bluuebunny/crossref_metadata_2025_split huggingface dataset:
Circulating Tumor Cell Count Is a Prognostic Factor in Metastatic Colorectal Cancer Patients Receiving First-Line Chemotherapy Plus Bevacizumab: A Spanish Cooperative Group for the Treatment of Digestive Tumors Study
Authors: Sastre Javier , Maestro M. Luisa , Gómez-España Auxiliadora , Rivera Fernando , Valladares Manuel , Massuti Bartomeu , Benavides Manuel , Gallén Manuel , Marcuello Eugenio , Abad Albert , Arrivi Antonio , Fernández-Martos Carlos , González Encarnación , Tabernero Josep M. , Vidaurreta Marta , Aranda Enrique , Díaz-Rubio Eduardo 
Published: May 2012

Abstract

Background.
The Maintenance in Colorectal Cancer trial was a phase III study to assess maintenance therapy with single-agent bevacizumab versus bevacizumab plus chemotherapy in patients with metastatic colorectal cancer. An ancillary study was conducted to evaluate the circulating tumor cell (CTC) count as a prognostic and/or predictive marker for efficacy endpoints.

Patients and Methods.
One hundred eighty patients were included. Blood samples were obtained at baseline and after three cycles. CTC enumeration was carried out using the CellSearch® System (Veridex LLC, Raritan, NJ). Computed tomography scans were performed at cycle 3 and 6 and every 12 weeks thereafter for tumor response assessment.

Results.
The median progression-free survival (PFS) interval for patients with a CTC count ≥3 at baseline was 7.8 months, versus the 12.0 months achieved by patients with a CTC count &lt;3 (p = .0002). The median overall survival (OS) time was 17.7 months for patients with a CTC count ≥3, compared with 25.1 months for patients with a lower count (p = .0059). After three cycles, the median PFS interval for patients with a low CTC count was 10.8 months, significantly longer than the 7.5 months for patients with a high CTC count (p = .005). The median OS time for patients with a CTC count &lt;3 was significantly longer than for patients with a CTC count ≥3, 25.1 months versus 16.2 months, respectively (p = .0095).

Conclusions.
The CTC count is a strong prognostic factor for PFS and OS outcomes in metastatic colorectal cancer patients.
A Successful Remoaval Inorganic Hard Scale Deposits in an Offshore Pipeline in Gemsa Oil field, Egypt: Field Study
Authors: Bakr M. , Abdel Hay A. , Hamdy E. 
Published: May 2012

Abstract
Water flooding is the hinge pin for Gemsa Oil Field. Water injection is supplied from shallow water supply wells. Compatibility tests had indicated probable deposition of calcium sulphate scale on surface and subsurface production equipment. Calcium sulphate scale has been recognized to be a major operational problem. The bad consequences of scale formation comprised the contribution to flow restriction thus resulting in oil and gas production decrease. The nature of calcium sulphate scale is very hard and can't be dissolved with known dissolver. Sister companies that has similar problem were always going to the mechanical remover options.
Extensive lab and field work was conducted to determine the suitable chemicals to dissolve calcium sulphate scale. This paper describes the development and field application of chemical treatment to remove scale in an offshore 8" production line in Gemsa oil field. Continuous precipitation of calcium sulphate scale caused partial plugging of the pipeline. This partial plugging created a back pressure on production wells which decreased the productivity. The field production has been decreased to almost one tenth of the normal field production level(1).
A thorough investigation was conducted to identify the composition and location of the scale, in order to recommend a suitable chemical to remove the scale, and to assess the effectiveness of the treatment method in the field.
Based on extensive lab studies, SAG-01 was tested and applied in production line to remove the scale efficiently, the program was designed taking into consideration the nature of the scale. The treatment program included three - staged process: The use of an organic solventThe main treatment (SAG-01).The post flush stage (injection water),
The job results were outstanding, where as 1-Production increased by about 2,000 BOPD2-Launcher pressure dropped by about 350 psi.3-Decrease the back pressure on our producing wells.4-Additional producing wells into production.5-Efficient cost /Bbl.
Novel Scale Squeeze Technology and Treatment Designs for Improving Scale Inhibitor Retention and Treatment Lifetimes - Use of Ionic Polymers in the Overflush
Authors: Heath Steve , Juliussen Bjorn , Chen Ping , Chen Tao , Benvie Ronald 
Published: May 2012

Abstract
A common method to prevent scale forming in oil production wells is to inject scale inhibitor into the formation in so called squeeze treatments. Conventional scale inhibitor treatments with a brine pre-flush, main scale inhibitor pill and brine over flush stages are often not considered to be economically efficient as a large proportion of the scale inhibitor introduced into the squeeze treatment is returned almost immediately and therefore does not serve to provide long term scale protection.
Various techniques have been used successfully to increase the proportion of scale inhibitor retention in the well during squeeze treatments. For example, it has been reported previously in many papers where poly amino acids and poly quaternary amines have been injected into a well as part of the pre flush process and have significantly improved scale inhibitor retention and scale squeeze lifetimes. It has now been found that scale inhibitor treatment lifetimes can be improved by incorporating an ionic polymer such as a poly amino acid or poly quaternary amine in the over flush stage of the squeeze treatment. Indeed this method has been found to further extend the treatment lifetimes when combined with the same additives in the pre-flush stage of the scale squeeze treatment.
The new scale squeeze design technology can be considered very flexible as it can be applied with most scale inhibitor chemistries including both phosphonates and polymers with minimal formation damage potential compared to most precipitation scale squeeze treatments. It should be applicable over a wide temperature range from 30°C to 200°C and, in addition, the treatment strategy also lends itself to both aqueous and non-aqueous deployment and hybrid treatments and could provide extra protection against fines production in water sensitive wells depending upon the ionic polymer deployed. Initial field treatments have demonstrated the potential to extend treatment lifetimes by retaining up to 20 to 50% more useful chemical in the treatment reservoir.
This paper will highlight the proposed mechanisms of how the ionic polymer additives can improve squeeze treatment lifetimes as part of the over flush and will present field data for treatments on two wells in an HP/HT field at 165°C that demonstrated improved chemical retention and scale inhibitor returns compared to treatments without the ionic polymer additive in the over flush.
Automatic Isotherm Derivation from Field Data for Oilfield Scale Inhibitor Squeeze Treatments
Authors: Vazquez O. , Corne D. , Jordan M. M. , Mackay E. J. 
Published: May 2012

Abstract
Oilfield scale formation represents a very significant flow assurance challenge to the oil and gas industry, with increasing water production worldwide and higher oil prices. Scale Inhibitor (SI) squeeze treatment is the most widespread method to combat downhole scaling. In order to predict SI squeeze treatments accurately for further optimisation, it is necessary to simulate the SI retention in the formation, which may be described by pseudo-adsorption isotherms. While these are often derived from core flood experiments, sometimes they are not appropriate for modelling well treatments because the core tests on which they are based cannot fully represent field scale processes. In practice, the parameters of an analytic form of the isotherm equation are modified by trial and error by an experienced practitioner until a match is obtained between the prediction and the return profile of the first treatment in the field.
The main purpose of this paper is to present a Stochastic Hill Climbing Algorithm for automatic isotherm derivation. The performance of the algorithm was evaluated using data from three field cases. Two success criteria were defined: firstly, ability to match a single historical treatment and secondly, ability to predict subsequent successive treatments. To test for the second criterion, a candidate isotherm was derived from the first treatment in a well that was treated with the same chemical package on consecutive occasions, and then the predictions using the suggested solution were compared with the observed scale inhibitor concentration return profiles from the subsequent treatments. In all the calculations, performance of the isotherms suggested by the Hill Climbing algorithm and isotherms derived by trial and error were compared. The results demonstrate that the Hill Climber Algorithm is a very effective technique for deriving an isotherm to enable accurate modelling of scale inhibitor squeeze treatments.
The Effect of pH on Static Barium Sulphate Inhibition Efficiency and Minimum Inhibitor Concentration of Generic Scale Inhibitors
Authors: Shaw S. S. , Sorbie K. S. 
Published: May 2012

Abstract
This paper discusses the effect of pH on the static barium sulphate inhibition efficiency (IE) of four scale inhibitors: DETPMP and HMTPMP (both penta-phosphonates), EDTMPA (a tetra-phosphonate), and PPCA (a phosphino poly carboxylate). pH is an important parameter with regard to SI functionality. The effect of pH on each SIs IE is explained in terms of SI speciation and binding to Ca2+ and Mg2+ (and possibly Ba2+, Sr2+). In some cases there is an "optimum pH" for the effective operation of a specific SI, depending on the nature of the functional groups present in the chemical structure.
All static IE experiments were carried out at 95°C and using a North Sea Seawater/Formation Water (NSSW/FW) mixing ratio = 80/20. pH levels of 4.5, 5.5, 6.5 and 7.5 were chosen for testing since this covers the entire range which threshold level SI concentration might normally experience in a reservoir. The IE was determined for each SI at each pH level, where the [SI] was chosen close to the threshold MIC (i.e. pre-2 hour MIC) such that the specific effects of varying pH on 2 and 22 hour IE were clearly visible. In some tests MIC levels were reached, and in these cases, findings are presented in terms of MIC versus pH. For all four species tested, IE versus pH charts are presented. Furthermore, two brine mix compositions (maintaining NSSW/FW = 80/20) were examined, one with [Ca2+] = 742ppm and [Mg2+] = 1242ppm (base case) and one with [Ca2+] = 2000ppm and [Mg2+] = 739ppm (fixed case). The base case [Ca2+] and [Mg2+] result from the normal mixing of NSSW and FW in an 80/20 ratio, molar ratio Ca2+/Mg2+ = 0.36. In the fixed case mix, molar ratio Ca2+/Mg2+ = 1.64. This is done in order to compare and context results within an extensive earlier series of IE results for SIs which were tested in this manner (Shaw et al, 2010a, 2010b).
A Simple Model of Precipitation Squeeze Treatments
Authors: Sorbie K. S. 
Published: May 2012

Abstract
Scale inhibitors are retained within porous media by the two main mechanisms of "adsorption" (Γ) and "precipitation" (Π). In previous experimental and modelling work, we have demonstrated for static (equilibrium) "apparent adsorption" tests where the system exhibits either (a) adsorption only or (b) it is in the coupled adsorption/precipitation (Γ/Π) regime. A complete model of SI retention must have (i) an equilibrium description of the coupled Γ/Π process (Kahrwad et al, 2008); (ii) a kinetic model of coupled Γ/Π which correctly limits to the equilibrium case (i.e. the kinetics must be consistent with the equilibrium Γ/Π model as t → ∞); (iii) the full kinetic Γ/Π model must then be embedded in a transport model for flow through porous media. Some progress towards this full model has been made and reported previously (Sorbie, 2010; Vazquez et al, 2010).
The full coupled kinetic Γ/Π model is comprehensive and is currently being verified by experiment. However, this full model is quite complex and difficult to understand. Therefore, in this paper, we present a new simple model of kinetic precipitation (Π) which explains some key features of this process. This work will present 3 key new findings, as follows: (i)a very simple mathematical explanation of the mechanism and observations in kinetic precipitation;(ii)some simple but novel analytical formulae which describe the process;(iii)a worked field scale radial kinetic precipitation examples is presented which demonstrates how to estimate whether a given field system is close to or far from precipitation/dissolution equilibrium.
This simpler model represents an end-member where a precipitating SI system is described by a solubility (Cs) and a dissolution rate, k. In most practical cases, some level of adsorption is also superimposed upon this behaviour but this is neglected in this simple model. However, understanding the behaviour of this idealized system does give us some mechanistic insights and some simple practical formula for precipitation squeeze design purposes.
Modelling of Enhanced Scale Control via Inhibition of Stimulation Fluids for Deepwater Developments
Authors: Ishkov Oleg , Mackay Eric , Jordan Myles 
Published: May 2012

Abstract
The injection of seawater into oil bearing reservoirs to maintain reservoir pressure and improve secondary recovery is a well-established, mature operation. Moreover, the degree of risk posed by deposition of mineral scales (carbonate/sulphate) to the injection and production wells during such operations has been much studied. The current deepwater subsea developments offshore West Africa, Gulf of Mexico and Brazil have brought into sharp focus the need to manage scale in an effective way.
In recent years there has been some consideration given to deployment of scale inhibitor within the fluids associated with the completion of production wells, prior to the start up of production. Until now, effective scale control in frac packed wells at low water cuts has been achieved with phosphonate-based inhibitors applied as part of the acid perforation wash and overflush stages, prior to the actual frac packing operation itself. The deployment of these inhibitors has proved effective in controlling barium sulphate scale formation during initial seawater production, and eliminating the need to scale squeeze the wells at low water cuts (&lt;10% BS&W). Recent developments allowing inclusion of scale inhibitor in the linear and cross linked gel stages has highlighted the need to be able to model this process effectively, thereby enabling optimal use of the chemical and improved squeeze designs.
This paper outlines simulation work carried out using the Petroleum Experts REVEAL software to assess introduction of scale inhibitor into frac pack operations, and identify the most suitable stage of the well completion process during which to apply the inhibitor, to maximise treatment life. Simulation results and field data from these treatments are compared to demonstrate the opportunity this technique presents, and to highlight the importance of chemical placement and the post stimulation flow regime to squeeze life.
Industrial Experience in Sea Water Desulfation
Authors: Pedenaud Pierre , Hurtevent Christian , Baraka-Lokmane Salima 
Published: May 2012

Abstract
Large quantities of sea water are injected in oil and gas fields all over the world for pressure maintenance support and sweeping efficiency of the reservoir in order to maximize the hydrocarbon production. Many difficulties are linked with sea water injection such as risks of reservoir souring, loss of injectivity, incompatibility between sea and reservoir waters. One specific problem is the risk of sulfate based scale formation like barium sulfate. Indeed sea water contains around 2800 mg/l of sulfate and some reservoir contains high concentration of barium and strontium. If nothing is done to prevent the mixing of these two waters, scale deposits will occur at the producer wells once the breakthrough happened, with the loss of production.
One solution is to remove the sulfate from sea water prior to injection, and this is possible by using the nanofiltration process. This desulfation process based on membrane technology is in operation in TOTAL sites for more than 10 years and it works very succesfully.
This paper presents the feedback of ten years of operations both on the desulfation process and also on the scale prevention strategy. Based on the experience of three big desulfation units operated offshore on FPSOs, this paper presents the various parameters of this process such as the operational constraints, membrane cleaning requirements, need for efficient pre treatment, membrane life time, and efficiency in sulphate removal. Moreover at the beginning anti scale injection was installed on the producer wells to inhibit the residual sulphate coming from desulfation (40 ppm), however better efficiency of process and sulphate elimination in reservoir showed that this residual risk is nil. Results showed that the choice of desulfation is the best solution to prevent barium sulphate scale, even if this process can appear firstly as constraining and costly.
Understanding Mechanisms of Scale inhibition Using Newly Developed Test Method and Developing Synergistic Combined Scale Inhibitors
Authors: Liu Xuan , Chen Tao , Chen Ping , Montgomerie Harry , Hagen Thomas , Wang Bin , Yang Xu 
Published: May 2012

Abstract
Static jar and dynamic loop tests are two major test methods used in the oilfield scale industry to evaluate the performance of scale inhibitors. The minimum inhibitor concentration (MIC) under the test conditions can be determined, but with a certain amount of assumptions and theoretical analysis of the mechanism of scale inhibition, especially for scale inhibitors with dispersive effects.
Unlike these traditional test methods, a newly developed test method, using an ultrasonic technique along with turbidity measurement, has been used to evaluate scale inhibitors and understand the inhibition mechanisms. In comparison with traditional test methods, this test method provides a quick and effective way to understand the scale inhibitors, including the effect of scale inhibitors on the induction, nucleation and growth stages of scale formation, and also the dispersion functions of scale inhibitors.
Several typical commercial scale inhibitors, including phosphonate and polymer based chemistries have been tested using this newly developed test method. Different scale inhibitors demonstrated different inhibition mechanisms and will be addressed in detail in this paper.
Results showed a polymer based scale inhibitor has good inhibition on the induction time of scale formation and a phosphoric based scale inhibitor showed a major dispersive effect on scale inhibition. The combined formulation based on these two inhibitors has been evaluated and a synergistic effect was observed and later confirmed by both the traditional static jar test and dynamic loop test, where the mixture of 75% polymer based scale inhibitor and 25% phosphoric based scale inhibitor showed much better performance than both neat scale inhibitors.
In this paper, this newly developed test method will be introduced in detail and the benefits and limitations will also be discussed. By understanding the mechanism of the scale inhibitors, this technique might provide a new and alternative route of developing and formulating scale inhibitors.
Retention and Release of Scale Inhibitor in Different Clay Minerals
Authors: Jordana Rut , Howe Russell F. , Guan Hua 
Published: May 2012

Abstract
Addition of scale inhibitor into the reservoir allowing its adsorption and or precipitation into the rock formation and subsequent release during production is one of the most common treatments used in oil field industries to avoid scale formation. Little is known however about the surface chemistry of scale inhibitor interaction with the various mineral phases present in subsea rock formations. This paper presents some recent work investigating these interactions with the spectroscopic techniques commonly employed in surface chemistry. Uptake of NTMP, a model scale inhibitor, by kaolin, halloysite and montmorillonite has been monitored by liquid phase 31P NMR spectroscopy. 31P NMR has also been used to follow the release of scale inhibitor during desorption experiments. The adsorbed inhibitor has been detected directly and quantified with X-ray photoelectron spectroscopy (XPS). XPS combined with argon ion etching has also been able to distinguish between inhibitor adsorbed onto the external surface of the clays and occluded into the interlayer spacing.
Application of BDD thin film electrode for electrochemical decomposition of heterogeneous aromatic compounds
Authors: Czupryniak Justyna , Fabiańska Aleksandra , Stepnowski Piotr , Ossowski Tadeusz , Bogdanowicz Robert , Gnyba Marcin , Siedlecka Ewa 
Published: May 2012

Abstract
The aim of the presented study is to investigate the applicability of electrochemical oxidation of aromatic compounds containing heteroatoms, e.g. waste from production of pesticides or pharmaceutics, at a borondoped diamond (BDD) electrode. The BDD electrodes were synthesized by microwave plasma enhanced chemical vapour deposition (MW PE CVD). Investigation of the electrode surface by optical microscopy and scanning electron microscopy (SEM) confirmed that the synthesized layer was continuous and formed a densely packed grain structure with an average roughness of less than 0:5 μm. The influence of important electrochemical parameters: current density, kind of reactor, pH or mixing operation, on the efficiency of the oxidation was investigated. The fouling of electrode’s surface caused by the deposition of organic material was observed during CV and galvanostatic experiments. At low current density the oxidation rate constant k was low, but the current efficiency was relatively high. The BDD can be used successfully to remove heterogeneous aromatic compounds existing either as molecules or cations. During 4 h of electrolysis 95% of aromatic compounds were electrochemically decomposed to mineral forms. It was observed that the influence of the initial pH on mineralization was marginal.
Determination of freeze-out conditions from lattice QCD calculations
Authors: Karsch Frithjof 
Published: May 2012

Abstract
Freeze-out conditions in Heavy Ion Collisions are generally determined by comparing experimental results for ratios of particle yields with theoretical predictions based on applications of the Hadron Resonance Gas model. We discuss here how this model dependent determination of freeze-out parameters may eventually be replaced by theoretical predictions based on equilibrium QCD thermodynamics.