bluuebunny/crossref_metadata_2025 huggingface dataset:
Entre o planejamento estratégico formal e informal: um estudo de caso exploratório sobre a prática de estratégia nas organizações
Authors: Souza Caio Motta Luiz de
Published: September 2011

Grande parte dos estudos sobre formação estratégica possui um elemento contingencial constitutivo que estabelece variáveis por meio das quais é possível ordenar as organizações de forma a indicar qual o tipo de formação estratégica é adequada a cada uma delas (e.g. Mintzberg & McHugh, 1985). Esta ordenação quase prescritiva sobre o conteúdo, o processo e a prática de estratégia nas organizações pode causar a percepção de que é possível determinar o padrão de formação estratégica de uma organização pela simples análise de algumas variáveis pré-determinadas. Guiado pela abordagem de estratégia como prática (Jarzabkowski, 2005, 2008; Whittington, 1996, 2006), este trabalho explora a prática de planejamento estratégico com base num estudo de caso exploratório em uma empresa organizada por projetos, por meio do qual foi possível identificar processos de mudança que configuraram diferentes fases de aplicação dessa prática ao longo dos anos com características distintas de (in)formalidade. Analisando o caso por meio uma abordagem baseada na teoria da estruturação (Giddens, 1984), indica-se que, se há um nível adequado de formalização da prática de planejamento estratégico nas organizações, este nível deve ser definido pela estruturação da prática na sua dinâmica social.
Teoria da reciprocidade e sócio-antropologiado desenvolvimento
Authors: Sabourin Eric
Published: September 2011

No momento em que o ensino da sociologia do desenvolvimento está declinando nas universidades européias e, em menor grau, nas latino-americanas, afirma-se uma renovação da teoria da reciprocidade, precisamente nesse campo e no da economia social, a partir da antropologia e da sociologia econômica. O artigo trata, portanto, da contribuição da teoria da reciprocidade para a sócioantropologia do desenvolvimento. Divide-se em duas partes. A primeira apresenta brevemente os precursores e os fundamentos da teoria da reciprocidade. A segunda ilustra, a partir de alguns exemplos contemporâneos, a aplicação dessa teoria à sócio-antropologia do desenvolvimento rural. As considerações finais tratam dos limites e novas perspectivas heurísticas dessa teoria.
Rumo ao desenvolvimento espacial sustentável? Explorando as implicações da nova bioeconomia no setor agroalimentar e na inovação regional
Authors: Horlings Ina , Marsden Terry
Published: September 2011

O paradigma da bioeconomia pode ser descrito como o conjunto das atividades econômicas que captam o valor latente em processos biológicos e nos biorecursos renováveis, para produzir melhores condições de saúde, além de crescimento e desenvolvimento sustentáveis. Este artigo faz uma revisão crítica do impacto da bioeconomia emergente sobre o desenvolvimento rural. São descritas algumas das consequências do desenvolvimento rural bioeconômico, na esfera agroalimentar e da inovação regional baseada em uma definição específica -e, de nosso ponto de vista, fraca -de Modernização Ecológica. A questão central, então, é: quais são as bases conceituais, a força impulsora, as expressões empíricas e as implicações do desenvolvimento bioeconômico? Argumenta-se que, embora a bioeconomia faça duras cobranças em relação à sustentabilidade, também deixa lacunas, apresenta al-guns efeitos secundários negativos, tanto ambientais como sociais, e corre o risco de ser uma economia parcial. Sustentamos, ainda, que a trajetória do desenvolvimento ecoeconômico pode constituir uma boa alternativa para localidades particularmente vulneráveis que queiram aumentar sua resiliência.
Leitura: entre leitor e texto
Authors: Hillesheim Betina , Cruz Lílian Rodrigues da , Cavagnol Karen Cristina , Marquetto Virgínia da Silva
Published: September 2011

O artigo propõe discutir os sentidos que o ato de ler assume, abordando os diferentes entendimentos sobre a leitura e a relação entre leitor e texto. A leitura aqui é entendida como uma experiência que cancela a fronteira entre o que sabemos e o que somos. Propomos pensar na questão deste encontro entre leitor e texto: o que se passa entre estes mundos? Considerando-se que o texto se constrói no encontro com o leitor, na relação entre um e outro, não se pode dissociar texto e leitor; assim, para além de uma noção de troca, deparamo-nos com novas combinações.
A política empresarial: a responsabilidade social como mecanismo de segurança
Authors: França Sonia Moreira , Zanetti Fernando
Published: September 2011

Neste ensaio, tomamos como problema as ações da política empresarial no Brasil, em específico a política de responsabilidade social das empresas, por entender que existe nessa iniciativa um status de inovação tecnológica que precisa ser interrogado, pois se inscreve no interior de uma racionalidade que objetiva o governo das populações e tem como instrumento técnico, para realizar esse fim, uma sociedade controlada por mecanismos de segurança. Para tanto, partimos da análise de três procedimentos efetivados por alguns projetos sociais desenvolvidos por empresas brasileiras - a pesquisa científica, o protagonismo juvenil e a metodologia participativa. A referência de análise são textos de diversas naturezas, veiculados por esses projetos e disponíveis ao acesso público.
Will Imatinib Compromise Reproductive Capacity?
Authors: Zamah Alberuni M. , Mauro Michael J. , Druker Brian J. , Oktay Kutluk , Egorin Merrill J. , Cedars Marcelle I. , Rosen Mitchell P.
Published: September 2011

Imatinib mesylate is the first in a family of highly effective, minimally toxic, targeted agents used widely to treat Philadelphia-positive leukemias and selected other cancers, leading to a steady rise in the prevalence of patients using such therapy. Because failure of therapy would require conventional gonadotoxic chemotherapeutics, many female patients using imatinib may choose to preserve fertility. Herein, we provide evidence of a potential negative effect of imatinib on ovarian function by reporting the first case of a woman who showed a severely compromised ovarian response to gonadotropin stimulation while on imatinib, with a normal ovarian response after stopping this medication.
Reaction of GLDA with Calcite: Reaction Kinetics and Transport Study
Authors: Rabie Ahmed I. , Mahmoud Mohamed A. , Nasr-El-Din Hisham A.
Published: September 2011

Chelating agents have been used in the oil industry as iron control agents and scale removers, and recently as effective stand-alone stimulating fluids in matrix acidizing, especially for deep wells where using hydrochloric acid is restricted due its corrosion problems. The ultimate goal from using chelating agents is to create highly conductive wormholes that connect the formation to the wellbore. Glutamic acid diacetic acid (GLDA) is a new chelating agent that can be used for this purpose. The objective of this work is to study the reaction of GLDA with calcite and investigate the effectiveness of the created wormholes by both kinetics and transport studies that have been performed experimentally in the laboratory.

The reaction of GLDA with calcite was investigated by measuring the rate of dissolution using the rotating disk apparatus. The effect of initial pH (1.7, 3.8, and 13) and disk rotational speed (100-1800 rpm) on the rate of reaction was studied at 150, 220 and 300°F. Pink Desert limestone cores 1.5 in. diameter and 0.65 in. length were utilized. GLDA transport and its effect on wormhole creation were investigated in core flood experiments using samples of 1.5 in. diameter and 6 in. length. The cores were scanned using CT-scan before and after the injection of GLDA solutions into the cores. Core flood experiments were conducted at temperatures of 200 and 300°F.

The calcite dissolution rate was found to be a strong function of temperature and increased significantly by increasing the temperature from 80 to 300°F. Increasing the pH from 1.7 to 13 resulted in a reduction in the rate of dissolution. GLDA reacted with calcite by one of two mechanisms; hydrogen ion attack and calcium complexation reaction. The GLDA chelation ability (expressed as a percentage of the total rate of dissolution) decreased by increasing temperature, but was not affected much by changing the disk rotational speed.

Acid diffusivity was determined at pH 1.7, 3.8, and 13 and the data was used with core flood results to determine the Damköhler number. An optimal Damköhler number was found in all experiments that corresponds to a minimum pore volume required to breakthrough the cores. Increasing temperature or reducing the pH increased the optimum Damköhler number with a reduction in the minimum pore volume required to breakthrough.
Case Histories: Overcoming Lost Circulation During Drilling and Primary Cementing Operations Using an Environmentally Preferred System
Authors: Metcalf Arthur S. , Nix Kenneth , Martinez-Guedry John
Published: September 2011

Partial or total lost circulation is prevalent in the Permian Basin of West Texas during many drilling and cementing operations. Whether losses are due to highly vugular or cavernous intervals or due to low fracture gradients, the problem occurs over the entire region. The common practices for fighting these losses are foamed mud sweeps, foamed cements, lost circulation pills and high-viscosity gel spacers containing lost circulation materials.

This paper presents case histories representing more than 100 wells in which a new environmentally preferred system has been employed. Specifically, instances during drilling are discussed where partial to total losses in returns have occurred and have been restored by pumping 40 to 50 bbls of this new material. These same wells after restoring circulation resume drilling to total depth without any further losses. In addition, cases are presented where the system is used as a spacer pumped ahead of cement, resulting in the circulation of cement in an area where this has not occurred before. Another example resulted in the improvement of bonding by the cement. Additional scenarios demonstrate that pumping this material on a single stage cementing job, could replace the normal two stage job.
Enhancing Production by Removing Zinc Sulfide Scale From an Offshore Well: A Case History
Authors: Berry Sandra L. , Boles Joel L. , Singh Amit , Hashim Imran
Published: September 2011

Deposition of mineral scales is the root cause of many production problems in oil and gas operations. These scale deposits have resulted in formation damage, production losses, significant rate and pressure reductions, and equipment failure due to corrosion issues. The most commonly encountered mineral scales in the oilfield are carbonates and sulfate-based calcium sulfate, barium sulfate, and strontium sulfate scales. However, a more unusual form of these mineral scales— zinc sulfide—has recently been reported.

This paper focuses on the systematic study of a zinc sulfide scale and the operation that removed it from a well in the Gulf of Mexico. Identifying the scale form and composition, and the factors affecting its dissolution resulted in a treatment that successfully removed the scale, thereby enhancing gas production from the well.

This scale was identified as wurtzite, a form of zinc sulfide scale. Extensive laboratory testing considered acid solubility and other scale-removal issues at downhole temperature and pressure conditions, as compared to the theoretical solubility of zinc sulfide in HCl acid. The study also determined that other factors may affect the real-world dissolution efficiency of the acid: pressure changes, hydrogen sulfide scavenger concentration and type, the ratio of acid volume to scale weight, pre-treatment oxidizer use, and pH values that prevent re-precipitation of dissolved scale.

The paper will describe the pre-job testing process and a field case history of a coiled tubing acid scale treatment that effectively removed the zinc sulfide scale from tubulars and the formation. Data will be presented showing the composition of the acid-flowback samples as well as the treatment and production charts.
Evaluation of New Drilling Approach for Widening Operational Window: Implications for Wellbore Strengthening
Authors: Salehi S. , Nygaard R.
Published: September 2011

The window between pore pressure and fracture gradient is usually the most critical factor in well design. The width of this window dictates well control and loss circulation prevention. Most notably, in deep offshore basins this window becomes narrower which makes it more challenging to control the ECD. Similar scenario happens in highly deviated and/or horizontal borehole in which fracture gradient significantly decrease as deviation angle increases.

To mitigate the small tolerance between pore pressure and fracture gradients an engineering practice referred to as "wellbore strengthening" is conducted to increase the fracture gradient. The method relies on propping and/or sealing the fractures with specially designed materials. Different competing theories exist for wellbore strengthening mechanisms. These can be categorized into two groups. The first group believes that strengthening happens as a result of increasing wellbore hoop stress when a wedge inserted into the fracture while the second group emphasis on fracture tip isolation with suitable materials and enhancing fracture propagation pressure. The existing numerical models and lab experiments done so far did not fully replicate the same operational phenomenon to understand the true mechanism.

The main objective of this study was to compare the existing wellbore strengthening models using both numerical simulations and analytical solution for different field cases. Results of finite-element analysis for fracture initiation, propagation, sealing and stress changes after each step are provided. Our numerical results indicate that wellbore hoop stress cannot be higher than its ideal case in the fractured zone by plugging and/or sealing fractures. However, strengthening the wellbore and increasing the fracture gradient can be done by enhancing fracture propagation pressure.
Development of Water-Based Drilling Fluids Customized for Shale Reservoirs
Authors: Deville Jay P. , Fritz Brady , Jarrett Michael
Published: September 2011

Drilling activity has increased dramatically in unconventional shale gas reservoirs. The drilling fluid of choice in these shale plays is often non-aqueous based fluid (NAF). While NAFs can provide advantages such as shale stabilization, lubricity, and contamination tolerance, environmental consequences and associated costs are an issue. These disadvantages cause operators to seek water-based muds (WBM) for drilling many of these gas reservoirs.

Despite some operational similarities, a wide variety of unique downhole conditions can be found in the shale plays. Shale mineralogy and bottomhole temperature represent just two highly variable critical factors in unconventional gas reservoirs. Therefore, a single water-based solution for addressing shale plays globally is not a realistic option. Instead, a customized approach that delivers water-based muds formulated specifically for a given shale play has been pursued.

Customization relies on detailed analysis of the well parameters of a given shale play. This analysis includes not only the shale morphology and lithology, but also well drilling program plans, environmental factors and other reservoir-specific considerations. Applying appropriate drilling fluid chemistries based on this detailed analysis has led to the successful field deployment of a number of new shale fluids.

Details of the process utilized for customizing a WBM for a shale play, as well as specific examples of new fluids developed for the Barnett, Fayetteville, and Haynesville shales are presented in this paper. Full laboratory development and testing is described. Additionally, field trial results are presented that show specially-designed WBMs can provide comparable performance to NAFs, but with enhanced environmental and economic benefits. Application of the customization process to develop WBMs for other shale plays around the globe is also discussed.
Development of a Continuous Directional Coring System for Deep-sea Drilling
Authors: Shinmoto Y. , Miyazaki E. , Wada K. , Yamao M.
Published: September 2011

Core sampling is one of most important methods to gain knowledge on formation properties below the sea-floor or to extract such potential new energy resources as methane hydrates. The riser-equipped deep-sea drilling vessel Chikyu carries out scientific expeditions for such underwater formation core drilling and to analyze the origin of hydrate generation around the coast of Japan. Among the various systems available, continuous coring using wireline is the most promising in obtaining a steady supply of core samples.

Although MWD/LWD methods are deployed, an advanced directional control system specifically for deep-sea coring is presently under technical development. Core barrels consisting of the inner and outer barrels have been designed with an inner barrel that is retrievable and resettable. The new method combines an adjustable bent housing sub which is located between the outer barrel and just above the inner core tube.

Laboratory tests in which the inner barrel is passed through the bent housing section have been carried out with results showing bent housing angles of 0.25 ∼ 2.0 degrees. Land drilling tests with the bent housing were also carried out in order to ensure drilling efficiency and core recovery. This paper presents the progress of our newly developed coring system with an integrated analysis of directional drilling and coring capabilities.
Bridging the Gap between Laboratory Characterization and Field Applications of Friction Reducers
Authors: Zhou Jia , Sun Hong , Stevens Richard , Qu Qi , Bai Baojun
Published: September 2011

Slickwater fracturing technology has been widely and successfully used for well stimulation because it is inexpensive and causes relatively little formation damage. Friction reducers are always employed in the slickwater fracturing fluid system due to the high friction pressures resulting from the high rates of fluid injection. Polyacrylamide-based polymer is the most common friction reducer in the industry. Many papers have reported the results of tests on friction reducers in water-based fluids in laboratory-scale straight and coiled tube, but few have attempted to address the gap between laboratory and field operation data. For example, laboratory tests using conventional fluid rheological parameters do not accurately predict friction reduction when applied to the large pipes used in field operations. Friction reducer evaluation using full-scale flow loop testing with tube sizes comparable to those used in field operations are typically expensive and require large volumes of fluids, making them impractical. This paper describes an attempt to address the gap between laboratory characterizations and field operations. It reports a study of two common friction reducers studied in a laboratory setup and compares the results with the recorded data from a large number of slickwater fracturing treatments over a wide range of pumping rates and well tube sizes. It introduces a new concept of effective pipe diameter, which, correlated with a fluid velocity profile, permits development of a model to reliably predict field friction reduction from laboratory results. The correlation between laboratory and field data is validated by comparing predictions with actual field data. The study demonstrates that correct lab testing parameters are essential for reliably using laboratory results to predict the effectiveness and performance of friction reducers under field conditions.
Field Study of the Physical and Chemical Factors Affecting Downhole Scale Deposition in the North Dakota Bakken Formation
Authors: Cenegy Lawrence M. , Mcafee Clyde A. , Kalfayan Leonard J.
Published: September 2011

North Dakota Bakken oil recovery has increased nearly 100 fold over the last five years, driven by technological advancements in hydraulic fracturing and completion design. For one North Dakota operator with 150 Bakken-producing wells, 22 of the wells have experienced at least one event of severe calcium carbonate scaling in the pump and production tubing, leading to well failure. Bakken wells are completed to a vertical depth of approximately 10,000 ft with horizontal laterals up to 10,000 ft and produced via multi-zone hydraulic fracturing.

The operator initially conducted a typical scale prediction study in order to reduce well failures and maintain oil production. However, the scale prediction study was challenging to perform for these Bakken wells due to the variability of the composition of the produced water. Attention then turned to the tracking and analysis of historic field conditions. A ‘post-mortem’ of data collected from all failed wells due to scale was conducted, considering the failure type, date, type of hydraulic fracturing procedure, pump intake pressure, scale inhibitor residual, calcium carbonate scaling index, geographic failure concentration, production time to failure, and cumulative water production to failure.

Results showed that 82 percent of the wells failed during early production (defined as less than 20,000 barrels of water produced and two years production since first oil), after which failures became increasingly rare. This correlated with transient alkalinity spikes in the water analyses attributed to fracturing fluid flowback during this critical period. Simulated blending of fracturing and formation waters demonstrated that this was the most important period to maintain high scale inhibitor residuals due to high deposition potentials.

This paper discusses the various field and laboratory studies conducted in an effort to understand the problem, results obtained and implications. Also discussed is the evaluation of two scale inhibitors before and after laboratory aging in simulated fracturing fluids.
Development and Application of Foamers to Enhance Crude Oil Production
Authors: Debord Saet Byul , Lehrer Scott , Means Nancy , Crosby Simon
Published: September 2011

As a well ages, the reservoir pressure decreases and the liquid starts to accumulate at the bottomhole. Without reducing the hydrostatic head via deliquification technology, production would decrease more rapidly than the natural decline curve and would cease prematurely. In gas fields, foamers became emerging deliquification technology because they are relatively economic and flexible technology. Conventional foamers have been very successful for deliquifying brine-loaded wells to enhance gas production. However, there has been little success in treating oil-loaded wells with foamer due to the difficulties in foaming crude oil.

Novel chemistry that foams crude oil was identified, and new oil foamers were developed as a solution for oil-loaded wells. Two oil foamers were developed to handle different range of bottomhole temperature and application methods. The oil foamer performance was evaluated in a wide ranges of crude oils and water cuts to determine the type of liquid that the new oil foamers could treat cost-effectively. Lab evaluation of six oil samples showed that the new oil foamers effectively treated oils. Capillary tests determined the thermal stability limit of the foamers for down-hole injection. Sparge column tests assured that foam created by the oil foamers can be controlled with commercially available defoamers.

A field trial at a well in south Texas proved that the new oil foamer increases gas and oil production. Previously, this well produced intermittently due to low reservoir pressure. The lab tests determined the recommended dosage of the oil foamer and defoamer, and the dosage was optimized during the field trial. The oil foamer was applied continuously through a capillary tubing at a rate of 750 ppm after optimization. The defoamer was injected at the wellhead to control the foam issue at the surface equipment. The oil foamer application increased the days of production from 7 days to 12 days. Gas production was enhanced from 122 Mcf/D to 400 Mcf/D, and oil production increased from 13 BOPD to 100 BOPD. During the entire field trial, the defoamer successfully controlled the foam issue, and the foam did not pose any upset to surface equipment.
Shear Stability of EOR Polymers
Authors: Zaitoun A. , Makakou P. , Blin N. , Al-Maamari R. S. , Al-Hashmi A. R. , Abdel-Goad M. , Al-Sharji H. H.
Published: September 2011

An experimental study of shear stability of several high-molecular-weight polymers used as mobility control agents in EOR projects has been performed in well-controlled conditions. The shearing device was made of a capillary tube with ID of 125 μm, through which polymer solution was injected at controlled rate. The set-up enables a precise measurement of the shear rate to which the polymer macromolecule is submitted. The degradation rate was measured by the viscosity loss induced by the passage into the capillary tube. The shear rate was gradually increased up to 106 sec-1 while checking degradation rate at each stage.

Different commercial EOR polymer products were submitted to the test with polyacrylamide backbone and different substitution monomer groups. All macromolecules behave as flexible coils in solution. The parameters investigated were: Molecular weight (between 6 and 20x106)Nature of substitution group (Acrylate, ATBS/sulfonate, nVP/Vinyl-Pyrrolidone)Salinity

Polymer shear degradation increases with molecular weight and salinity, but decreases with the presence of Acrylate, ATBS and nVP. All results can be interpreted in terms of chain flexibility. The highly flexible polyacrylamide homopolymer is the most sensitive to shear degradation. Introduction of acrylate groups in the polymer chain induces some stability because of the rigidity provided by charge repulsion, which vanishes in the presence of high salinity (due to the screening of acrylate negative charges). ATBS and VP groups, which are larger in size, provide significant chain rigidity thus better shear stability. It is also shown that some very-high molecular-weight polymers, after passing the shearing device, attain a final viscosity lower than lower-molecular-weight products with the same chemical composition. This factor has to be taken into account in the final choice of a polymer for a given field application.

As a comparison, although less popular today than two decades ago, xanthan gum, which behaves like a semi-rigid rod, is shown to be much less sensitive to the shear degradation test than the coiled polyacrylamides.
New Steam Resilient Cement: Evaluation of Long-term Properties Under Extreme Conditions
Authors: Chougnet-Sirapian Alice , Pershikova Elena , Loiseau Anthony
Published: September 2011

There are more than 1200 heavy oil deposits worldwide containing approximately 13,000 billion bbls of oil. Various steam injection methods are used to mobilize the viscous fluid to flow so that it can be produced to surface. During the production process, the cement sheath maintaining wellbore zonal isolation is subjected to large mechanical strains imposed by temperature variations. Under these extreme conditions, mechanical and thermal cement properties are key factors to maintain wellbore integrity and to achieve the desired reservoir productivity. Significant heavy oil reserves are found in unconsolidated sandstone formations and carbonate formations. To avoid fracturing of these formations during cement placement, systems with densities below 1,800 kg/m3 are required. Further, during exposure to steam temperatures, formation type may affect cement structure and, hence, its material properties.

A new steam resistant cement system was designed to have tailored mechanical and thermal properties for slurry densities in the range of 1,400–1,700 kg/m3. To simulate the influence of formation composition on the material properties, cement samples were aged in autoclaves containing either water or water-saturated sand. Aging was continued up to six months at temperatures of 250-344 degC. A two-fold improvement of the material properties in the conditions simulating contact with the formation (water-saturated sand) is observed compared to standard curing conditions.

Cement sheath integrity is simulated for the new and conventional steam resistant cements for typical conditions of heavy oil wells, including the effect of the formation. The higher durability of the new cement material compared to conventional systems is confirmed. Operators can count on cement sheath integrity as they apply thermal processes to produce heavy oils.
Development of New Chemical Additive Detection Methods Inspired by the Life Sciences
Authors: Fuller Anne-Marie , Mackay Fiona , Mackenzie Cameron , Rowley-Williams Catherine , Perfect Emma
Published: September 2011

On first consideration it may not be immediately apparent that biological detection methods could be applied to oilfield fluid analysis; however there are strong analogies between the two. Like produced fluids, biological fluids such as blood are also complex multiphase liquids with solid components. Decades of research in healthcare has provided technologies which provide fast and accurate detection to ppm concentrations or below of a wealth of species present in bodily fluids. Many such techniques have been made simple and portable for home care formats. This paper will describe a range of detection techniques inspired by the life sciences being applied to the analysis of chemical additives in oilfield fluids, with particular focus on thermodynamic hydrate inhibitors and polymeric treatment chemicals.

Colourimetric detection reagents have been developed for the analysis of methanol and monoethylene glycol (MEG) in produced fluids and the method has been qualified with real fluids using inexpensive equipment that is simple to operate. Also, novel chemical tags have been tested for use with polymeric treatment chemicals, with highly selective detection being provided by complementary detection reagents. The results show precise and robust detection of methanol and MEG (down to 1 part per million (ppm)) in produced fluids and comparison with gas chromatography (GC) is discussed. Results of a chemical tagging study are also presented and discussed in terms of tagging strategies, simplicity of detection method (using inexpensive handheld equipment) and the detection sensitivity (down to parts per billion (ppb)) of the tags in the presence of oilfield fluids.

These methodologies demonstrate the promise of applying life science inspired technologies to the accurate, on-site measurement of chemicals which are difficult to detect using other, less simple methods. These technologies offer significant benefits to the production chemist due to the knowledge gleaned and the reduction in time to result.
Associative Polymer System Extends the Temperature Range of Surfactant Gel Frac Fluids
Authors: Gupta D. V. , Carman Paul S.
Published: September 2011

Early viscoelastic surfactant fluid systems provided a non-damaging, non-polymer viscous fluid option for many tight gas fracturing applications. These fluids were operationally simplistic with only a few additives. However, their rheological properties limit their use to about 140°F as a single fluid. For applications to about 250°F, foaming the fluids with CO2 or N2, usually 65 to 75 quality, can achieve stability with adequate viscosity, but this increases costs as well as operational and logistical complication. In addition, these fluids provide minimal friction reduction because at high shear they tend to behave more like water.

A new thickening system extends the temperature range of traditional viscoelastic surfactant (VES) fluids and provides additional downhole benefits. Based on a low-molecular-weight associative polymer, the thickener forms an associative gel with surfactants at elevated temperature. The polymer and surfactants can be considered environmentally preferred. The system uses only three or four additives, compared to nine or ten for conventional systems. The footprint for field operations is considerably reduced, as hydration units and chemical additive units are not necessary. In rheology testing, the system achieves a good structure with viscosity. The time required to gel with temperature can be accelerated or delayed chemically. Regain conductivity tests indicate performance is similar to that of VES fluids alone. The system also has beneficial traits for clay control, friction reduction, water-wetting and post-frac fluid recovery. If foamed, the system may provide stability at even higher temperatures. This paper will present the chemistry and results of laboratory testing of this new and unique fluid system. The system should have applications in areas requiring excellent regain conductivities, such as unconventional formations.
Mitigating Silicate Scale in Production Wells in an Oilfield in Alberta
Authors: Arensdorf Joseph , Kerr Scot , Miner Kirk , Ellis-Toddington Tyler
Published: September 2011

Alkaline surfactant polymer (ASP) floods in sandstone reservoirs are associated with silicate scaling of production wells. Many wells require numerous workovers and some must be abandoned. Mineral scale inhibitors are generally ineffective at treating silicate scale in these wells.

An oilfield in southern Alberta was placed under an ASP flood for enhanced oil recovery and subsequently experienced severe silicate scaling of production wells. The wells were under artificial lift with submersible progressing cavity pumps (PCPs). The silicate scaling resulted in numerous well workovers to replace the pumps and associated rods. Two new silicate scale inhibitors were developed and applied down hole to production wells via continuous injection.

The dose of chemical applied was approximately 250-500 ppm per well. The inhibitors decreased silicate scaling as evidenced by significantly increased run life of most wells. One well that required consecutive workovers after three and four months, respectively, was treated with inhibitor at 500 ppm and has subsequently produced without problems for more than 12 months. Similar results were seen with other wells. PCP torque has generally not increased, and, in some cases, has actually decreased with the scale treatment. In addition, coupons of treated wells have generally been clean, indicating that silicate scale is not depositing on metal surfaces.

Even though the inhibitors must be applied at several hundred ppm to mitigate silicate scaling, significant cost savings have been realized because of the reductions in well workovers and associated lost production. This paper will discuss the issues encountered at this oilfield and the resultant solutions and successful outcome.
Advanced Casing Design with Finite-Element Model of Effective Dogleg Severity, Radial Displacements and Bending Loads
Authors: McSpadden Albert R. , Coker Oliver D. , Ruan G. Colin
Published: September 2011

A purpose-built finite-element model (FEM) is applied to simulate radial displacement of a casing string constrained within an outer wellbore. The FEM represents a fully stiff-string model wherein the casing is approximated by general beam elements with 6 degrees of freedom at each node to account for all possible physical displacements and rotations. Results predicted include deflection of the casing centerline from the wellbore centerline, effective dogleg curvature, bending deformation, wall contact forces, and bending stress magnification.

In critical well casing design, accurate assumptions regarding bending stiffness may be necessary to avoid overly-conservative as well as non-conservative analysis. Challenging HPHT and extreme temperature wells are opportunities where increased design efficiency can be crucial. Alternatively, design for extreme loads such as overpull loads in long deviated wells may be non-conservative if severe bending stresses are not considered.

A realistic case study is presented which demonstrates the possibility to achieve cost efficiency by means of optimized casing design. Also a case study is presented where a non-conservative design may result if severe bending loads are not modeled. The purpose-built FEM code is in many ways preferable to use of commercial FEA packages because of the timeconsuming effort required to build up the detailed model.

In typical casing and tubular stress design, a "soft-string" model assumes casing strings are coincident with the wellbore centerline. The known or assumed wellbore curvature is applied directly to the casing string. Any effect of casing string stiffness and allowable radial displacement within the outer wellbore is ignored. In many cases this results in an overlyconservative analysis. Likewise the impact of bending stress magnification is typically ignored along with the effects of centralizer placement. This may also be non-conservative for critical overpull situations such as in ERD and horizontal wells.
Enyzmatic Synthesis of a Non Ionic Biosurfactant Derived from Ricinoleic Acid and D-glucose: Stability of its Surface Action Properties
Authors: de Medeiros Suzan I. , Souto Carlos R. , Fagundes Fabio P. , Costa Marta
Published: September 2011

Alkaline Bacillus subtilis protease catalyzed the synthesis of a biosurfactant derived from castor oil by esterification between ricinoleic acid and D-glucose in organic media using N,N- dimethylformamide as solvent. This mixture was kept under constant agitation at 60 °C. The conditions of enzymatic synthesis had been optimized before, with a maximum yield of 60% in 48 hours of D-glucose esters of long chain. Afterwards, the product obtained (Biosurfactant) was purified and characterized by different analytical techniques. This product reduced the water surface tension from 72 mN/m to 30 mN/m at room temperature and neutral pH. The purified biosurfactant was very stable over a broad range of pHs (2 – 12) and temperatures (25 – 100 °C). Besides, it showed a great solubility and stability in saline conditions (50 – 115 g/L). Aforementioned results suggest that D-glucose ester obtained can be efficiently used as a tensoactive agent, remaining stable under all conditions studied, thereby allowing its use as an emulsifier and/or lubricant in downstream processes of the petroleum industry, representing, therefore, a alternative for conventional surfactants.
Chemical Additives for Improving Compatibility of Drilling Fluid, Completion Fluid, and Other Well-Treatment Fluids for Deepwater Wells
Authors: Qiu Xiaoping (Victoria) , Morgenthaler Lee , Martch Eddy , Vu Hiep , Chtay Mootasem , David Vanessa Farrell
Published: September 2011

In deepwater completions in the GOM, synthetic-based mud (SBM) has been widely used for drilling the reservoir section. With increasing well depth and higher reservoir pressure, higher-density drilling fluids are used more and more often. It has been observed that with increasing density of drilling fluid, the incompatibility between drilling fluid, completion fluid, and other well-treatment fluids can cause more problems to drilling and completions. Consequently, the incompatibility can reduce the effectiveness of well completions and result in lower production. Often, the formation damage caused by the incompatibility can be very difficult to remediate.

We have identified incompatibility between drilling fluid, completion fluid, and other-well treatment fluids for many GOM wells in lab studies. Chemical additives were studied for preventing the incompatibility between drilling fluid, completion fluid, and other well-treatment fluids. Chemical additives selected from lab study have been applied to many GOM wells, and their use has resulted in improved well production and has prevented catastrophic damage to the wells. We developed proper lab test protocol to subjectively evaluate chemical additives that can prevent or minimize incompatibility between drilling fluid, completion fluid, and other well-treatment fluids. The application of the selected chemical additives on several GOM wells will be discussed.

This paper will summarize the lab test methods and lab test results based on testing for several GOM wells. It will also summarize the end results of well performance with the application of these chemicals.
ESP Recirculation System Solves Production Issue in Granite Wash Gas Well
Authors: Reid L. C. , Irish L. M. , Holland N. G. , Howard T. L.
Published: September 2011

A deep Granite Wash well was tested on an Electrical Submersible Pump (ESP) after being shut-in for 11 months due to uneconomic and unsatisfactory rod lift operations.

The three main objectives of the test were: (1) to determine if an ESP system can be successfully utilized on a gas well; (2) to implement a downhole recirculation system; and, (3) to monitor the economic impact of the installation of the ESP unit.

The challenges for the ESP system for this specific test included: (i) motor cooling restriction due to absence of adequate rathole; (ii) production from multiple perforations over 600 ft spread; (iii) low liquid flow (<400 BPD); (iv) high gas-liquid ratio (>1600 CF/BBL); (v) deep well depth (10,000 ft); (vi) small ID production casing (5.5" 17lb/ft); and, (vii) high potential wellbore scaling/corrosion issues.

Due to these challenges, using a traditional motor shroud jacket was considered a disadvantage. As a result, a downhole recirculation system was used as an alternative method to (a) prevent potential gas locking; (b) circulate fluid to keep the motor cool; and, (c) enhance capillary deployment of scale and corrosion chemical treatment.

This paper presents basic principles of the application of ESP systems in a gas well, principles of implementing a downhole recirculation system, and uncommon techniques to effectively operate an ESP unit in dewatering gas wells. It also includes the historical design challenges, system specific design/operation, and production results of the tested well.

The test concludes that it is possible to successfully and economically de-water a deep non-conventional gas well utilizing a properly designed ESP with a downhole recirculation system. In addition, the test had demonstrated the benefits of web-based monitoring of the variable speed controller and downhole sensor information.
Using Lines-of-Solutions to Understand Fracture Conductivity and Fracture Cleanup
Authors: Gdanski Rick , Fulton Dwight
Published: September 2011

Evaluation of fracturing treatments in tight-gas sands is often frustrated by uniqueness problems when matching gas rates and bottomhole flowing pressure (BHFP) data alone. A fit-for-purpose simulator was used to match gas rates, BHFP, cumulative water, and composition of the water during cleanup after a fracturing treatment.The simulator models physics of flow and chemical physics to provide improved history matching of the cleanup process. The well was cycled through several production and shut-in periods. Pressure transient analysis(PTA)was used along with a recently published line-of-solutions concept for evaluating the evolution of properties of the reservoir/fracture system.

History matching of the well-returns data with the fracture-cleanup model provided multiple solutions when matching gas, water, and BHFP. These solutions all fell on a "line-of-solutions" using a special plot of reservoir properties as a function of conductive length. In addition, a new line-of-solutions was discovered relating fracture conductivity as a function of conductive length. PTA of several buildups provided lines-of-solutions that evolved during the course of the cleanup. These tools demonstrated that the conductive length was roughly 100 ft, but apparently cleaned up to at least twice that over the next several weeks. The fracture conductivity was much lower than expected and was the cause of the disappointing productivity.

This work demonstrates that matching well-return compositionswith a fracture-cleanup model capable of chemical physics can lead to improved interpretations of both reservoir properties and fracture structure. The two lines-of-solutions provide a potentially powerful method of understanding the reservoir/fracture system
3D Hydraulic Fracture Simulation for Injection in Plastic Shales
Authors: El-Fayoumi A. , Zaki K. S. , Abou-Sayed A. S.
Published: September 2011

Injection and hydraulic fracturing in plastic shales can be a complex and problematic operation. Issues that accompany such treatments include shale swelling, plastic deformation, embedment’s and perforation tunnel stability issues. Simulators that model fluid or slurry injection in plastic shale have always overlooked the plasticity issues associated with these formations. The approach has led to erroneous estimation of fracture extent and dimensions. Post injection shale deformation due to pore pressure changes can also lead to detrimental effects on productivity (fracture closure due to creep) and well/casing failure.

The current paper offers clear quantitative insights into the overall effect of injection in plastic shales. The experience is gained through drill cutting injection operations that have been taking place in highly plastic shales in an environmentally sensitive remote location. Fracture and slurry containment have been investigated using state-of-the-art 3D fracture simulator to provide assessment of the injection and to estimate out-of zone growth as well as shale plastic deformations and the effects on fracture vertical growth at different batch volumes. Analysis of historical pressure trends and pressure fall-off tests confirmed results from the 3D Simulation and the injection history. The results provide insights that have implications on the job design and implementation of hydraulic fracturing in plastic shale gas, particularly the Haynesville.

The results from the 3D fracture simulator and pressure transient analysis combine to accurately assess fracture vertical and lateral extents in similar formations, hence, minimizing the risks associated with injection and fracturing in these highly plastic shales.
Impact of Hydrolysis at High Temperatures on the Apparent Viscosity of Carboxybetaine Viscoelastic Surfactant-Based Acid: Experimental and Molecular Dynamics Simulation Studies
Authors: Yu Meng , Mu Yan , Nasr-El-Din Hisham A.
Published: September 2011

Carboxybetaine visco-elastic surfactants have been applied in acid diversion, matrix acidizing and fracturing treatments, in which high temperatures and low pH are usually involved. Amido-carboxybetaine surfactants are subject to hydrolysis under such conditions due to the existence of a peptide bond (-CO-NH-) in their molecules, leading to alteration of the rheological properties of the acid. The objective of this paper is to study the impact of hydrolysis at high temperatures on the apparent viscosity of carboxybetaine visco-elastic surfactant-based acids, and determine the mechanism of viscosity alterations by molecular dynamics (MD) simulations.

Surfactant-acid solutions with different compositions (surfactant concentration varied from 4 to 8 wt%) were incubated at 190°F for 1 to 6 hours. Solutions were then partially spent by CaCO3 until the sample pH was 4.5, and the apparent viscosity was measured using a HT/HP viscometer. To determine the mechanism for viscosity alteration on molecular level, MD simulations were carried out on spent surfactant-acid aqueous systems using the Materials Studio 5.0 Package.

It was found that short time hydrolysis at high temperatures (for example, 1 to 2 hours at 190°F) led to a significant increase in surfactant-acid viscosity. However, after long time incubation, phase separation occurred and the acid lost its viscosity. Simulation results showed that the viscosity alteration of amido-carboxybetaine surfactant-acid by hydrolysis at high temperatures may be due to different micellar structures formed by carboxybetaine and fatty acid soap, its hydrolysis product. The optimum molar ratio of amido-carboxybetaine and fatty acid soap was found to be nearly 3:1 from our simulations.

Our results indicate that hydrolysis at high temperatures has great impact on surfactant-acid rheological properties. Short time viscosity build-up and effective gel break-down can be achieved if surfactant-acid treatments are carefully designed; otherwise, unexpected viscosity reduction and phase separation may occur, which will affect the outcome of acid treatments.