bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reservoir Performance Estimation for Huff & Puff CO2 Injection Using Newly-Developed Predictive Model
Authors: Setiawan Muhammad Bhakti , Syihab Zuher , Lumban Gaol Ardhi Hakim , Yasutra Amega , Rahmawati Silvya Dewi , Metra Fadhillah , Merdeka Mohammad Galang , Winata Denie Tirta , Sitompul Victor , Buhari Ari , Aziz Muhamad Choirul 
Published: October 2019

Abstract
CO2 Injection is one of the EOR methods that holds potential to be widely implemented. However, the underlying issues in implementing CO2 injection include the availability of CO2 sources as well as the steep capital cost associated with the surface facilities required to deliver and process the CO2. In such case, the cyclic injection, so-called Huff & Puff CO2 injection is seemingly more feasible. In this study, we propose an alternative predictive model to determine the performance of CO2 cyclic injection. This model can be utilized as a preliminary screening tool and to understand the feasibility of the operation in a quick manner. In addition, the uncertainties associated with the reservoir conditions can also be considered within the model.
Most of the efforts to develop predictive model for CO2 cyclic injection have been concentrated around empirical approach, and hence, only limited parameters are considered. In this study, we establish experimental design through reservoir simulation and perform machine learning to construct the predictive model. Therefore, most important factors driving the performance of the well underwent CO2 cyclic injection including reservoir rock and fluid properties, interaction between rocks and fluids, drainage geometry, and operating condition are incorporated. Compared to the simulation results, the proposed predictive model shows an acceptable accuracy with R-squared of above 0.95.
The result of this study can be used to help find suitable well and reservoir to be injected with cyclic CO2 injection, as preliminary analysis on the individual well performance can be conducted before performing full field simulation. The model can also be utilized to determine the optimum amount of CO2 needed, as well as the length of injection and soaking time before the well is put into production.
Acceleration Pressure Induced from Wellbore Inflow and its Influence on Productivity
Authors: Chen Zhen , Shaalan Tareq , Dogru Ali 
Published: October 2019

Abstract
Modelling the full physics in the wellbore is very important for investigating the wellbore pressure drop on well productivity in reservoir simulation. The pressure drop along the wellbore includes a hydrostatic, a friction and an acceleration component. The acceleration component is generally small in comparison with the overall pressure drop, and in the majority of literature it is neglected. In certain circumstance, it was shown in the literature (Ozkan, Sarica, and Haci 1999) that the acceleration pressure drop can have a significant impact on productivity in a horizontal well.
In this paper, a new formulation of acceleration pressure is derived and the results are compared with those in a commercial reservoir simulator. The new model is derived from the material balance and momentum balance equations in a coupled wellbore and reservoir system. Due to the impact of inflow from the reservoir on the velocity in the well segments, an acceleration pressure drop is induced. The physics of acceleration pressure is implemented as part of complex wellbore model in a multimillion grid reservoir simulator in a massively parallel computational environment. Detailed formulation of acceleration pressure and its derivatives with regards to primary variables are derived. Its influence on wellbore performance is shown using reservoir simulation examples. The effect of acceleration pressure is investigated using sensitivity studies of parameters such as reservoir permeability, well completion and well configuration. Simulated results show that the magnitude of impact of acceleration component on wellbore performance can be large within horizontal wells in a high-porosity high-permeability reservoir. The observations can be used for better history match and more accurate forecast.
Study on Microsphere Injections in Permeable Carbonate and Sandstone Matrix
Authors: Cao Dongqing , Han Ming , Alshehri Amar , AlSofi Abdulkareem 
Published: October 2019

Abstract
Significant challenges have been addressed in the application of gel-based materials for permeable carbonate matrices with multi-modal pore systems. Different from near wellbore treatments, this study focuses on a large slug microsphere injection aiming at deep fluid diversion. The objective is to demonstrate the efficiency of the microsphere injection in carbonates in comparison with that in sandstones by conducting a series of coreflooding displacement tests. Numerical simulation studies were carried out to capture response in different wettability regimes.
Coreflooding tests were conducted to study the potential of oil production that can be achieved through microspheres suspended in a polymer solution. Two sets of microsphere systems, with a median size of 0.05 and 0.3 μm in injection water, were used in this study. The tests were conducted at 95°C and 3100 psi pore pressure. The injection procedure started with waterflooding, followed by 1 pore volume of microsphere injection then post waterflooding. Effects of core mineralogy and microsphere particle size on incremental oil production were investigated. The coreflooding displacement processes including microsphere injection were simulated using UTCHEM simulator.
The effectiveness of microspheres, which are smaller than the pores/throats of the porous media, relies on the amount of microspheres injected. The coreflooding displacement with one pore volume of microsphere injection demonstrated significant incremental oil production in carbonate and sandstone core plugs, compared to polymer flooding only. The results showed that higher oil production came from higher differential pressure, which can be attributed to disjoining pressure and pore channel plugging incurred in the porous media. The microsphere injection had higher oil production in the oil-wet carbonate cores than the water-wet sandstone cores with similar permeability. It was supported by the differential pressure data that indicated that microspheres reduced the permeability in carbonates more effectively than that in sandstone cores. Moreover, microsphere injection with larger particle size yielded higher oil production. The experimental results were well matched by the fluid-flow simulator. The simulation results revealed that microsphere injection had a quick and lasting response on oil production, compared to polymer flooding. The simulation results also support our findings that the performance of the microsphere injection is more effective in oil-wet carbonates than in water-wet sandstones.
This work provides an insight of microsphere injection effectiveness in terms of achieved microsphere size, incremental oil production, rock type; and reveals the applicability and durability of such injectant in oil-wet carbonate reservoirs at harsh reservoir conditions, namely high temperature and high salinity.
Unlocking Low Resistivity Pay as New Reservoir Backbone for Mature Field Redevelopment Strategy: A Case Study of Alengka Field, Offshore North West Java
Authors: Wibowo Icuk Dwi , Prawesti Annisa , Sobani Sobani , Saputra Lulus Ilmiawan , Maulana Taufik , Luciawaty Mery 
Published: October 2019

Abstract
Alengka Field has been producing for more than thirty years. Like the vast majority of oil and gas field in the world, Alengka field production is on decline. Alengka Field pay reservoirs consist of more than fifteen zones which are separated in three structures. Latest infill and workover activities reveal that the major productive zones are showing watered-out and depleted reservoir pressure. The last remaining potential reservoir is a low resistivity pay zone which not fully developed yet, called as Rama and Shinta zones.
These low resistivity pay reservoirs are member of Main Formation which deposited in shallow marine depositional environment. It is characterized by 30-60 feet of pay thickness, with resistivity ranging from 1.4 ohmm up to 2.2 ohmm, with shale background resistivity up to 1.2 ohmm. It has an effective porosity up to 22% and permeability up to 10 md. The hydrocarbon existence is emphasized by the ratio of total gas reading to the background gas which more than 10 times; with peak gas up to 830 unit and poor to fair oil shows.
It is a huge contest for the offshore company to seek mature field redevelopment strategy with aging facilities to extend the economic producing life by using cost-effective and low-risk technologies. Commingle Rama and Shinta zones have demonstrated to be productive reservoirs by hydraulic fracturing. Each well can contribute 300 up to 700 BOPD of initial rate by utilizing gas lift and add 0.5 up to 0.7 MMBO of reserves. Naturally, hydraulic fracturing reservoir has rapid decline in the beginning production period which will be followed by plateau decline. The optimum fracturing parameter and gas lift performance which is combined with low angle trajectory well is identified as the essential key to improve production rate and to add maximum reserves.
Low resistivity pay zones has become the new reservoir backbone for redevelopment of Alengka field with total of 14 wells that will be drilled and 4 workover wells from 5 existing platforms that will be executed within next 3 years to add more than 7 MMBO of reserves. It will sustain Alengka field production rate more than 4000 BOPD. The recent activities consist of one infill drilling and one workover has excellent result with more than 800 BOPD in total. The successful of this campaign could open the opportunity to develop field further to the eastern part of the Alengka Field by adding new platforms and wells with total potential reserves is more than 10 MMBO. The paper will discuss about the low resistivity pay zone, production approach, recent drilling-workover results, redevelopment strategy in mature field and its challenges.
Malaysian Governance Completion Benchmarking Application towards Improving Operation Performance and Cost Efficiency
Authors: Mohd Mokhtar Shahril Ridzauddin , Omar Norjusni , Fazilah Siti Rodhiah , Bakar M. Farris , Khalid Zaidan 
Published: October 2019

Abstract
Between the years 2013 to 2014, the completions operations in Malaysia have shown irregular performance across all the operators and service companies. Low uptime level, exceeding budget, non-standardized design, unreasonable contingency level and excessive surplus material are among the identified elements that causes such irregular performance. The value leakage from these elements has become a huge concern to Malaysia Petroleum Management (MPM); the regulatory body of PETRONAS. A strategy was required to set up a uniform way to standardize, optimize and improve the efficiency of how completions scope is implemented in Malaysia.
Based on the analysis of over 300 wells completed from 2013 to 2015, MPM set up a 3-year roadmap on elevating the completions performance covering the pre-engineering design, operation execution, contingency computation and hardware inventory management. These elements are the basis that operators use to meet MPM Completion Minimum Standards (CMS). This CMS was set up to outline the performance benchmarking for all operators in Malaysia.
This paper will outline the strategy that MPM implemented to curb the value leakage that was effecting the completions performance. The strategy includes the establishment of an industry level collaboration known as Completions Standardization Technical Committee (COMSTEC), which comprises members from MPM, operators and service companies. This committee have jointly produced a guideline to standardize and optimize a complete end-to-end completion cycle in order to meet the performance benchmarking.
After a year of implementation, the impact of this strategy implementation was evident. The number of wells completed in 2017 that met the CMS improved by 45% compared to 2016. This optimized execution of completions scope created a value of 19% in cost efficiency throughout all the operators. Although there were challenges in the early stage of implementation, the value that all the stakeholders gained from it have exceeded the expectation and will continue to be implemented in the coming years. Astoundingly the benchmarking drives more new technologies implementation despite in low oil prices period. The relevance of both the performance benchmarking and the guideline are maintained at all times as its effectiveness is constantly monitored to reflect the latest state of the industry.
Tuberculosis Treatment Outcomes Among Prisoners And Non-prisoners In Zomba, Malawi
Authors: Singano Victor Hamilton , Kip Esther , Ching’ani Wilson , Chiwaula Lawrence 
Published: October 2019

Abstract
Background TB remains a major global health problem. It is particularly prevalent in prisons in sub-Saharan Africa due to overcrowding, malnutrition, high HIV prevalence and insufficient medical services. Prisoners have experienced worse treatment outcomes than the general population. We investigated the TB treatment outcomes and predictors of unsuccessful treatment outcomes among prisoners and non – prisoners.Methods We retrospectively reviewed TB registers of prisoners and non - prisoners diagnosed with TB from January 2011 to December 2016 at Zomba Maximum Central Prison and Zomba Central Hospital, Malawi. The study used routinely collected data extracted from national, standardized TB treatment monitoring tools. Successful treatment outcome was classified as the total for cured and completed treatment while unsuccessful treatment outcome was classified as the total of deaths and treatment failures. We used descriptive statistics to compare the demographics and TB treatment parameters among prisoners and non – prisoners and computed multivariate analysis to predict the independent factors of unsuccessful treatment outcomes.Results Of 1652 registered cases, 27% were prisoners (all males) and 72% were non-prisoners (58% males). The median age was 35 years (IQR: 29 - 42); 76% were Pulmonary TB cases (78% among prisoners vs 75% among non-prisoners); 83% were new TB cases (77% among prisoners vs 86% among non-prisoners); and 65% were HIV positive (50% among prisoners vs 71% among non – prisoners). Regarding treatment outcome, 1472 (89%) were cured and/or completed treatment (93% among prisoners vs 88% among non – prisoners), 2(0.2%) were treatment failures, 122 (8%) died (5% among prisoners vs 8% among non – prisoners) and 55 (3%) were not evaluated (1% among prisoners vs 4% among non – prisoners). Independent factors of unsuccessful TB treatment outcomes were noted in those with age greater than 35 years (aOR = 0.68: 95% C.I: 0.58 – 0.80), Extra-Pulmonary TB (aOR=1.69: 95% C.I: 1.08 – 2.63), HIV positive status (aOR = 0.63: 95% C.I: 0.42 – 0.94).Conclusion Good TB treatment outcomes which are comparable to the general population can be achieved among Malawian prisoners despite the challenging prison conditions.
Motivational climate, need satisfaction, self-determined motivation, and accelerometer-measured physical activity among secondary school students in China
Authors: Chen Ruzhuan , Wang Lijuan , Wang Bingnan , Zhou Yulan 
Published: October 2019

Abstract
Objectives Based on integration constructs from self-determination theory (SDT) and achievement goal theory (AGT), this study aims to investigate the relationship among classroom motivational climate from four perspectives (i.e., autonomy support, relatedness support, task-involving climate and ego-involving climate), three psychological needs (i.e., autonomy, competence and relatedness), self-determined motivation and physical activity (PA) in secondary physical education (PE).Methods The participants consisted of 1,186 Chinese students aged 11 to 16 years from three secondary schools around Shanghai. An accelerometer was adopted to measure moderate-to-vigorous physical activity (MVPA). Questionnaires were used to measure SDT variables (i.e., classroom motivational climate, perceived competence, autonomy, relatedness, self-determined motivation). Structural equation modelling (SEM) was used to analyze the hypothesized relationship.Results A SEM analysis revealed that autonomy support and task-involving climate were positively associated with autonomy, relatedness and competence. Relatedness support was positively related with autonomy and relatedness, whereas ego-involving climate was only associated with competence. The three psychological needs positively affected self-determined motivation, and self-determined motivation positively affected the MVPA time of secondary school students in PE lessons.Conclusion These findings support a model of motivation that integrate SDT and AGT, provides new insight into understanding MVPA in Chinese PE, and establishes a solid basis for intervention research.
Use of technology for public health surveillance reporting: opportunities, challenges and lessons learnt from Kenya
Authors: Njeru Ian , Kareko David , Kisangau Ngina , Langat Daniel , Liku Nzisa , Owiso George , Dolan Samantha , Rabinowitz Peter , Macharia Daniel , Ekechi Chinyere , Widdowson Marc-Alain 
Published: October 2019

Abstract
Background Infectious diseases remain one of the greatest threats to public health globally. Effective public health surveillance systems are therefore needed to provide timely and accurate information for early detection and response. In 2016, Kenya transitioned its surveillance system from a standalone web-based surveillance system to the more sustainable and integrated District Health Information System 2(DHIS2). As part of Global Health Security Agenda(GHSA) initiatives in Kenya, training on use of the new system was conducted among surveillance officers. We evaluated the surveillance indicators during the transition period in order to assess the impact of this training on surveillance metrics and identify challenges affecting reporting rates.Methods From February to May 2017, we analysed surveillance data for 13 intervention and 13 control counties. An intervention county was defined as one that had received a refresher training on DHIS2 while a control county was one that had not received training. We evaluated the impact of the training by analysing completeness and timeliness of reporting 15 weeks before and 12 weeks after the training. A chi-square test was used to compare the reporting rates between the two groups. A structured questionnaire was administered to the training participants to assess the challenges affecting surveillance reporting. A Likert scale was used to grade the challenges.Results The completeness of reporting increased after the training by 17 percentage points (from 45% to 62%) for the intervention group compared to 3 percentage points (49% to 52%) for the control group. Timeliness of reporting increased by 21 percentage points (from 30% to 51%) for the intervention group compared to 7 percentage points (from 31% to 38%) for the control group. Major challenges identified for the low reporting rates included lack of budget support from government, lack of airtime for reporting, health workers strike, health facilities not sending surveillance data, use of wrong denominator to calculate reporting rates and surveillance officers being given other competing tasks.Conclusions Training plays an important role in improving public health surveillance reporting. However, to improve surveillance reporting rates to the desired national targets, other challenges affecting reporting must be identified and addressed accordingly.
Factors affect on implementation of home dental care
Authors: Nomura Yoshiaki , Kakuta Erika , Okada Ayako , Otsuka Ryoko , Saito Hideaki , Maekawa Hiroshi , Daikoku Hideki , Hanada Nobuhiro , Sato Tamotsu 
Published: October 2019

Abstract
Background In Japanese super aging society, there is a need to establish home dental care service supply system. Current situation of home dental care should be analyzed.Methods A cross-sectional survey was conducted using a self-administered postal questionnaire distributed to all members of Iwate Dental Association. Implementation of home and nursing home dental care, number of staffs of dental clinic and the contents of dental home care were analyzed. For the analysis, correspondence analysis, item response theory, and zero-inflated model were used.Results Among 354 dental clinics, 187 (52.8%) were implemented home dental care and 195 (55.1%) were implemented nursing home dental care. Dental clinics handle home dental care by part-time workers. Denture treatment and oral care was the common treatment of dental home care.Conclusion More than half of the dental clinics were not managed the home dental care. Infrastructure improvement is necessary for the sufficient supply of dental home care service.
Trends and Spatial Variation of Female Genital Mutilation among Reproductive Age Women in Ethiopia based on 2000, 2005, and 2016 Ethiopian Demographic and Health Surveys: Spatial-temporal and Multivariate Decomposition Analysis
Authors: Tesema Getayeneh Antehunegn , Teshale Achamyeleh Birhanu , Agegnehu Chilot Desta , Alem Adugnaw Zeleke , Liyew Alemneh Mekuriaw , Yeshaw Yigizie , Kebede Sewnet Adem 
Published: October 2019

Abstract
Introduction: Even if FGM has been declined dramatically in the world, the rate of decline is far below the rate needed to achieve SDG in Ethiopia. FGM remains as a serious public health concern in Ethiopia and the prevalence has varied across and within countries. Therefore, this study aimed to assess the trends and geographic variation of FGM practice in Ethiopia based on EDHSs.
Methods: The study used the data from the three DHSs conducted in Ethiopia. Trend and Logistic based decomposition analysis technique was used for analyzing the change in FGM practice overtime and factors contributing to the change in FGM practice. STATA 14 was used for data management and analysis. The Bernoulli model was fitted using spatial scan statistics version 9.6 to identify hotspot areas and ArcGIS version 10.6 to explore the spatial distribution FGM.
Results : The prevalence of FGM practice was decreased from 79.9% in 2000 to 70.4% in 2016. The decomposition analysis indicated that about 95% of the overall decrease in FGM practice was due to the difference in the change in the behavior of FGM practice among urban residents, orthodox and Muslim followers, self-employed, education, and media exposure were significant factors contributed to the change in FGM over the study period. The SaTScan analysis identified 141 most likely clusters (LLR=711.9, p<0.001) in 2000, 175 (LLR=576.4, p<0.001) in 2005, and 220 (LLR= 243.6, p<0.001) in 2016 which was located in Somali, Somali, Harari, and border areas of Somali consistently over the three surveys.
Conclusions: These results showed that FGM practice has been declined in Ethiopia. The decrease in FGM practice could be attributable to the difference in the change in effects of residence, media exposure; religion, region, and educational status. The spatial analysis provides further insight into differences in FGM practice within the country and highlights primary and secondary clusters. This could enable efficient and timely spatial targeting of hotspot areas of FGM practice to achieve the goals of eliminating FGM practice in Ethiopia by 2025 and the government should scale up the public health programs to improve the rate of reduction.