bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemomechanics with molecular force probes
Authors: Huang Zhen , Boulatov Roman
Published: March 2010

Chemomechanics is an emerging area at the interface of chemistry, materials science, physics, and biology that aims at quantitative understanding of reaction dynamics in multiscale phenomena. These are characterized by correlated directional motion at multiple length scales—from molecular to macroscopic. Examples include reactions in stressed materials, in shear flows, and at propagating interfaces, the operation of motor proteins, ion pumps, and actuating polymers, and mechanosensing. To explain the up to 1015-fold variations in reaction rates in multiscale phenomena—which are incompatible within the standard models of chemical kinetics—chemomechanics relies on the concept of molecular restoring force. Molecular force probes are inert molecules that allow incremental variations in restoring forces of diverse reactive moieties over hundreds of piconewtons (pN). Extending beyond the classical studies of reactions of strained molecules, molecular force probes enable experimental explorations of how reaction rates and restoring forces are related. In this review, we will describe the utility of one such probe—stiff stilbene. Various reactive moieties were incorporated in inert linkers that constrained stiff stilbene to highly strained macrocycles. Such series provided the first direct experimental validation of the most popular chemomechanical model, demonstrated its predictive capabilities, and illustrated the diversity of relationships between reaction rates and forces.
Applied Restorative Justice as a Complement to Systemic Family Therapy: Theory and Practice Implications for Families Experiencing Intra‐Familial Adolescent Sibling Incest
Authors: McNevin Elizabeth
Published: March 2010

This article considers the impact on and therapeutic responses to families where there has been intra‐familial sexual assault (IFSA) by an adolescent member of the family against another younger member of the family. In doing so, the article will specifically highlight the nexus between systemic family therapy ideas and an applied restorative justice response in the form of Youth Justice Conferencing (YJC), as experienced through working as a family therapist in the area of adolescent sexual offending.
The Effect of Task-Specific Self-Efficacy on Stages of Change of People With Substance Abuse Problems
Authors: Cardoso Elizabeth Da Silva , Chou Chih Chin , Yasui Naoko Yura , Chronister Julie , Chan Fong , Lyons Valerie , Muller Veronica R.
Published: March 2010

The objective of the study was to determine the effect of task-specific self-efficacy on stages of readiness for change among people with substance abuse problems. Participants were 140 men and 33 women with substance abuse problems receiving services in outpatient therapeutic community service programs. The Stages of Change Scale-Substance Abuse (SCS-SA) was the outcome measure. People with substance abuse problems receiving outpatient treatment services can be meaningfully classified into four stages of change groups: (1) Precontemplation, (2) Inactive, (3) Ambivalent-Conforming, and (4) Participation. Readiness for change is related to self-efficacy in work-related skills and risk-avoidance skills. Task-specific self-efficacy is related to stages of change. The findings of this study suggested that providing skill training to enhance task specific self-efficacy can help people with substance abuse problems progress from lower level to higher level of stages of change.
On the occurrence of the Neotropical Otter (Lontra longicaudis) (Mammalia, Mustelidae) in Northeastern Brazil
Authors: Astúa Diego , Asfora Paulo H. , Aléssio Filipe M. , Langguth Alfredo
Published: March 2010

No abstract available
Evaluating the Optimal City in South China for New Medical Facilities: The Application Modified Porter’s Diamond Framework
Authors: Lin Chin-Tsai , Tsai Meng-Chuan
Published: March 2010

This study presents the methods for modeling optimal city selection for new medical facilities in South China. This study has the objective of identifying the key criteria determining the relative advantages of different cities as a location for a new medical facility to help optimize the location of such facilities. The optimal city depends on various complex and interdependent criteria from the perspective of investors and managers. The weights of the multi-interrelationships criteria are assessed using the analytic network process (ANP) technique. Then, the values obtained for each city are determined using the technique for order preference by similarity to ideal solution utilizing the weights from ANP. Finally, Shenzhen was identified as the best city for a new facility.
Bayesian Inference of Genetic Parameters Based on Conditional Decompositions of Multivariate Normal Distributions
Authors: Hallander Jon , Waldmann Patrik , Wang Chunkao , Sillanpää Mikko J
Published: March 2010

It is widely recognized that the mixed linear model is an important tool for parameter estimation in the analysis of complex pedigrees, which includes both pedigree and genomic information, and where mutually dependent genetic factors are often assumed to follow multivariate normal distributions of high dimension. We have developed a Bayesian statistical method based on the decomposition of the multivariate normal prior distribution into products of conditional univariate distributions. This procedure permits computationally demanding genetic evaluations of complex pedigrees, within the user-friendly computer package WinBUGS. To demonstrate and evaluate the flexibility of the method, we analyzed two example pedigrees: a large noninbred pedigree of Scots pine (Pinus sylvestris L.) that includes additive and dominance polygenic relationships and a simulated pedigree where genomic relationships have been calculated on the basis of a dense marker map. The analysis showed that our method was fast and provided accurate estimates and that it should therefore be a helpful tool for estimating genetic parameters of complex pedigrees quickly and reliably.
Critical Determinants for Chromatin Binding by Saccharomyces cerevisiae Yng1 Exist Outside of the Plant Homeodomain Finger
Authors: Chruscicki Adam , MacDonald Vicki E , Young Barry P , Loewen Christopher J R , Howe LeAnn J
Published: March 2010

The temporal and spatial regulation of histone post-translational modifications is essential for proper chromatin structure and function. The Saccharomyces cerevisiae NuA3 histone acetyltransferase complex modifies the amino-terminal tail of histone H3, but how NuA3 is targeted to specific regions of the genome is not fully understood. Yng1, a subunit of NuA3 and a member of the Inhibitor of Growth (ING) protein family, is required for the interaction of NuA3 with chromatin. This protein contains a C-terminal plant homeodomain (PHD) finger that specifically interacts with lysine 4-trimethylated histone H3 (H3K4me3) in vitro. This initially suggested that NuA3 is targeted to regions bearing the H3K4me3 mark; however, deletion of the Yng1 PHD finger does not disrupt the interaction of NuA3 with chromatin or result in a phenotype consistent with loss of NuA3 function in vivo. In this study, we uncovered the molecular basis for the discrepancies in these data. We present both genetic and biochemical evidence that full-length Yng1 has two independent histone-binding motifs: an amino-terminal motif that binds unmodified H3 tails and a carboxyl-terminal PHD finger that specifically recognizes H3K4me3. Although these motifs can bind histones independently, together they increase the apparent association of Yng1 for the H3 tail.
The Experiences of Children Enrolled in Pediatric Oncology Research: Implications for Assent
Authors: Unguru Yoram , Sill Anne M. , Kamani Naynesh
Published: March 2010

BACKGROUND:

Most children with cancer enroll in clinical research trials. Whenever possible, children must provide their assent before enrolling in research studies. We studied what children aged 7 to 18 with cancer understand about research, their research-related treatment, and their preferences for inclusion in decision-making.

PROCEDURE:

Thirty-seven face-to-face, audiorecorded interviews using a novel, semi-structured tool, the quality-of-assent instrument, were conducted. Exploratory univariate and bivariate analyses of the quantitative data elucidated patterns and trends of understanding and preferences.

RESULTS:

Nineteen of the 37 children (51%) did not know or recall that their treatment was considered research, and 19 of 22 (86%) did not understand their doctor when he or she discussed the trial. More children enrolled in trials to help future children with cancer (27 of 37 [73%]), than to get better personally (22 of 37 [60%]). Irrespective of age, children with Hodgkin's disease, germ-cell tumors, and leukemia had significantly greater research awareness and appreciation than children with other cancers (P = .019 and P < .001, respectively). Although all children wanted to be involved in decision-making, 18 of 37 (49%) did not have or recall having a role in deciding to enroll in their trial, and 14 of 37 (38%) did not feel free to dissent to trial enrollment. Only 4 of 37 children (11%) discussed increased decision-making roles with parents, and only 7 of 37 (19%) discussed them with their doctors.

CONCLUSIONS:

Most children have limited understanding of research despite physicians' explanations. Many children reported that they feel minimally involved in the decision to enroll in clinical trials. Tools to assist investigators ascertain that children understand what they are agreeing to when they assent to research and to determine their preferences for inclusion in research may help make assent more meaningful.
Changes in Neonatal Transfusion Practice After Dissemination of Neonatal Recommendations
Authors: Motta Mario , Testa Marcella , Tripodi Gino , Radicioni Maurizio
Published: March 2010

OBJECTIVE:

To evaluate the change in neonatal transfusion practices after the introduction of national recommendations for transfusion of blood products to neonates in 2006.

METHODS:

A questionnaire-based survey on neonatal transfusion practice of 79 Italian NICUs was completed in 2008. Results were compared with those obtained from a previous national Italian neonatal transfusion-practice survey performed in 2001.

RESULTS:

Responses were received from 62 of 79 (78.5%) neonatal units. Prophylaxis for transfusion-transmitted cytomegalovirus infection in 2001 and 2008 had been performed in 96.8% and 98.4% of NICUs, respectively. Filter leukoreduction of red blood cell donor units was preferred over cytomegalovirus antibody testing to obtain cytomegalovirus-safe blood components. Prophylaxis for graft-versus-host disease increased from being performed at 61.3% of neonatal units in 2001 to 77.4% in 2008 (P = .08, Pearson χ2), whereas usage of dedicated red blood cell donor units (paedipack system), permitting multiple transfusions from the same unit, improved from 53.2% to 82.2% (P = .001, Pearson χ2). The 2008 survey documented a continuation of wide variability in transfusion practice for fresh-frozen plasma and platelet concentrates.

CONCLUSIONS:

This nation-wide Italian self-report survey highlighted improvements in NICU transfusion practice after the neonatal recommendations issued in 2006. Prophylaxis for transfusion-transmitted cytomegalovirus infection continued with nearly total adherence to national recommendations, and both prophylaxis for graft-versus-host disease and paedipack-system usage suggested a trend of improvement of adherence rates. The continuing wide diversity observed among neonatal units in fresh-frozen plasma and platelet-concentrate transfusion practice may indicate a lack of acceptable criteria for the administration of these blood products.
Emergency Information Forms and Emergency Preparedness for Children With Special Health Care Needs
Authors:   American Academy of Pediatrics,   Committee on Pediatric Emergency Medicine and Council on Clinical Information Technology,   American College of Emergency Physicians,   Pediatric Emergency Medicine Committee
Published: March 2010

This Policy Statement was revised. See https://doi.org/10.1542/peds.2022-060970.

Children with chronic medical conditions rely on complex management plans for problems that cause them to be at increased risk for suboptimal outcomes in emergency situations. The emergency information form (EIF) is a medical summary that describes medical condition(s), medications, and special health care needs to inform health care providers of a child's special health conditions and needs so that optimal emergency medical care can be provided. This statement describes updates to EIFs, including computerization of the EIF, expanding the potential benefits of the EIF, quality-improvement programs using the EIF, the EIF as a central repository, and facilitating emergency preparedness in disaster management and drills by using the EIF.
Health Equity and Children's Rights
Authors:   Council on Community Pediatrics and Committee on Native American Child Health
Published: March 2010

Many children in the United States fail to reach their full health and developmental potential. Disparities in their health and well-being result from the complex interplay of multiple social and environmental determinants that are not adequately addressed by current standards of pediatric practice or public policy. Integrating the principles and practice of child health equity—children's rights, social justice, human capital investment, and health equity ethics—into pediatrics will address the root causes of child health disparities.

Promoting the principles and practice of equity-based clinical care, child advocacy, and child- and family-centered public policy will help to ensure that social and environmental determinants contribute positively to the health and well-being of children. The American Academy of Pediatrics and pediatricians can move the national focus from documenting child health disparities to advancing the principles and practice of child health equity and, in so doing, influence the worldwide practice of pediatrics and child health. All pediatricians, including primary care practitioners and medical and surgical subspecialists, can incorporate these principles into their practice of pediatrics and child health. Integration of these principles into competency-based training and board certification will secure their assimilation into all levels of pediatric practice.
Analysis of lateral root growth in Arabidopsis in response to physiologically active auxin analogues
Authors: Novickienė L. , Gavelienė V. , Miliuvienė L. , Kazlauskienė D. , Pakalniškytė L.
Published: March 2010

The aim of this work was to investigate the formation and development of lateral roots in model trials onArabidopsis thalianaL. Heynh wild type (Col-0), thealf4-1mutant and its allele by applying the physiologically active auxin analogues IBA, IAA, TA-12 and TA-14.Differences were observed between thealf4-1mutant and its allele phenotype in the formation of lateral roots. The application of auxin analogues was unable to restore the formation of lateral roots in thealf4-1mutant. In some cases, under the impact of IBA (1 μM), a cluster of xylem cells was activated in the pericycle of the primary roots and lateral root primordia were formed. The auxin analogues induced the growth of primary roots in thealf4-1allele and the formation and growth of lateral roots. The impact of IBA (1 μM), TA-12 (1 mM) and IAA (1 μM) was particularly evident. The intense formation of lateral roots under the impact of IBA and TA-12 could be related with the ability of these compounds to intensify mitotic activity in the apical meristem cells of the lateral roots. New data were obtained, showing that IBA and other physiologically active auxin analogues can modify the root system architecture of the test-plantArabidopsis.
Dihaploid induction ability of three clones of Solanum phureja (2n = 2x = 24) in interploidy cross with S. tuberosum (2n = 4x = 48)
Authors: Panahandeh J.
Published: March 2010

Potato,Solanum tuberosumL. (2n = 4x = 48), is an autotetraploid species, the breeding of which at the tetraploid level is complicated by tetrasomic inheritance. Dihaploids (2n = 2x = 24) from the tetraploid cultivated potato have great potential for breeding and genetic studies. The common method deployed to obtain potato dihaploids is to make interspecific-interploidy (4x × 2x) crosses between a tetraploid seed parent and special clones from the diploidS. phurejaas pollinator. Pollinators carrying a marker gene have been used, but unfortunately, these clones were very weak, with rare flowering and low male fertility under the given conditions. To find a suitable pollinator, three clones were selected fromS. phurejabased on flowering, pollen shed and male fertility and were crossed with five cultivated tetraploid potatoes to evaluate their dihaploid induction ability. A total of 1529 interploidy crosses were made, resulting in 1116 berries and 1456 seeds. The progeny were divided into two groups based on stem, flower and tuber colour: hybrids and non-hybrids (putative dihaploids). Chromosome counting in non-hybrid genotypes detected 39 dihaploids. The clonephu 3and cv. Picasso, with 12.1 and 10.7 dihaploids per 100 berries, respectively, were the best dihaploid inducer and seed parent for dihaploid production.
New influenza virus (H1N1) related pneumonia with fatal outcome
Authors: Bidiga László , Asztalos László , Fülep Zoltán , Fülesdi Béla , Méhes Gábor
Published: March 2010

A H1N1-influenzavírus-fertőzéssel kapcsolatban a legsúlyosabb szövődményként a víruspneumoniát, illetve az ehhez társuló másodlagos fertőzéseket szokás emlegetni. A fatális kimenetelű esetekben a halált progresszív légzési elégtelenség okozza. Egyes, laboratóriumban igazolt H1N1-fertőzött esetekben ugyanakkor nem lehet egyértelműen tüdőgyulladást megállapítani, ilyenkor az amúgy elesett beteg kórlefolyásában a H1N1-fertőzés szerepe is tisztázatlan marad. Ismertetőnkben egy súlyos, veseelégtelenség miatt kezelés alatt álló beteg H1N1-fertőzés asszociált, szervülő pneumoniáját mutatjuk be, mely típusosnak tartható. A vírusfertőzés szövődményeinek igazolása nélkül a járvány epidemológiai és halálozási kimutatásai is torzulhatnak.
Prognostic and Predictive Biomarkers in Resected Colon Cancer: Current Status and Future Perspectives for Integrating Genomics into Biomarker Discovery
Authors: Tejpar Sabine , Bertagnolli Monica , Bosman Fred , Lenz Heinz-Joseph , Garraway Levi , Waldman Frederic , Warren Robert , Bild Andrea , Collins-Brennan Denise , Hahn Hejin , Harkin D. Paul , Kennedy Richard , Ilyas Mohammad , Morreau Hans , Proutski Vitali , Swanton Charles , Tomlinson Ian , Delorenzi Mauro , Fiocca Roberto , Van Cutsem Eric , Roth Arnaud
Published: March 2010

The number of agents that are potentially effective in the adjuvant treatment of locally advanced resectable colon cancer is increasing. Consequently, it is important to ascertain which subgroups of patients will benefit from a specific treatment. Despite more than two decades of research into the molecular genetics of colon cancer, there is a lack of prognostic and predictive molecular biomarkers with proven utility in this setting. A secondary objective of the Pan European Trials in Adjuvant Colon Cancer-3 trial, which compared irinotecan in combination with 5-fluorouracil and leucovorin in the postoperative treatment of stage III and stage II colon cancer patients, was to undertake a translational research study to assess a panel of putative prognostic and predictive markers in a large colon cancer patient cohort. The Cancer and Leukemia Group B 89803 trial, in a similar design, also investigated the use of prognostic and predictive biomarkers in this setting. In this article, the authors, who are coinvestigators from these trials and performed similar investigations of biomarker discovery in the adjuvant treatment of colon cancer, review the current status of biomarker research in this field, drawing on their experiences and considering future strategies for biomarker discovery in the postgenomic era.
Advanced Technology To Reduce Water Cut: Case Studies From the Pemex Southern Region
Authors: Romo Gustavo A. , Leyva Héctor Hernández , Aguilar Raúl Bonifacio , Campos Carlos Caballero , Eoff Larry , Dalrymple Dwyann
Published: March 2010

This paper presents the results of a successful application of a new-generation polymeric relative permeability modifier (RPM) that enables treatments to reduce water cut without workover equipment. The new RPM can be bullheaded into open intervals without the need for isolating water zones from hydrocarbon zones. This treatment was applied to several wells in the Pemex southern region. As a result of the treatment, the productive life of the wells has been extended, with a gradual decrease in water cut. These results indicate high potential profitability values for mature fields with high water cut requiring a simple, low-cost treatment without the need for workover equipment or shut-in times. The new treatment can increase the hydrocarbon recovery percentage in sands that in all probability would be destined for abandonment otherwise.

This paper describes the treatment methodology, which begins with problem identification and an understanding of the origin of the water breakthrough. Next, the paper describes the new technology, which uses hydrophobically modified water-soluble polymers, and explains how applying such polymers can control water selectively. In addition, the detailed execution of the treatment is described, followed by the very positive production results of the treatment. The results of this low-investment, high-profit technology are very promising for other wells under similar conditions in which workovers with conventional technologies would be cost prohibitive.
From Lean to Extreme-Lean Well Profile: Field Experience in the Mediterranean Sea
Authors: Calderoni A.. , Donati F.. , Ferrara P.. , Maestrami M.. , Oppelt J.. , Krüger S..
Published: March 2010

The main subject of this paper will be to outline the field experience achieved with a new type of well profile and directional drilling system. Reducing the cost of well construction has been a driver for many new technologies. The lean casing profile introduced by Eni SpA, the major Italian oil and gas company, about a decade ago was a successful step towards lowering the drilling and completion cost in the vertical, top-hole section. Automated vertical-drilling tools have been the technical enabler of such a concept. Recently, this oil company has moved further towards an even more radical "extreme-lean well profile." This paper gives a brief insight into the well-design concept and the enabling technology behind it. The drilling technology is based on the well-known automated vertical-drilling system, which has been enhanced by the capability to drill an enlarged hole size below a casing without compromising the verticality and hole quality. In the main part of the paper, two field applications, in the Mediterannean Sea and offshore Egypt, are described. The paper will also cover the lessons learned especially from the second of the first two field applications. The extreme-lean well profile and automated vertical-reaming technology can provide value to several drilling campaigns not only through the reduction of well-construction cost. Another major benefit is the ability to run an intermediate casing string, if required because of difficult well conditions, and still arrive at the same diameter of casing in the reservoir. The completion concept and the enabling tool technology are very unique and have not been available to the industry until recently.
Lithological and Petrophysical Core-Log Interpretation in CO2SINK, the European CO2 Onshore Research Storage and Verification Project
Authors: Norden B.. , Förster A.. , Vu-Hoang D.. , Marcelis F.. , Springer N.. , Le Nir I..
Published: March 2010

The storage of carbon dioxide (CO2) in saline aquifers is one of the most promising options for Europe to reduce emissions of greenhouse gases from power plants to the atmosphere and to mitigate global climate change. The CO2SINK (CO2 Storage by Injection into a saline aquifer at Ketzin) project is a research and development (R&D) project, mainly supported by the European Commission, the German Federal Ministry of Education and Research, and the German Federal Ministry of Economics and Technology, targeted at developing an in-situ laboratory for CO2 storage.

The preparatory phase of the project involved a baseline geological-site exploration and the drilling of one injection and two observation wells, as well as the acquisition of a geophysical baseline and geochemical monitoring, in Ketzin, located near Berlin. The target saline aquifer is the lithologically heterogeneous Triassic Stuttgart formation, situated at approximately 630- to 710-m (2,070- to 2,330-ft) depth. A comprehensive borehole-logging program was performed consisting of routine well logging complemented with an enhanced logging program for one well that recorded nuclear-magnetic-resonance (NMR) and borehole-resistivity images, to characterize the storage formation better. A core analysis program carried out on reservoir rock and caprock included measurements of helium porosity, nitrogen permeability, and brine permeability at different pressure conditions.

The saline aquifer at Ketzin shows a variable porosity/permeability distribution, which is related to grain size, facies variation, and rock cementation with values in the range from 5 to > 35% and 0.02 to > 5,000 md for porosity and permeability, respectively. On the basis of core analysis and logging data, an elemental loganalysis model for the target formation was established for all three wells. In addition, permeability was estimated using the Coates equation and compared with core data and NMR log-derived permeability, which seems to provide meaningful permeability estimates for the Ketzin reservoir. On the basis of the good core control that guided the petrophysical well-log interpretation in the first two CO2SINK wells, a porosity and permeability prediction by analogy for the third well is appropriate and applicable. The availability of cores was crucial for a sophisticated formation evaluation at borehole scale that characterizes the real subsurface conditions.
Improved Prediction of Oil Recovery From Waterflooded Fractured Reservoirs Using Homogenization
Authors: Salimi Hamidreza , Bruining Johannes
Published: March 2010

Most simulations of waterflooding in fractured media are based on the Warren and Root (WR) approach, which uses an empirical transfer function between the fracture and matrix block. We use homogenization to obtain an improved flow model in fractured media, leading to an integro-differential equation; also called the boundary-condition (BC) approach. We formulate a well-posed numerical 3D model for the BC approach. This paper derives this numerical model to solve full 3D integro-differential equations in a field reservoir simulation. We compare the results of the upscaled model with ECLIPSETM results. For the interpretation, it is useful to define three dimensionless parameters that characterize the oil production in fractured media. The most important of these parameters is a Peclet number, defined as the ratio between the time required to imbibe water into the matrix block and the travel time of water in the fracture system. The results of the WR approach and the BC approach are in good agreement when the travel time is of the same order of magnitude as the imbibition time. However, if the travel time is shorter or longer than the imbibition time, the approaches give different results. The BC approach allows the use of transfer functions based on fundamental principles (e.g., the use of a rate-dependent capillary pressure function). When implemented, it can be used to improve recovery predictions for waterflooded fractured reservoirs.
Erosion Study for a 400-MMcf/D Completion: Cannonball Field, Offshore Trinidad
Authors: Healy J.C.. C. , Martin John , McLaury Brenton , Jagroop Raynald
Published: March 2010

The Cannonball field is a 1 Tcf gas/condensate development offshore Trinidad producing at a sustained rate in excess of 800 MMcf/D from three wells. The completion design selected was 7⅝- in. production tubing with an openhole gravel pack. The initial well (CAN01) has produced at 333 MMcf/D. These rates are higher than typically experienced, which has raised concerns about the resultant potential for metal erosion. As a result, a rigorous erosion study was initiated. The objective was to evaluate erosion quantitatively at various rates over the life cycle of the well to design the completion appropriately and select the appropriate materials.

The erosion nodes within the completion—changes in flow direction (e.g., a tee such as in the wellhead) and/or flow constric- tions—were identified as the tree, a landing-nipple profile near the surface, and a formation-isolation device (FID) positioned in the gravel-pack assembly. The key parameters were defined as particles of sharp sand, with a diameter of 50 μm, at a concentration of 0.1 lbm/MMcf. Erosion rates were calculated using the erosion model, Sand Production Pipe Saver (SPPS), developed by the Erosion/Corrosion Research Center (E/CRC) at the University of Tulsa, USA. Erosion rates were calculated over the life cycle, starting at initial rates of 280 and 400 MMcf/D. Erosion rates were also calculated with and without a liquid film (a protective layer on the pipe wall that can reduce the erosion rate). Erosion results (without a liquid film) at all nodes exceeded BP's erosion limit; however, the erosion results with a thin liquid film were mostly below the company's erosion limit. Determination of the presence and thickness of the liquid film was critical. A multiphasepipeline simulation calculated that a sufficient liquid film would exist at all critical areas. Erosion of the tree was assessed further by computation-fluid-dynamics (CFD) models, which identified several hot spots; thus, additional cladding of all flow-wetted surfaces and rounding of the outlet corner was required. The Cannonball completion design, including the tree, was determined to be capable of sustained rates up to a maximum of 400 MMcf/D. The three-well development, where initial rates have been as high as 333 MMcf/D, has been on production for several years without any erosion issues.
Pore-Pressure-Coefficient Anisotropy Measurements for Intrinsic and Induced Anisotropy in Sandstone
Authors: Al-Tahini Ashraf , Abousleiman Younane
Published: March 2010

In this study, we determine experimentally the effect of inherent and stress-induced anisotropy on stiffness components, elastic moduli, and Biot's pore-pressure coefficients (PPCs) for Lyons outcrop Colorado sandstone, which exhibits a clear transverse isotropic rock structure. Both dynamic and quasistatic methods were used under a nonhydrostatic state of stress to perform the measurements on dry core samples. Our assumption of apparent transverse anisotropy was confirmed initially with acoustic velocity measurements and at a later stage in the loading with experimental transverse anisotropic failure analysis. The objective of this study is to identify and isolate the effect of stress-induced anisotropy from the inherent transverse anisotropy on the measured stiffness components, elastic moduli, and Biot's PPCs. The effect of stress-induced anisotropy appears to have significant control on measured stiffness components, elastic moduli, and Biot's PPCs in comparison to the inherent-transverse-anisotropy effect. Our work shows that the stiffness components, Mij and thus the computed elastic moduli, are highly influenced by the stress-induced anisotropy, especially the off-diagonal stiffness components, M12 and M13, where the increase in their magnitudes from the dynamic measurements before failure is determined to be 100 and 81%, respectively. The difference in the magnitude between the axial and lateral Biot's PPCs in line with bedding planes and perpendicular to them is measured to be 24 and 16% from the quasistatic and dynamic methods, respectively; whereas, the effect of stress-induced anisotropy reduced the dynamic average magnitude of the Biot's PPCs along the bedding planes and transverse to these planes by 63% across a stress range of 145 MPa.
Entrance Pressure of Oil-Based Mud Into Shale: Effect of Shale, Water Activity, and Mud Properties
Authors: Oleas Andres M. , Osuji Collins E. , Chenevert Martin E. , Sharma Mukul M.
Published: March 2010

Oil-based muds (OBMs) have been developed to combat drilling problems caused by shale hydration. This paper presents experimental data that show the factors that control the movement of oil filtrate into a shale, as described by its "entrance pressure." Although the oil filtrate of the OBM does not hydrate the shale, it can penetrate the shale, increase the pore pressure, and cause wellbore failure. It is of primary interest to understand this when troublesome shales are drilled. It is also important to understand how factors such as the emulsifier concentration in the OBM and the porosity of the shale affect this entrance pressure.

The objective of this study is to determine and quantify the factors that control the oil entry pressures of shales. For this purpose, five OBMs, containing different concentrations of emulsifiers, water, and oil, were studied.

The study was also intended to determine the effect of shale porosity on entrance pressure. Data are reported for the Arco China shale samples having porosities of 1.8 (native), 3.9, and 4.9%.

It was observed that for a given OBM water content, as the emulsifier concentration increased, the required entrance pressure and the electrical stability (ES) of the mud increased. Also, for shales that had higher porosities and, therefore, larger pore throats, the oil entrance pressure decreased.
A Quantitative and Qualitative Comparison of Coarse-Grid-Generation Techniques for Modeling Fluid Displacement in Heterogeneous Porous Media
Authors: Mostaghimi P.. , Mahani H..
Published: March 2010

To apply upscaling techniques is an undeniable demand in reservoir simulation, when one considers the difference between the level of detail in a geological model and the level of details that can be handled by a reservoir simulator. Upscaling the reservoir model involves first constructing a coarse grid by using gridding algorithms and then computing average properties for coarse gridblocks. Although various techniques have been proposed for each of these steps, one needs to be aware of strengths and weaknesses of each technique before attempting to apply them. In this paper, we focus on different gridding methods and evaluate their performances. Three main grid-generation techniques are considered: permeability-based (PB), flow-based (FB), and vorticity-based (VB) methods. We apply all three methods to a number of 2D heterogeneous models and simulate two-phase flow on the constructed grids. Then we compare their obtained global and local results. Fluid cuts at the producer is employed as the global performance indicator and saturation-distribution error as the local indicator. We show that FB and VB gridding, which are dynamic methods, are superior to PB gridding, which is a static method. On the basis of this analysis, we then concentrate on FB and VB gridding and investigate their performance in greater detail. While FB gridding uses fluid velocity as gridblock density indicator, VB gridding combines velocity and permeability variation in gridding according to its definition and takes advantage of both. Therefore, although performance of FB and VB gridding is comparable in many cases, VB has the benefit of producing coarse gridblocks with more-uniform permeability and fluid-properties distribution. This in turn yields more-accurate global and local results and reduces application of sophisticated upscaling techniques and fulltensor permeability upscaling.
Data Assimilation of Coupled Fluid Flow and Geomechanics Using the Ensemble Kalman Filter
Authors: Chang Haibin , Chen Yan , Zhang Dongxiao
Published: March 2010

In reservoir history matching or data assimilation, dynamic data, such as production rates and pressures, are used to constrain reservoir models and to update model parameters. As such, even if under certain conceptualization the model parameters do not vary with time, the estimate of such parameters may change with the available observations and, thus, with time. In reality, the production process may lead to changes in both the flow and geomechanics fields, which are dynamically coupled. For example, the variations in the stress/strain field lead to changes in porosity and permeability of the reservoir and, hence, in the flow field. In weak formations, such as the Lost Hills oil field, fluid extraction may cause a large compaction to the reservoir rock and a significant subsidence at the land surface, resulting in huge economic losses and detrimental environmental consequences. The strong nonlinear coupling between reservoir flow and geomechanics poses a challenge to constructing a reliable model for predicting oil recovery in such reservoirs. On the other hand, the subsidence and other geomechanics observations can provide additional insight into the nature of the reservoir rock and help constrain the reservoir model if used wisely. In this study, the ensemble-Kalman-filter (EnKF) approach is used to estimate reservoir flow and material properties by jointly assimilating dynamic flow and geomechanics observations. The resulting model can be used for managing and optimizing production operations and for mitigating the land subsidence. The use of surface displacement observations improves the match to both production and displacement data. Localization is used to facilitate the assimilation of a large amount of data and to mitigate the effect of spurious correlations resulting from small ensembles. Because the stress, strain, and displacement fields are updated together with the material properties in the EnKF, the issue of consistency at the analysis step of the EnKF is investigated. A 3D problem with reservoir fluid-flow and mechanical parameters close to those of the Lost Hills oil field is used to test the applicability.
Experimental Study of MSE of a Single PDC Cutter Interacting With Rock Under Simulated Pressurized Conditions
Authors: Rafatian Navid , Miska Stefan , Ledgerwood L.W.. W. , Ahmed Ramadan , Yu Mengjiao , Takach Nicholas
Published: March 2010

The downhole pressure environment is one of the most important factors affecting the rate of penetration (ROP). It is believed that impermeable rocks experience high differential pressures because of shear dilatancy and become stronger and, thus, more difficult to drill. However, recently performed atmospheric and pressurized single-cutter experiments show that contrary to this belief, even at low pressures (100-200 psig) and even with permeable rocks, significant increase in mechanical specific energy (MSE) is observed compared to atmospheric tests.

The experiments were carried out in a single-cutter high-pressure testing facility refurbished with high-precision sensors and a data acquisition system. In the experiments, a 13-mm polycrystalline-diamond-compact (PDC) cutter was used to cut Carthage marble and Indiana limestone samples with depths of cut ranging from 0.025 to 0.050 in. More than 70 high-precision tests were performed on these two rock types under confining pressures ranging from 0 to 1000 psig. The confining fluids were either water or mineral oil.

Unexpectedly, analysis of the MSE consistently showed that increases in the confining pressure as small as 150 psig can increase the MSE of the cutting process significantly and reduce the cutting efficiency by half. These reductions in the cutting efficiency that were even more dramatic in the permeable and saturated Indiana limestone could not be explained by the strengthening of the rock under confining pressures.

Upon analysis of the results of experiments (cutting forces, volume of cuts, and visual inspections of cuttings), a new theory was proposed to explain this unexpected behavior. This new theory, based on the frictional forces and the cutting mechanism under pressure, gives useful insights into the physics of cutter-rock interaction. Such insights are invaluable to the improvements of drilling practices selection [weight on bit (WOB), type of drilling fluid, and its properties] and the ROPs.
What Is Stimulated Reservoir Volume?
Authors: Mayerhofer M.J.. J. , Lolon E.P.. P. , Warpinski N.R.. R. , Cipolla C.L.. L. , Walser D.. , Rightmire C.M.. M.
Published: March 2010

Ultralow-permeability shale reservoirs require a large fracture network to maximize well performance. Microseismic fracture mapping has shown that large fracture networks can be generated in many shale reservoirs. In conventional reservoirs and tight gas sands, single-plane-fracture half-length and conductivity are the key drivers for stimulation performance. In shale reservoirs, where complex network structures in multiple planes are created, the concepts of single-fracture half-length and conductivity are insufficient to describe stimulation performance. This is the reason for the concept of using stimulated reservoir volume (SRV) as a correlation parameter for well performance. The size of the created fracture network can be approximated as the 3D volume (stimulated reservoir volume) of the microseismic-event cloud. This paper briefly illustrates how the SRV can be estimated from microseismic-mapping data and is then related to total injected-fluid volume and well performance. While the effectively producing network could be smaller by some proportion, it is assumed that the created and the effective network are directly related. However, SRV is not the only driver of well performance. Fracture spacing and conductivity within a given SRV are just as important, and this paper illustrates how both SRV and fracture spacing for a given conductivity can affect production acceleration and ultimate recovery. The effect of fracture conductivity is discussed separately in a series of companion papers. Simulated-production data are then compared with actual field results to demonstrate variability in well performance and how this concept can be used to improve completion design, well spacing, and placement strategies.
Gas/Condensate Relative Permeability of a Low Permeability Core: Coupling vs. Inertia
Authors: Jamiolahmady M.. , Sohrabi M.. , Ghahri P.. , Ireland Shaun
Published: March 2010

Flow around the wellbore of gas/condensate systems, when pressure drops below dewpoint, is controlled by complex interaction of capillary, viscous, and inertial forces. Hence, it is challenging to determine accurately gas/condensate relative permeability (kr) that is affected by the relative impact of these competing forces.

There are a number of reports demonstrating kr of high permeability rocks affected by both coupling [the increase of kr as velocity increases and/or interfacial tension (IFT) decreases] and inertia (i.e., the reduction of kr as velocity increases) for these low IFT systems. However, there is little information on this subject for low-permeability rocks.

In this work, different series of steady-state k r values for a 3.9- md sandstone reservoir rock with a porosity of 6% are reported. These k data sets have been measured experimentally at three IFT levels below 1 mNm-1 and five velocity levels below 200 md-1.

The results indicate that at the highest IFT, inertia is dominant at low condensate-/gas-flow-rate ratio(CGFR) at test conditions, whereby kr reduces with increasing velocities. At higher CGFR, an increase in kr is observed because of the dominant effect of coupling. At lower IFT, the negative impact of inertia on k as velocity increases is observed at all CGFR. Jamiolahmady et al. (2008) have recently reported kr of highly conductive propped fractures showing a more pronounced effect of inertia at lower IFT, but this is the frrst report of such behavior for low permeability rocks. These k r measurements are also compared with the corresponding predicted k using the generalized kr correlation recently developed by Jamiolahmady et al. (2009). The correlation expresses the combined effect of coupling and inertia with universal parameters. The unique contribution of inertia, as observed in the experiments and predicted by the correlation, is attributed mainly to the high single-phase inertial factor of the rock and fluid properties of the flowing phases.
Using Distributed Volumetric Sources to Predict Production from Multiple-Fractured Horizontal Wells Under Non-Darcy-Flow Conditions
Authors: Amini Shahram , Valkó Peter P.
Published: March 2010

The method of distributed volumetric sources (DVS) has been applied to predict gas production from a horizontal well with multiple transverse fractures in a bounded reservoir. Combining the quasianalytical DVS method, which provides us with the opportunity to predict pressure and production behavior of complex well/fracture configurations, with non-Darcy flow in the fracture enables us to calculate the optimum configuration in terms of the number and dimensions of fractures per well for a certain amount of proppant of a given type. The method is applied to an example case of a tight gas reservoir to maximize the production performance of this complex well/fracture configuration. Comparing results with and without inclusion of the non-Darcy effect in the fracture shows that a decrease in production occurs because of non-Darcy flow in all cases. However, a systematic screening of a realistic set of well/fracture configurations reveals that the detrimental effect of non-Darcy flow can be substantially compensated for by selecting the right number of fractures and shifting the fracture dimensions in favor of thicker fractures. While a simultaneous decrease in optimum lateral (and vertical) extension is necessary, it has limited effect on productivity. The simplicity, robustness, and small computational demand of the model allow seamless integration with external economic and operational constraints, providing a tool to screen and optimize a large set of possible configurations most suited for the development of economically marginal fields.
Modeling of Sand Cleanout With Foam Fluid for Vertical Well
Authors: Li Songyan , Li Zhaomin , Lin Riyi , Li Binfei
Published: March 2010

Foam has proved to be effective and economical in underbalanced operations and is gaining wider applications in many areas. Foam fluid has low density and high blocking ability. It can effectively reduce leaking of fluid into formation in low-pressure wells, protecting the oil formation and improving sand-cleanout efficiency. According to energy-conservation equations, mass-conservation equations, and momentum-conservation equations, a mathematical model for sand cleanout with foam fluid was established that considers the heat transfer between foam in the annulus and foam in the tubing. The model was solved by numerical method. Distributions of foam temperature, foam density, foam quality, pressure, and foam velocity in the wellbore were obtained. Calculation results show that temperature distribution is affected greatly by thermal gradient. As the well depth increases, foam pressure and foam density increase and foam quality and velocity decrease. Foam velocity at the well bottomhole is the minimum. Friction pressure loss of foam is less than that of water at the same volume flow rate. Site applications show that sand cleanout with foam fluid can prevent fluid leakage effectively. It can avoid damage of sealing agents and reduce pollution. The average relative error and standard deviation between model and field data on injection pressure are–0.43 and 2.55%, respectively, which proves the validation of the mathematical model.