bluuebunny/crossref_metadata_2025 huggingface dataset:
Benign eccrine poroma of neck: an unusual presentation
Authors: Munjal Manish , Arora Archana , Talwar Gopika , Sood Neena
Published: March 2017

Poroma refers to benign adnexal neoplasm derived from the terminal portion of the duct of sweat gland. About two-thirds are seen in middle aged and the elderly. The plantar surface or sides of feet followed by hands and fingers, and rarely the face or neck are the sites of predilection. This study included case report of 36 year old male presented with a lower midline neck swelling, insidious in onset and gradually progressive. On examination: swelling was about 2×2 cm, doughy in consistency, non-tender and freely mobile over the underlying muscles. Ultrasonography neck showed a hyperintense adnexal soft tissue with no fixity to the underlying structures. Surgical intervention via an elliptical incision was undertaken. Skin and subcutaneous tissue separated and underlying swelling identified to be attaching superficially. It was removed in toto and base was cauterized and transfixed. Postoperative period was uneventful. No recurrence recorded till 6 months. Histopathological examination was consistent with benign adnexal tumor eccrine poroma. Meticulous evaluation of the individual presenting with poroma is undertaken to reach the correct diagnosis. Existing literature suggests the treatment of eccrine and apocrine poromas consists of simple excision. If the lesion recurs after excision or presents with ulceration, bleeding, pain, or accelerated growth, a suspicion of eccrine “porocarcinoma” should be considered and the lesion investigated accordingly. 
Pleomorphic adenoma in para pharyngeal space: a rare presentation
Authors: Kansal Latika , Davessor Jai Lal , Singh Gurbax , Kaur Jasmine
Published: March 2017

Parapharyngeal space is one of the potential space for neoplasms and infections and represent less than 1% tumours of all head and neck tumours. Pleomorphic adenoma occurrence in para pharyngeal space is rare presentation. The anatomy of the parapharyngeal space is complex. The complex anatomy and wide variety of pathology make the management of these tumours very challenging.
Ossifying pleomorphic adenoma presenting as a nasopalatine mass
Authors: Bhat Vikram K. , Shenoy Supreetha B. , Sangoli Bhavana
Published: March 2017

Pleomorphic adenomas are benign tumors that are uncommon in the nasal cavity. However, they can rarely arise from septum, erode hard palate and thus masquerade a bone tumor. We report one such rare case of septal pleomorphic adenoma with hard palatal extension and ossification. A combined endoscopic intranasal and transpalatal surgical approach was performed and tumor was excised completely. A high index of clinical suspicion and biopsy can diagnose such swellings.
Análisis exergético de una planta de cogeneración operando bajo ciclo combinado
Authors: Patiño-Duque Hernán Darío , Rosero-Coral Bryan Dario
Published: March 2017

En la actualidad, hay diversas formas para generar energía eléctrica, una de ellas consiste en aprovechar la cantidad de energía liberada al quemar un combustible y efectuar una serie de procesos de conversión de energía mediante un ciclo termodinámico. Para hacer estos procesos más eficientes, existen herramientas que permiten analizar en qué equipos de la planta se está desaprovechando energía, una de estas técnicas es el análisis exergético, que consiste en la aplicación simultanea de la primera y segunda ley de la termodinámica. En el presente trabajo se realiza el análisis exergético a una planta de generación de electricidad y calor a partir de la producción de vapor operando bajo un ciclo combinado. Inicialmente se definen conceptos importantes para realizar el análisis. Después de aplicar la primera y segunda ley de la termodinámica los resultados indican que la eficiencia exergética de la planta de ciclo combinado es 53% y se encuentra que la cámara de combustión es el componente del sistema que más exergía destruye y que las bombas son los dispositivos donde hay menor pérdida de energía útil.
Control multivariable lineal con desacoples en un intercambiador de calor
Authors: Ricardo-Barrera Jaime Freddy , Barrios-Urueña Edgar
Published: March 2017

El presente artículo describe la validación de los diseños de control multivariable lineal en un intercambiador de calor bajo ambiente virtual usando Hysys, cuyo interés se centró en analizar las diferentes respuestas del sistema MIMO cuando se realizó el control regulatorio con diferentes desacopladores y sin desacoplador. Se usaron tres tipos de desacopladores: Simplificado de Estado Estacionario, Simplificado y Generalizado. Los valores de las consignas fueron 60 °C para la temperatura del caudal a la salida de los tubos, y 41 °C para la temperatura del caudal a la salida de la carcasa; las variables manipuladas fueron los caudales de entrada a los tubos y la carcasa, gracias a los porcentajes de apertura de las válvulas correspondientes. Se emplearon controladores PI que fueron sintonizados con la aplicación del diseño IMC. De los resultados se pudo apreciar que el desacople simplificado fue el que más disminuyó el efecto del acoplamiento.
Empreendedorismo familiar e o desenvolvimento local: estudo de caso no Projeto Pacu
Authors: Grillo Jocimara Paiva , Naka Marco Hiroshi , Pistori Hemerson , Martins Deisi Graziela Lima , Porto Carlos Roberto Bernardes
Published: March 2017

Este trabalho é um estudo de caso sobre uma empresa chamada Projeto Pacu, criada em 1986 e localizada na cidade de Terenos, no Estado do Mato Grosso do Sul. O objetivo deste trabalho é destacar o papel dessa empresa no desenvolvimento local e também avaliar algumas ações que a destacam como promotora e agente para o desenvolvimento local e, especificamente, em termos de empreendedorismo, desenvolvimento e implantação de projetos no setor de piscicultura. Pesquisas bibliográficas e visitas in loco foram realizadas, referenciando-se no método indutivo, com abordagem qualitativa, a fim de reconhecer a importância do empreendedorismo familiar do Projeto Pacu como agente de desenvolvimento local.
Biodiversidade e conservação de recursos genéticos de espécies arbóreas
Authors: Ribeiro Nathalia Pereira , Sanches Cristiane Camargo , Oliveira Michel Ângelo Constantino , Costa Reginaldo Brito
Published: March 2017

A exploração intensa e seletiva de madeira, mudanças no uso da terra pelo agronegócio e ocupação urbana são os principais fatores responsáveis pela perda na diversidade de espécies arbóreas. Junto com o agravamento do processo de degradação ambiental e esgotamento dos recursos naturais disponíveis no planeta, nota-se um substancial crescimento da preocupação com os danos ambientais causados na reprodução e diversidade genética das espécies arbóreas. Com essa constatação, tornou-se fundamental conservar a variabilidade das espécies utilizando-se bancos de germoplasmas. Nesse contexto, a presente revisão objetivou reunir informações sobre a biodiversidade e o ambiente para a conservação de espécies arbóreas nativas. Demonstra-se que especialmente aqueles métodos em que se utilizam os bancos de germoplasmas in situ ou ex situ contribuem e garantem a preservação das espécies, mantendo ampla diversidade e variabilidade genética das populações arbóreas.
TINGKAT PENCEMARAN WADUK PENJALIN KECAMATAN PAGUYANGAN KABUPATEN BREBES DITINJAU DARI STRUKTUR KOMUNITAS PLANKTON
Authors: Arum Octyviana , Piranti Agatha Sih , Christiani Christiani
Published: March 2017

Penjalin Reservoir is located in Brebes Regency, Indonesia. Human activity around Penjalin Reservoir, such as irrigation, aquaculture, and sanitation can affect its water’s quality. Plankton can be used as bioindicator since its existence is heavily affected by water physical and chemical factors. Polluted waters can affect diversity and abundance of plankton. The purpose of this research were to determine waters quality of Penjalin Reservoir, to know plankton community structure (abundance, diversity, and domination), and pollution level of each sampling station based on plankton diversity. This research used survey method on 6 sampling stations covering inlet, middle of reservoir, and outlet with 3 replicates and 4 weeks interval. Water quality were analyzed descriptively based on criteria of PP No. 82 Tahun 2001. Abundance and diversity were estimated as Shanon-Wiener index. Domination were estimated as Simpson index. Plankton abundance values varies from 4,970.30 to 12,923.37 ind/l with the most abundant species was Tetraedon minimum. Diversity index (H’) were high with value around 3.28–3.55 and domination index were around 0.04–0.07. These diversity indexes showed that the water quality of Penjalin Reservoir were not polluted.
INTERNAL TRANSCRIBED SPACER (ITS), AN IDEAL DNA BARCODE FOR SPECIES DISCRIMINATION IN CRAWFURDIA WALL. (GENTIANACEAE)
Authors: Zhang Dequan , Jiang Bei , Duan Lizhen , Zhou Nong
Published: March 2017

Background: DNA barcoding is a technique used to identify species based on species-specific differences in short regions of their DNA. It is widely used in species discrimination of medicinal plants and traditional medicines.

Materials and Methods: In the present study, four potential DNA barcodes, namely rbcL, matK, trnH-psbA and ITS (nuclear ribosomal internal transcribed spacer) were adopted for species discrimination in Crawfurdia Wall (Genetiaceae). Discriminatory ability of these DNA barcodes and combinations were evaluated using three classic methods (Distance, Blast and Tree-Building).

Results: As a result, ITS, trnH-psbA and rbcL regions showed extremely great universality for a success rate of 100%; whereas matK was disappointing for which only 65% samples gained useful DNA sequences. ITS region performed very well in this study which could clearly and effectively identify the five species in Crawfurdia. On the contrary, trnH-psbA and rbcL were much weaker in discrimination among these species.

Conclusion: ITS marker was an ideal DNA barcode in Crawfurdia and it should be incorporated into one of the core barcodes for seed plants.
ANTIMICROBIAL ACTIVITY OF AQUEOUS, ETHANOLIC AND METHANOLIC LEAF EXTRACTS FROM ACACIA SPP. AND Eucalyptus nicholii
Authors: Silva Ermelinda , Fernandes Sara , Bacelar Eunice , Sampaio Ana
Published: March 2017

Background: In Europe, Acacia and Eucalyptus, originate large amounts of biomass, due to their need by industries and other

biological control, that can be used to extract antimicrobial substances.

Materials and Methods: Foliar aqueous, ethanolic and methanolic extracts of Acacia baileyana (Cootamundra wattle), Acacia

dealbata (silver wattle), Acacia melanoxylon (black wattle) and Eucalyptus nicholii (narrow-leaved black peppermint) were assessed

for antimicrobial activity against Escherichia coli, Bacillus cereus, Candida albicans and Candida parapsilosis, using the disc

diffusion method.

Results: Ethanolic extracts from A. baileyana and A. dealbata showed significant (P< 0.05) antimicrobial activity. Concerning the

microbial species tested, differences were found in A. baileyana (P< 0.01) and E. nicholii (P< 0.0001) extracts. These two extracts

were effective mostly against B. cereus, followed by C. parapsilosis. According to the antimicrobial activity classification, eucalypt

and Cootamundra and silver wattles extracts (both water and ethanol) presented good efficacy against B. cereus, a food poisoning

agent, and moderate efficacy against the remaining microorganisms. E. coli, a Gram negative, exhibited low sensibility to all foliar

extracts.

Conclusion: A. baileyana, E. nicholii and A. dealbata foliar biomass could be used to develop alternative substances in microbial

control.
Management of Change Delivery Decision Making Through the Force Field Analysis in Georgia
Authors: Cheishvili Jilda , Zarnadze Irene , Zarnadze Shalva
Published: March 2017

Children’s generation of Georgia recovers parent’s generations only for 70-80%. According to same data, there are only 14 countries with the similar low indicators. The increase of C-section can cause the decrease of birthdates.

WHO recommended The Partnership for Maternal, Newborn, and Child Health - through the creation of an Advocacy Team. (WHO, 2005). This model ensures the relaxed environment where the mothers can receive information delivered by qualified health workers, who teach pregnant women and family members about health and well-being.  Advocacy Team comprises - nurses, medical students, and volunteer.

Project benefit will be increased antenatal and postnatal care services through  the country, in the lead the better attitude and knowledge about health and well-being  across all Social levels .  Further families will save money because they couldn't pay for C-section  

Evaluation of the project –annual statistical analysis by NCDC (National Center for Disease Control and Public Health) decrease C-section rate for mother request.

Project outcome will be increased maternal and Child health and well-being, Increase right participation from the community, Support of pregnant women and her family economically.
A New In-Situ Generated Acid System for Carbonate Dissolution in Sandstone and Carbonate Reservoirs
Authors: Sokhanvarian Khatere , Pummarapanthu Thanakrich , Arslan Emre , Nasr-El-Din Hisham A. , Shimek Nicole , Smith Kern
Published: March 2017

Matrix acidizing has long been used for permeability and productivity enhancement purposes in oil and gas wells. In sandstone reservoirs, a preflush is needed to dissolve carbonate minerals so that HF is not consumed in the main step on carbonate minerals. The preflush step also prevents the potential precipitation of the reaction products of HF. HCl has been an important component in preflush; however, it has high corrosion and reaction rates, especially in high pressure/high-temperature (HP/HT) wells. An acidizing system that is comparable to HCl in terms of availability and price is needed; however, the shortcomings associated with HCl, such as its fast reaction rate and high corrosion rate, must be addressed in the development of similar systems. Therefore, this study investigates the effectiveness of a new in-situ generated HCl acid that offers a slower reaction and corrosion rate in high-temperature reservoirs.

The new in-situ generated HCl acid treatment was used to acidize two types of sandstone cores (Grey Berea and Bandera) and two type of carbonate cores (limestone and dolomite). X-Ray Diffraction (XRD) analysis was performed on the sandstone cores to determine the mineralogy to design a better treatment. Coreflood experiments were conducted at 250 and 300°F to study the impact of the treatment on the permeability of sandstone cores. Acid injection rates were set at 1 and 5 cm3/min in the case of the sandstone treatments and 1 and 2 cm3/min for the carbonate stimulation. The effluent samples were collected every quarter pore volume to further analyze the ability of acid to dissolve carbonate and oxide minerals. Porosity profiles and wormhole propagation were determined before and after acid treatment using Computed Tomography (CT) scans.

Superior stimulation results were achieved at 250 and 300°F with the in-situ generated acid system. However, 15 wt% regular HCl caused 79% damage to the Berea core at 300. The new acid system resulted in positive stimulation results (kf/ki ranging from 1.7 to 2.7) in both Grey Berea and Bandera sandstone cores without any sign of fines migration or sand deconsolidation. In the case of carbonate stimulation, more PV of acid was needed to reach breakthrough if 15 wt% regular HCl was used as a treatment fluid. The wormhole propagation was more efficient in the case of the new acid system. Face dissolution was observed when using 15 wt% regular HCl in carbonate acidizing. The corrosion rate of low-carbon steel (L-80 and C-95) and chrome-based tubular (Cr-13) was significantly less than that noted with 15 wt% regular HCl at 300.

This study will assist in developing a more cost-effective and efficient design of acid treatments with minimal impact to the formation's integrity. This new in-situ generated acid system efficiently removes carbonate and oxide minerals in HP/HT sandstone reservoirs.
Unique Mixtures of Anionic/Cationic Surfactants: A New Approach to Enhance Surfactant Performance in Liquids-Rich Shale Reservoirs
Authors: He Kai , Xu Liang
Published: March 2017

Surfactants are important components in fracturing fluids for helping ensure higher productivity from unconventional reservoirs. Conventional wisdom suggests that surfactant mixtures generally exhibit better performance than individual surfactants. Additionally, the synergism between surfactants increases with the degree of charge difference. Some current commercial surfactants were formulated by mixing nonionic and anionic surfactants (Sn/a), but few were formulated by mixing cationic and anionic (Sa/c) surfactants because of the risk of precipitation or formulation instability.

This paper discusses binary mixtures of Sa/c surfactants prepared with different mole ratios to determine their synergisms; mixtures of nonionic/anionic (Sn/a) and nonionic/cationic (Sn/c) surfactants are also compared. Surface/interfacial properties [maximum surface excess concentration (Γmax), minimum molecular area (Amin), critical micelle concentrations (CMC), and Gibbs free energy (ΔG)] and interaction parameters (βm and βs) in both the mixed micelle and interface were quantified to demonstrate the synergistic effect between various surfactants. Additionally, the potential application of these mixtures for unconventional treatments was examined with regards to emulsion behavior and column-packed oil recovery testing.

The results for the Sa/c surfactant mixtures show that, compared to parent species, Γmax of the Sa/c system is approximately one order of magnitude higher (corresponding to one order of magnitude lower in Amin). The resultant CMC is approximately two orders of magnitude lower than the parent species, and the ΔG of Sa/c is more negative. Notably, the interaction parameters further indicate that strong synergism exists for the Sa/c system at various mole ratios in both mixed micelle and monolayers at the interface (with an optimized ratio at 2/3), while, for the Sn/a system, weak synergism was identified in the mixed micelle at the mole ratio of 3/2. No synergism was observed for the Sn/c system.

Additionally, phase behavior testing indicated that a weak emulsion was formed in the presence of the Sa/c using Eagle Ford crude oil. Column-flooding testing also revealed improved oil recovery of the Sa/c system compared to individual species. The synergistic effect between Sa/c surfactant mixtures, as well as the laboratory results of the emulsion behavior and oil recovery, suggests a new practice for applying Sa/c surfactant blends for unconventional applications.
A Novel Solid Inhibitor for Anhydrite Scale Control Under Extreme Well Conditions
Authors: Shen Dong , Bhaduri Sumit , Vo Minh , Carman Paul , Gupta D. V. , Pandey Yash
Published: March 2017

The formation and deposition of mineral scale can detrimentally impact production rates and affect the overall well performance during oil and gas production. This is especially challenging in HTHP stimulation treatments where compatibility of the scale control chemical with fracturing fluids is critical, and longer-term inhibition performance is desired. A new solid inhibitor was developed for this purpose and applied in multiple wells in the Eastern offshore basin of India to combat mineral scale within the proppant pack and production tubing over the long term, under extreme downhole conditions (T= 400°F, P=13,500 psi). Neither downhole chemical injection mandrels nor surface treatments can adequately control scale deposition under these conditions, spurring the need for a longer-term inhibition program for these wells.

A liquid scale inhibitor with excellent inhibition performance and good compatibility with various fracturing fluid systems at high temperature was first identified. The new solid inhibitor product was made by adsorbing the scale inhibitor onto a high-strength, proppant-sized substrate with a large surface area. The substrate is synthesized using nanotechnology, to prevent any possible conductivity loss under high formation closure pressure. Various chemical modifications were made to this adsorbed solid inhibitor to prevent excessive inhibitor release during early stages of production, resulting in a longer-term scale protection. This modification allows the solid inhibitor product to be completely compatible with the fracturing fluid.

Scale modelling indicates that the wells treated have a severe anhydrite scale problem under downhole conditions. The results of comprehensive laboratory testing show the new solid inhibitor can prevent anhydrite scale up to 400°F, and is completely compatible with zirconium- crosslinked fracturing fluid at 350°F and above. To date, six fracture treatments have been performed by using a total 23,800 lbs of this new solid inhibitor. The wellhead water samples are being collected for scale inhibitor residuals analysis, as the wells start to produce water. The residuals data review and comparison with laboratory-derived data are discussed in this paper.

Adding scale inhibitors to a fracturing fluid has been a well-established practice to provide long-term inhibitor protection during hydrocarbon production. However, to ensure compatibility of the inhibitors with high-temperature fracturing fluids, especially metal based cross-linked fracturing fluids, without compromising the inhibition longevity at high pressure and temperature remains a stiff challenge. The new approach described here meets this objective, extending the long-term well performance under HTHP conditions.
Matrix Acidizing of Carbonate Rocks Using New Mixtures of HCl/Methanesulfonic Acid
Authors: Kankaria Sneha , Nasr-El-Din Hisham A. , Rimassa Shawn
Published: March 2017

Successful matrix acidizing of carbonate reservoirs depends on the selection of optimal stimulation fluids. Because of the rapid reaction rate and corrosive nature of HCl in downhole conditions, other alternatives are much in demand. Organic acids, particularly methanesulfonic acid (MSA), offer a viable alternative to HCl in terms of being less reactive as well as less corrosive and environmentally benign. However, MSA is expensive. To reduce the cost, this study proposes to use blend of HCl and MSA for carbonate stimulation, while enhancing the properties of HCl. Coreflood studies were performed and the results were compared to those obtained by equivalent concentrations of the individual acids.

Three different ratios of HCl and MSA were used to conduct coreflood experiments on 6-in. long Indiana Limestone cores at 250°F. The volume of acid required to reach breakthrough was recorded, and the cores were analyzed using CT scans. Wormhole structures were identified, and their tortuousities were determined. The effluent samples were analyzed for pH, calcium concentration, and unconsumed acid concentration.

Coreflood studies indicated that 5:5 wt% HCl:MSA blend was the most suitable candidate for matrix acidizing among the three blends tested (2.5:7.5 and 7.5:2.5 wt% HCl:MSA being the other two blends investigated). At the optimum injection rate of 7.5 cm3/min, both 2.5:7.5 and 5:5 wt% HCl:MSA mixture required lesser pore volumes (PVs) of acid to reach breakthrough, compared to their individual acid controls. A single, straight, and dominant wormhole was observed with no branching and less tortuousity in both the cases. The control experiments with equivalent concentrations of HCl and MSA required higher PVs of acid to reach breakthrough with branching during wormhole propagation. Calcium ion dissolution was least for the 5:5 wt% mixture among the three blends tested. Higher unconsumed acid concentration was noted in case of 5:5 wt% compared to 2.5:7.5 wt% blend, thus promising greater penetration depth with the same PV of acid. On the other hand, the wormhole formed by the acid blend of 7.5:2.5 wt% HCl:MSA required almost the same PV of acid to reach breakthrough as its corresponding HCl control, and it was more enlarged and tortuous than its corresponding MSA control. 5:5 wt% HCl:MSA blend creates deeper wormholes and retards the HCl reaction with the rock matrix.

Major advantages rendered by the new acid mixture include: (1) deeper wormholes that will ultimately result in enhanced well productivity, and (2) cost effectiveness in carbonate stimulation compared to standard systems currently used in the market.
Method for Estimating and Analyzing for TOC of Hydraulic Fracturing Fluids
Authors: Harry David N. , Mallory Matt , Tucker Scott
Published: March 2017

Total Organic Carbon (TOC) is a characteristic of the amount of organic carbon present in a chemical compound or mixture, such as a hydrocarbon-bearing formation, water, or even a fracturing fluid. Organic carbon is a potential measure of food available for bacteria, and, as such, an indirect measure for the potential for wellbore fouling, formation damage, and regained permeability. For this reason, TOC is often used as an indicator of overall water quality across multiple industries, and is becoming more prevalent as a general indicator of water quality for frac reuse. TOC has been demonstrated to be directly correlative to the much-more difficult and time-dependent determination of Biochemical Oxygen Demand (BOD), and a recently developed method by which TOC can be analyzed in the field has made TOC determinations even more accessible.

The paper provides a theoretical determination of the TOC of over 100 fracturing fluid additives and compares the results with a field method for making TOC determinations. Also provided are examples on how to use TOC values for individual stimulation fluid additives to estimate the TOC of the entire frac fluid as pumped. The result of the exercise in assessing the TOC content of various slickwater and crosslinked polymer fluids provides a comparative guide for potential downhole bacterial and formation damage issues.

It is therefore possible to estimate the potential for proppant pack and/or formation damage with knowledge of the TOC of a fracturing fluid prior to its selection without having to resort to an analysis of the fluid. Also provided are insight into the range of TOC's that might be observed in various spent frac flowback waters as they are associated with general frac fluid types, such as Slickwater or Crosslinked frac fluids. Armed with knowledge of the TOC of actual flowback it may be possible to determine whether or not additional well cleanout operations might improve well productivity.
Inhibition of Calcium Carbonate Scale in the Presence of EOR Chemicals
Authors: Wang Qiwei , Al-Nasser Waleed , Al-Dawood Faez , Al-Shafai Tawfiq , Al-Badairy Hameed , Shen Shouwen , Al-Ajwad Hassan , Liang Feng
Published: March 2017

A field trial has been planned for a chemically enhanced oil recovery (EOR) project in Saudi Arabia. The injection chemicals will be a combination of surfactants and polymers. There is a concern that the breakthrough of these chemicals in produced water could affect scale formation process and interfere with the scale treatment program. The objective of this study is to investigate the potential impacts of the injected EOR chemicals on calcium carbonate (CaCO3) scale inhibitor performance.

Laboratory tests were carried out using static bottle and dynamic tube blocking methods. CaCO3 scale inhibition was studied in the absence and presence of the EOR chemicals at the estimated peak breakthrough concentrations, i.e., 200 mg/L polymers and 150 mg/L surfactants. Three different types of inhibitors were evaluated: tri-phosphonate, penta-phosphonate, and polyacrylate. Inhibition (%) from the bottle test and minimum effective dose (MED) based on the tube blocking method were determined for each inhibitor at 160 °F. Scale precipitates from the bottle tests were also characterized for morphology and polymorphs using environmental scanning electron and X-ray diffraction (XRD) techniques.

Obtained results showed significant reductions in scale inhibitor performance by the EOR chemicals. In dynamic tube blocking tests, the MED vaules of inhibitors were increased roughly 10 times with the EOR chemicals. The static bottle tests showed considerable changes under the test conditions. For example, the inhibition (%) of the penta-phosphonate based inhibitor at 20 mg/L was diminished from 100% to 20%; and the inhibition (%) of the tri-phosphonate inhibitor was decreased from 100% to below 50% and 70%, respectively, at 10 mg/L and 20 mg/L. The polymeric inhibitor completely lost its inhibition efficiency over the tested concentration range of 2 mg/L to 20 mg/L. The impact of EOR chemicals were also demonstrated by the remarkable ranges of crystal morphologies, changing from simple aragonite columns to nanorod, distorted spheroid, and flower-like superstructure in the presence of EOR chemicals and inhibitors.

This paper presents the first reported comprehensive study on the impacts of the EOR chemicals on CaCO3 scale formation and prevention. Results suggest that the performance of scale inhibitors could be substantially affected by the EOR chemicals. Such potential impact should be determined and a new scale treatment program should be developed for the success of EOR projects.
Automatic Optimisation of Oilfield Scale Inhibitor Squeeze Treatments Delivered by DSV
Authors: Vazquez Oscar , Ross Gill , Jordan Myles , Baskoro Dionysius Angga , Mackay Eric , Johnson Clare , Strachan Alistair
Published: March 2017

Oilfield scale deposition is one of the important flow assurance challenges facing the oil industry. There are a number of methods to mitigate oilfield scale such as sulphate reduction of the injected brine, flow modification to reduce water flow, damage removal by dissolvers or physically by milling or reperforating, and finally, inhibition, particularly recommended if a severe risk of sulphate scale deposition is present. Inhibition consists of the injection of a chemical which prevents the deposition of scale, either by stopping nucleation or retarding crystal growth. The inhibiting chemicals are either injected in a dedicated continuous line, or bull-headed as a batch treatment into the formation, commonly known as a scale squeeze treatment. Generally, scale squeeze treatments consists of the following stages: preflush, to condition the formation or act as a buffer to displace tubing fluids; main treatment, where the main pill of chemical is injected; overflush, to displace the chemical deep into the reservoir; followed by a shut-in stage to allow further chemical retention; finally, the well is put back in production. The well will be protected as long as the concentration of chemical in the produced brine is above a certain threshold, commonly known as minimum inhibitor concentration (MIC), usually this value is between 1 and 20 ppm. The most important factor in a squeeze treatment design is the squeeze lifetime, which is determined by the volume of water or days of production where the chemical return concentration is above MIC.

The main purpose of this paper is to describe the automatic optimisation of squeeze treatment designs using an optimisation algorithm, in particular, using particle swarm optimisation (PSO). The algorithm provides the optimum design, which strictly speaking in terms of squeeze treatment designs, it provides the longest squeeze lifetime, although, it might not be the most efficient. To determine the most efficient design, an optimisation algorithm is used to provide an optimum design based on the following objectives: operational deployment costs, chemical cost, total injected water volume and squeeze treatment lifetime. Operational deployment costs include support vessel, pump and tank hire. There might not be a single design optimising all objectives, thus the problem becomes a multi-objective optimisation. The algorithm is capable of analysing a great number of designs, making it easy to identify the designs that are non-dominated, which provides the right amount of information to identify the most cost effective squeeze treatment design, and therefore cutting total treatment costs.
Benign Use of Inclusion Complex Formation Property of Cyclodextrin and Its Application in Cement Fluid-Loss Control
Authors: Remitha A K , Agashe Snehalata , Reddy B R
Published: March 2017

Synthetic polymers have long been used as fluid-loss additives (FLAs) in hydraulic cement slurries for cementing subterranean zones. Typically used synthetic polymeric materials include N,N-dimethylacrylamide and sulfonated acrylamide monomers, which are preferred for high temperature applications. However, as these materials are less environmentally acceptable, the search for more environmentally acceptable chemical increases. Although preferred materials are biopolymers, they sometimes impart high slurry viscosity at ambient temperature, and cause thinning and settling of the cement slurries at elevated temperatures. Thus, there is a need for an additive composition that is environmentally acceptable and performs better over a wide temperature range.

This paper presents a novel idea of using a combination of two biopolymers, a hydrophobically modified (HM) biopolymer and a hydroxypropyl derivative of cyclodextrin (DCY) for controlling fluid loss, while imparting better cement slurry properties, stability, and viscosity. HM biopolymer as an FLA by itself causes excessive surface slurry viscosification at ambient temperature. However, when DCY was added into the cement slurry, optimum slurry viscosities were observed at ambient temperature, thus avoiding pumping issues. Laboratory experiments showed that the fluid-loss control was excellent, but the viscosity of cement slurry was high at ambient temperature when the HM biopolymer was used as a FLA by itself. The addition of DCY reduced the surface viscosity without compromising fluid-loss control and without affecting other properties. Studies conducted at elevated temperatures revealed that the HM biopolymer was left intact to maintain the cement slurry viscosity at that temperature, thereby helping prevent settling issues. Also, no significant effect on compressive strength development and thickening time of the cement slurry was observed with the addition of DCY molecules. The results of laboratory experimentation at ambient and elevated temperatures support the formation of in-situ inclusion complex formation of DCY molecules with the HM biopolymer.
A New Theoretical Model for the Induction Time and Scale Inhibitor Dosage Predictions for Calcite and Barite Over Wide Ranges of Temperature, Inhibition Concentration and Saturation Index
Authors: Dai Zhaoyi , Zhang Fangfu , Yan Fei , Bhandari Narayan , Ruan Gedeng , Zhang Zhang , Liu Ya , Alsaiari Hamad A. , Lu Yi-Tsung , Deng Guannan , Kan Amy T. , Tomson Mason
Published: March 2017

Mineral scale formation can lead to the blockage and shutdown of production wells in the oil and gas industry. Large amounts of scale inhibitors are added to mitigate the losses due such mineral scale formation. Both insufficient and excessive scale inhibitor additions can cause unnecessary expenses. Because inhibition mechanisms are poorly understood, current models do not predict accurately the minimum effective dosage (MED) required for different inhibitors, temperatures, and inhibition times over wide ranges. Using a new approach, this paper developed a theoretical model to predict scale inhibition kinetics based on the classical nucleation theory and the regular solution theory. This model assumes that scale inhibitors can change the nucleus structure and the apparent saturation status of the scale minerals. These impacts were modeled to be proportional to the inhibitor concentrations. The model accurately predicted the precipitation and inhibition kinetics of barite and calcite with or without the presence of eight different scale inhibitors up to 90 and 175°C, respectively. This study can be used as a template to evaluate scale and inhibition kinetics, predict MED, and elucidate scale inhibition mechanisms on a common theoretical basis.
Isothermal Titration Calorimetry: A New Tool for the Development of Structure Activity Relationships for Sulphide Scale Control
Authors: Ackermann L.-M. , Klapper M. , Kayser C. , Kaiser A.
Published: March 2017

Smart scale management techniques are of great demand in nowadays oil and gas industry. The formation of zinc, iron and lead sulphide scales can cause severe damages of production equipment which ultimately results in loss of productivity.1-4 Currently used materials act inefficient, as high amounts of materials are needed, which makes research in this field demanding.5 However, to develop anti-scaling agents, a deeper understanding of the molecular interactions of the typically used polymers is required. To understand the occurring interactions, isothermal titration calorimetry (ITC) is introduced as a new method, which allows for a more rational design of a new material and makes screenings, as the have been done in the past, unnecessary. With the use of ITC it was proven, that several sulfonic acid, phosphonic acid and carboxylic acid carrying monomers are suitable candidates showing strong interaction with the zinc sulfide surface, which is one of the exotic problems in scale formation.6 Furthermore, the influence of the molecular weight and the composition was identified during the investigations of the different homopolymers and copolymers of the previously tested monomers.
Which Cations are Detrimental to Shale Preservation?
Authors: Recio Antonio , Benoit Denise , Henkel Kristina , York Kevin
Published: March 2017

The water-sensitive nature of shale is traditionally thought to be a factor of the clay content of the rock. Because current practices to mitigate formation damage entail the use of brines to control the osmotic potential of stimulation fluids, we posited that not all brines will induce the same response from Bentonite, Illite, and more importantly shale.

Current industrial practices to mitigate permeability damage in source rock shale reservoirs typically entail the use of sodium-, potassium-, calcium-, tetramethyl ammonium-, and/or choline chloride salt brines to control the rate of cation exchange between formation clays and stimulation fluids. Industrial and literature precedent suggests that below a critical salt concentration (CSC) osmostically-driven cation-exchange between injected fluid and the formation is the primary damage mechanisms for both swelling and migrating clays; however, above the CSC, the potential still exists for crystalline swelling and mechanical destabilization. Examining various clays and clay laden formation materials revealed that certain cations, even above their CSC, will induce formation damage.

To accurately assess the effect and permanency of various brines when introduced to pure clay as well as shales, a statistically relevant laboratory protocol has been developed to evaluate the role differing cations play in shale preservation. The clay and formation cuttings were evaluated for swelling and mechanical stability, then subjected to dynamic experiments using sandpack, coreflow, and API conductivity testing methods. The evaluated formation materials were diagnosed with computed tomography (CT), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy to diagnose permeability damage mechanisms for given treatment fluids and formation material composition.

This paper seeks to advance the existing understanding of the damage mechanisms involved when brine containing stimulation fluids are introduced to shale reservoirs. Currently, there is a lack of consensus on the significance of the identity of the ideal salt-cation treatment to preserve permeability in shale reservoirs. The authors have probed the effect various brines have on clay and unconventional material, which compliments the current body of literature related to shale inhibition.
Short Term Gas Migration Control in Well Cementing: Comparative Behavior of Fluid Loss Control Polymers
Authors: Cadix A. , Thant K. , Neufeld J. , Nelson T. , Auneau L. , Phan C. , Wilson J.
Published: March 2017

Short term gas migration control is one of most critical aspects of zonal isolation that must be achieved through the cementing of a well. It has long been discussed and demonstrated that gas migration occurring either immediately at the placement or in the short-term (e.g. within few hours after plug bump) is a combination of many factors including cement design and density matching. In addition, it is generally considered that fluid loss control additives can play a significant role in the ability of a cement sheath to be considered as gas tight. It is of course mandatory to obtain low fluid loss values to hold cement initial design with adapted density, water content for full cement hydration and effective placement but even with identical fluid loss and rheology, very different gas permeability results can be obtained with different types of fluid loss control additives.

This study is focused on the investigation of the relative performance of several fluid loss polymers and their ability to form a gas tight sheath. Systems that were considered for the study were conventional additives based on high molecular weight water soluble polymers such as so called "AMPS" based anionic copolymers and styrene butadiene latex which were compared to a newly developed block copolymer. This latter comprises first a strong adsorbing block, then a long second hydrophilic block providing filtration control. This technology was already demonstrated to be very effective in preventing performance losses in the presence of competitive formulation additives such as dispersant or retarders (see SPE173758). In addition in this work gas permeation through setting cement sheath was investigated and a systematic study on permeability and porosity within filter cake and setting cement using Mercury Intrusion Porosimetry (MIP) was carried out. MIP results were discussed versus direct scanning electron micrograph imaging.

As expected, it was confirmed that low fluid loss is mandatory to successfully pass a gas migration test. In addition, it was shown that in spite of comparable standard fluid loss control performance, actual permeability and porosity reduction within the filter cake can be significantly different. As far as pore sizes within the setting cement are concerned, there was here very limited impact of the fluid loss additive system. It was confirmed as expected from industry standards that styrene butadiene latex very effectively reduce permeability but diblock copolymer can to a fair extent be considered as a very effective substitute to design gas tight slurries.
Squeezing the Bakken: Successful Scale Squeeze Programs Lead to Shift in Bakken Scale Control
Authors: Spicka K. J. , Eagle L. Holding , Littlehales I. , Fidoe J. , Jordan M. M. , Zosel Z. , Glasser S.
Published: March 2017

This paper highlights efforts taken in answering the following question: "Can horizontal unconventional shale wells be successfully squeezed for scale control?".

The Bakken shale formations in North Dakota, Montana and Alberta have presented unique operational challenges during the unconventional play boom. Despite the ability to control scale formation with conventional scale inhibitors under Bakken conditions, scale formation (primarily calcium carbonate) can still remain an operational challenge due to well design and sub-optimal scale inhibitor deployment.

Due to limited experience in the industry in scale squeezing fractured long reach horizontal wells, scale squeezes have not been frequently applied in the Bakken. As a result of sub-optimal scale control despite application of suitable scale inhibitors, an in-depth evaluation of scale squeeze chemistries, application methods and scale squeeze modeling has been ongoing in the Bakken. These successful applications are being studied to improve current scale squeeze modeling approaches for horizontal, fracked wells in addition to understanding the factors that impact Bakken scale squeezes. The lessons learned in modeling, application and monitoring of the scale squeezes will be discussed in this paper. Squeeze9 and Place-iT™ field history matching indicate the primary impact to squeeze life is the amount of scale inhibitor (both concentration and volume) used while overflush volumes have less of an impact. This varies from traditional scale squeezes that combine scale inhibitor and overflush volumes to achieve the desired scale squeeze lifetime. Due to the unique brine chemistry of the Bakken, squeeze monitoring has relied less upon traditional ion tracking and almost exclusively upon more advanced environmental scanning electron microscopy (ESEM) of suspended solids within the produced brine samples. Examples of successful Bakken squeezes lasting more than 1 year will be highlighted.

The successful applications of scale squeezes in the Bakken are bringing a new method of efficient, cost effective, long term scale control to unconventional plays. The lessons learned in the Bakken, and the resulting advancement of unconventional scale squeeze models and theories, have implications for the global industry as unconventional plays across the world are identified, explored and produced.
Low-Interfacial-Tension Foaming System for Enhanced Oil Recovery in Highly Heterogeneous/Fractured Carbonate Reservoirs
Authors: Dong Pengfei , Puerto Maura , Ma Kun , Mateen Khalid , Ren Guangwei , Bourdarot Gilles , Morel Danielle , Bourrel Maurice , Biswal Sibani Lisa , Hirasaki George
Published: March 2017

Oil recovery in highly heterogeneous carbonate reservoirs is typically inefficient because of the high permeable fracture networks and unfavorable capillary force resulting from oil-wet matrix. Foam as a mobility control agent has been proposed to mitigate reservoir heterogeneity by diverting injected fluids from the highly permeable fractured zones into the low permeable unswept rock matrix, hence improving the sweep efficiency. This paper presents the use of a low-interfacial-tension foaming formulation to improve oil recovery in highly heterogeneous/fractured oil-wet carbonate reservoirs. The novel formulation providesboth mobility control and oil-water interfacial tension (IFT) reduction to overcome the unfavorable capillary forces preventingdisplacing fluids from entering oil-filled matrix. Thus, as expected, the combination of these two effects significantly improves oil recovery compared to either foam or surfactant flooding.

In this research, the three-component surfactant formulation was tailored by phase behavior tests in seawater with crude oil from a targeted reservoir. The optimized formulation can simultaneously generate 10−2 mN/m IFT and strong foam in porous media with oil present, as demonstrated by IFT measurements and foam floodingtests. Foam flooding was investigated in a representative fractured core system, in which a well-defined fracture was created by splitting core lengthwise and precisely controlled of aperture by applying specific confining pressure. The foam flooding experiments reveal that the low-IFT foaming formulation in an oil-wet fractured Edward Brown dolomite recovers about 72% of oil while water flooding only recovers less than 2%,and it is more efficient than foam flooding lacking low oil-water IFT property.The core flood test results also indicate that low-IFT foam diverts mostly surfactant solution into matrix because of (1) the mobility reduction due to foam in the fracture network, (2) significantly lower capillary entry pressure for surfactant solution compared to gas and (3) the increase of mobility to water in the matrix by the low oil-water IFT displacing residual oil in the matrix. This selective diversion effect of the novel foaming system allows to carry out the surfactant flooding at low IFT condition in the low permeability matrix to recover the trapped oil, which is otherwise impossible with simple surfactant or high-IFT foam flooding in highly heterogeneous or fractured reservoirs.