bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of different starch types on the physico-mechanical and morphological properties of low density polyethylene composites
Authors: Hossen Beg Md. Dalour , Bin Kormin Shaharuddin , Bijarimi Mohd , Zaman Haydar U.
Published: March 2015

The aim of this research is to investigate the effects of different thermoplastic starches and starch contents on the physico-mechanical and morphological properties of new polymeric-based composites from low density polyethylene (LDPE) and thermoplastic starches. Different compositions of thermoplastic starches (5–40 wt%) and LDPE were melt blended by extrusion and injection molding. The resultant materials were characterized with respect to the following parameters, i.e., melt flow index (MFI), mechanical properties (tensile, flexural, stiffness and impact strength) and water absorption. Scanning electron microscopy (SEM) was also used in this study for evaluating blend miscibility. MFI values of all blends decreased as the starch content increased, while the sago starch formulation showed a higher MFI value than others. The incorporation of fillers into LDPE matrix resulted in an increased in tensile modulus, flexural strength, flexural modulus and slightly decreased tensile strength and impact strength. However, sago starch filled composites exhibited better mechanical properties as compared to other starches. The SEM results revealed that the miscibility of such blends is dependent on the type of starch used. The water absorption increased with immersion time and the thermoplastic sago starch samples showed the lowest percentage of water absorption compared with other thermoplastic starches.
Synthesis, crystal structure and spectroscopic properties of one-dimensional zinc(II)–cyanide complex with 1-methylimidazole, [Zn(μ-CN)(CN)(1-meim)]n
Authors: Sayın Elvan , Kürkçüoğlu Güneş Süheyla , Yeşilel Okan Zafer , Hökelek Tuncer
Published: March 2015

A new one-dimensional Zn(II)–cyanide complex with 1-methylimidazole ligand, [Zn(μ-CN)(CN)(1-meim)]n(1-meim: 1-methylimidazole) has been synthesized and characterized by spectral (FT-IR and Raman) methods, elemental analysis, thermal (TG, DTG and DTA) analysis and single crystal X-ray diffraction techniques. The complex crystallizes in the monoclinic system,P21space group. The asymmetric unit contains one Zn(II), one 1-meim and two cyanide ligands. The coordination sphere of the Zn(II) ion exhibits a distorted tetrahedral geometry. In the crystal structure, the symmetry related zinc(II) atoms are bridged by the cyanide anions to form one dimensional chains running along the b-axis. Intermolecular C–H···N hydrogen bonds link the adjacent polynuclear chains forming two dimensional layers through theR1818(2)$R_{18}^{18}(2)$ring motifs, where the layers formed are oriented in parallel to (020).
Highly Secure and Fast Video Encryption Using Minimum Overhead in H.264/AVC Bitstream
Authors: Joshi Jay M. , Dalal Upena D.
Published: March 2015

This paper primarily focuses on the encryption method used to design a selective video encryption scheme to meet following objectives. Encryption and decryption are able to secure in bits-level cryptographic security (after encryption), as well as in the pixel-level visual content security (after decoding for unauthorized user) to meet with sensitive video applications with minimum encryption overhead. It provides perceptual encryption with total scrambling of visual content. Besides, it also makes provision for randomness, not only in spatial but also in the temporal domain. It is presumed that an overall encryption and decryption scheme is quick enough to meet real-time applications. There is no change in the quality of video for genuine users. However, these objectives have been achieved in our proposed algorithm in expense of slight changes in compression bandwidth. The proposed algorithm encrypts residue data and motion vectors after entropy encoding to scramble spatial and temporal resolution. Encryption of motion vectors is based on Expo-Golomb entropy coding in inter-coded macroblock and DC value of residues is encrypted based on context-adaptive variable-length coding (CAVLC) in intra-coded macroblock. In addition, encryption is carried out using an advanced encryption system (AES) in a counter mode stream cipher. The paper deals with security analysis of a proposed scheme in terms of cryptography, as well as perception security.
Assessment of Infrared Thermography for Cyclic High-Temperature Measurement and Control
Authors: Jones J. P. , Brookes S. P. , Whittaker M. T. , Lancaster R. J. , Ward B.
Published: March 2015

Infrared thermography (IRT), a non-invasive temperature measurement technique has been investigated and developed for use with cyclic high-temperature loading. The technique utilizes an infrared thermography camera (IRTC) and Rolls-Royce HE23 black thermal paint (TP). The TP is applied to a test-piece surface to provide a stable emissivity value and accurate temperature measurement for the duration of thermal cycling. Spot-welded type N thermocouples (NTCs) are utilized for accuracy validation of the IRTC technique for both temperature monitoring and temperature control. An evaluation of the technique has been employed upon diverse test specimen geometries and alloy compositions at temperatures between 100°C and 700°C. Unfavorable effects during cyclic temperature measurement such as thermocouple shadowing are also highlighted and quantified. In combination with HE23 TP, IRTC control and measurement have proven accurate to within ±2°C NTCs, a validated cyclic high-temperature measurement technique.
Inhibition of lethal inflammatory responses through the targeting of membrane‐associated Toll‐like receptor 4 signaling complexes with a Smad6‐derived peptide
Authors: Lee Youn Sook , Park Jin Seok , Jung Su Myung , Kim Sang‐Doo , Kim Jun Hwan , Lee Jae Young , Jung Kyeong Cheon , Mamura Mizuko , Lee Sangho , Kim Seong‐Jin , Bae Yoe‐Sik , Park Seok Hee
Published: March 2015

We have previously reported that Smad6, one of the inhibitory Smads of transforming growth factor‐β (TGF‐β)/bone morphogenetic protein (BMP) signaling, inhibits Toll‐like receptor (TLR) 4 signaling by disrupting the Pellino‐1‐mediated TLR4 signaling complex. Here, we developed Smaducin‐6, a novel membrane‐tethered palmitic acid‐conjugated Smad6‐derived peptide composed of amino acids 422–441 of Smad6. Smaducin‐6 interacted with Pellino‐1, located in the inner membrane, thereby disrupting the formation of IRAK1‐, RIP1‐, IKKε‐mediated TLR4 signaling complexes. Systemic administration of Smaducin‐6 showed a significant therapeutic effect on mouse TLR4‐mediated inflammatory disease models, cecal‐ligation–puncture (CLP)‐induced sepsis, and lipopolysaccharide‐induced endotoxemia, by inhibiting pro‐inflammatory cytokine production and apoptosis while enhancing neutrophil migration and bacterial clearance. Our findings provide clues to develop new peptide‐based drugs to target Pellino‐1 protein in TLR4 signaling pathway for the treatment of sepsis.
Patient reported outcome in posttraumatic pituitary deficiency: results from The Danish National Study on posttraumatic hypopituitarism
Authors: Klose Marianne , Stochholm Kirstine , Janukonyté Jurgita , Christensen Louise Lehman , Cohen Arieh S , Wagner Aase , Laurberg Peter , Christiansen Jens Sandahl , Andersen Marianne , Feldt-Rasmussen Ulla
Published: March 2015

Objective

Posttraumatic pituitary hormone deficiency is often suggested. The impact of these predominantly mild and often irreproducible deficiencies on outcome is less clear. The aim of the present study was to describe patient reported outcome in a nationala prioriunselected cohort of patients with traumatic brain injury (TBI) in relation to deficiencies identified upon pituitary assessment.

Design and methods

We conducted a nationwide population-based cohort study. Participants were Danish patients with a head trauma diagnosis recorded in the Danish Board of Health diagnostic code registry; 439 patients (and 124 healthy controls) underwent assessment of anterior pituitary function 2.5 years (median) after TBI. Questionnaires on health-related quality of life (QoL) (SF36, EuroQoL-5D, QoL assessment of GH deficiency in adults) and fatigue (MFI-20) were completed in parallel to pituitary assessment.

Results

Patients with TBI had significant detriments in QoL. Impairment (mainly physical scales) related to pituitary deficiency, although only partially confirmed after adjustment for demographic differences. Hypogonadotropic hypogonadism related to several QoL scores. Increasing impairments were observed with declining total testosterone concentrations (men), but not free testosterone concentrations or any other hormone concentrations. Total testosterone was not independently related to impaired QoL and fatigue, after adjustment for demographics, and treatment with antidiabetics, opioids, antidepressants, and anticonvulsants.

Conclusions

Only a very limited relationship between pituitary hormone deficiencies and QoL/fatigue was demonstrated. Due to the dominating influence of concurrent comorbidities, pituitary deficiencies were not independently related to QoL/fatigue. Causality is still to be shown, and whether substitution therapy could be of additional relevance in selected patients needs to be proven.
Human spermatozoa possess an IL4I1 l-amino acid oxidase with a potential role in sperm function
Authors: Houston B , Curry B , Aitken R J
Published: March 2015

Reactive oxygen species (ROS) are known to play an important role in the regulation of human sperm function. In this study, we demonstrate for the first time that human spermatozoa possess interleukin-induced gene 1 (IL4I1), anl-amino acid oxidase (LAAO) which is capable of generating ROS on exposure to aromatic amino acids in the presence of oxygen. The preferred substrates were found to be phenylalanine and tryptophan while the enzyme was located in the acrosomal region and midpiece of these cells. In contrast to equine and bovine spermatozoa, enzyme activity was lost as soon as the spermatozoa became non-viable. On a cell-to-cell basis human spermatozoa were also shown to generate lower levels of hydrogen peroxide than their equine counterparts on exposure to phenylalanine. Stimulation of LAAO activity resulted in the induction of several hallmarks of capacitation including tyrosine phosphorylation of the sperm flagellum and concomitant activation of phospho-SRC expression. In addition, stimulation of LAAO resulted in an increase in the levels of acrosomal exocytosis in both the presence and absence of progesterone stimulation, via mechanisms that could be significantly reversed by the presence of catalase. As is often the case with free radical-mediated phenomena, prolonged exposure of human spermatozoa to phenylalanine resulted in the stimulation of apoptosis as indicated by significant increases in mitochondrial superoxide generation and the activation of intracellular caspases. These results confirm the existence of an LAAO in human spermatozoa with a potential role in driving the redox regulation of sperm capacitation and acrosomal exocytosis.
Effect of hyperandrogenism on ovarian function
Authors: Velez Leandro M , Heber Maria F , Ferreira Silvana R , Abruzzese Giselle A , Reynoso Roxana M , Motta Alicia B
Published: March 2015

The objective of this work was to study the ovarian function when follicular development is induced during a hyperandrogenic condition. Female rats were injected with either equine chorionic gonadotropin (eCG group) to induce folliculogenesis or eCG together with DHEA to induce folliculogenesis in a hyperandrogenic condition (eCG+HA group). The control group was injected with vehicle. Ovarian mRNA levels of the peroxisome proliferator-activated receptor gamma (PPARγ) co-activator PGC1α, the PPARγ co-repressor NCoR, the main enzymes involved in the ovarian steroidogenesis (CYP17, 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-HSD, and CYP19A), and cyclooxygenase 2 (COX2) were evaluated only by real-time PCR. COX2 was evaluated by both real-time PCR and western blot. Serum steroid hormones and both the oxidative and inflammatory statuses were also quantified. We found that eCG-induced folliculogenesis induced increased mRNA levels of PGC1α and decreased those of NCoR when compared with controls. In addition, we found an increase in serum estradiol (E2) levels and enhanced mRNA expression of CYP19A. A pro-inflammatory status and a pro-oxidant status were also established. When folliculogenesis was induced in a hyperandrogenic condition, the mRNA levels of the PPARγ co-repressor NCoR remained higher than in controls and the pro-inflammatory and pro-oxidant statuses were enhanced. In addition, the enzymes involved in ovarian steroidogenesis were altered leading to the accumulation of testosterone and an unfavorable E2/testosterone ratio. These alterations led to abnormal follicular development.
Geriatric Assessment-Identified Deficits in Older Cancer Patients With Normal Performance Status
Authors: Jolly Trevor A. , Deal Allison M. , Nyrop Kirsten A. , Williams Grant R. , Pergolotti Mackenzi , Wood William A. , Alston Shani M. , Gordon Brittaney-Belle E. , Dixon Samara A. , Moore Susan G. , Taylor W. Chris , Messino Michael , Muss Hyman B.
Published: March 2015

Background.

We investigated whether a brief geriatric assessment (GA) would identify important patient deficits that could affect treatment tolerance and care outcomes within a sample of older cancer patients rated as functionally normal (80%–100%) on the Karnofsky performance status (KPS) scale.

Methods.

Cancer patients aged ≥65 years were assessed using a brief GA that included both professionally and patient-scored KPS and measures of comorbidity, polypharmacy, cognition, function, nutrition, and psychosocial status. Data were analyzed using descriptive statistics and multivariable logistic regression.

Results.

The sample included 984 patients: mean age was 73 years (range: 65–99 years), 74% were female, and 89% were white. GA was conducted before (23%), during (41%), or after (36%) treatment. Overall, 54% had a breast cancer diagnosis (n = 528), and 46% (n = 456) had cancers at other sites. Moreover, 81% of participants (n = 796) had both professionally and self-rated KPS ≥80, defined as functionally normal, and those patients are the focus of analysis. In this subsample, 550 (69%) had at least 1 GA-identified deficit, 222 (28%) had 1 deficit, 140 (18%) had 2 deficits, and 188 (24%) had ≥3 deficits. Specifically, 43% reported taking ≥9 medications daily, 28% had decreased social activity, 25% had ≥4 comorbidities, 23% had ≥1 impairment in instrumental activities of daily living, 18% had a Timed Up and Go time ≥14 seconds, 18% had ≥5% unintentional weight loss, and 12% had a Mental Health Index score ≤76.

Conclusion.

Within this sample of older cancer patients who were rated as functionally normal by KPS, GA identified important deficits that could affect treatment tolerance and outcomes.
Age-Stratified Risk of Unexpected Uterine Sarcoma Following Surgery for Presumed Benign Leiomyoma
Authors: Brohl Andrew S. , Li Li , Andikyan Vaagn , Običan Sarah G. , Cioffi Angela , Hao Ke , Dudley Joel T. , Ascher-Walsh Charles , Kasarskis Andrew , Maki Robert G.
Published: March 2015

Background.

Estimates of unexpected uterine sarcoma following surgery for presumed benign leiomyoma that use age-stratification are lacking.

Patients and Methods.

A retrospective cohort of 2,075 patients that had undergone myomectomy was evaluated to determine the case incidence of unexpected uterine sarcoma. An aggregate risk estimate was generated using a meta-analysis of similar studies plus our data. Database-derived age distributions of the incidence rates of uterine sarcoma and uterine leiomyoma surgery were used to stratify risk by age.

Results.

Of 2,075 patients in our retrospective cohort, 6 were diagnosed with uterine sarcoma. Our meta-analysis revealed 8 studies from 1980 to 2014. Combined with our study, 18 cases of leiomyosarcoma are reported in 10,120 patients, for an aggregate risk of 1.78 per 1,000 (95% confidence interval [CI]: 1.1–2.8) or 1 in 562. Eight cases of other uterine sarcomas were reported in 6,889 patients, for an aggregate risk of 1.16 per 1,000 (95% CI: 0.5–4.9) or 1 in 861. The summation of these risks gives an overall risk of uterine sarcoma of 2.94 per 1,000 (95% CI: 1.8–4.1) or 1 in 340. After stratification by age, we predict the risk of uterine sarcoma to range from a peak of 10.1 cases per 1,000, or 1 in 98, for patients aged 75–79 years to <1 case per 500 for patients aged <30 years.

Conclusion.

The risk of unexpected uterine sarcoma varies significantly across age groups. Our age-stratified predictive model should be incorporated to more accurately counsel patients and to assist in providing guidelines for the surgical technique for leiomyoma.
Early Diagenesis by Modern Acid Brines in Western Australia and Implications for the History of Sedimentary Modification on Mars
Authors: Bowen Brenda B. , Benison Kathleen C. , Story Stacy
Published: March 2015

Mineralogical and geochemical data collected from multiple sites on Mars suggest that acid saline surface waters and groundwater existed there in the past. The geologic context and sedimentology suggest that these acid saline waters were associated with groundwater-fed ephemeral lakes. Ephemeral acid saline lakes in southern Western Australia (WA) are some of the few known natural systems that have the same combination of extreme acid brine chemistry and lacustrine depositional setting as is observed on Mars. Thus, the WA acid saline environments provide a modern analog for understanding past depositional and diagenetic processes that may have occurred on Mars. Here, we examine surface sediments and sedimentary rocks that have been in contact with acid (pH down to ∼1.5) and saline brines (total dissolved solids up to ∼32%) in southern Western Australia. Through sedimentological, mineralogical, geochemical, and petrographic analyses, we identify the impacts of early diagenesis in and adjacent to eight acid saline lakes and evaluate the processes that have been important in creating these deposits. The combination of extreme chemistry, spatial variability, arid climate, and reworking by winds and floods contributes to make spatially complex depositional products that are a combination of siliciclastics and chemical sediments. Important syndepositional and very early diagenetic processes in these settings include the chemical precipitation of minerals from shallow groundwaters to form displacive crystals and cements, dissolution/partial dissolution of chemical sediments, replacement/partial replacement of some minerals, cracking due to repeated wetting and drying, and the formation of iron-oxide concretions. Minerals observed in these sediments include a variety of chlorides, sulfates, iron oxides, and phyllosilicates, many of which have textures and mineral associations that suggest authigenic formation. These observations are supported by the chemistry of the modern acid brines, which appear to be supersaturated with respect to these minerals. The range of early diagenetic products, compositions, and textures that are apparent in the WA acid saline lake sediments may provide insights into the processes that influenced the sediments on Mars and the timing of sedimentary formation processes on Mars.
Characteristics of Terrestrial Ferric Oxide Concretions and Implications for Mars
Authors: Chan Marjorie A. , Potter Sally L. , Bowen Brenda B. , Parry W.T. , Barge Laura M. , Seiler Winston , Petersen Erich U. , Bowman John R.
Published: March 2015

Concretions are diagenetic products of cementation that establish significant records of groundwater flow through porous sedimentary deposits. Common spheroidal ferric oxide concretions form by diffusive coupled with advective mass transfer and share similar physical characteristics with hematite spherules from Meridiani Planum (Mars “blueberries”), investigated by the Mars Exploration Rover Opportunity. Terrestrial concretions from the Jurassic Navajo Sandstone are not perfect analogs to Mars, particularly in terms of their geochemistry. However, the Navajo Sandstone contains exceptional examples that represent typical concretion characteristics from the geologic record. Both ancient and modern analogs provide information about concretion forming processes and their relationship to porosity and permeability, fluid flow events, subsequent weathering, and surficial reworking.

Concretions on Earth possess variable mineralogies and form in a variety of lithologies in formations of nearly all geologic ages. Despite the prevalence of concretions, many unknowns exist, including their absolute ages and their precise nucleation and growth mechanisms. Some opportunities for future concretion research lie in three approaches: (1) New analytical techniques may show geochemical gradients and important textures reflecting biotic (role of bacteria) or abiotic origins. (2) Concretion modeling can determine important formation mechanisms. Sensitivity tests and simulations for different parameters can help show the magnitude of influence for different input factors. (3) New age-dating methods that remove preservational bias and expand the supply of datable material may yield quantitative limits to the timing of diagenetic events beyond what relative cross-cutting relationships can show.

The discovery of hematite spherules on Mars has driven efforts to better understand both terrestrial examples of ferric oxide concretions and the competing mechanisms that produce spheroidal geometries. The integration of geologic and planetary sciences continues to encourage new findings in the quest to understand the role of water on Mars as well as the tantalizing possibility that extraterrestrial life is associated with mineral records of watery environments.
Using Nanoparticles to Formulate Sag-Resistant Invert Emulsion Drilling Fluids
Authors: Wagle Vikrant , Al-Yami Abdullah S. , AlAbdullatif Ziad
Published: March 2015

Invert-emulsion fluid (IEF) systems formulated without organophilic clay have successfully addressed issues of barite sag while drilling wellbores. In the absence of organoclay, the “organoclay-free” IEFs have to use additional materials like sized calcium carbonate or clay-type materials to bolster the rheological properties and suspension character of the system. In the absence of low-gravity solids (LGS), the loss of suspension, especially in an inclined well, can lead to sag and cause a density gradient along the fluid column that may fracture the formation.

This paper presents a solution toward barite sag in an invert emulsion drilling fluid with the use of novel nanoparticles. The use of nanoparticles was shown to prevent sag in 9 ppg, 12 ppg, and 16 ppg organoclay-free IEF in a static-aging cell held vertical at 90° and then inclined at 45°. Fluids formulated with nanoparticles showed good sag control in different base oils with minimal oil separation. Extended sag testing with the sag-control additive at 250°F for 24 hours and at 150°F for 60 hours gave minimal oil separation and no barite sag. The nanoparticles based IEF was also subjected to contamination testing. Barite sag measurements performed on “contaminated” nanoparticle-based IEF shows that the suspension characteristics remain unaffected and the mud properties are tolerant to the presence of contaminants. Experimental data demonstrating the anti-sag performance of the nanoparticles in IEF is presented and compared to fluids without the nanoparticles.
Percussion Drilling System Combined with Hybrid PDC Bit Increases ROP and Interval Drilled on Taoudenni Basin Well in Mauritania
Authors: Powell Scott , Garcia Alexis , Barocio Hector , Alonso Alvaro
Published: March 2015

Drilling the Taoudenni Basin in Mauritania has posed a costly and time consuming challenge for operators looking to develop the basin economically. The formation's compressive strength limits the bit selection to heavyset PDC bits or hard rock roller cone insert bits due to their abrasive composition. One way to increase the effectiveness and drilling efficiency is to add a percussion force, increasing the axial energy, along with a hybrid PDC bit with PDC cutters and impregnated diamond material on the blades and secondary cutting structures.

The main similarity between fixed cutter hybrid bits and roller cone bits is that both incorporate a similar means of energy transfer when used with a positive displacement motor. Axial weight from a drilling rig is applied while a hydraulic motor turns the bit at different speeds. A proposed improvement to this drilling system would be a new energy distribution system that induces axial oscillations and percussion force while still applying the same weight and torsional energy as previous systems.

The system combines the torsional power of a conventional positive displacement motor with a high frequency axial pulse created by a mechanical action. The torque is still transferred directly to the bit and 100% of the hydraulic flow is utilized by the bit nozzles. The mechanical lifting and falling action creates a rapid variation in weight on bit (WOB), allowing the bit's depth of cut to fluctuate while overcoming different stresses. The percussion force created after each downward stroke, along with weight on bit variations, lead to increased rates of penetration (ROP).

This system has already been utilized on two wells in Mauritania, drilling a variety of formations with PDC, hybrid fixed cutter and roller cone insert bits. This paper will focus on the 8½″ interval, drilling the Atar Group and Jbeliat Teniagouri formations. These formations consist of sandstone, shale interbedded with siltstone, dolerite and pyrite. Confined compressive strengths range from 20 to 30kpsi in top section to 60kpsi in lower intervals where dolerite appears. This new technology increased ROP by more than 52% and interval drilled by over 100% through these intervals.
Integrated 3-D Method for Prediction of Mud-Weight Window for Subsalt Well Sections
Authors: Shen Xinpu , Hu Xiaomin , Zheng Xiuyun , Standifird William
Published: March 2015

Owing to the complex distribution of stress directions around a salt body, accurate prediction of mud-weight window (MWW) for subsalt wells has presented a challenge to the industry for a long time. This paper presents an integrated 3-D method for the prediction of mud-weight window. An example of the application of the proposed method in the VK field in deep-water Gulf of Mexico (GoM) is presented. In this integrated 3-D method and the example, 3-D stress solutions obtained by the finite-element method are used as input data to the 1-D prediction tool. The field-scale model used in the calculation is a cubic block with a TVD depth of 30,000 ft, a width of 25,000 ft, and a length of 25,000 ft. The salt body's thickness along the wellbore trajectory is 20,000 ft, and its width is 18,000 ft. Based on seismic sectional data, an anti-cline structure is constructed accordingly at its bottom surface. A 3-D, porous, elastoplastic, finite-element calculation was performed first with the field-scale model. The numerical results of effective-stress components were provided for the 1-D prediction of MWW along the given wellbore trajectory. The finite-element model simulates the geometry of the salt body in detail. Comparisons have been made between the results obtained with the integrated 3-D method, conventional 1-D method, and the finite-element submodeling method. Solutions obtained with conventional 1-D method have missed the abnormality of stress distribution at the salt base and have smaller values of MWW compared to the other solutions. The solution of MWW obtained with the integrated 3-D method is very close to the one obtained with the finite-element submodeling method, but at only one-tenth of the time cost. The integrated 3-D method proposed here has proven to be the most effective and cost-efficient method for MWW prediction for subsalt wells. This work also presents an example of best practice for using the proposed 3D method to predict MWW.
Drillpipe Influence on Drilling Performance
Authors: Herbig Christian , Oueslati Hatem , Hohl Andreas , Reckmann Hanno , Heinisch Dennis , Pessier Rolf , Silva Nalon , Castilho Carlos Alexandre , Gozzi Danilo Signorini
Published: March 2015

Many drilling operations are longer, more complex and harder to achieve. Combined with strict timelines and the demand for higher rates of penetration (ROP), the entire drilling system is being pushed to its physical (loads, bending moment, etc.) and operational limits (drilled formation, drilling parameters, well path, etc.). Exceeding these limits can induce excessive loads and drilling vibrations that can be harmful for the complete drilling systems, including the drill bit, bottomhole assembly (BHA) and drillpipe. Neglecting the drilling dysfunctions can lead to damage, wear and tool failures that finally result in non-productive time (NPT) and higher costs.

Previously published papers concentrated on BHA and drill bit combinations to deliver optimum drilling performance. In this paper, the authors focus on the drillpipe influence on drilling performance and vibration mitigation. Statistics on the influence of stick-slip and ROP for various drillpipe sizes were created and compared. An extensive database containing drilling data, from the past three years, was used as the data source.

To eliminate the effect of various BHA configurations, data from only one high-end standard rotary steerable system (RSS) BHA, without a mud motor, were analyzed. To ensure formation influence on the drillstring dynamics was reduced, only data from horizontal sections within a specific region in US land were considered within this analysis (same target formation).

In addition, a case study from Brazil provides an example where two drillpipes with different diameters were used, resulting in different dynamic behavior. To confirm and understand these observations numerical time domain simulations were performed, analyzed, visualized and compared to the results from the field. The insights gained from the previously described case study and time domain simulations highlight further opportunities to deliver optimal performance and improve bit, BHA and drillstring integrity.
Utilization of Electrical Plasma for Hard Rock Drilling and Casing Milling
Authors: Kocis Igor , Kristofic Tomas , Gajdos Matus , Horvath Gabriel , Jankovic Slavomir
Published: March 2015

Worldwide, the research groups have been dealing with several innovative drilling technologies. Their common aim is to significantly decrease the overall price of the drilling process, particularly to keep the high constant speed, energy efficiency and shorter drilling time. There are above twenty innovative non-contact technologies at different maturity such as: laser, water jet, plasmatorch, ultrasonic, microwave, and several others. However few of them reached Proof-of-the-Concept in laboratory and are currently developed in outside testing sites. This paper presents one of such activities – development of technology based on electrical plasma for hard rock drilling. During its development, another application was identified – milling of steel casing and cement for well Plug&Abandonment operations. Both of these applications are developed by the team of engineers led by the authors.

The electrical plasma-based tool changes completely from its inception the paradigm of the drilling as well as casing milling. The most important advance in comparison to conventional plasmatorch technology is that the electrical arc with temperatures of tens of thousands of degrees Kelvin heats directly the surface, especially the radiation component, with minimalized heating of intermediate gas (the intermediate gas flow in conventional plasmatorches reduces the efficiency of heat transfer into the rock). Moreover, the arc creates area-wide, relatively homogeneous heat flow from spiral arc on the whole surface for high-intensity disintegration process. Compared to conventional plasmatorch technology, electrical plasma-based technology allows the use of electrohydraulic phenomenon, generating shock waves for the destruction and transport of disintegrated material. System also allows obtaining electrical and/or optical characteristics of the arc in the interaction with the rock to derive indirect sensory information (e.g. online spectroscopy for logging while drilling.).

This paper includes the nature of challenges in both application areas – hard rock drilling and casing milling, the description of the developed solutions, the results obtained until now, possibilities of some spin-off technologies using the same core technology concluded by expected impacts. The technology has been tested on various rock types including sandstone, limestone, halite, granite and quartzite. Currently, the demonstration prototype is being tested for drilling of testing borehole in the quarry.
Innovative Hybrid Bit Delivers Breakthrough in a Deepwater Exploration Well on the West Coast of Ireland
Authors: Holub Chase M. , Chiniwala Barzin , Montgomery Jonathan , Buske Robert J.
Published: March 2015

The new hybrid drilling technology which combines the two primary rock failure modes of crushing and shearing was effectively deployed in the challenging drilling environment on the west coast of Ireland. It improved drilling efficiency by reducing the mechanical specific energy (MSE) and mitigating stick-slip and excessive torsional oscillations.

The 12¼-in. section was drilled through a relatively homogenous cretaceous limestone sequence with a small percentage of chert bands. The limestone became progressively harder with depth but remained drillable using the PDC bit. The initial bit, an eight-bladed PDC design, was considered the best choice to drill through the limestone sequence. The initial rate of penetration (ROP) through the top of the limestone was 20 to 30m/hr. After 30 to 40m of drilling, the ROP decreased rapidly to 0 to 2 m/hr over a 10m interval. The bit was pulled. When on surface, the dull condition of the bit confirmed the presence of interbedded chert.

When the hybrid drill bit was run into the hole it drilled an average of 5 to 7m/hr with an instantaneous ROP of 22 to 24m/hr. Isolated chert bands occasionally reduced the ROP to a 3 to 4m/hr range. However, the bit returned to the average ROP upon exiting the chert. The operator, therefore, selected a second identical bit to complete the section. Both hybrid bits endured similar wear on the PDC and TCI cutting elements without any evidence of bearing or seal damage.

The hybrid cutting action generated smoother rotation and lower vibrations throughout the drilling system which improved ROP and extended bit life. The bit thus provided a viable solution to drilling firm limestone with interbedded chert stringers.
Reliable High-speed Mud Pulse Telemetry
Authors: Emmerich Wojciech , Akimov Oleg , Brahim Imed Ben , Greten Alexander
Published: March 2015

Mud pulse telemetry (MPT) has been the dominant measurement-while-drilling (MWD) data transmission technology for more than three decades. Continuous development has enabled the oil and gas industry to drill deep and complex well paths and deliver valuable real-time measurements. With the advent of recent logging-while-drilling (LWD) technologies, the amount of information collected downhole has considerably increased the demand for real-time transmission bandwidth. Driven by this demand, new developments in downhole and surface equipment have made higher data rates available. In addition, reliable high-speed MPT (HSMPT) is needed when utilizing a complex LWD bottom hole assembly (BHA) to deliver answers while drilling.

Transmitting data at high rates introduces new challenges for MPT due to the higher signal attenuation and distortion that occurs when drilling very deep wells with high-density, high-viscosity oil-based muds. This paper describes improvements to the MPT system to overcome these challenges. Optimized surface signal processing and enhanced telemetry sequences are used to automatically tune adjustable filters at the receiver.

These adaptive filters respond to new drilling conditions, adjust for changes in the MPT channel, and test their performance automatically, thereby enabling field personnel to easily make decisions when optimizing decoding quality. Advanced manual options complement these automated processes. The new system has been successfully run in challenging fields in the North Sea. Compared to offset runs, the automated system has significantly increased reliability. Examples of the improved decoding capability and operational performance are provided.

This paper will highlight the necessary changes to further improve reliability for high-speed telemetry to enable real-time log density measurements. The MPT system can enable answers while drilling without having to limit the drill rate in critical sections.
Strain-Gauge Bending-Moment Measurements Used to Identify Wellbore Tortuosity
Authors: Marland Chris , Greenwood Jeremy
Published: March 2015

To determine wellbore tortuosity, the industry uses different methods. Well trajectories can be calculated between survey stations in the wellbore with the resolution of the tortuostity dependent on the survey frequency. Friction factors within the wellbore can be back calculated from surface torque-and-drag information and used as empirical indicators of tortuosity change over the open-hole section. Neither of these previous methods however provides sufficient resolution to accurately quantify the severity and location of the wellbore macro- and micro-tortuosity. The use of downhole strain gauges to identify variations in hole condition and wellbore tortuosity, as well as how they effect the bending stresses in the bottomhole assembly (BHA), has enabled a significantly more accurate method of quantifying this tortuosity.

Downhole strain gauges are used to measure compression and tension, torque, bending moment, and bending-moment direction at specific locations within the BHA. These measurements are used in the following manner to derive the actual downhole values for the following properties: weight on bit uses downhole tension and compression; overpull uses downhole tension; the downhole torque is used to determine how much of the surface power is reaching the BHA and drillbit; and the bending moment of the BHA is used to determine the bending stresses being applied to the BHA. In addition to these accepted methods, the bending moment is used by this new approach to show details of the location and severity of wellbore tortuosity and highlights how the measurement is influenced more by changes in the wellbore trajectory than by the application of compression or tension to the BHA.
Brittle Longitudinal Splits of P-110 Couplings Due to Local Material Defects and Insufficient Control of Material Properties During Manufacturing of High Collapse P-110 Casing
Authors: Koneti Srinivasa , Gokhale Samit
Published: March 2015

Brittle longitudinal splits of P-110 couplings in shale operations cause immense financial loss to oil and gas operators. Unfortunately, there seems to be an increasing trend in these coupling failures, particularly in operations where high-collapse grades of P-110 casing is used.

A common method employed by manufacturers to increase the collapse capacity of P-110 material is to push the yield strength up close to the maximum requirement specified in API Specification 5CT for P110 grade. Sometimes, the yield strength even exceeds the upper limit specified in API 5CT, which increases the hardness of the material, making the couplings more susceptible to environmentally-assisted cracking like hydrogen stress cracking (HSC).

This paper presents case studies of such split coupling failures. In one particular case, metallurgical analysis was performed on both the split couplings and the non-failed couplings from the same string. The analysis indicates a clear trend that correlates the higher coupling strengths to the failure instances.

Split coupling failures can also be caused by local material defects even when the overall fracture surface presents signatures similar to those observed on environmentally-assisted cracking. Case studies of such failures are also presented along with discussions on forensic testing methodology used to identify the cause of failure.

This paper discusses metallurgical testing methods that can be used to identify the local material defects which contribute to longitudinal splits. This paper also presents manufacturing guidelines and specification requirements needed to control the manufacturing processes of the high-collapse P-110 couplings to mitigate split coupling failures.
Drilling Modeling and Simulation: Current State and Future Goals
Authors: Sugiura Junichi , Samuel Robello , Oppelt Joachim , Ostermeyer G. P. , Hedengren John , Pastusek Paul
Published: March 2015

The process of drilling a borehole is very complex, involving surface and downhole drilling systems, which interact with the drilling fluid and the surrounding rocks. Modeling and simulating every aspect of the drilling process and drilling system is still considered too complex to be realized. However, many areas of modeling and simulation are currently undergoing very aggressive development. These areas include rig systems, downhole dynamics, rock-bit interaction, drilling/formation fluid, and the Earth model. High-fidelity models in these well-defined areas have demonstrated some success. Lately, drilling modelling and simulation has become one of the key factors for advancing drilling systems automation/control, intelligent managed pressure drilling and drilling optimization by understanding and/or predicting downhole dynamics.

Modeling the magnitude and spatiotemporal distribution of uncertainty in the actual drilling process poses serious challenges in constructing high-fidelity models of the entire drilling system. However, the advancement of technology may dramatically improve the future of such an attempt to accurately model and simulate the whole drilling process.

The topics presented in this paper include the current state of drilling process simulation software and simulators, the challenges of modelling drilling systems for automation and control, adaptive simulations for downhole drilling systems and the operator's perspective on drilling modelling. This paper examines the current state of drilling modelling and simulation and identifies its future goals.
Drilling with Liner Technology Enables Successful Sidetrack through Depleted Sands in Shallow Water Gulf of Mexico
Authors: Bridgeman Wayne , Salminen Chuck , Rosenberg Steve , Karimi Moji , Shahri Mojtaba P.
Published: March 2015

The maturation of fields in the Gulf of Mexico shelf means that many future sidetracks and recompletions will require drilling through depleted formations. The difficulty of drilling through such formations is especially high when adjoining zones are over-pressured since the mud weight required to maintain overbalance creates significant risk of differential sticking and lost circulation in the depleted zone. Three dump waterflood wells drilled conventionally in 2012 encountered significant problems while drilling the depleted zones. These included lost returns while cementing, hole pack-off and in one case, differential sticking which required the drill string to be severed and a sidetrack to be performed. The three wells incurred an average of 258 hours of associated NPT, which negatively affected project economics and led the operator to evaluate other drilling methods for such depleted sections.

Following a detailed and collaborative planning process between the operator and an integrated service provider, it wasdecided to sidetrack an existing well and use drilling with liner (DwL) method to drill through two depleted sandstone intervals bounded by over-pressured shale zones and cement the liner to facilitate the completion of a dump flood well. There were no observed losses while drilling the entire 577 ft. interval, and also during the cement job with the liner lap testing successfully. An additional benefit was the exceptionally low formation damage observed during the subsequent frac-pack completion as compared to the previous wells. Overall, this operation suggests that DwL is an enabling technology for drilling depleted sands.

In this paper the authors will describe the planning process in detail and will continue to describe how drilling with liner technology was successfully implemented to drill a sequence of depleted sands and over-pressured shale formations in a field where conventional drilling had presented many problems.
Alternate Weighting Material for High Pressured Jurassic Wells in Kuwait - Case Histories of Successful K-Formate Mn3O4 Drilling Fluids
Authors: Jumah Al-Foudari Saud , Al-Muhailan M.S. , Rajagopalan Arun , Al-Qadhi Fahad Khaled
Published: March 2015

Deep wells drilled into the Jurassic formations of Kuwait have long utilized oil based mud (OBM) with barite as the weighting material. However, barite caused considerable damage to the reservoir sections, resulting in reduced production rates. The high oil content in the OBM also prevented recording of good quality image logs, which was necessary to identify the micro-fractures in the reservoir. To overcome these issues, it was necessary to use a water based mud (WBM) with non-damaging weighting material suitable for high pressure conditions.

The existence of high pore pressures and a requirement for mud weights up to 18.5 lb/gal in these wells ruled out the use of conventional WBM. Laboratory tests conducted using a fluid based on Potassium Formate (K-Formate) brine weighted with Manganese Tetraoxide (Mn3O4) as an alternate weighting material. This fluid was successfully applied in a number of deep wells, resulting in increased production rates, up to three times higher than the wells drilled with OBM. Damage to the reservoir was considerably reduced as the wells were easily activated. High quality image logs were also recorded which was not previously possible with OBM. K-Formate-Mn3O4 fluid is a non-corrosive, biodegradable, environmentally friendly fluid, capable of long term storage without degradation of mud properties and recyclable, which reduces fluid cost in subsequent wells.

This paper will review the case histories of twelve deep exploratory wells where the K-Formate-Mn3O4 fluid was applied successfully. Issues including, high rheology encountered while increasing the mud weight using Mn3O4, fluid related complications in drilling and solutions developed to overcome the problems will be discussed in detail. Lessons learned in each deep high pressured well, mud loss scenarios and well control issues will be discussed.

K-Formate-Mn3O4 based drilling fluid has been highly successful in drilling high pressured Jurassic reservoirs in Kuwait. Following the success of the fluid in these wells, it is now being planned to apply in all future deep exploratory wells.