bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pentavalent Rotavirus Vaccine in Developing Countries: Safety and Health Care Resource Utilization
Authors: Christie Celia D. C. , Duncan Newton D. , Thame Kirk A. , Onorato Matthew T. , Smith Hyacinth D. , Malcolm Lavern G. , Itzler Robbin F. , DiNubile Mark J. , Heaton Penny M. 
Published: November 2010

OBJECTIVE:
In the international, placebo-controlled, Rotavirus Efficacy and Safety Trial, the pentavalent rotavirus vaccine reduced the rate of rotavirus-attributable hospitalizations and emergency department visits by 95%. This study investigated the effect in Jamaica.

METHODS:
The vaccine effect on rates of hospitalizations and emergency department visits in Jamaica was evaluated in both modified intention-to-treat and per-protocol analyses. Rates of serious adverse events, including intussusception, also were compared between groups.

RESULTS:
A total of 1804 Jamaican infants, 6 to 12 weeks of age at entry and primarily from low/middle-income families of African heritage, received ≥1 dose. During the first year after dose 1, there were 2 and 11 hospitalizations or emergency department visits attributable to rotavirus gastroenteritis involving any serotype among 831 evaluable vaccine recipients and 809 evaluable placebo recipients, respectively (rate reduction: 82.2% [95% confidence interval: 15.1%–98.0%]). In the per-protocol analysis, all 8 G1 to G4 rotavirus-attributable events that occurred ≥2 weeks after dose 3 were in the placebo group (rate reduction: 100% [95% confidence interval: 40.9%–100%]). Of the 1802 subjects included in the safety analyses, intussusception was confirmed for 1 vaccine recipient (115 days after the third dose) and 3 placebo recipients. One vaccine recipient and 3 placebo recipients died during the follow-up period, but none of the deaths was considered to be vaccine-related.

CONCLUSIONS:
In this posthoc subgroup analysis, the vaccine reduced health care resource utilization attributable to rotavirus gastroenteritis, without increased risk of intussusception or other serious adverse events, among infants in a resource-limited country.
Developing Culturally Responsive Approaches With Southeast Asian American Families Experiencing Developmental Disabilities
Authors: Baker Dian L. , Miller Elizabeth , Dang Michelle T. , Yaangh Chiem-Seng , Hansen Robin L. 
Published: December 2010

OBJECTIVE:
Southeast Asian American families are underrepresented among recipients of special education and social services for people with developmental disabilities. Our aims were to use a community-based participatory research approach to examine Hmong and Mien families' perceptions of developmental disabilities and understand barriers to and facilitators of service provision among families experiencing developmental disabilities. We describe here a case study of a successful attempt to engage marginalized and underserved communities to understand their needs to improve access and services for persons with developmental disabilities.

METHODS:
We conducted 2 focus groups with 11 key informants and 1 focus group with 10 family members of persons with developmental disabilities, as well as in-depth interviews with 3 shamans. Using a thematic analysis approach, we coded notes and transcripts to assess community members' understanding of developmental disabilities, experiences negotiating educational and health care systems, and barriers to high-quality care.

RESULTS:
A predominant theme was the perception that reliance on governmental support services is not appropriate. Common barriers identified included lack of accurate information, language difficulties, lack of trust, and limited outreach. These perceptions and barriers, combined with limited access to services, interfere with community acceptance and use of available support services. Despite these barriers, participants indicated that with education, outreach, and culturally responsive support, families would likely accept services.

CONCLUSIONS:
Community-based participatory methods are effective for eliciting root causes of health inequities in marginalized communities. Outreach to community-based organizations and an inclusive research practice identified social and cultural reasons for low service uptake and provided a pathway for the community to improve services for persons with developmental disabilities.
Joint Updating of Petrophysical Properties and Discrete Facies Variables From Assimilating Production Data Using the EnKF
Authors: Agbalaka Chinedu C. , Oliver Dean S. 
Published: November 2010

Summary
The ensemble Kalman filter (EnKF), is a sequential data-assimilation technique that has been shown to work quite well in obtaining conditional facies models from assimilating production data. Because the problem of history matching geological facies is quite complex, most efforts at solving this problem typically assume that facies properties are constant and spatially homogeneous. In this paper, we propose a method for updating both the categorical facies variables and the spatially heterogeneous and nonuniform properties of the facies in a consistent manner within the EnKF framework. Tests of our proposed approach on two representative examples with different features of nonstationarity resulted in satisfactory history-match solutions and geologically consistent estimates of the nonuniform and heterogeneous petrophysical properties.
Sixty Days Ahead of Schedule: Reducing Drilling Risk at Valhall Using Computational Geomechanics
Authors: Kristiansen Tron Golder , Flatebø Roar Egil 
Published: November 2010

Summary
The Valhall field is an overpressured, undersaturated Upper Cretaceous chalk reservoir located in the Norwegian sector of the North Sea. The reservoirs consist of weak chalk. The weak chalk results in significant reservoir compaction, exceeding 10 m in places, and corresponding seafloor subsidence, exceeding 6 m above the center of the field. Previous papers have documented the increasing drilling challenges in the shale overburden at Valhall because of the subsidence. This paper presents the computational-geomechanics technology developed and implemented to assist drilling into the highly depleted and compacted crest from the new water-injection platform at Valhall. The work focuses on handling the stress changes occurring in the overburden above a compacting reservoir and not the more traditional situation associated with depletion-induced fracture-gradient changes in the reservoir itself. The technology is based on a history-matched full-field finite-element-based geomechanics model to calculate stresses, strains, and displacements. The results are exported from the finite-element model (FEM) to a geological modeling software to perform wellbore-stability calculations using BP best practices for prediction of wellbore stability. In this environment, one can also easily use as supporting data 4D seismic from the permanent life-of-field seismic array at Valhall. By calculating the operational mud-weight window over a high risk interval in the overburden, a good correlation to historical nonproductive time (NPT) was found. The methodology is used in detailed well planning where moving the well 50 m in one direction is the difference between problem-free drilling or huge drilling challenges. The paper presents the first application of this technology on a new water injector delivered 60 days ahead of schedule with reduced costs of approximately USD 20 million and with avoidance of a potential "train wreck" that could have cost USD 60 million.
Petrophysical Analysis Method to Identify "Sweet Spots" in Tight Reservoirs: Case Study From Punta Rosada Formation in Neuquen Basin, Argentina
Authors: Naides C. 
Published: December 2010

Abstract
One of today challenges to increase reserves and gas production in Argentina is to develop low permeability reservoirs, with particular characteristics regarding reservoirs considered as conventional.
Therefore assessment and characterization of tight gas reservoirs should be conducted differently from conventional reservoirs, adapting data acquisition, processing and interpretation to these low permeability reservoirs.
In a tight gas field operated by Petrobras in the Neuquen basin, an adapted methodology is implemented for analysis and integration of data in order to identify the best areas of the reservoir, called "sweet spots", to assess their potential and optimize completion programs.
The field has 7 wells with data acquired from the 70's to recent days. Petrophysical analyses on rock samples are scarce and unrepresentative related to the total sand thickness of Punta Rosada Formation, and were conducted with an inappropriate methodology for this type of reservoir. The set of logs shows strong variation both in used technology and in the acquisition.
Thus in new wells it has been decided to acquire new logs and rock samples in order to characterize these tight gas reservoirs with an adapted methodology allowing the identification of the "sweet spots".
This paper shows the results obtained with this methodology that uses information from petrophysical laboratory analysis and well-logs (including conventional logs, image logs and NMR). This "tight gas" methodology is based on the integration among capillaries pressures with NMR logs and interpreted data from conventional logs. Finally, to validate this petrophysical characterization, the rock types obtained with the new methodology are compared with the results of production tests and PLT logs.
Impact of Organic Acids/Chelating Agents on the Rheological Properties of an Amidoamine-Oxide Surfactant
Authors: Li Lingling , Nasr-El-Din Hisham A. , Crews James B. , Cawiezel Kay E. 
Published: November 2010

Summary
Surfactant-based acids have been used for diversion because they are less damaging to the formation. Amphoteric viscoelastic surfactant (VES) is the main type of surfactant being used today. Low viscosity is observed in the live-acid systems, whereas significantly increased viscosity is found when HCl reacts with carbonate and generates divalent salts. The surfactant/acid system can be broken after acid treatments by mixing with reservoir hydrocarbons, or by using an external or internal breaker.
Amidoamine oxide, an amphoteric surfactant, was examined in this work. The prepared surfactant-based live-acid system contained 20 wt% HCl, 4 wt% surfactant, and 1 wt% corrosion inhibitor. Different organic acids/chelating agents were added to live and spent acids. Calcium carbonate particles were used to neutralize live acids. The objective was to examine how these organic acids/chelating agents affected the rheological properties of spent-acid systems. Measurements were made at temperatures from 75 to 200°F at a shear rate of 10 sec–1 and a pressure of 300 psi. Several simple organic acids (formic, acetic, propionic, and butyric) and chelating agents [glycolic acid, lactic acid, gluconic acid, citric acid, tetrasodium ethylenediamine tetraacetic acid (EDTA), tetrasodium L-glutamic acid, N, N-diacetic acid (GLDA), and disodium L-glutamic acid, N, N-diacetic acid (HEIDA)] that are used in the field were examined.
Experimental results indicated that the addition of simple organic acids or chelating agents reduced the viscosity of spent acids significantly. This reduction in viscosity increased with the number of carbon atoms in the organic acid. The addition of organic acids reduced the temperature range in which the surfactant can be used. Chelating agents (α-hydroxy carboxylic acids and amino carboxylic acids) also tended to break the surfactant gel if enough chelant was used. On the basis of the results obtained, organic acids can be used to break surfactant gel. Transmission electron microscopy (TEM) tests were first conducted to examine how organic acids/chelating agents interfered with the formation of rod-like micelles in the surfactant-based acid. The results showed that the addition of organic acids to the spent acid generated a fewer elongated micelles and resulted in less apparent viscosity. In addition, if chelating agents or simple organic acids are used, then the concentration of the surfactant should be increased to compensate for the loss of viscosity induced by the addition of the organic acids.
New Insights Into Polymer Rheology in Porous Media
Authors: Seright R.S.. S. , Fan Tianguang , Wavrik Kathryn , de Carvalho Balaban Rosangela 
Published: November 2010

Summary
This paper clarifies the rheology of xanthan and partially hydrolyzed polyacrylamide (HPAM) solutions in porous media, especially at low velocities. Previous literature reported resistance factors (effective viscosities in porous media) and an apparent shear thinning at low fluxes that were noticeably greater than what is expected on the basis of viscosity measurements. The polymer component that causes the latter behavior is shown to propagate quite slowly and generally will not penetrate deep into a formation. Particularly for HPAM solutions, this behavior can be reduced or eliminated for solutions that experience mechanical degradation or flow through a few feet of porous rock. Under practical conditions where HPAM is used for enhanced oil recovery (EOR), the degree of shear thinning is slight or nonexistent, especially compared to the level of shear thickening that occurs at high fluxes.
Two Novel Multistage Fracturing Processes for Unconventional Reservoirs: Unique Approach for Branch-Fracturing Stimulation
Authors: Stanojcic M. , Rispler K. 
Published: December 2010

Abstract
Shales, tight-gas reservoirs, and coal beds are the main sources of what are generally known as unconventional oil and gas reservoirs. Unconventional oil and gas are now a core business of many large, independent producers and a growing number of major operating companies. The reservoirs are becoming more complex and well designs are becoming more complicated and costly. The need to develop and commercialize new, more effective wellsite technologies that can help meet the increasing demand for energy, despite the dwindling domestic resource base, has been pursued by many operators. A number of unique technologies and methods have been developed to help operators produce unconventional oil and gas profitably. The objective of this work was to assess each existing stimulation technology and seek ways of combining the best available capabilities into a new stimulation technique capable of setting a new level of multizone-stimulation efficiency and effectiveness. The successful development and exploitation of unconventional reservoirs has relied on innovative technologies, such as horizontal drilling, multistage completions, modern multistage fracturing, and fracture mapping to pursue economic completions. Simulations demonstrate that shale reservoirs with ultralow permeability require an interconnected fracture network of moderate conductivity (branch fractures) with a relatively small spacing between fractures to obtain reasonable recovery factors. In this paper, two new methods and two existing methods for a wide variety of unconventional-reservoir applications are presented, to include: Fracturing preperforated, cemented horizontal liners, and isolating intervals with straddle packers. (The straddle-packer method has advantages that include the opportunity to fracture stimulate a large number of closely spaced, preperforated intervals in a horizontal well.)Hydrajet perforating with annular path (HPAP) fracturing with a more efficient method of providing sand-plug diversion. (A new BHA increases efficiencies of current application of this technique.)Using the HPAP method for high-rate, slickwater techniques. (Using the HPAP method for high-rate, slickwater- fracturing treatments can improve the effectiveness of unconventional-reservoir stimulation.)Fracturing using a method of mechanically shifted sleeves that use an unconventional approach to interval sequence to maximize fracture-network complexity.An overview of a newly developed hybrid rig that can extend reach and improve efficiencies for all of the above methods using both jointed and coiled tubing (CT).
The Influence of the Production Lines Pressure Drop in the Definition of the Oilfield Drainage Strategy
Authors: Bento Débora F. , Schiozer Denis J. 
Published: December 2010

Abstract
The success of an oil field drainage project depends on the production strategy, defined by an optimization process that maximizes the project Net Present Value (NPV). Considering the complexity of the process, the industry tends to simplify the numerical simulations used, mainly by separating behaviour analysis of the reservoir and production facilities. The pressure drop in the production facilities, for instance, is not generally considered in the selection of number and position of the wells. The main objective of this work is to verify if these simplifications have significant influence on the final result of the production strategy selection process. For this purpose, three studies have been done, with different operational conditions and fluid types. For each case, two production optimization processes of an oil field drainage project have been made, considering a simplified and a dynamic pressure drop calculation. The simplified pressure drop analysis consists in a bottom-hole pressure definition that allows the fluid to rise to the platform. In the dynamic option, it is necessary to define the production line geometry and the fluid conditions to calculate the bottom-hole pressure for each configuration, and the pressure drop is calculated dynamically, at each time step. With the result of both processes, the number and position of wells and performance of the optimized production strategies were compared. Significant differences were observed in the two cases tested, showing that the pressure drop influences the definition of the production strategy, although this influence should be minimized by operational conditions. It was also observed that the greater influence occurs on the heavy oil reservoir and that the locations are more influenced by the reservoir particularities.
A Finite-Mixture Approach for Drilling Optimization Using Formation Density Information
Authors: Li Gang , Bai Mao 
Published: December 2010

Abstract
Understanding formation strength and its mechanical properties has become increasingly important with continued development of horizontal/directional oil-and-gas well drilling and with more wells being drilled in locations under complicated geological conditions. Well coring is typically only carried out at certain depths of interest and is generally considered to be expensive and time consuming. In practice, sonic measurements are always used to estimate mechanical properties of formations, which are then adopted for further drilling or completion analysis. However, in many cases, sonic data may not be available while only formation density logs exist. Therefore, in this study, we first investigate correlations between density and sonic logs under different circumstances, and a best practice for estimating formation velocity based on density log is recommended for various areas.
A finite-mixture procedure considering various factors, such as porosity, clay volume, and pore pressure, is adopted to develop formation strength and mechanical properties. A new approach for drilling optimization using formation density information is developed. The new finite-mixture procedure illustrates a great improvement in describing correlations between velocity and density. As a result of an example of drilling optimization analysis, by considering the influence of GR as a lithology indicator, we can greatly improve the accuracy of our geomechanical analysis in different geological conditions.
The solution can lead to significant improvements in mechanical behavior prediction for drilling and completion, especially when only density logs exist. The same procedure could also be applied to other rock property-related logs.
Mercury Removal Process is Applied to Crude Oil of Southern Argentina
Authors: Salvá C. , Gallup D. 
Published: December 2010

Abstract
The presence of elemental mercury and mercury compounds has been reported in some produced hydrocarbons from southern fields in South America.
Although mercury removal from natural gas is a common industrial practice, that is not the case for crude oil. Mercury is a trace contaminant that is known to have severe associated problems in the petroleum industry, whose consequences may have impact on both environmental and facilities integrity/safety with undesirable costs.
Petrobras Argentina has worked in a mercury removal project that has been implemented with success. The process treatment is being applied to crude oil from E&P Petrobras Argentina concessions areas. As a result, a purified oil with much lower mercury concentration is achieved. Crude oil having acceptable mercury content is now commercialized in the market, with no restrictions.
Long Horizontal Gravel Pack With the Lightest Gravel Ever Used
Authors: Trujillo H. , Tengono J. A. , Hernández A. , Castaño R. , Ortiz E. , Charry W. , Anaya L. A. , Portela F. , Castillo R. , López M. , Calderón C. 
Published: December 2010

Abstract
Hocol Colombia operates in Ocelote field at the eastern part of Colombia, a land called as Llanos Orientales (Eastern Plains). In this field Hocol produced from Carbonera formation observing problems with formation deconsolidation. Normally, gravel packs jobs are performed on vertical wells with sustained good results.
However, new reservoir studies showed that horizontal wells with regular length extension (around 1000 ft) would be more profitable for this field. In order to get this objectives, Hocol design a horizontal wells Program to drill and test alternatives to get good completion of these wells. The first well was completed and gravel packed using conventional technologies and a 35% of pack efficiency was achieved.
The objective for the second well was to get at least 75% of packing efficiency. In a synergetic team effort, service companies proposed operator company new technologies that are used in other places but never were applied in Colombia. After simulations and technical meetings, the Operator decided to test two new technologies to try to get their operative and technical objective.
This paper presents the technical and operative fundamental used to support these changes and the results obtained with theses applications.