single channel measurement by the proposed method, and the fault diagnosis precision can be enhanced significantly. The detection rate can be increased by 3.75% or better when the ICA based preprocessing is carried out, and the proposed nonlinear ICA outperforms the linear ICA detection model.
Study on Online Intelligent Control of Cutting Vibration in Milling Process
Authors: Hongya Fu , Maoyue Li , Yuan Liu , Zhenyu Han
Published: December 2011

To realize online and real-time suppressing vibration amplitude in milling, an open architecture intelligent controller is designed and developed, which is modular and can achieve machining parameters' online adjustment based on acceleration constraint condition. According to the idea of the velocity control, a spindle speed control model is constructed. This controller can realize both the right codes translation and assume the effective coordination and synchronization among the thread of adaptive control, interface display and interpolation and so on. A series of fuzzy control rules have been designed to reduce the vibration amplitude about stepped-weir work-piece, and some actual experiments based on acceleration constraints have been also completed. The results show the open architecture variable spindle speed controller can be used in the practical machining, and the spindle speed can realize online real-time adjustment based on the acceleration constraint condition. All these technologies can effectively suppress the cutting vibration, which protect the machine and work-piece tool system.
Rail Dynamic Vibration Absorber Design and Vibration Reduction Analysis
Authors: Liu Linya , Zhang Bin , Wang Jin
Published: December 2011

The rail between two adjacent fasteners is regarded as the research object, and the rail is simplified as the main vibration system of undamped single degree of freedom, which supports the elastic components. The dynamic vibration absorber is simplified as a spring and damped system of 3-DOF(three degrees of freedom), to establish a mathematical model of rail dynamic vibration absorber. Through relevant theories, the parameter values of dynamic vibration absorber can be deduced when it achieves the best absorption effect. In accordance with the parameters, the scantlings of the structure of the dynamic vibration absorber can also be designed. Through the finite element software, the finite element model CRTS _ Ballastless Track system is established; with consideration of the value of irregularity, we load it variously. Analysis results showed that: compared to the rail and track where the dynamic vibration absorber is not installed, the maximum vertical displacement of the rail and track where a dynamic vibration absorber is installed was reduced by 65% and 67% respectively, the maximum vertical acceleration decreased by 75% and 70% and around, which reveals that the rail dynamic vibration absorber has a good vibration-reducing effect.
Impact of Gas Exploitation on the Environmental Radioactivity of Ogba/Egbema/Ndoni Area, Nigeria
Authors: Ononugbo Chinyere P. , Avwiri Gregory O. , Chad-Umoren Yehuwdah E.
Published: December 2011

A key component of the current national energy policy of Nigeria is to efficiently utilize her abundant natural gas reserves, especially in the energy sector. This paper reports a study of the terrestrial radioactivity in the industrial areas of Ogba/Egbema/Ndoni Local Government Area (ONELGA) of Rivers State. These industrial areas and their host communities were divided into six (6) zones, each having an oil and gas facility. An in-situ measurement was done using two well calibrated nuclear radiation meters (digilert–100 and digilert–50) and geographical positioning system (GPS). Ten readings were taken in each of the six zones and the host community at randomly selected sites, making a total of 60 sampling points. The mean site radiation level ranges from 0.014 ± 00.001mRh−1 (1.183 ± 0.060mSvy−1) to 0.018 ± 0.002mRh−1 (1.689± 0.085mSvy−1) while the mean community radiation level ranges from 0.014 ± 0.001mRh−1 (1.183 ± 0.06mSvy−1) to 0.017 ± 0.001mRh−1 (1.435 ± 0.072mSvyr1). The equivalent dose has an average range of 1.056 mSvy−1 to 2.871 mSvy−1, which is far below the recommended dose limit for radiological workers (20mSvy−1) but averagely above that for the general public (1mSvyr−1). Comparison of the measured radiation level of site locations with the normal background level shows that 43 locations, representing 71.7% of the sampled area, exceed the normal background level of 0.013mRh−1. This study indicates that there is no immediate radiological health hazard for the host communities and workers, however there may be long-term health challenges.
Applied Multi-Criteria Ideal Rehabilitation Model for Budget Allocation Across Road Infrastructure
Authors: Yadollahi Mohammadreza , Zin Rosli
Published: December 2011

The solution of prioritization problem for budget allocation across road infrastructure rehabilitation projects is highly complicated. This complexity is often due to the contradictions exist in budget allocation process. Such process concerns allocation of rehabilitation funds across various road infrastructures and taking into account multiple evaluation criteria. Therefore, budget allocation is a complex process with too many contradictions in form of criteria or attributes. According to the Systematic Innovation methodology, solving a problem means removing a contradiction. This paper presents a decision support approach for management of budget in rehabilitation process of road infrastructure, introducing Applied Multi-Criteria Ideal Rehabilitation Model. To achieve this, with the help of multi-criteria decision analysis, the Degree of Ideality is introduced as a function of all criteria. "Ideality" is the measure of how close the system is to the ideal final result. If the useful feature improves or harmful feature lessens, the ideality improves. In order to maximize the Degree of Ideality in the proposed Model, contradictions and resources are identified and ideal final result is introduced. This will result in a simple mechanism for allocation of budget across all the road infrastructures need to be rehabilitated.
CFD Prediction of Erosion Wear in Centrifugal Slurry Pumps for Dilute Slurry Flows
Authors: Pagalthivarthi K. V. , Gupta P. K. , Tyagi Vipin , Ravi M. R.
Published: December 2011

The paper discusses numerical prediction of erosion wear trends in centrifugal pump casing pumping dilute slurries. The casing geometry is considered two-dimensional. Discrete Phase Model (DPM) in FLUENT 6.1® is utilized to obtain dilute slurry flow field through the pump casing employing two-way coupling. Standard k — ε model is used for turbulence. Effect of several operational parameters viz. pump flow rate, pump speed (RPM), particle diameter and various geometry conditions viz. tongue curvature, slope of the discharge pipe and casing width is studied. Qualitative trends of erosion wear is described for these operational and geometric parameters with an idea to lower the wear rates and to make the wear pattern along the casing wall as uniform as possible. For example, with increase in pump flow rate, wear rates tends to even out whereas with increased casing width, wear rates are found to decrease.
Fire Behaviour of Concrete Columns with Restrained Thermal Elongation
Authors: Martins Alberto , Rodrigues João
Published: December 2011

This paper presents the results of an experimental and numerical study to clarify the influence of the surrounding building structure in the fire behaviour of reinforced concrete columns with restrained thermal elongation. The parameters studied were: the longitudinal reinforcement ratio, the slenderness of the column and the stiffness of the surrounding structure to the column in fire. The experimental study was complemented by a numerical study carried out using the finite element program SAFIR. Simplified calculation methods proposed in EN1992-1-2 were also used to evaluate the fire resistance of the tested columns. From the application of the 500°C isotherm method, proposed in EN1992-1-2, it can be noticed that this method led to smaller values of the fire resistance than those obtained in the experimental tests. The tabulated data method A, proposed in EN1992-1-2, proved to be very conservative.
Velocity Attenuation and Force Transfer by a Single- and Double-Layer Claddings Made of Foam Materials
Authors: Karagiozova Dora
Published: December 2011

The mechanism of air blast attenuation in a single- and double-layer sacrificial claddings comprising a steel cover plate and a foam core is examined applying an analytical and numerical analysis. In contrast to the commonly used approach to idealise the foam material by the rigid-perfectly plastic locking model, the unique relationship between the strains and stresses in foam materials exhibiting strain hardening is used in the present analytical model.

The present analytical approach allows for a further explication of the compaction mechanism of the foam layers in sacrificial claddings. It is established that the blast energy is absorbed by the cladding core due to multiple reflections of the compaction wave. The proposed model of foam compaction is used to obtain the strains and stresses at the stationary end of the cladding within the reflected compaction wave. It is confirmed that among the equal mass claddings, those with lower density core transfer lower stresses to the stationary end when subjected to identical load. The use of double-layer claddings comprising foam layers with different densities is discussed. It is demonstrated that a reduction of the total thickness of the cladding can be achieved by placing a higher density foam layer near to the loaded end while lower density foam layer is preferable near to the stationary end of the cladding.
Characterizing the Material Properties of a Tube from a Lateral Compression Test
Authors: Rathnaweera Gayan , Durandet Yvonne , Ruan Dong , Kinoshita Shigeaki
Published: December 2011

Material characterization is essential for finite element analysis (FEA) as the accuracy of the outputs of the simulation depends on the quality of the input material data. Conventional tests such as the uniaxial tensile test and uniaxial compression test have some drawbacks and limitations in characterizing tubular materials. In this paper, an improved methodology to determine the material properties of a tube based on lateral compression testis reported.

Mechanical properties such as yield strength and elastic modulus were obtained from lateral compression experimental data. The material work hardening coefficient and work hardening exponent were obtained by inverse finite element analysis (IFEA). The proposed methodology was used to determine the material properties of an aluminium 6060T5 tube, and results were compared with those reported from uniaxial tensile tests. Comparison showed that the proposed methodology could be used to easily and accurately predict the tube material properties based on the lateral compression test.
Dynamic Pricing with Loss-Averse Consumers and Peak-End Anchoring
Authors: Nasiry Javad , Popescu Ioana
Published: December 2011

We study the dynamic pricing implications of a new, behaviorally motivated reference price mechanism based on the peak-end memory mode. This model suggests that consumers anchor on a reference price that is a weighted average of the lowest and most recent prices. Loss-averse consumers are more sensitive to perceived losses than gains relative to this reference price. We find that a range of constant pricing policies is optimal for the corresponding dynamic pricing problem. This range is wider the more consumers anchor on lowest prices, and it persists when buyers are loss neutral, in contrast with previous literature. In a transient regime, the optimal pricing policy is monotone and converges to a steady-state price, which is lower the more extreme and salient the low-price anchor is. Our results suggest that behavioral regularities, such as peak-end anchoring and loss aversion, limit the benefits of varying prices, and caution that the adverse effects of deep discounts on the firm's optimal prices and profits might be more enduring than previous models predict.
Benders Decomposition for Large-Scale Uncapacitated Hub Location
Authors: Contreras Ivan , Cordeau Jean-François , Laporte Gilbert
Published: December 2011

This paper describes an exact algorithm capable of solving large-scale instances of the well-known uncapacitated hub location problem with multiple assignments. The algorithm applies Benders decomposition to a strong path-based formulation of the problem. The standard decomposition algorithm is enhanced through the inclusion of several features such as the use of a multicut reformulation, the generation of strong optimality cuts, the integration of reduction tests, and the execution of a heuristic procedure. Extensive computational experiments were performed to evaluate the efficiency and robustness of the algorithm. Computational results obtained on classical benchmark instances (with up to 200 nodes) and on a new and more difficult set of instances (with up to 500 nodes) confirm the efficiency of the algorithm.
Refining Square-Root Safety Staffing by Expanding Erlang C
Authors: Janssen A. J. E. M. , van Leeuwaarden J. S. H. , Zwart Bert
Published: December 2011

We apply a new corrected diffusion approximation for the Erlang C formula to determine staffing levels in cost minimization and constraint satisfaction problems. These problems are motivated by large customer contact centers that are modeled as an M/M/s queue with s the number of servers or agents. The proposed staffing levels are refinements of the celebrated square-root safety-staffing rule and have the appealing property that they are as simple as the conventional square-root safety-staffing rule. In addition, we provide theoretical support for the empirical fact that square-root safety-staffing works well for moderate-sized systems.
Growth Differentiation Factor-15 in the Early Diagnosis and Risk Stratification of Patients with Acute Chest Pain
Authors: Schaub Nora , Reichlin Tobias , Twerenbold Raphael , Reiter Miriam , Steuer Stephan , Bassetti Stefano , Stelzig Claudia , Wolf Claudia , Winkler Katrin , Haaf Philip , Meissner Julia , Drexler Beatrice , Mueller Christian
Published: December 2011

BACKGROUND

Growth differentiation factor-15 (GDF-15) is a stress-responsive marker that might aid in the early diagnosis and risk stratification of patients with suspected acute myocardial infarction (AMI).

METHODS

In a prospective, international multicenter study, GDF-15, high-sensitivity cardiac troponin T (hs-cTnT), and B-type natriuretic peptide (BNP) were measured in 646 unselected patients presenting to the emergency department with acute chest pain. The final diagnosis was adjudicated by 2 independent cardiologists. The primary prognostic end point was all-cause mortality during a median follow-up of 26 months.

RESULTS

AMI was the adjudicated final diagnosis in 115 patients (18%). GDF-15 concentrations at presentation were significantly higher in AMI patients compared to patients with other diagnoses. The diagnostic accuracy of GDF-15 at presentation for the diagnosis of AMI as quantified by the area under the ROC curve (AUC) was lower (AUC 0.69, 95% CI 0.64–0.74) compared to hs-cTnT (AUC 0.96, 95% CI 0.94–0.98, P < 0.001) and BNP (AUC 0.74, 95% CI 0.69–0.80, P = 0.02). A total of 55 deaths occurred during follow-up. GDF-15 predicted all-cause mortality independently of and more accurately than hs-cTnT [AUC 0.85 (95% CI 0.81–0.90) vs 0.77 (95% CI 0.72–0.83), P = 0.002] and BNP (AUC 0.75, 95% CI 0.68–0.82, P = 0.007). Net reclassification improvement was 0.15 (P = 0.01), and the absolute integrated discrimination improvement was 0.07, yielding a relative integrated discrimination improvement of 0.36 (P = 0.07).

CONCLUSIONS

GDF-15 predicts all-cause mortality in unselected patients with acute chest pain independently of and more accurately than hs-cTnT and BNP. However, GDF-15 does not seem to help in the early diagnosis of AMI.
New unusual skeletal structure in an upper Carboniferous rugose coral, Klamath Mountains, northern California
Authors: Stevens Calvin H. , Fedorowski Jerzy , Kawamura Toshio
Published: December 2011

Unique among the Rugosa are specialized cyst-like structures in corals from an upper Carboniferous limestone within the Baird Formation in the Klamath Mountains, northern California. These structures, here referred to as septal cysts, occur mostly along the distal margins of the dark line extending along the axes of the major septa as seen in transverse section. However, they also commonly extend beyond the distal extent of those lines and may interrupt the fibrous coating in the more proximal parts of some septa. Their function is uncertain. Also present are small dissepiments which form a ring around the distal margins of the minor septa. These structures, however, do not appear to be related to the development of those septa. Some other taxa, including corals from the Bashkirian of Spain and the Kasimovian of Kansas, possess some specialized structures similar to those in the California specimens suggesting at least a remote relationship.
Fruits ofHemitrapa(Trapaceae) from the Miocene of eastern China, their correlation withSporotrapoidites erdtmaniipollen and paleobiogeographic implications
Authors: Wang Qi
Published: December 2011

The fruits of the extinct genusHemitrapaMiki (Trapaceae) are described from the Miocene Shanwang Formation, representing its first fossil record in the Cenozoic of China. Bearing a fusiform, relatively small fruit body with a very long stalk and four sub-equal, strongly ascending, horn-like arms, the Chinese fossil fruits are described asH. shanwangensisQ. Wang new species. Prior to this discovery, a dispersed, trapaceous pollenSporotrapoidites erdtmanii(Nagy) Nagy was documented from the same formation. Recent paleobotanical and palynological studies in Europe demonstrated thatHemitrapawas closely related toS. erdtmanii, so the co-occurrence ofHemitrapafruits andS. erdtmaniipollen at Shanwang implies that they may stem from the same parental plant population.Hemitrapafruits have been widely recognized from the Miocene of mid-latitudes in France, Austria, the Czech Republic, Kazakhstan, Russia, Korea, Japan and the U.S.A. as well as from the late Oligocene–Miocene of Germany and the late Eocene of the Czech Republic. In contrast, dispersedS. erdtmaniipollen has been recovered from the Miocene in central Europe as well as from the late Eocene to the Pliocene of eastern Asiatic shelf basins near the Bohai Sea, Yellow Sea, East China Sea, and the Sea of Japan. Overall, the microfossil and macrofossil records demonstrate that the parental plants ofHemitrapamight have begun to diversify from the mid-latitudes of Eurasia since the Eocene, flourished in eastern Asia and Central Europe during the Miocene, and become extinct after the Pliocene.
Maturity and Impedance Analysis of Organic-Rich Shales
Authors: Prasad Manika , Mba Kenechukwu C. , McEvoy T. Elizabeth , Batzle Michael L.
Published: December 2011

Organic-rich shales (ORSs) need to be studied in detail to understand the provenance and the generation of hydrocarbons from source rocks. In recent years, ORSs have gained importance as hydrocarbon resources as well. Successful exploration and production programs for ORSs need reliable identification of their kerogen content as well as maturity through indirect seismic methods. However, the properties of kerogen are poorly understood, so predictions about maturity and rock-kerogen systems remain a challenge. Assessment of maturity from indirect measurements can be greatly enhanced by establishing and exploiting correlations between physical properties, microstructure, and kerogen content.

We show correlations between the impedance microstructure of ORSs and their maturity and elastic properties. We have used scanning acoustic microscopy to analyze and map the impedance microstructure in ORSs. We quantified textural properties in the images and related these textural properties to maturity and to impedance from acoustic-wave propagation measured at centimeter scales. This combined study of acoustic properties and microstructures of ORSs gives important insight into changes resulting from kerogen maturation. We introduce a modified porosity term and find that (1) there is a significant correlation between velocity and modified porosity of all ORSs; (2) imaging and quantifying microscale impedance texture and contrast in the images allow us to correlate them with ultrasonic measurements on a centimeter scale; and (3) textural heterogeneity, elastic impedance, velocity, and density increase with increasing shale maturity.

We also discuss possible methods to predict maturity from impedance on the basis of understanding the changes resulting from maturity in well-log response, core measurements, and microstructure of ORSs. Our work has important bearing on developing successful production and stimulation methodologies.
Alkaline/Surfactant/Polymer Flood: From the Laboratory to the Field
Authors: Stoll W. M. , al Shureqi H.. , Finol J.. , Al-Harthy S. A. , Oyemade S.. , de Kruijf A.. , van Wunnik J.. , Arkesteijn F.. , Bouwmeester R.. , Faber M. J.
Published: December 2011

After two decades of relative calm, chemical enhanced-oil-recovery (EOR) technologies are currently revitalized globally. Techniques such as alkaline/surfactant/polymer (ASP) flooding, originally developed by Shell, have the potential to recover significant fractions of remaining oil at a CO2 footprint that is low compared with, for example, thermal EOR, and they do not depend on a valuable miscible agent such as hydrocarbon gas. On the other hand, chemical EOR technologies typically require large quantities of chemical products such as surfactants and polymers, which must be transported to, and handled safely in, the field.

Despite rising industry interest in chemical EOR, until today only polymer flooding has been applied on a significant scale, whereas applications of surfactant/polymer or alkaline ASP flooding were limited to multiwell pilots or to small field scale. Next to the oil-price fluctuations of the past two decades, technical reasons that discouraged the application of chemical EOR are excessive formation of carbonate or silica scale and formation of strong emulsions in the production facilities.

Having identified significant target-oil volumes for ASP flooding, Petroleum Development Oman (PDO), supported by Shell Technology Oman, carried out a sequence of single-well pilots in three fields, sandstone and carbonate, to assess the flooding potential of tailor-made chemical formulations under real subsurface conditions, and to quantify the benefits of full-field ASP developments.

This paper discusses the extensive design process that was followed. Starting from a description of the optimization of chemical phase behavior in test-tube and coreflood experiments, we elaborate how the key chemical and flow properties of an ASP flood are captured to calibrate a comprehensive reservoir-simulation model. Using this model, we evaluate PDO's single-well pilots and demonstrate how these results are used to design a pattern- flood pilot.
A Comprehensive Model of High-Rate Matrix-Acid Stimulation for Long Horizontal Wells in Carbonate Reservoirs: Part I—Scaling Up Core-Level Acid Wormholing to Field Treatments
Authors: Furui K.. , Burton R.C.. C. , Burkhead D.W.. W. , Abdelmalek N.A.. A. , Hill A.D.. D. , Zhu D.. , Nozaki M..
Published: December 2011

Matrix-acidizing models have traditionally underpredicted acid-stimulation benefits because of underprediction of wormhole penetration and the corresponding magnitude of completion-skin factors in vertical wells. For long horizontal wells drilled in carbonate reservoirs, productivity enhancement is a function of acid placement and effective wormhole penetration. However, prediction of wormhole penetration requires more effective analysis than that provided by current industry models. This paper presents results of matrix-acid modeling work for horizontal wells and describes a practical engineering tool for analyzing the progress of matrix-acid stimulation in carbonate reservoirs.

The wormhole-growth model is based on the Buijse and Glasbergen empirical correlation. Combining with the mechanistic model of the wormhole propagation based on acid transport and fluid loss from a single wormhole, a modified Buijse-Glasbergen wormhole-growth model is developed that relates the wormhole growth rate to the in-situ injection velocity at the tip of the dominant wormhole. The wormhole constitutive model developed in this study also accounts for core-size dependencies seen in laboratory acid-flood experiments. A semianalytical flow correlation is derived for estimating interstitial velocities at the tip of the dominant wormholes based on a number of 3D FEM simulation analyses, accounting for more realistic flow regimes (radial and spherical flow) typically observed in field application. The scaleup procedure developed in this study extends the wormhole geometry and penetration from laboratory flow tests on small cores to field-sized treatments.

The scaleup procedure developed in this work can be applied to cemented and uncemented horizontal wells, including barefoot and perforation-cluster completions typically employed in carbonate reservoirs. Application of this modeling shows that acid wormholing through carbonate formations can provide significant stimulation, resulting in post-stimulation skins as low as–3.5 to–4.0 vs. previously predicted values in the –1.0 to–2.0 range.
Drillpipe Cutting at Ultrahigh Pressure Proven for Remediating Deepwater Stuck-Pipe Hazards
Authors: Seguras John
Published: December 2011

Efficient separation of stuck drillstrings with proven results is a must for deepwater wells where depths can reach 35,000 ft and daily rates often exceed USD 1,000,000. Operators want proven results instead of theoretical calculations or critical-path experimentation during a stuckpipe hazard event. Historical pipe cutting or severing has been hindered for decades by high bottomhole pressures (BHPs) and internal-diameter restrictions. Chemical cutters and plasma cutters are most affected by the effect of hydrostatic pressure on their method of pipe separation, while jet cutters and severing tools’ explosive charges could overcome more BHP. After leaping the 20,000-psi hurdle, we were still limited to 25,000 psi or less and had unproven products until now.

From conceptual development to laboratory data, this paper will describe the need for and development, testing, and results of jet cutters and severing tools for use in ultrahigh-pressure environments up to 30,000 psi for today's deepwater, ultradeep-well market. Designing and building of a new, first-of-its-kind test vessel allowed for visualization and verification of actual separation of drillstring components at BHPs with zero tension applied.

Extrapolation of data from previous cutter designs at lower pressure ratings allowed us to tailor each cutter size and charge quantity for the pipe thicknesses and test pressures desired. The material component of the cutter housing and the timing of explosive initiation are critical for the cutters to withstand the descent through the drillstring components and the constantly increasing wellbore pressure and still provide an accurate, efficient detonation for separating the thick metal wall of the pipe. Laboratory testing proved that jet cutting and severing drillstring tubular components are achievable at pressures up to 30,000 psi in drillpipe and heavyweight-drillpipe (HWDP) bottomhole drilling assemblies.

Substantial cost and critical-path time savings for deepwater operators can be realized during stuck-pipe incidents by using tested technology proven to separate drillstring components at BHPs up to 30,000 psi.
Retardation of CO2 Caused by Capillary Pressure Hysteresis: A New CO2 Trapping Mechanism
Authors: Altundas Y.B.. B. , Ramakrishnan T.S.. S. , Chugunov Nikita , de Loubens Romain
Published: December 2011

Containment security of geologically stored CO2 is improved substantially through trapping mechanisms. Therefore, to simulate the potential viability of a storage site, it is necessary to account for immobilization processes. In this paper, we focus on a quantitative measure for the contribution of hysteresis in reducing plume transport, with particular emphasis on capillary-pressure-induced migration retardation. Rocks with large pore-body-to-throat-size ratio, or a low permeability, are the best candidates for this mechanism to be operative.

In the present work, a self-consistent relative permeability and capillary pressure hysteresis model is incorporated within a simulator. With this model, it is possible to compare and contrast hysteresis-induced retardation to other mechanisms of trapping. The self-consistent parameterization of all of the transport properties is used to quantify sensitivity compactly. The sensitivity of the CO2-plume shape and the amount of CO2 trapped to the strength of the capillary pressure hysteresis is also described.

Simulated results show that the CO2-plume shapes with and without capillary pressure hysteresis are significantly different. As expected, capillary pressure hysteresis retards the buoyant transport of the CO2 plume. Although a portion of the CO2 is connected, and therefore not residual, the plume remains immobile for all practical purposes. Also, because of the decreased driving potential, gravity tonguing below the caprock is reduced in comparison to the case without capillary pressure hysteresis, thus suggesting enhanced storage efficiency. However, the total dissolution of CO2 in saline water is reduced because of the reduced contact area with the brine. Thus, one mechanism of containment is offset by the other.

Inclusion of accurate hysteresis models is important for qualifying storage sites constrained by spatial-domain limits. It is anticipated that site-acceptability criteria would change as a result of this study, thereby impacting risk evaluation.
Stabilizing Viscoelastic Surfactants in High-Density Brines
Authors: van Zanten R..
Published: December 2011

Viscoelastic-surfactant (VES) systems are the preferred gelling and viscosity-generating agents for fluids used in the production zone because of their nondamaging effects on the reservoir. Polymer gels have relatively higher rock-retention values and can often damage the invaded zone, in most cases requiring acid treatment to remove. In contrast, VES systems behave as "equilibrium" or "living" polymers, and their viscosity can be reduced by contact with the produced hydrocarbons or with an internal breaker. This can eliminate the need for remedial treatments, greatly reducing operating cost/time and damage to the formation.

Cationic, anionic, and cationic/anionic VES systems have historically demonstrated limitations in high-density brines. Electrostatic screening generally reduces the viscosity or causes phase separation. Many surfactants generally have low salt tolerance and minimal to zero tolerance of divalent brines. Most surfactants exhibit a dramatic decrease in viscosity after a certain concentration of salt is reached and even phase separation in some cases.

A novel method has been developed to stabilize different VES packages in high-density completion brines. By controlling the curvature of surfactant aggregates using low-molecular-weight surfactant polymers, nanometer-scale manipulation of the phase behavior is achieved. We have viscosified mono-and divalent high-density brines using cationic, anionic, and catanionic mixtures that were previously considered ineffective. This unlocks a vast range of surfactants for use in high-density completion brines, fracturing/stimulation/acidizing fluids, and sand-control operations.

This paper details the laboratory work performed to develop VES packages for fluids ranging from fresh water to completion brines. Extensive rheology experiments have been run on several fluids, showing the viscoelasticity of these systems. The selfbreaking nature of VES systems when in contact with hydrocarbons or exposed to a built-in breaker has also been demonstrated by laboratory experiment.
Optimal Well Placement Under Uncertainty Using a Retrospective Optimization Framework
Authors: Wang Honggang , Ciaurri David Echeverría , Durlofsky Louis J. , Cominelli Alberto
Published: December 2011

Subsurface geology is highly uncertain, and it is necessary to account for this uncertainty when optimizing the location of new wells. This can be accomplished by evaluating reservoir performance for a particular well configuration over multiple realizations of the reservoir and then optimizing based, for example, on expected net present value (NPV) or expected cumulative oil production. A direct procedure for such an optimization would entail the simulation of all realizations at each iteration of the optimization algorithm. This could be prohibitively expensive when it is necessary to use a large number of realizations to capture geological uncertainty. In this work, we apply a procedure that is new within the context of reservoir management—retrospective optimization (RO)—to address this problem. RO solves a sequence of optimization subproblems that contain increasing numbers of realizations. We introduce the use of k -means clustering for selecting these realizations. Three example cases are presented that demonstrate the performance of the RO procedure. These examples use particle swarm optimization (PSO) and simplex linear interpolation (SLI)-based line search as the core optimizers (the RO framework can be used with any underlying optimization algorithm, either stochastic or deterministic). In the first example, we achieve essentially the same optimum using RO as we do using a direct optimization approach, but RO requires an order of magnitude fewer simulations. The results demonstrate the advantages of cluster-based sampling over random sampling for the examples considered. Taken in total, our findings indicate that RO using cluster sampling represents a promising approach for optimizing well locations under geological uncertainty.
Multipoint Statistical Characterization of Geologic Facies from Dynamic Data and Uncertain Training Images
Authors: Khodabakhshi Morteza , Jafarpour Behnam
Published: December 2011

Discrete geologic features that contribute to preferential flowpaths or act as flow barriers are rarely amenable to second-order descriptions. Using a conceptual model or training image (TI), multipoint statistics (MPS) provides a systematic approach to describe the higher-order spatial statistics of discrete geologic features. Conditioning MPS facies realizations on flow data poses a challenging nonlinear inverse problem, primarily because of the nonlinear relation between facies properties and flow response measurements. Since MPS simulated facies imitate the spatial patterns in the TI, the quality of the generated facies depend on the reliability of the TI. However, given the uncertainty in the knowledge used to construct a TI, it is imperative to account for and represent the uncertainty in any given TI. One approach to account for TI uncertainty is to use multiple TIs to cover the expected range of structural variability in geologic facies. When several TIs are used to represent the uncertainty in the conceptual geologic model for a given field, flow data may be used to quantify the importance of different TIs. Here, we present a new method for adaptively sampling conditional facies from multiple uncertain TIs. By applying a fast flow-based clustering approach, we show that one can adaptively sample facies realizations from multiple TIs to honor the observed flow data. We apply a probability conditioning method (PCM) to invert the flow data to construct a facies probability map that can be included in drawing conditional facies realizations from each TI. We illustrate that the proposed adaptive sampling scheme can be used to weigh different TI s according to their performance in matching the flow data. We demonstrate the suitability of the proposed method using numerical experiments in fluvial formations where several TIs are used to account for the uncertainty in facies structural connectivity.