bluuebunny/crossref_metadata_2025 huggingface dataset:
Uso do exercício resistido antagonizado por naloxone como fator de analgesia em sinovite aguda de joelho de ratos Wistar
Authors: Bertolini Gladson Ricardo Flor , Rosa Camila Thieime , Silva Lígia Inez , Meireles Anamaria , Rocha Bruno Pogorzelski
Published: June 2012

A analgesia advinda do exercício físico pode ocorrer via liberação de opioides endógenos, no sistema nervoso central e na periferia. Contudo, a literatura ainda é controversa sobre vias e ações do exercício na dor. Assim, o objetivo da pesquisa foi avaliar se o exercício resistido produz alterações sobre o quadro nociceptivo e se sofre interferências pela aplicação de um inibidor de opioides. Foram utilizados 18 ratos, divididos em três grupos: G1 - hiperalgesia no joelho direito e não tratados; G2 - hiperalgesia e tratados com saltos em meio aquático; G3 - hiperalgesia, com prévia injeção de naloxone e posterior saltos. Para produzir a hiperalgesia, foi injetado no espaço articular tibiofemoral 100µl de formalina 5%. Para avaliação da dor foi utilizado o filamento de Von Frey digital na face medial da articulação tibiofemoral direita. Os momentos de avaliação foram: pré-lesão (AV1), após 15 (AV2) e 30 (AV3) minutos e uma hora (AV4). O exercício foi saltos em meio aquático e ocorreu após AV2. Com sobrecarga de 50% do peso, o animal realizou quatro séries de cinco saltos, com intervalo de três minutos. Para G1, houve aumento nociceptivo, com redução significativa e volta dos valores iniciais em AV4; G2 mostrou, após o exercício físico, restauração do limiar, com retorno aos valores basais; para G3, houve diminuição do limiar, sem restauração ou aumento significativo do mesmo. Conclui-se que houve analgesia com uso do exercício físico e que a mesma foi alterada por bloqueador de betaendorfina.
Developing an operational framework for health policy analysis
Authors: Araújo Jr José Luiz C. de , Maciel Filho Romulo
Published: June 2012

This article develops an original framework supporting health policy analysis that may be carried out by distinct research on various situations. The Walt and Gilson model for health policy analysis and its categories: Context, Content, Actors and Process, was taken as the basic framework of analysis. However, to be applied in practice that model needs to be unravelled. Its four major categories need to be operationalised and transformed into a matrix, with each one revealling the elements or sub-categories, and the necessary procedures to conduct a systematic analysis on the Context, Content, Actors and Process of a given health policy. Such an initiative was treated in this work.
Maturação, composição corporal e aptidão cardiorrespiratória em crianças e adolescentes na área do grande Porto, Portugal
Authors: Leandro Carol , Guerra Sandra , Duarte José Alberto , Mota Jorge
Published: June 2012

OBJETIVOS: determinar, em escolares portugueses de oito a 16 anos (256 do sexo masculino e 268 do sexo feminino): os padrões de mudanças na composição corporal e no VO2máx; a relação entre o percentual de massa gorda (%MG), índice de massa corporal (IMC) e o somatório de dobras de adiposidade subcutânea (SSKF) com o VO2máx; a percentagem de obesos. MÉTODOS: o percentual de massa gorda foi estimado do SSKF (subescapular e tricipital). A amostra foi subdividida em estágios maturacionais de Tanner. A aptidão cardiorrespiratória foi avaliada através do teste Shutlle-run de 20 metros. RESULTADOS: as variáveis antropométricas e o percentual de massa gorda estiveram de acordo com dados já publicados. Os rapazes apresentaram VO2máx mais elevado (p < 0,05) do que as moças na maioria dos estágios. Correlações negativas, moderadas e significativas (p < 0,05) entre o percentual de massa gorda o VO2máx foram obtidas em ambos os sexos, em todos os estágios. Na análise dos três indicadores de obesidade (IMC, %MG e SSKF), 11,2% dos rapazes e 14,3% das moças apresentaram valores acima dos padrões normativos. CONCLUSES: padrões normais de crescimento foram verificados em ambos os sexos. Crianças que apresentaram menor VO2máx também apresentaram maior percentual de massa gorda. Ambos os sexos apresentaram valores sugerindo excesso de gordura corporal no início da adolescência.
Travel plans: a way forward?
Authors: Enoch Marcus , Ison Stephen
Published: June 2012

The travel plan can be defined as a long-term management strategy for an organisation and its various sites or business park; the plan seeks to deliver transport objectives through positive action and is articulated by a document that is regularly reviewed. Importantly, unlike more ‘traditional’ measures, they can be effective at reducing car use while being politically acceptable and relatively cheap and quick to introduce. Given that politicians and their officials have often seen transport problems as being extremely difficult to solve, it is therefore strange that they have seemingly ignored the apparent significant potential of the travel plan. Interviews were undertaken with ten travel plan experts in the UK, the aim being to ascertain their views on the current state of play with respect to travel plans and their predictions for the future. From these a series of recommendations is presented as to how travel plan policy may be conducted in the future.
Improving Horizontal Wells Offshore Operations and Production Management Through the Deployment of Inflow Control Devices in Bouri Field, Libya
Authors: Amari Mustafa , Misherghi Nasser Ali , Algdamsi Hossein Ali , Sharaf Hosam Eldin , Abid Mohamed Lakhdar , Porturas Francisco , Zeglam Schlumberger Adel
Published: June 2012

With the advances made in drilling long horizontal wells over the past decades it has become economically attractive to produce oil from thin oil rims. However, the production from these types of reservoirs presents several challenges. Gas coning is one of the most important ones. Horizontal well drilling traditionally helps to improve the oil recovery and avoid problems of premature gas/water breakthrough. In Bouri field, offshore Libya, the main concern of the operator was to establish an advanced method of controlling gas and water encroachment in a fractured carbonate reservoir characterized by high vertical permeability. This paper describes the first Inflow Control Device (ICD) installation for Mellitah Oil & Gas, and the first such application in Libya Offshore field. It was an integral part of a well completion aimed at evenly distributing inflow in a horizontal well, and at limiting the negative effects after occurrence of expected gas breakthrough. Due to small clearances involved, the ICD deployment presented a significant operational challenge. Despite the higher initial completion costs associated with ICDs, they can provide a cost-effective way to reduce long-term operating costs and increase yield. Production targets are achieved with longer, but fewer wells, maintenance and overhead. From a reservoir management point of view, ICDs can improve the productivity index (PI) by maximizing reservoir contact, minimizing gas coning by operating at lower drawdown, and increasing overall efficiency. Swellingpackers were used to compartmentalize the horizontal and build sections, allowing better drawdown control and eliminating crossflow issues. The completion required re-thinking of the established acid-wash treatment procedures, ultimately improving the overall well clean-up. Integrated analysis methods using steady-state wellbore hydraulic and 3D dynamic simulators were performed to generate flow profiles and calculate ICD pressure drop along the horizontal section. The models were updated using results from logging-while-drilling (LWD) and with real-time modifications to the initial design.

To verify the inflow profile along the length of the ICD completion, production logging (PLT) was conducted. The inflow profiles compared favorably with those predicted by the models.
Cementing in Front of Soluble Salt Zones
Authors: Simão C. A. , Miranda C. R. , Vargas A. A. , Pereira R. F. , Santos R. L. , Soares M. A. , Conceição A. C.
Published: June 2012

Cementing in front Salt Zones requires an appropriate cement slurry design to assure minimum dissolution of the formation by the cement slurry and also minimum deleterious impact on the properties of the cement. The influence of halite on the cement slurry properties is already well discussed in the literature, but there’s no much information regarding the influence of other salts like taquidrite, carnalite, which are much more soluble than halite and are found in Brazil Offshore Fields.

The first stage of the work consisted in evaluating the influence of different levels and types of salt on the hydration process and its effects on the behavior of the main physical properties. It was produced fourteen cement pastes, five of them containing NaCl at the contents of 5, 10, 15, 20 and 36% by weight of water and eight containing KCl at contents of 1, 3, 5, 7, 10, 15, 20 and 34% by weight of water. It was also prepared a cement slurry with no salt added to be used as reference. The dissolution rate of the different salts core formation in these cement slurries was determined. The influence on the cement slurry properties, such as free fluid, thickening time, compressive strength and rheological parameters due to halite, carnalite and taquidrite incorporation were also determined.

This paper presents the studies conducted to design cement slurries for cementing well through salt layers (halite, carnalite and taquihydryte) located in the Aguilhadas Field in Northeast, Brazil. Based on the results, about 500 m of salt were cemented with a semi-saturated cement slurry which provided an excellent quality of the cementing, proved by acoustic logs.

Salt cores of halite, carnalite and taquihydryte were used to determine the dissolution rate of salt into the cement slurry. X-Ray tomography was used to visualize and to quantify the salt dissolution in the dynamic tests.

The shear bond strength between halite core and hardened cement slurry with 15% NaCl was determined showing good results.
Reaming on Demand - Selective Activation of an Integrated Under Reamer at the Grane Field in the North Sea
Authors: Pragt Jos , Herberg Wolfgang , Meister Matthias , Clemmensen Carl , Grindhaug Gaute , Hanken Knut
Published: June 2012

The Integrated Under-Reamer (IUR) was developed in 2007 in a joint project between an Operator and Service company. The tool was designed to allow for unlimited opening and closing of the tool to provide selective hole opening in unstable formations e.g. unstable shale or swelling salt. Furthermore the tool should be able to close for pull out of hole (POOH) while keeping the circulation continuously on.

To accommodate for this the tool was designed to be fully integrated into the modular bus structure of the downhole BHA. Electronics were developed to activate and deactivate the tool from downlink commands sent downhole and distributed via the communication bus to the IUR. Sensors in the IUR detect the status of the tool: such as position of the cutter blades and the health of the tool. This data is transmitted to surface using the MWD pulser. The data is displayed in real-time for immediate review by the drilling team. Additional diagnostic data are stored in memory for post run analysis.

Advanced autonomous fail safe control was designed to make sure the tool can always be closed either by downlink or other procedures to allow unrestricted pulling out into smaller hole or the casing shoe. In the case of communication problems a procedure is available for back-reaming with automatically closing the blades.

A case history is presented where a water injection well needed increased clearance to run 6 5/8" completion screens. Using the IUR, the well was opened up while drilling from a 8 ½" pilot hole to 9.05". The IUR was de-activated and re-activated successfully several times during drilling the section. The operational procedure is described, and caliper data are presented. The well was completed on plan. At the end an outlook will be given on future reaming on demand applications.
Offshore ESP Selection Criteria: An Industry Study
Authors: Romer Michael C. , Johnson Mark E. , Underwood Pat C. , Albers Amanda L. , Bacon Russ M.
Published: June 2012

Most offshore wells that require artificial lift are gas lifted, as gas typically is readily available and compared to other lift systems, gas lifting is relatively inexpensive and low maintenance. However, electric submersible pumps (ESPs) can efficiently and economically increase oil production and reserves recovery under the appropriate operating conditions. This may translate to a lower abandonment pressure in the long term—possibly reducing the total number of wells required to deplete an asset.

Since few ESPs currently are installed in offshore wells, an ESP screening "Rules of Thumb" was created as a simple guide for prioritizing offshore ESP candidates. The selection criteria focus on feasibility of installation, operability conditions and operating practices to maximize run life, and economic considerations. ExxonMobil† and industry experience from North America, South America, West Africa, Asia, Australia, the Middle East, and the North Sea provided the basis for the study.
Development and Characterization of a Modified Polymeric Material for HP/HT Downhole Sealing Applications
Authors: Ren Jiaxiang (Jason) , Gerrard Dave , Duan Ping , Vu Chau , Leung Hoi Yin
Published: June 2012

Emerging ultra high-pressure/high-temperature applications in downhole service have created the need for the development of new sealing materials. To address this emerging need, a series of modified polymeric materials were developed. The new material displayed strong mechanical properties below glass transition temperature (Tg). Above Tg, the material displayed stable elastomeric properties up to 400° C. The thermal rating of the material is beyond the available commercial thermoplastics and elastomeric materials. Furthermore, the Tg of the material can be adjusted from 97° C to 215° C. The material was aged in a crude oil at high temperature. Dynamic Mechanical Analysis (DMA) measurements were performed on the material before and after aging. The material displayed excellent resistance to the crude oil. In addition, API extrusion-resistance measurements were performed on the new material at various temperatures and various pressures. The extrusion resistance of the new material was superior to the available commercial elastomeric materials, including perfluoroelastomers. Thus, the material has great potential for use in emerging high-temperature sealing applications and other oil and gas applications. This paper describes the work involved in conducting this development work and test results.
The Application of Light and Ultra-Light Weight Proppant in Horizontal Well Sand Control: Unified Model and Case Histories
Authors: Chen Zhongming
Published: June 2012

Unconsolidated sand reservoirs, with the characteristics of high permeability, large porosity, and low fracture gradient, are common and present challenge sand control tasks facing completion engineers. Avoiding fracturing such formation and preventing excessive fluid leakoff are the primary concerns to achieve successful gravel placement during job execution. Gravel packing these wells needs innovative technologies and practices. The light and ultra-light weight proppants, with their unique properties and advantages over conventional gravel, are important options to ensure wellbore be successfully packed under low pump rate.

Light and ultra-light weight particles transport phenomena and their Alpha and Beta wave packing behaviors were studied. An unified particle transport model is developed to accurately model Alpha and Beta wave behaviors. The paper presents the validation of unified model by wide ranges of field case histories under different pump rates and particle over fluid density ratios. Particle density and geometry, fluid properties, and wellbore configuration are the dominant factors to affect wave building up process. The paper presents the guidelines to design proper pumping schedule and optimal Alpha wave dune height under given well condition.

Carrying fluid leakoff and excessive Alpha wave dune height are the causes of many early time screenout and job failures. Underachieved gravel packing will reduce the effectiveness of sand control and result in screen damage during early production. Job histories are presented in the paper to demonstrate the practical considerations of job design and execution, and the use of light and ultra-light weight proppant over conventional gravel to ultimately increase the effectiveness of sand control.
Advantages of Integrating Geomechanics Modeling and Hydraulics Modeling in Well Planning and Execution
Authors: Hargis Virgil , Fowler William
Published: June 2012

Geomechanics and hydraulics modeling are commonly used to optimize drilling performance and to reduce non-productive time (NPT). The geomechanics model indicates safe mud weight parameters, optimum casing points, and wellbore stability analyses. The hydraulics model simulates the wellbore and drilling fluid parameters to optimize the flow rate and rate of penetration (ROP) within equivalent circulating density (ECD) constraints. Real-time drilling data are used to update the models: the pore-pressure/shear-failure gradient and fracture gradient boundaries for geomechanics; and ECD, circulating system pressure drops, and annular cuttings load parameters for hydraulics. Each real-time model strives to ensure that operations are optimal, safe, and cost effective, as well as to provide updated models for future planning purposes.

This paper focuses on collaboration between geomechanics and hydraulics analysts in the planning, drilling, and postdrilling phases of the well. A geomechanics model determines the safe mud weight operating window and casing points, whereas the hydraulics model simulates ECD for defined mud properties, drilling parameters, and wellbore geometry. A synthesis of the two models enables the previously mentioned information to be compared and merged before spudding the well. Real-time collaboration between models enables each model to be updated with pertinent information from the other, ensuring that drilling operations are performed within optimum mud weight and ECD constraints. The geomechanics model can use real-time ECD data from the hydraulics model when a pressure-while-drilling (PWD) tool is not being used. In turn, the hydraulics model requires updating when the safe mud weight limits are being exceeded. The two models can each use information from the other when performing the post-well analysis and planning for the next well. Both models are valuable tools when used individually, but they become powerful, superior companions when used in conjunction with one another.
A Comprehensive Theoretical and Experimental Study on Fluid Displacement for Oilwell Cementing Operations
Authors: Aranha Pedro Esteves , de Miranda Cristiane Richard , Cardoso Walter F. , Campos Gilson , Martins André Leibsohn , Gomes Frederico C. , de Araujo Simone Bochner , Carvalho Marcio S.
Published: June 2012

Displacing fluids in downhole conditions and for long distances is a complex task, affecting several steps on well construction. Cementing gains relevance in the moment that fluid contamination compromises cement sheath integrity and consequently zonal isolation.

Density and rheology design for all the fluids involved are essential to achieve operational success. Properties hierarchy and preferred flow regimes have been empirically defined and tend to provide reasonable generic results. Challenging operations, including ultra deepwaters and their narrow operational windows scenarios, require further knowledge of the physics involved in order to prevent undesirable events

This article presents the in house development of a software for annular two-phase flow, which analyzes fluid displacement in typical vertical and directional offshore wells, for Newtonian and non Newtonian liquids, laminar and turbulent flow regimes. The formulation proposed provides accurate results for a wide range of input parameters, including the cases in which the ratio between the inner and outer radii of the annulus is small. Operational guidelines for fluid and placement schedules are provided.

The computational work is validated by unique results obtained from an experimental test rig where detailed displacement tests were conducted. Contamination degrees were measured after the displacement of a sequence of fluids through 1192 m of vertical well. Effect of fluid density and rheology hierarchy, flow regimes and displacement concepts were investigated. The results provide relevant information for the industry and fundamental understanding on displacement of Newtonian and non Newtonian liquids through annular sections.
Centralizer Selection and Placement Optimization
Authors: Liu Gefei , Weber Lawrence
Published: June 2012

Casing centralization is one of the key elements to ensure the quality of a cementing job by preventing mud channeling and poor zonal isolation. Centralizers can also assist in running of the casing and prevention of differential sticking. The challenge that both operators and service companies face is to place the right amount of centralizers at the optimum positions on the casing. While operators may be conservative, service companies tend to be liberal, in selecting the number of centralizers for a given application.

Casing standoff depends on well path and hole size, casing size, centralizer properties, and many other variables, but most importantly, centralizer placement. Experience plus computer modeling enable both centralizer vendors and operators to conduct centralizer optimization prior to field execution. One approach is to specify spacing using our experience, then let software check if it yields satisfactory standoff profile. Alternatively, we can specify required standoff and let the software tell us how to space centralizers. "Specify spacing" mode gives the simple-to-install centralizer placement because of its constant spacing result. However, this method may compromise the quality of standoff or quantity of centralizers. "Specify standoff" mode ensures the minimum standoff of casing between centralizers, while yielding difficult-to-follow placement program.

To get the best elements from both approaches, we have developed an optimum placement solution, which is specifying standoff with incremental spacing requirement. For high impact operations such as deepwater and use on inline bowspring centralizers, once a casing schematic is available, the centralizer placement is re-evaluated to optimize exact placement of each centralizer.

With the help of computer modeling, centralizer placement can be evaluated and optimized. This practice will result in better cementing job and cost-effective centralizer placement for directional wells. This paper will report examples of how such optimization can be achieved.
Borehole Instability in Tertiary Shales in the Norwegian North Sea
Authors: Nes Olav-Magnar , Bøe Reidar , Sønstebø Eyvind F. , Gran Kjetil , Wold Sturla , Saasen Arild , Fjogstad Arild
Published: June 2012

Severe hole stability problems were encountered in a recent exploration well in the Norwegian North Sea. The problems occurred when drilling through Tertiary shale sections interbedded with permeable sand layers. Drilling was initially performed with water based drilling fluid. However, being unable to reach the section target after more than two weeks of operation, the section was plugged back and a sidetrack was drilled using an oil based drilling fluid without encountering major operational problems.

On the basis of the post-drill analysis of drilling data, well logs, drill cuttings and borehole cavings sampled from the well, this paper describes how the complex combination of drilling fluid salt concentration and geological constraints may be utilized to ensure successful future drilling operations in this part of the North Sea.

Cuttings and preserved cavings collected during the drilling operation were selected from several depth intervals identified as potentially troublesome from drilling experience and log data. Determination of cuttings mineralogy enabled better prediction of how the time dependency of the stable drilling fluid density window is influenced by interaction between the shale and the drilling fluid. Mechanical strength is a key input parameter when predicting borehole stability. Dedicated rock mechanical punch measurements on cavings were used to confirm the prediction of strength from log data alone. Examination of caving surfaces revealed the possible presence of in-situ fractured rock. Such fractures would require special measures while drilling to maintain stability.

Subsequently a borehole stability sensitivity analysis was performed focusing on time dependent stability in the shale formations. The analysis used cuttings and cavings properties and logs as input. In particular, the modelling showed how the optimum KCl concentration in the drilling fluid changes with depth. The modelling further identified a relatively large sensitivity towards borehole inclination – even at fairly small inclinations. This paper thus illustrates the significance of properly accounting for rock mechanical aspects when planning new wells.
Thermally Insulated Tubing Application to Prevent Annular Pressure Buildup in Brazil Offshore Fields
Authors: Ferreira M. V. , Santos A. R. , Vanzan V..
Published: June 2012

Heat transfer issues in offshore wells construction and maintenance are increasing in last years. New production development scenarios are bringing challenges related to flow assurance, well construction and maintenance. Insulation projects are being considered to enable the oil and gas production. This paper presents the studies carried out in two projects of thermal insulation using VIT (Vacuum Insulated Tubing) technology and its structural and thermal evaluation using commercial software for numerical simulation.

The present work aimed to evaluate VIT application in a production string to reduce APB (Annular Pressure Build-up) effects. This event happens when production flow is heating any well confined annulus causing its fluid expansion and increasing pressure inside it. In this way, annular pressure build up can lead casing collapse or burst even, in an exteme condition, production string damage. All these effects combined could lead to unacceptable well losses. VIT is uded to avoid APB effects.

However, a VIT string isn’t be able to provide a smiliar collapse and burst resistance than a usual same dimension tubing string. So VIT will dominate the string installation and production constraints due its back pressure lacking. In this way production string performance evaluation is a key issue on VIT design, length and technical specification.

In order to evaluate the performance of the production string designed for two Petrobras projects, several numeric simulations were performed to evaluate loads and strains on intermediate casing and production string during its installation and well production, including the APB events.

In addition, the length of pipes with insulation needed to mitigate the effect of AFE was defined and a sensitivity analysis performed to define the value of the minimum apparent thermal conductivity, which would allow operation without risk to well integrity.
The Effect of Equivalent Diameter Definitions on Frictional Pressure Loss Estimation in an Annulus with Pipe Rotation
Authors: Anifowoshe Olatunbosun , Osisanya Samuel O.
Published: June 2012

Annular flow of non-Newtonian fluids remains a ubiquitous phenomenon in drilling operations but accurately estimating the frictional pressure loss with drill pipe rotation still poses a great challenge. Since annular frictional pressure losses increases the equivalent circulating density (ECD), it becomes imperative to accurately estimate the annular pressure loss in order to keep the ECD above the pore pressure and below the fracture gradient especially in deep offshore drilling where the pore pressure and fracture pressure are so close together.

When annular flows are encountered, a common practice is to calculate an effective diameter such that the flow behavior in a circular pipe would be roughly equivalent to the flow behavior in the annulus. This equivalent diameter definition replaces the diameter term in the friction factor, effective Reynolds number and Taylors number equations used for pipe flow thus resulting in different frictional pressure loss estimation. As a result, the selection of appropriate correlation for the respective fluids, flow regimes and putting into consideration pipe rotation has become important but has received very little attention.

In this study, the seven different equivalent diameter definitions used for estimating frictional pressure losses in an annulus were reviewed and theoretical analysis were performed on experimental data obtained from literatures to determine the effect of these definitions on wellbore hydraulics. Pressure loss ratios (PLR) which relates pressure loss with pipe rotation to pressure loss without pipe rotation weredevelopedfor each equivalent diameter definitionusing dimensional analysis techniques. These hydraulic models combined with conventional frictional pressure loss estimation were tested with experimental measurements to determine the model with an equivalent diameter definition that best predicts frictional pressure losses for power law fluids.
Modeling Dynamic Behavior of Bottom Hole Assemblies Containing an Underreamer
Authors: Ishak G.. , Daily J.. , Miska S.. , Mitchell R..
Published: June 2012

Reaming while drilling can be a more economical drilling technique than conventional drilling. Downhole failures can occur for a variety of reasons, and failure as a result of excess dynamic loading on the bottom hole assembly (BHA) components may be the most mysterious. One of those mysteries is the static and dynamic distribution of axial load between the bit and the reamer. This paper presents an approach using the explicit finite element method to model the static and dynamic interactions between the bit, the reamer and the formation of the BHA.

The results for axial displacement from the explicit finite element method are compared to theoretical results for a selfweighted column. Also, the axial vibrations are compared to the theoretical natural frequencies. Once the comparison showed the explicit FE method gives the same theoretical results, the model is expanded to better reflect actual downhole conditions. The model includes a bit and a reamer from which the interaction can be studied with an emphasis on axial loading. A weight dependent velocity boundary condition is used to model formation penetration of the bit and reamer. This models the relationship between the axial load on the reamer and the bit. This so-called drill-ahead model can be used to better understand the dynamics of the BHA.

Results from this study show the amplitude of the axial oscillating force on the reamer was greater than that of the force on the bit. Drilling with a more aggressive reamer will decrease the side forces on these components for the case studied. In addition, for a change of load at the top of the model, the reamer can take more of the transient load than the bit.
A New Buckling Severity Index to Quantify Failure and Lock-up Risks in Highly Deviated Wells
Authors: Menand S..
Published: June 2012

Buckling of tubulars inside wellbore has been the subject of many researches and articles in the past. Evidences in the laboratory and in the field have shown that existing buckling criteria (sinusoidal and helical buckling) have to be challenged, as they fail to predict the onset of buckling phenomenon in complex or unconventional wells drilled today. Indeed, existing buckling criteria assume generally that the wellbore is idealistically perfect without any dog legs. Recent advancements in drillstring mechanics modelling has demonstrated that dog legs, friction and rotation affect greatly the buckling phenomenon. Buckling does not imply necessarily failure neither lock-up, but indicates the onset of a condition that may generate poor drilling performance that could lead to failure or lock-up. In this paper, one proposes a new buckling severity index that quantifies the severity of the buckling phenomenon enabling drilling engineers to take appropriate decision.

A fully validated numerical buckling model has been used to derive a new buckling severity index based on the risk of drill pipe failure or lock-up. This index ranges from 1 for acceptable buckling condition with low risk of failure, to index 4 for severe buckling with high risk of failure or lock-up. This new buckling severity index has been compared to well-known sinusoidal and helical buckling loads in a few case studies, and demonstrates that past buckling criteria should be used very cautiously.

This paper proposes an update of past conventional buckling criteria in recommending a new buckling severity index that enables to quantify the risks of failure or lock-up in unconventional and deviated wells. These new results presented in this paper should improve significantly well planning and operational procedures to drill and operate increasing complex wells.
Anomalous Behaviors of a Propagating Borehole
Authors: Perneder Luc , Detournay Emmanuel
Published: June 2012

This paper uses a novel directional drilling model to explain seemingly anomalous behaviors of the evolving geometry of a borehole. The two cases of a BHA without and with a push-the-bit RSS are considered.

The directional propagation of a borehole essentially depends on the bending of the BHA, which is constrained to deform within the borehole, and on the interaction between the drill bit and the rock formation. The directional model is used to illustrate, through theoretical examples, the consequence of the interrelation between these two elements of the problem. Also, a small set of dimensionless parameters governing the behavior of the directional drilling system is derived. They contrast properties of the bit/rock interface laws with those of the BHA.
Resilient Lost Circulation Material (LCM): A Significant Factor in Effective Wellbore Strengthening
Authors: Savari Sharath , Whitfill Donald L. , Kumar Arunesh
Published: June 2012

High resiliency graphitic carbon lost circulation material (LCM) is one of several graphitic materials that achieve varied success. Effectively controlling loss of circulation (LC) is more than just selecting LCM and requires an engineered approach. Particulate LCM like ground marble, graphitic carbon and cellulosic fibres have been widely used but careful consideration should be given to how these materials are combined based on fracture types. Induced fractures created when the equivalent circulating density (ECD) exceeds the formation fracture gradient or during wellbore strengthening applications, could be "pressure-sensitive" as reported in fracture closure studies (Dupriest 2005). Resilient graphitic carbon (RGC) has many unique properties (Whitfill 2003) that can be exploited in lost circulation scenarios.

Laboratory methods developed to characterize the resiliency of different graphitic carbons are presented, and the lack of resiliency of other LCM is demonstrated. RGC also imparts resiliency to other LCM combinations (Kumar 2010). Resiliency associated with RGC can be enhanced in an LCM combination that exhibits a granular nature, rather than forming a solid plug. RGC also imparts crush resistance to other more brittle LCM and can help reduce attrition, thereby retaining particle size for effective wellbore strengthening, while also acting as a solid lubricant.

RGC is manufactured in a proprietary two-stage furnace process that produces 99.9% carbon content. It is conductive material with no magnetic properties, so it does not interfere with logging tools (e.g., density and neutron) and other downhole equipment. RGC is suitable for use in reservoir sections because it is completely inert and may be combined with acid-soluble ground marble to allow flow back.

The paper includes field and laboratory data that validate RGC characteristics related to resiliency, lubricity, resistance to attrition, and compatibility with downhole tools, making it a versatile material for most LCM combinations for LC control and wellbore strengthening applications.
Modeling Dynamic Shock Loads for High-Pressure/Deep-Water Tubing-Conveyed Perforating Operations in the Gulf of Mexico
Authors: Giunta Rick , Le Cam , Schoener-Scott Martin , Anderson Ryan , Glass Joshua
Published: June 2012

Good perforating design is essential in maximizing the value that can be pulled from the reservoir. Poorly-planned and/or executed perforating strategies in high-pressure, deep-water wells can easily increase operational costs and reduce production and revenue streams.

With the increased demand for oil and gas over the last decade, operators have been forced to explore deeper to find the most prolific reservoirs to meet this growing need. In the U.S. Gulf of Mexico, these deep-water opportunities have required constant improvements to equipment and services to increase their technical capabilities for performing in more critical environments while minimizing non-productive time (NPT). Higher shot densities, propellants, larger perforating guns, electronic firing heads, shrouded assemblies, and dynamic shock modeling have been used to meet these new challenges.

A major problem with these deep wells is the increased cost it takes to develop them. The use of more powerful perforating systems to increase flow area is required to maximize well productivity and recoup this cost. With the use of such systems comes the additional explosive load and the difficulty in predicting dynamic wellbore behaviors that could cause tubulars to burst, collapse, bend, buckle, and shear, as well as tubing to move excessively, packer seals to fail, and packers to unset as perforating guns are detonated.

Understanding and mitigation of dynamic events at gun detonation, in addition to solid loading imparted to the tubulars, packers, and other completion hardware in the perforating assembly, were needed if the industry was to continue exploring new frontiers with complex challenges. A high-confidence level was needed to use these larger gun assemblies to go forward with these well completions without incurring NPT.

This paper discusses a successful execution of a high-pressure, deep-water shoot-and-pull job with a custom-designed bottomhole assembly to address casing integrity challenges and the dynamic shock-modeling software program that evaluates the mechanical integrity of all well components.
Challenges Associated with Drilling a Deepwater, Subsalt Exploration Well in the Gulf of Mexico: Hadrian Prospect
Authors: Moyer Mark C. , Lewis Scott B. , Cotton Mike T. , Peroyea L. Miles
Published: June 2012

The Hadrian-5 prospect in the United States (US) Gulf of Mexico’s Keathley Canyon 919 block was drilled by the operator in ~7000-ft water depth as one of the first Gulf of Mexico wells drilled after the deepwater moratorium. This exploration well was permitted under the new regulatory requirements of the US Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE). These new requirements included additional blowout preventer (BOP) certification and testing, incorporation of selected API recommended practices, and certification of the well design by a registered professional engineer.

In addition to the well design regulations, BOEMRE required operators to calculate a worst-case discharge scenario and develop plans to contain that scenario. Well containment plans were developed that included the newly-formed Marine Well Containment Company’s (MWCC) response capabilities.

The well was drilled between March and August of 2011 to a total depth (TD) of 19,631 ft and encountered several hydrocarbon intervals that were safely managed. The rig selected for this well was the dynamically-positioned (DP), Maersk Developer semisubmersible.

This paper describes the planning, permitting, and execution of this challenging well. Topics covered include:

New permitting requirements for federal waters in the US Worst-case discharge scenario and impact on casing design Elimination of trapped annular pressure via well design Minimizing vibrations in the tuff formation of the Hadrian mini-basin Managing the uncertainties associated with sub-salt formation pore pressures Drilling and casing mobile tar zones

The well was drilled and evaluated in a safe manner with no significant incidents even though the geologic formations encountered were different than predicted.
Efficiency of Removing Filter Cake of Water-Based Drill-in Fluid Using Chelating Agents Utilizing a CT Method
Authors: Elkatatny S. M. , Nasr-El-Din H. A.
Published: June 2012

Hydrochloric acid, organic acid, or a mixture of these acids is used to remove filter cake, which consists mainly of calcium carbonate. However, the use of these acids in horizontal and deep wells has some major disadvantages, including high and uncontrolled reaction rate and corrosion to well tubular. To overcome these problems, chelating agents are used in oil and gas wells.

Extensive lab studies were done to determine: 1) the compatibility of various chelates with α-amylase at different pH values, 2) the optimum pH that should be used to remove filter cake, 3) the efficiency of filter cake removal using a modified HPHT filter press, 4) the return permeability of sandstone and limestone cores, and 5) assess the potential of formation damage using a computer tomography scanner. All of these tests were conducted at temperatures up to 225°F.

The results obtained showed that chelate solutions, GLDA (pH of 3.3 - 13) and HEDTA (pH 4 and 7) were incompatible with α-amylase solutions over a wide range of temperatures. At high pH, various chelates had removal efficiency of 40% and retained permeability of 30%, which indicated formation damage. To solve this problem, 20 wt% of the chelating agents at low pH (3.3 - 4) were used to remove the filter cake without the enzyme stage. The results obtained showed that the retained permeability increased to 85% for limestone cores and 110% for sandstone cores. The removal efficiency of the filter cake was 100% for limestone and sandstone cores. CT results showed that no formation damage was observed when using chelating agents as a breaker to remove the filter cake.
Wireless Reservoir Surveillance In Deepwater Completions
Authors: Williams Brock , Brough Brent
Published: June 2012

Deepwater developments are very high cost ventures in complex reservoir environments. Acquiring insight into the reservoir inflow distribution and location of water inflow using conventional technology, such as production logging tools, is very problematic in the deepwater environment where wireline intervention into live wells is a major risk and cost.

Intelligent chemical tracers are an emerging technology that provides insight into the inflow distribution without intervention operations or major alterations to the completion design. The tracers consist of unique chemical compounds that are combined with unique polymer formulations into a matrix that resembles strips of plastic. The matrix is designed to release the tracer when contacted by the target fluid, either oil or water.

The matrix strips are deployed with the initial completion installation at strategic locations in the completion so that fluids entering the completion contact the matrix. At the surface, samples of the produced fluid are acquired and analyzed for the presence and concentration of each unique tracer that has been deployed in the completion. The concentration data is plotted vs time or produced volume. Analysis of these plots can yield answers to very valuable reservoir management questions such as:

Are all the intervals producing? What is the relative contribution of each interval? Where is water break-thru occurring?

Deepwater completions are frequently completed with sand screens. The typical sand screen design contains spaces where the tracer can be integrated without any changes to the design. If the screen design is not readily compatible with the matrix strips, specially design tracer carrier mandrels can be added to the completion.

The passive nature and very low risk of deploying this technology is very attractive in deepwater wells.

This paper reviews the fundamentals of intelligent tracer technology, methods of integration into deepwater completions and some field examples previous deployments.
Modeling of Axial Vibrations to Allow Intervention in Extended Reach Wells
Authors: Wicks Nathan , Pabon Jahir , Auzerais Francois , Kats Roman , Godfrey Matthew , Chang Yong , Zheng Andrew
Published: June 2012

There are a significant number of extended reach wells that cannot be effectively intervened to total depth due to tubing string lock-up. If the horizontal section of the wellbore is sufficiently long, the axial compressive load needed to convey the tubing into the wellbore will cause the tubing to buckle. Buckling initiates in a sinusoidal mode and progresses to a helical mode. Once the tubing buckles helically, the string quickly locks-up due to increased normal forces and frictional interaction with the wellbore. We have developed an innovative technique to model extension of tubing conveyance in deep wells.

Several commercial vibration devices attempt to extend intervention depths in extended reach wells. One of the primary modes of vibration employed in these devices is axial. We developed a simulation tool to enhance understanding of how axial vibration devices extend reach. In the first section, we introduce a 1D finite rigid body dynamic model. This computational tool models the propagation of axial excitation in the presence of borehole frictional contact. A Coulombic dry friction law describes the interaction between tubing and borehole wall. 3D static computations precompute static axial loads and contact forces that serve as inputs to the 1D model. This allows the user to predict the behavior in complex 3D wellbore trajectories and to simulate several dynamic scenarios in a matter of minutes. In the second section, the behavior of axial excitation in the presence of frictional contacts is explored with the model. Simulations predict the distance of axial vibration propagation along a tubing string in a wellbore. A simple relationship is postulated that captures the axial wave propagation length as a function of axial excitation and tubing/borehole parameters. Modeling results demonstrate a mechanism by which axial vibration can extend reach. Synthetic case studies show the possible reach extension for prescribed axial load excitations. Results from a scaled experimental setup demonstrate the mechanism seen in the simulations.