bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Insights into the Removal of Calcium Sulfate Scale
Authors: Al-Khaldi M. H. , Al-Juhani A. M. , Al-Mutairi S. H. , Gurmen M. N. 
Published: June 2011

Abstract
Calcium sulfate has been one of the major scales which cause many significant and serious operating problems in producing oil/gas wells and in water injectors. Impermeable hard scale deposits of calcium sulfate can severely impair the formation permeability or lead to down-hole equipment failure. Typically, preventative treatments, such as use of scale inhibitors, are the best economical methods for calcium sulfate mitigation. However, application of a cost-effective treatment is needed, in case of emergency, when calcium sulfate precipitation occurs.
A comprehensive lab investigation was conducted in order to assess the effectiveness of several remedial methods for calcium sulfate removal. This work shows the amount of calcium sulfate dissolved after its exposure to different reactive fluids at 25 and 50°C. In addition, it discusses the effect of different factors on the efficiency of each remedial treatment. These factors include: pH, temperature, reactive fluid concentration and presence of magnesium/iron ions.
Based on obtained results, several new findings were identified. The presence of gypsum (CaSO4.2H2O) has negative impact on the performance of mud acid treatments. After initial dissolution of gypsum in live mud acid, dissolved calcium will precipitate as both calcium fluoride and calcium sulfate in spent HCl/HF solutions. Similarly, gypsum has higher solubility limit in live HCl acid compared to its spent solutions. This resulted in re-precipitation of calcium sulfate in spent HCl. This solubility trend of gypsum in acidic solutions could result in severe formation damage. Live acids can initially dissolve any precipitated calcium sulfate solids in wellbore area and then it will re-precipitate in the formation rocks as the acid spends.
Gypsum has higher solubility limit in EDTA solutions, compared to acidic solutions. No re-precipitation of calcium sulfate occurred in these solutions due to the fact that calcium ions exist as complex ions and not free to interact with other ions. The dissolving power of EDTA was found to be a function of the solution pH value. Higher dissolving power of EDTA for gypsum was observed at high pH values. The presence of both magnesium and iron (III) ions had negative effect on gypsum dissolution in EDTA fluid. Compared to magnesium, iron (III) ion resulted in significant decrease in gypsum solubility in EDTA. Dissolved magnesium ions in EDTA solutions could re-precipitate as magnesium sulfate when gypsum is dissolved. This re-precipitation is more at low pH EDTA solutions.
Reduced Solids Oil-Based Completion Fluid for Horizontal HPHT Openhole Completions
Authors: van der Zwaag C. H. , Svanes G. S. , Schiefloe B. S. , Ibragimova Z. , Austmo Moeller K. , Vikanes H. , Lund Smørdal C. , Pedersen G. E. , Bringsjord K. L. 
Published: June 2011

Abstract
A 1.9 SG oil-based fluid for suspending open-hole pre-perforated liner completions in 1100 m long, horizontal openhole sections, under HPHT conditions (162°C, +800 bar reservoir pressure) has been engineered for the Morvin field development. The main challenge was to provide this fluid with sufficient stability so that it still was mobile when wells were backproduced after up to 4 weeks of subsequent well completion activities.
The main drivers for the development were the constraints that alternative fluid concepts pose under such conditions. Standard oil-based fluids weighted with barite, under the prevailing conditions up to 1.4 tons per cubic-meter of fluid, showed to be highly instable under simulated reservoir conditions. Barite settled out and deposited thick immobile mud bodies that were potentially completion damaging. Other fluid alternatives such as Cesium-formate weighted water-based suspension fluids were suspected to be incompatible with the selected oil-based reservoir drilling fluid.
Based on previous experiences with low solids (barite free) oil-based completion fluids (screen running and perforation fluids), a so-called "reduced solids oil-based completion fluid" was engineered in cooperation with the fluids contractor. The main features of the fluid were a close-to 50/50 oil-to-brine ratio, a Cesium-formate internal brine phase and fine barite to weigh up the fluid to approach the required weight. Several variations of this fluid were rigorously tested to evaluate stability and mobility of fluid sample samples.
The fluid has so far successfully been used on three completions. This paper reports in detail on the fluid development process, operational experiences and well-clean-up observations.
Reduction of Fines Migration by Nanofluids Injection, an Experimental Study
Authors: Habibi A. , Ahmadi M. , Pourafshary P. , Ayatollahi Sh. 
Published: June 2011

Abstract
Formation damage of the oil reservoirs because of fines migration is a major reason for productivity decline. Formation fines are defined as unconfined solid particles present in the pore spaces of the formations. Their migration because of fluids flow in the reservoir would cause pore plugging or permeability reduction. In the last three decades, many studies have been done for the characterization of fines and their migration effect on permeability reduction. There are many techniques in the industry to remediate the damage, especially near well bore regions.
Nanofluids that contain nanoparticles show specific properties such as high tendency for adsorption and good candidate for the injection into the near wellbore regions because of their very small sizes. In this paper, a packed column is utilized to study the use of different types of nanoparticles to reduce fines migration in synthetic porous materials. Three types of nanoparticles; MgO, SiO2 and Al2O3 are used here to investigate their effects on the fines movement. The results indicate that the fines could stick into the grains hindering their migration when the porous materials are already soaked with nanofluids. Besides, to check the mechanisms of this remediation technique, the effect of nanoparticle concentrations and fluid flow rates in the medium on the fines detachment was studied. A theoretical model was employed to calculate the total energy of interaction for the surfaces to check the experimental results, which was also validated by using SEM pictures for samples from the synthetic cores.
The results showed that the addition of 0.1 wt% of MgO and SiO2 nanoparticles would reduce the fines migration by 15% compared to the reference state. MgO nanoparticles were found to be more effective even at high fluid rates when it is used at higher concentration as it is noticed in the macroscopic and microscopic results.
New Analysis Tool to Assess the Need for Enhanced Pumping Technologies for FrackPacks
Authors: Bhamidipati Srikalyan , Karadkar Prasad , Fitzpatrick Harvey , Hailey Travis 
Published: June 2011

Abstract
When frac packing as a completion technique, long treating intervals or heterogeneous lithology within the intervals being treated have led to the use of various methods, equipment, and techniques for ensuring the complete treatment of the intervals. Shunt tubes attached to sand screens can provide an alternate path for fracpack slurry to flow past a bridge if it were to form in the borehole-screen annulus. A concentric annulus packing system using a specific design of perforated liner around the sand screens has also been used to successfully fracpack producing intervals that were thought to have a high risk of forming a bridge inside the borehole before all parts of the interval were properly treated (Lemesnager et al. 2008).
Though using these technologies has led to successful completions, it is less clear how to determine when the fracpack enhancing technologies are actually required. The use of any of the enhancing technologies will likely require some compromise to the flow area (reduction to inner diameter), complexity in installation, or risk to potential retrieval, and at least adds to the cost of the completion. Thus, some means of analyzing when the technologies are required is desirable. A new treatment design analysis software tool has been developed for estimating the amount of liquid leak-off which will occur to a screened-out fracture and corresponding annular bridge if such were to form in the upper (or upstream in the case of high deviation or horizontal wells) portion of a long-treating interval. By determining the amount of liquid leak-off from the slurry being pumped during a fracpack to a bridged-off fracture, a better estimation of the likelihood of successfully packing or fracpacking the remaining portion(s) of the interval with the resulting slurry can be made. Alternatively, by estimating the leak-off in advance with this design tool, we can modify the slurry design to account for the anticipated liquid loss (e.g., by increasing the ratio of liquid to proppant), thus enhancing the likelihood of success. With this new analysis tool, more reliable decisions can be made about the need for treatment-enhancing alternate path or concentric path screens.
Optimizing the Displacement Design - Mud to Brine
Authors: Javora Paul H. , Adkins Mike 
Published: June 2011

Abstract
Displacing drilling mud with clear solids-free completion brine is one of the most critical steps during well completion. Drilling deeper below the mudline (25,000+ feet) and exploring deeper water depths requires critical evaluation of conventional displacement methods and testing procedures and leads to a more rigorous displacement scenario.
Deep wells generally contain greater volumes of working fluid, larger diameter wellbores and drill strings, more feet of casing, and significantly increased surface area that require effective cleaning of mud residue and debris during the displacement process. Therefore, such wells typically require larger volumes of displacement spacers, enhanced pumping rates, and enhanced cleaning chemicals that tolerate substantial mud contamination while maintaining cleaning effectiveness. In order to properly design displacement spacer systems, these parameters must be incorporated into the evaluation and testing scenarios.
This paper describes methods and processes that incorporate the key wellbore parameters, including temperature and density requirements, into the displacement spacer system in order to define the size of spacers, amount of cleaning chemical included in each spacer, number of spacers required, and test methods used to validate the displacement design for the target well. Case histories illustrate how to design and execute an efficient and effective displacement job and the cost savings involved when a displacement system is properly developed.
Failure to complete properly the displacement process can lead to complications in subsequent completion and tool operations, and contribute to wellbore control issues. Furthermore, increased formation damage due to residual solids and time lost to resolve any issues can significantly increase the cost of the completion.
Remedial Sand-Control in Mature Field: Results & Lessons Learnt from through-Tubing Sand Screens Operations in the Gulf of Guinea
Authors: Poitrenaud H. , Djomou S. , Poumerol F. 
Published: June 2011

Abstract
The field in which took place the remedial intervention discussed in this article is located offshore West-Africa, in the gulf of Guinea. Oil is produced from unconsolidated sandstone formations of Miocene/Pliocene reservoirs. Currently, out of 360 wells drilled in the field, about 140 wells are still in production and nearly all of them are equipped with sand-control. Historically, the wells were completed as vertical or slightly deviated Internal Gravel-Packs (IGP), Open-Hole Gravel Pack (OHGP) with milled-windows or with Pre-Pack screens, then since 2001 as Frac-Pack and High Rate Water-Pack (HRWP).
With the first development dating back from 1978 (over 30 years of production) and 50% of the producing wells older than 20 years, this asset is clearly a mature field. Therefore, the durability of sand control systems has been dearly challenged and on some wells, failure of the sand-control has occurred before the production had been exhausted.
This paper will present several rig-less operations that have been performed for sand-control remediation in this mature offshore field environment and the results obtained.
We will first discuss possible scenarios of failure of the existing sand-control completions and then present the choices that have been made for the sand-control remediation, in particular the use of premium through-tubing sand screens with no gravel placement and the use of swell packers for the screen anchoring rather than mechanical devices.
We will then present the productivity and longevity achieved with such equipment and will demonstrate that even in some unorthodox cases, as can be often found in mature fields, remedial sand-control operations can still prove successful. Practical aspects that are important when considering such operations will also be covered.
Finally, recommendations and lessons-learnt derived from successes and failures will be presented.
On the gravitodynamics of moving bodies
Authors: Mol Anderson 
Published: June 2011

Abstract
In the present work we propose a generalization of Newton’s gravitational theory from the original works of Heaviside and Sciama, that takes into account both approaches, and accomplishes the same result in a simpler way than the standard cosmological approach. The established formulation describes the local gravitational field related to the observables and effectively implements the Mach’s principle in a quantitative form that retakes Dirac’s large number hypothesis. As a consequence of the equivalence principle and the application of this formulation to the observable universe, we obtain, as an immediate result, a value of Ω = 2. We construct a dynamic model for a galaxy without dark matter, which fits well with recent observational data, in terms of a variable effective inertial mass that reflects the present dynamic state of the universe and that replicates from first principles, the phenomenology proposed in MOND. The remarkable aspect of these results is the connection of the effect dubbed dark matter with the dark energy field, which makes it possible for us to interpret it as longitudinal gravitational waves.
Secondary carbonates in loess-paleosoil sequences: a general review
Authors: Barta Gabriella 
Published: June 2011

Abstract
The literature dealing with secondary carbonates in loess-paleosoil sequences is in many cases ambiguous, which means that different concepts are used for the same features, whereas certain concepts referring to different types are used as collective nouns. The aim of this study is to give a review on this nomenclature and to draw comparision between the various types and concepts. As a main guiding principle the article of Becze-Deák et al. (1997) is used, because it has formulated a proposition of a nomenclature which would be worthwhile to adopt. The terms and concepts introduced by their work are exact, referring to certain separated secondary carbonates and are of decisive importance with a view to paleoenvironmental reconstruction.
The research of secondary carbonates in loess-paleosoil sequences is of great importance, through providing detailed information on the paleoenvironment, especially on the former moisture conditions (including leaching processes). Secondary carbonates originate from the vertical, horizontal or in situ resettlement of carbonates during pedogenesis in the soil-sedimentary environment. Among others, calcified root cells, hypocoatings and needle-fiber calcite are classified into the microscale category, while concretions (e.g. loess dolls) belong to the macroscale types.
Efficacy of Trunk Balance Exercises for Individuals With Chronic Low Back Pain: A Randomized Clinical Trial
Authors: Gatti Roberto , Faccendini Simone , Tettamanti Andrea , Barbero Marco , Balestri Angela , Calori Giliola 
Published: June 2011

Study Design Randomized clinical trial. Objectives To determine the efficacy of trunk balance exercises for individuals with chronic low back pain. Background The majority of exercises focusing on restoring lumbopelvic stability propose targeting the feedforward control of the lumbopelvic region. Less attention has been paid to feedback control during balance adjustments. Methods Seventy-nine patients were randomly allocated to 2 different groups. The experimental group performed trunk balance exercises in addition to standard trunk flexibility exercises. The control group performed strengthening exercises in addition to the same standard trunk flexibility exercises. The primary outcome measures were pain intensity (visual analogue scale), disability (Roland-Morris Questionnaire), and quality of life (12-Item Short-Form Health Survey). Secondary outcomes were painful positions, use of analgesic drugs, and referred pain. Analysis of variance and relative risk were used to analyze the data for the primary and secondary outcome measures, respectively. The number of participants reaching the minimal clinically important difference in the 2 groups for each outcome measure was compared using relative risk. Results A significant difference in scores on the Roland-Morris Questionnaire (P = .011) and the physical component of the 12-Item Short-Form Health Survey (P = .048), and in the number of participants reaching the minimal clinically important difference for the Roland-Morris Questionnaire (relative risk, 1.79; 95% confidence interval [CI]: 1.05, 3.04) and the secondary outcome of painful positions (relative risk, 1.37; 95% CI: 1.03, 1.83) were found in favor of the experimental treatment. Conclusions Trunk balance exercises combined with flexibility exercises were found to be more effective than a combination of strength and flexibility exercises in reducing disability and improving the physical component of quality of life in patients with chronic low back pain. Level of Evidence Therapy, level 1b-. J Orthop Sports Phys Ther 2011;41(8):542–552. Epub 7 June 2011. doi:10.2519/jospt.2011.3413
An Exploration of the Relationship Between Back Muscle Endurance and Familial, Physical, Lifestyle, and Psychosocial Factors in Adolescents and Young Adults
Authors: Campbell Amity C. , Briggs Andrew M. , O'Sullivan Peter B. , Smith Anne J. , Burnett Angus F. , Moss Penny , Straker Leon M. 
Published: June 2011

Study Design Cross-sectional investigation. Objectives To explore the relationship between back muscle endurance (BME) and a range of familial, physical, lifestyle, and psychosocial variables in adolescents and young adults. Background There is evidence that low back pain interventions which focus on improved BME are effective. However, the mechanisms associated with BME performance in adolescents and young adults are largely unclear. In particular, the potential familial relationship between parents and their children remains unexplored. Methods This study utilized a subset of participants from the Joondalup Spinal Health Study cohort. One hundred nine children (47 boys, 62 girls) and 101 parents (39 fathers, 62 mothers) completed a series of physical, lifestyle, and psychosocial assessments. The univariable relationship between each covariate and BME was explored. Those found to have an association with child BME (P<.2) were included in an initial multivariable model and sequentially removed, until all remaining covariates were statistically significant (P<.05). Results Mothers' BME performance was related to children's performance, accounting for 14.4% of the variance in the children 's BME. Fathers’ BME performance had a similar, albeit nonsignificant effect. Children's sitting trunk angle, pain sensitivity, percent trunk fat, waist girth, and body mass index were associated with their BME performance, accounting for between 5.2% and 20.9% of BME. Conclusions The final multivariable model, including mother's BME, percent trunk fat, and sitting trunk angle, explained 28% of the variance in BME performance, suggesting that for successful BME intervention a range of multidimensional variables should be considered. J Orthop Sports Phys Ther 2011;41(7):486–495, Epub 7 June 2011. doi:10.2519/jospt.2011.3638
Total Number and Severity of Comorbidities Do Not Differ Based on Anatomical Region of Musculoskeletal Pain
Authors: Coronado Rogelio A. , Alappattu Meryl J. , Hart Dennis L. , George Steven Z. 
Published: June 2011

Study Design Secondary analysis, cross-sectional study. Objectives To (1) compare differences in individual comorbidity rates among patients with cervical, lumbar, and extremity pain complaints and (2) compare rates based on total number and severity in these same patient groups. Background Comorbidities can impact recovery, prognosis, and potentially hinder participation in rehabilitation. Few studies have compared comorbidity rates among patients with different anatomical region of pain, to determine whether specific screening is warranted in physical therapy settings. Methods Included in the analyses were 2375 patients who reported complete demographic, clinical, and comorbidity information using Patient Inquiry software. Comorbidity data were collected from the Functional Comorbidity Index (18 items) and 6 additional comorbidities, to assess the presence of medical disease across multiple body systems. Comorbidities were further classified as “nonsevere” or “severe,” based on inclusion in the Charlson Comorbidity Index. Chi-square analyses investigated differences in the rates of total number and severe comorbidities. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated on rates with statistically significant differences (P<.001), using the lumbar spine as the reference group. Results Of the 24 comorbid conditions included in this analysis, 3 nonsevere medical conditions (degenerative disc disease, obesity, and headache) had different rates among anatomical region. A lower rate for degenerative disc disease was associated with the extremity conditions (x2 = 66.3; OR = 0.40; 95% CI: 0.32, 0.50). Higher rate of headache (x2 = 115.3; OR = 3.01; 95% CI: 2.45, 3.70) and lower rate of obesity (x2 = 16.2; OR = 0.64; 95% CI: 0.51, 0.80) were associated with cervical conditions. There were no differences among the 3 anatomical regions for total number or severe comorbidities. Conclusions Focused screening for degenerative disc disease, obesity, and headache may be warranted. However, the same strategy was not supported for total number or severe comorbidities, at least when considering comparative rates from this cohort. Physical therapists should consider the potential influence of total number and severe comorbidities equally for all anatomical regions of musculoskeletal pain. Level of Evidence Differential diagnosis/symptom prevalence, level 3b. J Orthop Sports Phys Ther 2011;41(7):477–485, Epub 7 June 2011. doi:10.2519/jospt.2011.3686
The stylistic role of the anticipatory genitive construction in sumerian literature
Authors: Haber Esther 
Published: June 2011

Résumé La construction génitivale inversée est assurément une construction morpho-syntaxique sumérienne originale; elle dérive de la construction génitivale standard et est employée comme outil stylistique dans la littérature. La construction génitivale inversée constitue un outil particulier pour mettre l’accent sur le nom régi, en le déplaçant au début de la construction génitivale. Une des fonctions stylistiques les plus significatives du génitif inverse est la singularisation d’un ou de plusieurs mots clés à l’intérieur d’une composition littéraire, en le(s) plaçant au début de la phrase. Un examen des textes sumériens littéraires montre que ce phénomène, à la fois grammatical et stylistique, est largement répandu. Dans ces compositions, le mot-clé apparaît souvent au début de la phrase, qu’il soit sujet, objet ou mot régi, et cela en dépit de l’ordre des mots habituel en sumérien.