bluuebunny/crossref_metadata_2025 huggingface dataset:
Cadeias produtivas sustentáveis no desenvolvimento territorial: a castanha na Bolívia e no Acre, Brasil
Authors: Brose Markus Erwin
Published: March 2017

A cadeia produtiva da castanha tem sua produção limitada a dois territórios vizinhos, historicamente baseada na servidão por dívida. Ambas as regiões passaram por profundas modificações nas últimas décadas e oferecem rara oportunidade para comparar as condições de trabalho em uma mesma cadeia produtiva. Apresentamos indicadores de que, ao contrário da Bolívia, a mobilização social no Acre viabilizou a reestruturação da cadeia produtiva, tornando-a mais inclusiva e sustentável.
Mensuração de ativos biológicos pelo método de custo histórico e valor justo na pecuária leiteira
Authors: Vieira Eloir Trindade , Itavo Luis Carlos Vinhas , Aranha Jose Aparecido Moura
Published: March 2017

Na pecuária leiteira, a mensuração pelo custo histórico se faz pelo registro de todos os custos ocorridos no período, tais como gastos com insumos, manejo, salários, ou aquilo que se pode chamar de gastos operacionais. Ocorre que há ressalvas quanto a essa mensuração. Assim, surgiu a mensuração contábil pelo valor justo (fair value), sugerida por órgãos reguladores em todo o mundo, pois possibilita segundo  autores, credibilidade nas informações.
Formación identitaria como eje articulador de permanencia y éxito académico de estudiantes de educación superior
Authors: Sandia Carlos Mejías
Published: March 2017

Las causas de la deserción y el fracaso académico originan variadas interrogantes que se desprenden del estudio del ingreso o de la deserción universitaria más bien desde lo cuantitativo. Sin embargo, ellas no dan cuenta de la problemática desde los propios actores ni de cómo la variable formación identitaria participa en este proceso y configura el conjunto de representaciones de las/os estudiantes y cómo estos influyen en la complejidad de conjugar factores sociales, motivacionales e institucionales.
Ecoinovações: um ensaio teórico sobre conceituação, determinantes e achados na literatura
Authors: Aloise Pedro Gilberto , Nodari Cristine Hermann , Henri Dorion Eric Charles
Published: March 2017

Esta pesquisa teve por objetivo identificar as principais características e os fatores direcionadores das ecoinovações, também, denominadas de inovações verdes, inovações ambientais ou inovações sustentáveis. A literatura que fundamentou este trabalho foi articulada a partir de uma pesquisa documental, com análise bibliométrica de artigos. Dentre os achados, foi possível identificar particularidades relacionadas às inovações ambientais que não comprovam totalmente algumas teorias, amplamente aceitas no meio acadêmico.
Os Terena e a escrita da história
Authors: Ximenes Lenir Gomes
Published: March 2017

A proposta deste artigo é refletir sobre o lugar reservado para os povos indígenas (e mais particularmente para os Terena) na historiografia brasileira, de acordo com as influências de diferentes correntes históricas, a partir do século XIX. A escrita historiográfica é, por si só, um constructo histórico. Ou seja, os autores não estão isolados no tempo, e as perguntas que fazem ao passado têm origem nas suas vivências, nos seus meios sociais e nas situações históricas em que se encontram. Esse é o ponto de partida para entendermos como os indígenas foram/são retratados nas obras historiográficas. Este texto traz um enfoque específico sobre os indígenas da etnia Terena, que atualmente habitam diversas áreas no estado do Mato Grosso do Sul, duas no estado de São Paulo e uma em Mato Grosso. Estão também em vários bairros de cidades sul-mato-grossenses como Campo Grande, Aquidauana, Anastácio, Miranda, Sidrolândia e Dois Irmãos do Buriti.
Educação da criança indígena e educação infantil em Mato Grosso: uma questão para o debate
Authors: Grando Beleni Salete
Published: March 2017

Em Mato Grosso, vivem 43 povos indígenas, sendo sua maioria atendida com escolas. Cada projeto educacional, no entanto, depende das estruturas socioeconômicas e culturais do povo e da proximidade geopolítica da comunidade com o município ou com outras organizações. Ao refletirmos sobre a Educação Escolar Indígena e sua relação com a educação pretendida por cada povo, problematizamos as políticas educacionais e a formação de professores a partir da nossa realidade e questionamos a obrigatoriedade da Educação Infantil nas aldeias, evidenciando os estudos que nos auxiliam a melhor compreender o protagonismo e autonomia da criança a partir das formas de educar e garantir a vida coletiva como um direito coletivo dos povos indígenas, explicitados na Constituição Brasileira e na LDB. Palavras-chave: educação infantil, formação docente, educação indígena.
Histoid Leprosy
Authors: Rinasari Umi , Sawitri Sawitri , Listiawan M. Yulianto , Prakoeswa Cita Rosita , Agusni Indropo , Santoso Rachmat , Izumi Shinzo
Published: March 2017

Histoid Leprosy is a variant of lepromatous leprosy with characteristic clinical and histopathological features. Usually it is occured in lepromatous patients who relaps after dapsone monotherapy, in those with dapsone resistance , sometimes even after multidrug treatment, or at times, de novo with characteristic clinical and histopathological features. A 36 years old male, originated from Papua, visited to the skin outpatient clinic with translucent shiny nodules on the left elbow and thumb for the last 18 months. The nodules were multiple, painless and firm. There were nasal congestion, tickening of ear lobes and loss of eye brows. Patient did not have any history of previous antileprotic treatment. Routine blood examination was normal. Bacteriological examination of slit skin smear revealed acid-fast bacilli of Bacterial Index 4+ and Morfologic Index 10%. Histopathology of skin suggested lepromatous leprosy of histoid type with characteristic interlacing bundles of spindle shaped cells. Anti-PGL1 antibody (ELISA) revealed high titer of IgM (>5.300 u/ml) and also IgG anti PGL-1 (>5.300 u/ml). Polymerase chain reaction examination test to detect M.leprae was positive and direct sequencing of M.leprae isolate shows no mutation, which means no resistancy to MDT treatment. Treatment with MDTWHO regiment give clinical improvements and the histoid lesions disappered after 3 months treatment.The histoid form of leprosy in this case developed without any prior treatment of anti leprotic drugs ( de novo ). Some theoretical aspects of the patho-mechanism of histoid leprosy are discussed.
BIOCOMPATIBILITY OF AZITROMICYN ON CONNECTIVE TISSUE
Authors: Kurnia Shafira
Published: March 2017

Background: periodontal disease is commonly caused by bacteria, especially actinomyces actinomycetemcomitans and porphyromonas gingivalis have an abilty enter epithelial cells objectives: to investigate systemic azithromycin as the antibiotic of choice for periodontal disease based on biocomptability test in connective tissue. Material and Methods: BHK 21 cell lines were exposed to 0.025%, 0.050%, 0.075%, and 0.1% azithromycin solution for seven times. Samples were put in incubator for 24 hours. Result: Azitrromycin 0.050%-0.1% showed significant difference between life cells percentage and control, however, azithromycin 0.025% revealed insignificant difference with control. Conclusion: 0.025% azithromycin was considered biocompatible with connective tissue and 0.050% was not.
COMPARATIVE STUDY ON THE INTENSITY OF Mycobacterium leprae EXPOSURE BETWEEN HOUSEHOLD AND NONHOUSEHOLD CONTACT OF LEPROSY
Authors: Arsyad Yuniarti , Jifanti Friska , Amiruddin Muhammad Dali , Anwar Anis Irawan , Adriaty Dinar , Wahyuni Ratna , Iswahyudi Iswahyudi , Agusni Indropo
Published: March 2017

Leprosy stills a public health problem in West Sulawesi which has a Case Detection Rate (CDR) around 43.69/100.000 population. Household contacts of leprosy are a high risk group to be infected, due to droplet infection mode of transmission of the disease. A nose swab examination and serological study was conducted to detect exposure of M. leprae of people who live in leprosy endemic area. Detection of M. leprae in the nasal cavity will represent the exposure rate from outside and the measurement of specific antibody is represented the result of exposure to the immune system. Two group of inhabitants (30 household contacts of leprosy and 30 nonhousehold contacts) were involved in the study. They live in Banggae district, a leprosy endemic area of Majene Regency, West Sulawesi. Sixty nose swab samples and sixty capillary blood samples from the same invidividuals of the two groups were collected and sent to Leprosy laboratory of the Institute of Tropical Disease, Airlangga University Surabaya. A Polymerase Chain Reaction (PCR) was performed to the nose swab samples for detection of M. leprae. The blood samples were examined serologically to measure the level of anti PGL-1 antibody. PCR examination of nose swab samples showed 1/30 positive result in the household contact group and also 1/30 positive result in non-household contact of leprosy (statistically no significant difference, p > 0.05). Serological study showed higher sero-positive result in the household contact group (15/30 or 50%) compared to non-household contact (11/30 or 36%), but statistical calculation revealed no significant difference between the two groups (p > 0.05) on sero-positive results of leprosy. It is concluded that household and non-household contact in leprosy have the same risk to be affected by the disease. The term of household and non-household contact need to be redefined. The possible role of exposure from the environment was also discussed, especially from non-human resource of M. leprae.
MYCOBACTERIA AND OTHER ACID FAST ORGANISMS ASSOCIATED WITH PULMONARY DISEASE IN JOS, NIGERIA PULMONARY DISEASE AND ACID FAST ORGANISMS
Authors: AE Ani , B Diarra , UR Dahle , C Lekuk , F Yetunde , AM Somboro , Tounkara Anatole , J Idoko
Published: March 2017

Objective: Acid fast bacilli (AFB) for sputum smear microscopy is the affordable method used for prompt diagnosis of tuberculosis in Nigeria despite its lack of specificity and limited sensitivity. The study aims to identify Mycobacterium tuberculosis and other acid fast organisms isolated from sputum of of HIV positive adult patients with pulmonary disease in Jos, Nigeria. Methods: Acid fast organisms isolated from 80 AFB positive sputa of HIV positive adult patients suspected for tuberculosis in Jos, Nigeria were identified for members of M. tuberculosis Complex (M tuberculosis, M bovis, M africanum, M canetti M. microti and M. caprae) by use of spoligootyping, Multiplex Gen Probe, Hain genotype assay and gene sequencing for spoligotype negative isolates. Results: Seven different spoligotypes of M. tuberculosis complex were identified from 70/80 (87.5%) total number of isolates. M. kansasii (1), M. dulvalii (1) Nocardia species (1) and Tsukamurella species (2) were detected from 5/10 spoligotype negative isolates. Conclusion and Recommendation: Although M. tuberculosis is the dominant AFB associated with chronic pulmonary disease in Jos, Nigeria, other clinically relevant mycobacteria were observed in the study. This suggests that other AFB positive microorganisms associated withtuberculosis -like symptoms could be misdiagnosed and incorrectly treated as M. tuberculosis. It is therefore necessary for laboratories in TB high burden countries to step up diagnostic procedures beyond routine smear microscopy.
ANALYSIS ON WHOLE BLOOD, SGOT, SGPT, AND TNF-a EXAMINATION IN PATIENTS WITH NON-DENGUE AND POSITIVE DENGUE FEVER (DF/DHF)
Authors: Anggraini Rahayu , Nasronudin Nasronudin
Published: March 2017

Background: In Indonesia has four serotypes, the DEN-1, DEN-2, DEN-3 and DEN-4. The management of Dengue virus becomes difficult because the patients were infected with different clinical profiles depending on the serotypes and genotypes of infecting dengue virus. Consequently, the diagnosis and treatment becomes difficult. Aim: The purpose of this study was to identify the difference between the results of laboratory tests between non-dengue fever and positive dengue fever. Method: This study was an observational cross-sectional study. Fifteen samples were diagnosed with dengue fever and fifteen samples with negative dengue fever on NS1, IgM / IgG-anti-DHF strip test results. Laboratory tests comprising whole blood, SGOT, SGPT, and TNFa were first examined when the patient came to the hospital. The collected data were analyzed by Chi-Square test SPSS version 13 for Windows. Result: The results of the study in two groups regarding sex, age, days of fever, grade, hemoglobin levels, leukocytes count, platelet count, hematocrit percentage, SGOT levels, and TNFa level were not significantly different with p > 0.050, whereas the SGPT level in non-dengue increased 3 x of normal value of 66.7%, n = 10/15 and in positive dengue fever the SGPT level was within normal limits, found in 60%, n = 9/15, so there was significant difference with p = 0.022 (p < 0.05). Conclusion: in non-dengue SGOT and SGPT levels increased of 1–3 times the normal value. In positive dengue fever SGOT levels increased 1–3 x normal value, but SGPT levels was within normal value, so SGPT levels can be used as a predictive factor for distinguishing the two types of fever.
The Relation of Obesity and Individual Factors with Knee Osteoarthritis
Authors: Anggraini Niken Enestasia , Hendrati Lucia Yovita
Published: March 2017

ABSTRACTOsteoarthritis represent disease at most found in the world, including in Indonesia. This disease cause pain in bone and disability at patient so disturb everyday activity. One of removed occurrence  of knee Osteoarthritis  was obesity. Other factors like age, gender, physical activity, and habit smoke were risk factors of knee Osteoarthritis . This research was the relationship of obesitas and individuals factors with occurrence knee osteoarthritis at Surabaya Islamic Hospital. The methods of this research was an observation with case control design. Level of sampel was 64 which consist of 32 case group and 32  control group from incomed patient to radiology unit  Islamic Hospital Surabaya for X-Ray photo. The dependent variable was occurence of knee osteoarthritis . The independent variables were obesity, gender, age, physical activity, habit smoke. The instrument used was a questionnaire and form BMI measurement. Data analysis used Chi-Square test with α=0,05 and to know oods ratio (OR)  used statclac. The results showed significant relationship between occurence of knee osteoartritis with obesity (p=0,001,OR=7,20), age (p=0,012,OR=3,67) , gender (p=0,005,OR=4,69). For the characteristic of habit smoke (p=0,268,OR=0,56) and physical activity (p=0.919,OR=0,71) were’nt associated with  occurence of knee Osteoarthritis  at Surabaya Islamic Hospital.  The conclusion there is relationship between obesity with knee osteoarthritis  at Surabaya Islamic Hospital. Risk factor knee osteoarthritis like gender and age also there were relation with occurence of knee osteoarthritis , for the risk factor of physical activity and habit smoke were’nt relation with occurence of knee osteoarthritis. Keyword : Knee osteoarthritis, obesity, individual factors
Improved Gender Recognition during Stepping Activity for Rehab Application Using the Combinatorial Fusion Approach of EMG and HRV
Authors: Mohd Rosli Nor Aziyatul Izni , Abdul Rahman Mohd Azizi , Balakrishnan Malarvili , Komeda Takashi , Mazlan Saiful Amri , Zamzuri Hairi
Published: March 2017

Gender recognition is trivial for physiotherapist, but it is considered a challenge for computers. The electromyography (EMG) and heart rate variability (HRV) were utilized in this work for gender recognition during the stepping exercise using a stepper. The relevant features were extracted and selected. The selected features were then fused to automatically predict gender recognition. However, the feature selection for gender classification became a challenge to ensure better accuracy. Thus, in this paper, a feature selection approach based on both the performance and the diversity between the two features from the rank-score characteristic (RSC) function in a combinatorial fusion approach (CFA) was employed. Then, the features from the selected feature sets were fused using a CFA. The results were then compared with other fusion techniques such as naive bayes (NB), decision tree (J48), k-nearest neighbor (KNN) and support vector machine (SMO). Besides, the results were also compared with previous researches in gender recognition. The experimental results showed that the CFA was efficient for feature selection. The fusion method was also able to improve the accuracy of the gender recognition rate. The CFA provides much better gender classification results which is 94.51% compared to Nazarloo's work (90.34%) and other classifiers.
Good Faith in Life Insurance Contract by Indonesian Court
Authors: Huda Mokhamad Khoirul
Published: March 2017

This paper reviews both the interpretation of good faith and its implementation by the Court in terms of life insurance contracts. The principle of good faith in life insurance contracts was under the provision of the Article 251 Wet Boek van Kophandel which assigned the obligation of good faith on the insured. Based on the context of its historical and systematical interpretation, the obligation of good faith should be on both sides, the insurer and the insured. The insured had an obligation to inform any material facts and the insurer had to investigate those all facts. Until recent days, however, judges in all levels of Court did not have any shared and full understanding on the interpretation of good faith in life insurance contracts. As the result, many Courts were frequently inconsistent with each other. Hence, the sense of fairness the people perceived from the court verdict was not achieved.
INFLUENCE OF FINANCIALIZATION OF INCOME INEQUALITY IN ASEAN: DATA PANEL ANALYSIS
Authors: Buhaerah Pihri
Published: March 2017

This paper examines the impact of financialization on income inequality in ASEAN-5 countries for the period of 1990-2013 by employing panel data analysis. The data was collected from various secondary sources by undertaking fixed effect model and generalized method moment. The result shows that there is a significant relationship between all financialization indicators and income distribution. Generalized method moment analysis using Arellano-Bond estimator also shows that all financialization indicators have a significant relationship with income distribution. There is no different sign estimator both in fixed model effect and generalized method moment analysis. This paper revealed that financialization indicators such as stock market capitalization and return on assets contribute positively to worsen income inequlality. Incontrast, domestic private debt securities have a negative effect on gini coefficient in ASEAN-5 countries indicating that increasing domestic private debt securities will improve income distribution in the region.
Novel Studies on Precipitated Phosphate Ester Scale Inhibitors for Precipitation Squeeze Application
Authors: Valiakhmetova A. , Sorbie K. S. , Jordan M. M. , Boak L. S.
Published: March 2017

Often, scale inhibitors (SIs) applied in oilfields are organic phosphorus compounds, either phosphonates, phosphorus containing polymers, or phosphate esters. The latter group of SIs, phosphate esters, have not been as extensively studied as the others and we focus on these in this paper. The current work is focused on the properties of precipitated calcium - phosphate ester (PE) complexes denoted as PE_Can, with the stoichiometry n.

SIs, injected into a wellbore during squeeze treatments, can be retained in the formation rock via two main mechanisms, adsorption and precipitation. Precipitation squeeze treatments are often based on the reaction between a SI and divalent cations where the mixed complexes that form, denoted SI_Mn2+, usually havea much lower solubility than the free SI itself.

In this work we show, that the phosphate ester precipitation process is quite different from that of SIs commonly used by industry, i.e.phosphonates and polymers. Unlike phosphonate-divalent complexes, the phosphate ester complexes stoichiometry is not sensitive to solution pH. However, it is found that elevated pH of PE/Ca solutions positively affects the activity of the precipitates which form; the higher the precipitation pH, the higher the inhibition efficiency (IE, to barite) of the resulting precipitate. The higher IE was determined for stock, precipitated and then re-dissolved phosphate ester and its supernatant solution. These IE results show that phosphate ester activity is very sensitive to temperature; the IE of all phosphate ester solutions decreases with increasing temperature. This phenomenon probably occurs due to hydrolysis reactions at the higher temperatures which changes the chemistry of the phosphate ester solutions. To check this assumption, Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR) were applied to monitor structural changes occurring in molecules of precipitated and stock phosphate ester solutions.

The results obtained in this work are of practical significance for the effective design of phosphate ester precipitation squeeze treatments, since these products offer (i) a more environmentally acceptable alternative to phosphonates, and (ii) a chemical that is significantly easier to detect within produced brine than many polymers used by the industry, many of which are phosphorus free polymers. However, PE scale inhibitors application environment is at lower temperatures, <80°C, relative to phosphonates which can fuctionup to 150°C, and polymers over 200°C.
Effect of Nitrate on Carbon Steel Corrosion
Authors: Vargas Silvia M. , Woollam Richard , Durnie William , Hodges Michael , Betancourt Daniel
Published: March 2017

Nitrate has been used to control Sulphate Reducing Bacteria (SRB) in oil and gas reservoirs. Nitrate is thermodynamically a strong oxidizer, which could increase carbon steel corrosion rates yet; literature documenting the effect of nitrate on corrosion is scarce and contradictory.

This study investigated the effect of nitrate on carbon steel corrosion under simulated oilfield produced water (rich in carbon dioxide with pH~5) and simulated seawater (minimum carbon dioxide and a pH~7). CO2 corrosion tests were conducted with carbon steel X65 exposed to uninhibited brines at 25°C, 60°C, and 80°C via rotating cylinder electrode (RCE). Inhibited synthetic brine was tested under acidic environments at 80°C. Changes in nitrate, nitrite, ammonium and ferrous ions were monitored using ion chromatography.

The results provide experimental evidence to demonstrate that the corrosivity of nitrate strongly depends on pH. Nitrate tends to increase CO2 corrosion rates in the presence of synthetic produced brine (pH~5) and is relatively benign when added to synthetic seawater (pH~7). At the conditions tested, nitrite impurities contained within the source of nitrate tend to increase carbon steel corrosion exposed to synthetic brines.

In the presence of metallic iron and under CO2 environments, nitrate reduces to ammonium, which is thermodynamically stable in acid solutions. The reduction of nitrate can be modelled based on first order kinetics. The main factors promoting the reduction of nitrate are pH, iron to nitrate ratio, and temperature.
A Microfludic Technique for the Evaluation of Demulsifiers
Authors: Loufakis D. N. , Schmitt A. K. , Nelson C. , Hoyles S. , Goodwin J. , White B. , Ayers C.
Published: March 2017

Crude oil is usually produced from the ground in a form of an oil-and-water emulsion. Prior to the treatment of crude oil in the refineries, the removal of water is necessary to prevent corrosion in the pipeline and the refinery equipment. Chemical agents and heat are the most common methods used in order to break the emulsion and enhance the separation of oil and water. The selection of the appropriate chemical (also known as demulsifier or emulsion breaker) is performed by an old, but well-accepted method in the oil industry, the "bottle test". Even though it is widely used, this procedure may be very tedious and time consuming. A typical set of bottle tests may include the testing of several hundred samples. This is partially due to the inability to preselect a promising set of demulsifiers, due to the variability of crude emulsions. As a result, the identification of new methods for fast evaluation of demulsifier performance is highly desirable.

During this study, the microfluidic platform was explored in an effort to identify a novel, fast, and accurate technique for the evaluation of crude oil demulsifiers. An X-junction microfluidic channel was used to generate water droplets in dry crude oil in a controlled manner. The addition of demulsifying agents in the oil phase resulted in the generation of droplets of varying size, and droplet coalescence downstream in the device. In an effort to better understand the microfluidic responses, and their relationship to the macroscopic performance of demulsifiers, these results were examined and compared against bottle test data of the crude oil/water emulsion. A strong correlation among the water drop and oil dryness performance (bottle test response) and the droplet coalescence and relative standard deviation of droplet size (microfluidic response) was observed. This study proves that the microfluidic platform has the potential to serve as an alternate and fast method for demulsifier screening.
Development of Structure-Property Relationships for Oilfield Water Clarifiers
Authors: Young Kaylie L. , D'Ottaviano Fabio , Rhodes Lisa , Gao Wei , Young Wen-Shiue , Behles Jacqueline A. , Khan Greg
Published: March 2017

The production chemical industry currently lacks a comprehensive fundamental understanding of how polymeric oilfield water clarifiers work at the molecular level and which polymer components are most important for increasing field performance. The existing method for choosing a water clarifier involves a brute force approach, bottle testing as many products as possible, and includes a significant amount of trial and error. The study herein describes an approach in which a statistical library of acrylic polymers was used to develop a predictive model of performance for clarifiers in an Alkaline Surfactant Polymer (ASP) flooded reservoir in order to develop a customized polymer.

A library of 50 acrylic polymers was synthesized and characterized with Asymmetric Flow Field Flow Fractionation (A4F). The polymers were evaluated for performance in three wells in an ASP flooded field by measuring the oil and grease remaining in the produced water after treatment. A three-step approach was taken to extract structure-property relationships. Principle Component Analysis was employed to reduce the dimensionality of the characterization properties. The principle components were then modeled using the polymer recipes in JMP/SAS. Finally, a model was developed to understand the field performance results in terms of the principle components.

In the ASP Flood, the performance model indicated that the molecular weight of the acrylic polymers was the most important parameter for water clarifier performance in the three wells tested. The three evaluated wells showed significant variation in sensitivity to molecular weight, which emphasizes the importance of testing polymers in a representative sample of the wells within a reservoir when choosing a product. Importantly, our method of measuring residual oil and grease levels after treatment to evaluate performance was found to have a strong correlation with the ranking system employed by the field bottle testers. This study is one of the first examples of the determination of quantitative structure-property relationships for polymeric oilfield water clarifiers. By using this approach, one can identify the most important parameters for performance in a given field. Using the resulting predictive model, a customized water clarifier can be built for the field to give optimal performance.
Investigation of Oil Adhesion to Shale Rocks for EOR
Authors: Nguyen D. , Phan T. , Phan J. , Hsu T. P.
Published: March 2017

Significant work is ongoing within the industry to determine a best practice for maximizing oil recovery from fractured oil-wet shale reservoirs. Rapid decline curves are often observed and water flooding can be largely ineffective because of negative capillary pressure. The goal of this work is to identify a chemical solution that can maximize oil and gas recovery in unconventional reservoirs by reduction of hydrocarbon adhesion to shale rocks. In order to evaluate an optimal solution, numerous formulations were developed and tested for their impact on adsorption and adhesion on rock and/or sand, changes in interfacial tension, and how the formulation affects the wettability of the formation. Shale rocks were characterized for their surface energy, as this governs the adsorption and adhesion tension of crude oil, water, and chemicals to the solid surface. Formulations were selected that minimized the adsorption on rock and sand surfaces since such adsorption may lead to an increase in the surface tension of fluid pumped into the well and the interfacial tension between the crude oil and fluid. Contact angle measurements were used to determine the Van der Waals and Lewis acid-base components of surface energies for Barnett, Eagle Ford, Niobrara, and Bakken shales. In addition, contact angle measurements and interfacial tension were used to determine the adhesion of crude oil to the rock. Numerous chemical formulations were evaluated to identify products that can decrease the work of adhesion, making oil recovery more efficient (i.e. less work is required to remove oil drops from the rock surface and mobilize them). Competitive adsorption of formulations at the oil-water and rock-water interface was evaluated. The amount of natural surfactants in the oil and their adsorption on the rocks (reversible vs. irreversible) affect whether the rock is oil-wet or water-wet. If the adsorption is reversible, the rock would be more water-wet, resulting in higher oil recovery. Formulations which altered the wettability to water wet rapidly, but reduced the interfacial tension slightly, exhibited the highest oil recoveries.

Based on wettability alteration, interfacial tension, and work of adhesion, a novel product was developed that is salt tolerant (in 30% TDS), thermally stable (115°C), and produces high oil recovery (i.e., 60% OOIP). Kinetics were also improved compared to conventional treatments and brine alone. In addition, this product showed a low static adsorption on the Bakken shale (0.20 mg product active/gram rock) and no emulsion tendency.
Optimization of Scale Treatment Program of a CO2 Water-Alternating-Gas System for Enhanced Oil and Gas Production
Authors: Lu Haiping , Stewart Preston , Jones Doug , Penkala Joe , Brooks Johnathon
Published: March 2017

The use of a water-alternating-gas (WAG) system for enhanced oil and gas production can introduce challenges from scaling issues. At a CO2-WAG facility in the western Rockies of the USA, scale solids were observed to accumulate in the produced fluid gathering and water injection systems. In addition to carbonate scales, suspended solids such as formation fines, corrosion products and bacteria were typically present in the production and injection waters. Although scale inhibitor applications are the preferred approach to prevent scale formation, the suspended solids can limit the performance or availability of these inhibitors by providing large surface areas for their adsorption.

To investigate the effects of pre-existing solids in diminishing performance of scale inhibitors, three types of solids, CaCO3, Fe2O3 and FeS were used in static bottle tests to mimic the impact on scale inhibitor performance in the operating system. A variety of scale inhibitor chemistries were screened, including various types of phosphonate-based and polymer-based scale inhibitors. Test bottles containing simulated field brine were spiked with 100, 1,000 or 10,000 mg/L of each solid and dosed with different scale inhibitors at various concentrations. Results showed that a decrease in scale inhibitor efficiency accompanies increasing amounts of added solids. With CaCO3 and Fe2O3 solids, equivalent amounts of solids limited scale inhibitor performance comparably. FeS solids had the greatest adverse impacts on scale inhibitor performance, possibly because of FeS oxidation or stronger adsorption of scale inhibitors onto FeS oxidation products. In the final phase of this study, scale inhibitor applications were conducted in the CO2 WAG system. Optimization was achieved based on monitoring and system performance. These applications are carefully documented and presented to provide a perspective for effective management of scale in WAG systems.

In conclusion, laboratory results on scale inhibitor performance in the presence of pre-existing solids provided insight into the influence of suspended solids on the efficacy of the scale treatment mechanism. It also established a guideline for inhibitor dosages during field applications to successfully manage scale in this CO2 WAG system in the western Rockies.
Microemulsion Phase Behavior Model Using Empirical Trends in Chemical Potentials
Authors: Torrealba V. A. , Johns R. T.
Published: March 2017

Surfactant-based enhanced oil recovery methods have been a promising technique for the last several decades due to the surfactant's ability to mobilize previously trapped oil by significantly reducing capillary forces at the pore-scale. However, the field-implementation of these techniques have been challenged by the high cost of chemicals, which makes the margin of error for the deployment of such methods increasingly narrow. Some commonly recognized issues are surfactant adsorption, surfactant partitioning to the excess phases, thermal and physical degradation, and scale-representative phase behavior.

Recent contributions to the petroleum engineering literature have used the hydrophilic-lipophilic difference net-average curvature (HLD-NAC) model to develop a phase behavior EoS to fit experimental data and predict phase behavior away from tuned data. The model currently assumes spherical micelles, which may yield errors in the bicontinuous region where micelles transition into cylindrical and planar shapes.

In this paper, we introduce a new empirical phase behavior model based on chemical potentials and HLD that eliminates NAC so that spherical micelles are no longer assumed. The model is able to describe physical two-phase regions, and is shown to represent accurately experimental data at fixed composition and changing HLD (e.g. a salinity scan) as well as compositional data at fixed HLD. Further, the model is extended to account for surfactant partitioning into the excess phases. The model is benchmarked against experimental data, showing excellent fits for a wide variety of experiments, and is compared to the HLD-NAC EoS model for reference.
Numerical Prediction of Reservoir Souring under the Effect of Temperature, Ph, and Salinity on the Kinetics of Sulfate-Reducing Bacteria
Authors: Hosseininoosheri Pooneh , Lashgari Hamidreza , Sepehrnoori Kamy
Published: March 2017

This paper presents an improved numerical model to predict the onset of reservoir souring in sea-water injected reservoirs. The model is developed to study the effect of temperature, salinity, and pH on the growth of sulfate-reducing bacteria (SRB), which are responsible for hydrogen sulfate generation. Furthermore, we investigate the influence of the environmental factors on the prediction of reservoir souring.

First, we model the mechanisms involved in reservoir souring and then identify the parameters that have the crucial effects on the prediction. Previous models assumed that the maximum growth rate is independent and represented by a constant value. They also neglected the competition between different types of substrates. Therefore, we introduce a new mathematical model to express the maximum growth rate of SRB as a function of temperature, salinity, and pH in the first-order Monod kinetics equation. Then, we discuss the modeling of the competition between different types of substrates. Finally, we implement the model into a 3D finite difference non-isothermal reservoir simulator.

The new model results are compared to previous model results and validated against experimental data. Next, a comprehensive sensitivity analysis is performed to show the effect of temperature, salinity, and pH on bacterial growth and the prediction of souring in a numerical reservoir (or core) model. Taking the effect of environmental parameters into account shows the deficiency of previous models to estimate the reservoir souring. Previous models underestimate the concentration of hydrogen sulfate generation per mass of biodegraded substrate (H2S generation coefficient). The results suggest that the hydrogen sulfide concentration increases as the reservoir temperature, salinity, and pH reach the optimum temperature, pH, and salinity required for SRB to reach its maximum growth rate.

The present work differs from earlier works by explicitly determining parametric values required for a kinetic model. This model is as an effective approach to accurately predict the concentration of hydrogen sulfide and thus facilitating accurate decisions on remedial actions.
Oilfield Biocide Performance in the Presence of Shale Formation Rock
Authors: Moore Joseph , Massie-Schuh Ella , Doshi Deepak , Schultz Christine , Castillo Catherine , Patel Bhavin , Moore Makensie , Rajan Jana , Ajayi Bolatito
Published: March 2017

Contamination of oil and gas operations by sulfate-reducing prokaryotes acid-producing prokaryotes, and facultative anaerobic prokaryotes can significantly reduce hydrocarbon quality, compromise asset integrity, and cause plugging in the formation. Complete treatment of these contaminants requires the use of biocides capable of retaining efficacy in the extreme conditions common in deep subsurface wells. This study investigates the interactions of several common oil and gas biocides with shale to determine their suitability for use in the downhole environment. Each biocide was submitted to studies analyzing (1) shale's effect on chemical stability and aqueous availability of the biocides, and (2) resulting biocidal efficacy on common facultative anaerobes. The chemical availability study was performed using high performance liquid chromatography, and the comparative biocidal efficacy study was performed using standard microbial viability assays. Due to variances in complexity of hydraulic fracture networks, the degree of adsorption was also measured as a function of shale surface area. The panel of biocides showed a variety of responses to exposure to shale. Surface-active, cationic biocides rapidly associated with shale preferentially over water, significantly reducing the availability of these compounds in the aqueous phase. Accordingly, their efficacy against planktonic bacteria substantially diminished. Across the range of shale types (surface area and reservoir source) tested, all surface-active biocides lost efficacy. Most biocides that rely on electrophilic reactivity (rather than surface activity) for efficacy against microorganisms showed little to no interaction with solid shale, and biocidal potency was not compromised. These results provide guidance for selection of biocides that will remain stable, chemically available, and ultimately efficacious in the extreme conditions of a subsurface shale reservoir.
Injection of CO2 into an Intact Methane Hydrate Reservoir
Authors: Qorbani Khadijeh , Kvamme Bjørn , Kuznetsova Tatiana
Published: March 2017

Storing captured CO2 within the under ground aquifers to reduced CO2 emission could serve the safe long term storage option. However, operation costs a lot. While, injection of CO2 within the natural gas hydrate reservoirs which is associated with CH4 production could compensate the cost of CO2 storage. Besides production of CH4 from natural gas hydrate reservoirs causes the de-stability of gas producing area which leads to land slides and geological hazards in the area. However, as a result of stable CO2 hydrate formation, combining the CO2 storage with CH4 production could hold the structural stability of the production areas. In this work, we used a reactive transport simulator to model injection of CO2 within the intact methane hydrate reservoir. Our model showed the CO2 hydrate formation within the gas hydrate areas.
ROP Optimization and Modeling in Directional Drilling Process
Authors: Wiktorski Ekaterina , Kuznetcov Artem , Sui Dan
Published: March 2017

Drilling optimization is an engineering strategy to drill wells more productively and efficiently. Specific objectives of directional drilling are good hole quality, firm directional control, high angle-build capacity, maximal durability, optimal rate of penetration (ROP) and low non-productive time (NPT). This can be achieved through a perfect combination of well design, mathematical drilling models, drilling data analysis, and applications of new and high techniques.

High ROP in safe and stable drilling conditions is the most valuable optimization objective. Our study mainly focuses on ROP improvement in directional wells. In this paper, three directional control technologies: steerable mud motors, targeted bit speed systems (TBS) and rotary steerable systems (RSS) have been investigated. Average ROPs with implementation of these technologies have been compared by analyzing more than 30 wells drilled in Russia.

When drilling directional wells with a steerable mud motor, the number of sliding intervals has to be increased to achieve higher dogleg severity (DLS). It results in decreased total ROP, an averaged value in sliding and rotating operations. Conventionally, ROP in rotating intervals is roughly estimated to be two times higher than ROP in sliding intervals. From the analysis of several field cases, a model to describe the total ROP has been developed, where the DLS influence is taken into account. It provides useful knowledge for wellbore trajectory design in terms of achieving high ROP.

Nowadays, factors as bit types, tooth-wear and hydraulics, formation characteristics, drilling mud properties and operational conditions, etc. are considered to optimize rotary drilling. However, the influence of wellbore trajectory, inclination and azimuth in particular, is ignored in existing ROP models. In this study, a traditional multi-regression Bourgoyne and Young ROP model has been extended by dogleg severity factor (DLS) to link the wellbore trajectory design to ROP optimization. The proposed empirical model has been applied to several drilling data sets. Calculated ROP values were compared, and the increased accuracy was seen for all cases. This model can be used for wellbore trajectory planning, more precise ROP prediction and optimization, and post-analysis of drilled wells.
Electrical Resistivity Autonomous Inflow Control Device ER-AICD and its Application in Gravel Pack Completions
Authors: Jadhav Nachiket , Zhambrovskii Dmitrii
Published: March 2017

As it becomes necessary to drill long horizontal extended reach wells to reach out for thin oil rim reservoirs, it also has its own challenges. Usage of new technologies and their implementation in terms of cost efficiency and increased reservoir performance is the primary objective. While producing through horizontal wells there is always a possibility of breakthrough of unwanted water or gas compromising the production of oil and to some extent leaving some valuable oil reservers behind. The reason behind this is that the heel of the well produces at higher rate than the toe because toe has to overcome the frictional pressure losses due to increased pressure drop along the horizontal length of the well.

To tackle this problem Inflow Control Device (ICD) was introduced which will delay the early breakthrough of water or gas. There are different designs of ICDs available in the industry which significantly delays the breakthrough. Most ICDs provide flow restriction for the produced fluid to create uniform inflow profile along the entire length of the wellbore. However, due to uncertainties in reservoir properties there might be water or gas inflow through ICD and no existing ICDs can reverse this problem undermining the optimization of oil production.

This paper presents the design of Electrical Resistivity Autonomous Inflow Control Device (ER-AICD) that on a par with creating uniform inflow profile along the wellbore; it opens and closes the valve when there is oil, water or gas inflow correspondingly. The device will work on the principle of electrical resistivity of reservoir fluids, resulting in more flexibility in downhole operations and optimizing oil production as a whole.
Automatic Model Calibration for Drilling Automation
Authors: Aghito Manuel , Bjørkevoll Knut Steinar , Nybø Roar , Eaton Ammon , Hedengren John
Published: March 2017

Physics-based hydraulic models are essential for proceeding to a high level of automation in drilling. Mathematical models can facilitate process understanding and problem detection, and determine appropriate actions in case of mismatch between model and data. Furthermore, calculations may replace measurements where and when the latter are not available, as normally occurs during connections or when instruments or signal transmissions fail. However, advanced hydraulic models rely on a large set of inputs, such as pipe and wellbore geometry, various tuning parameters and fluid properties. The models are therefore time-consuming and difficult to configure in the field, where third-party experts may be needed at each well, to properly initiate the automation system and adjust it during the drilling process. Although the methods described in this paper are relevant to any critical drilling operation, they are applied to Managed Pressure Drilling (MPD) as a widely deployed example of drilling automation. In MPD, hydraulic models predict downhole conditions and determine the requisite choke pressure for automatic adjustment. A new method for automatic configuration of key model parameters simplifies the tedious job of setting up the model and ensures that the automation system remains tuned to the well, even without onsite model tuning expertise.

The proposed scheme is based on a simple method for separating inaccuracies due to co-linearity in frictional pressure losses and static mud weight. The search for optimal correction factors is based on a sequence of small oscillations of pump rate that can be applied during drilling without interrupting the operation. A massively parallel computing architecture improves the speed of the calibration algorithm proportional to the number of available CPU cores. A set of hydraulic model instances runs in parallel, allowing for efficient testing of changes in input signals within ranges of uncertainty. A method for selecting a subset of the best models that more accurately represent a given well is proposed.

Computer simulations demonstrate how the novel calibration scheme allows automatic tuning of the friction factor and density correction factor, giving accurate prediction of the bottom hole pressure (BHP). The tuning scheme is run with a parallel architecture to demonstrate that correct values of unknown configuration parameters can be automatically determined sufficiently fast for real-time drilling control or as an advisory tool.

The deployment of automation systems in drilling is hampered by the need for dedicated expert personnel to maintain systems that could have reduced the personnel needed on the rig. The proposed automated physics-based model tuning contributes to removing this roadblock, aiming at making automation systems a more cost-efficient option for drilling operations.