bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overview of Advancement in Core Analysis and Its Importance in Reservoir Characterisation for Maximising Recovery
Authors: Gaafar Gamal R. , Tewari Raj Deo , Zain Zahidah Md 
Published: August 2015

Abstract
The expected worldwide average recovery factor is around 35% with current development strategies and practices in place. Recoveries in the offshore fields are much lower compared to onshore fields predominantly due to larger well spacing, inadequate reservoir characterisation and shorter life cycles. Efforts are in place to maximise recovery by applying Enhanced Oil Recovery (EOR) techniques. Reservoir rocks saturated with hydrocarbons are complex in both a macroscopic and microscopic scale and this complexity controls the initial quantity and distribution of hydrocarbons and flow behaviour of fluids within the reservoir. Therefore, reservoir characterisation is of utmost importance for the evaluation process in EOR. Core and log analysis along with pressure-production data greatly assist in defining the reservoir and reducing the uncertainties associated with it.
This paper discusses the importance and criticality of core analysis starting from core acquisition, preservation, laboratory studies, analysis to the application of data. Discussions are conducted for the selection of the most appropriate coring technique while lab studies were carried out on cores for reservoir description, estimation of EOR incremental oil and formation damage during injection and production processes. Critical analysis is made to highlight the quality and quantity of core analysis data needed for petrophysical interpretation, understanding the storage and flow behavior during primary, secondary and tertiary recovery stages. Important guidelines are also provided for the selection of number of plug samples for studies, laboratory methodologies, their strengths and weaknesses, and Quality Control (QC)/Quality Assurance (QA) techniques.
The paper further elaborates the recent advances in EOR processes particularly on core analysis, in-situ saturation monitoring, and the interaction between injectants and rock-fluid along with mitigation experiments. Digital core/Pore network modeling is one such emerging technique utilised for the visualisation, characterisation and special core analysis (SCAL) measurements of reservoir rocks. It can provide routine and special core analysis measurements and petrographic analysis which can be used in the quick evaluation of static and dynamic petrophysical properties and flow behavior.
Adsorption Inhibitors: A New Route to Mitigate Adsorption in Chemical Enhanced Oil Recovery
Authors: Tay A.. , Oukhemanou F.. , Wartenberg N.. , Moreau P.. , Guillon V.. , Delbos A.. , Tabary R.. 
Published: August 2015

AbstractIn this paper, we present a new route to mitigate surfactant retention in chemical EOR projects. Surfactants retention, either through adsorption on reservoir rocks or phase trapping, is one of the main constraints to achieve high performance and economical chemical EOR. Specific injection strategies thus need to be developed to mitigate surfactants retention. The use of alkaline and/or salinity gradient approaches present the disadvantage of being restricted to very specific conditions. For example, in hard brine environments, alkalis cannot be used because they can cause scaling. In an offshore environment, as sea water is the only injection water available, water treatment is required in order to use alkali or to perform a salinity gradient.The new route to mitigate adsorption proposed in this paper is based on the use of specific, cost effective, chemical additives which allow mimicking the effect of salinity gradient. The resulting processes, when properly optimized, can achieve very high performances in terms of oil recovery with a limited amount of injected chemicals. Final performance, at lab scale, is comparable to the highly performing ASP/ SP processes in soft brines with salinity gradient.
Evaluation of the First Cyclic Steam Pilot in Offshore Oilfield of China
Authors: Wang ShuTao , Li YunPeng , Ma KuiQian , Yang Jing , Zhang GuoHao 
Published: August 2015

Abstract
As a viscous offshore oilfield (600~2300 mPa·s at reservoir conditions), LD oilfield was developed by natural drive in early time. One well of the field initially produced around 20 m3/d with early water breakthrough until today. However, the production rate decline rapidly when the water production rate increased.
In order to improve the development effect, the cyclic steam pilot was founded. 12 horizontal wells were designed, two of which had been implemented. Through the comprehensive study, the injection parameters were optimized as follows: bottom hole temperature &gt; 340°C, steam quality &gt;0.4, injection rate equals 300 m3/d. The predicted oil recovery increases from 5% for cold production to 18% for cyclic steam injection.
In this paper we present the application and evaluation of the cyclic steam injection, which is a high quality steam injection with the miniaturization steam generator. For the evaluation of this thermal process for the first test well, an available history matched full field thermal model of the LD reservoir (Local refinement in space around the wells) was established.
Meanwhile, heat loss study of wellbore, decline rate analysis as well as suggestions about next well of this pilot project will be presented. The production effect of cyclic steam injection was compared with that of the cold production: peak oil production rate is 5.3 times and cycle oil productivity is 2.1 times of that for cold production; monthly decline rate is 23%;the valid time of first cycle is 200 days or more. The success of this pilot will provide technology and confidence for the better development of heavy oil in offshore oilfield of china.
Stabilization of Produced Crude Oil Emulsion in the Presence of ASP
Authors: Khan J. A. , Al-Kayiem H. H. , Aris M. S. 
Published: August 2015

Abstract
The contribution of alkaline/Surfactant/Polymer to the stability of produced crude oil emulsions is neither fully understood nor thoroughly investigated although there have been reports from previous projects that implicate risk produced water treatment. This study focuses on water in oil (w/o) emulsions imposed by ASP flooding for an EOR field in Malaysia to understand the stability of the emulsion layer under typical process conditions. A series of laboratory experiments was conducted to investigate the effects of different ASP concentration that is reported to break through into the separator feed and results in the growth of a rag layer. The samples in the experiments were prepared at 50 °C, 60 °C and 70 °C to represent the temperature range of actual field conditions. Emulsion stabilities were measured at different time from 30 minutes to 24 hours in different time step, depending upon the liberation of water volume fraction. The results demonstrated that ASP concentration plays a significant role in the stabilization of emulsion. The increase in the viscosity due to the presence of polymers, which decreased the rising velocity of oil droplets, and the presence of surfactants, reduced the coalescence of oil droplets. Emulsions were exceptionally stable at high polymer concentration compared with surfactants. However, emulsion stability decreased at low polymer concentrations even in combination with high surfactant concentrations. Among the three components in ASP, polymer induced a higher effect on the stabilization of the emulsion. Moreover, the temperature subsequently affected the instability of the emulsion, in which the destabilization of emulsion which had less amount of surfactant was higher at 70 °C compared with 50 °C and 60 °C. Surprisingly, it is found that increase in temperature had insignificantly affected the destabilization of emulsion containing high amount of surfactant, around 400ppm.
Brine Crude Oil Interactions at the Oil-Water Interface
Authors: Chakravarty Krishna Hara , Fosbøl Philip Loldrup , Thomsen Kaj 
Published: August 2015

Abstract
The impact of brine salinity and its ionic composition on oil displacement efficiency has been investigated extensively in recent years due to the potential of enhanced oil recovery (EOR). Wettability alterations through relative interactions at the mineral surface have been the basis of proposed mechanisms. The ion specific interaction between fines and polar fractions of crude oil at the oil-water interface has been less explored.
In this study the relative affinity between different ions and the oil surface was determined. The experiments prove the importance of Ca2+, SO42−, and HPO42− ions in enhancing oil emulsion formation by increasing interactions between polar acids and brine solutions. The results propose the potential use of HPO42− ions in reservoirs having inactive mineral surfaces.
The relative oil affinity of different ions including K+, Na+, Mg2+, andCa2+ (cations), and Cl−, SO42−, HPO42−, and HCO3− (anions), were studied through gas chromatographic analysis. Crude oil from the North Sea was doped with various fractions of organic acids to mimic different polar behavior. Increased brine concentration showed up to 15% upsurge of polar fractions on the oil-water emulsion formation. During emulsion formation the relative interactions at the oil-water interface are proved to follow the Hofmeister series: K+&lt;Na+&lt;Mg2+&lt;Ca2+. Beyond CaCl2concentrations of 0.08mol/l no additionalacid participation in emulsion formation was observed. Among anions, SO42−and HPO42− showed optimum emulsion formation at 0.05mol/l. The amount of emulsion formation showed significant dependency on the type of acid doped in oil.
Experiments demonstrate that the brine solution can alter the micro forces at the oil-water interface, and this ion specific interaction leads to oil emulsion formation andthus reduces the interfacial viscoelasticity of the trapped oil. These resultsshow significant correlation between oil emulsion formation and increased oil recovery.
Reservoir Surveillance Pilot Study for Midland Basin Tight Oil Spacing Optimization
Authors: Tang Yula , Liang Baosheng 
Published: August 2015

Abstract
Chevron has performed surveillance, analysis and optimization (SA&O) pilot study in its Midland Basin Wolfcamp tight oil development area. In this paper, we will focus on the pilot overview, production logs, rate transient analysis (RTA), and multiple well interference pressure transient analysis (PTA).
The pilot area consists of a center 20-acre vertical well and four pressure monitoring wells in four directions with a distance of 460 ft to the center well. Production is commingled by 8 hydraulically fractured stages. Four-array downhole microseismic shows the shape of reservoir stimulation. Each vertical monitoring well is equipped with 8 permanent downhole gauges with packers isolating 8 layers, and the real-time data is acquired through SCADA (Supervisory Control and Data Acquisition) system. Multiple production logs have been acquired in the center well during the earlier natural flow period.
RTA has been performed in the center well based on the production rate measured from a dedicated test separator, flowing bottomhole pressure from a downhole memory gauge, and zonal contributions from production logging (PLs). PLs show that fluid comes primarily from the Spraberry, secondly from the Lower Wolfcamp, and some from the Strawn and Atoka. The RTA shows that effective drainage area of the well is less than 20 acres. In addition, fracture half-length and effective permeability are degrading with time, which impacts the well's EUR. The acquired pressure responses in observation wells have been studied with non-linear numerical model in PTA to better characterize the fracture network and reservoir. It shows a high possibility of connecting with neighbor wells in certain formations and exhibiting characteristics of time-dependent fracture closing. Production performances with original 40-acre spacing wells and recently drilled 20-acre infilled wells are compared, indicating that 20-acre wells helps to improve oil recovery and economics. The center well was shut in for more than 9 months to get buildup data. During the 5 month post shutin production (PSP), the well had significantly higher oil rate and positive net oil recovery with decreased GOR and water-cut.
The pilot sheds light on first principles and tight oil development strategy. Accurate microseismic data, production logs, interference well testing, and rate transient analysis are powerful tools for unconventional studies.
Effectiveness of Simulations on Well Control During HPHT Well Drilling
Authors: Auwalu I. M. , Zahra I. Z. , Adamu M. B. , Usman A. L. , Sulaiman A. D. 
Published: August 2015

Abstract
The conventional methods of oil and gas wells drilling has been to keep drilling mud in the active mud pit at ambient temperature and pressure to drill oil and gas wells; despite the effect of temperature and pressure on mud properties at bottom hole condition. Although, this practice has proved to be adequate in shallow and conventional wells owing to relatively small difference in temperature between surface and bottom hole and the existence of sufficient margin between pore and fracture pressures. Conversely, lots of changes occur on mud properties especially in drilling High Pressure High Temperature (HPHT) wells leading to increased incidences and serious well control situations.
One of the key characteristics of HPHT wells is the existence of small margin between pore pressure and fracture pressure as well as elevated bottom hole temperature. This property of the well (HPHT) presents series of challenges to both drilling fluid management at bottom hole condition and well control incidents. Literature survey puts well control incident rate for conventional wells at 4 to 5% whereas in non-conventional wells such as the HPHT wells, an alarming rate of 100 to 200% or even greater has been recorded. This represents at least one well control incident in every 20 to 25 wells drilled for conventional wells and at least one to two well control incidents for every non-conventional well like HPHT.
In this study, tier I HPHT well was examined to ascertain the severity of kick intensity and kick volume on well control using Drill Bench. Simulations were performed on 6.5bbls and 1bbls kick taken in 12¼” hole prior to reaching the next casing seat at 13780ft-ss TVD. The research presents results of delay in shut-in the well, kick volume and volume development during well control as well as gas migration. In addition, the study examined implication of well control methods and drilling fluid type on bottom hole pressures and timing to handle well control incident during HPHT well drilling.
Software for Reservoir Performance Prediction
Authors: Sylvester Okotie , M.O. Onyekonwu 
Published: August 2015

Abstract
Predicting the performance of reservoirs helps engineers to estimate reserve, development planning which requires detailed understanding of the reservoir characteristics and production operations optimization and more importantly, to develop a mathematical model that will adequately depict the physical processes occurring in the reservoir such that the outcome of any action can be predicted within reasonable tolerance of errors. In this paper, software “REPAT” was built based on material balance and an expansion of Tarner's method by incorporating water influx and time concept to the material balance equation. The history matching process consists of modifying the aquifer parameters until an acceptable match was obtained within engineering accuracy. Example 9.2 in L.P. Dake was used as a case study. A STOIIP value of 311.48 STB was obtained with an error of 0.00195 and R value of 0.99999 which is an indication of a good fit, while the STOIIP obtained from MBal gave an error of 0.00253. The reservoir is supported by a combination of water drive and fluid expansion drive and Hurst Van Everdingen radial aquifer model was selected as the most likely case. The parameters used to obtain the history match and the STOIIP compare favourably with the expected values from L.P Dake and MBal. A good pressure and historical production simulation match was obtained.
Developing and Applying Fluid Properties for the Wara Formation, Greater Burgan Field, Kuwait: A Supergiant Field With Variable API Oil Gravity
Authors: Al-Shammari Hana'a , Moon Mark S. , Pederson John M. 
Published: August 2015

Abstract
API gravity vs. Depth correlations were developed for the Greater Burgan Field. The results of this work dramatically changed the determination of fluid PVT properties for the field which were used in Build-up analysis, wellbore flow correlations, simulation model initialization and OOIP estimates. Past PVT studies based solely on fluid sample analyses failed to honor the heavy oil or tar near the oil-water contact. Additional API gravity Vs depth data available from core data, and initial production tests were incorporated into the analysis. As a result, new correlations were developed which recognized values down to 10° API near the original OWC. Previous correlations did not have oil gravity samples lower than 24° API gravity.
Effect of Selective Etch on the Bond Strength of Composite to Enamel Using a Silorane Adhesive
Authors: Bermudez L , Wajdowicz M , Ashcraft-Olmscheid D , Vandewalle K 
Published: August 2015

SUMMARY
An improvement in bond strength to enamel has been demonstrated with the use of phosphoric acid prior to bonding with self-etch methacrylate-based adhesive agents. No research has evaluated the effect of phosphoric-acid etching of enamel with a newer self-etch silorane adhesive. The purpose of this study was to evaluate the shear-bond strength of composite to enamel using the self-etch silorane adhesive compared to other self-etching methacrylate-based adhesives, with or without a separate application of phosphoric acid. Bovine incisors were sectioned using a diamond saw and mounted in plastic pipe. The bonding agents were applied to flattened enamel surfaces with or without the application of 35% phosphoric acid. The bonded tooth specimens were inserted beneath a mold, and composite was placed incrementally and light cured. The specimens were stored for 24 hours and six months in water and tested in shear. Data were analyzed with a three-way analysis of variance (ANOVA) to evaluate the effects of surface treatment, adhesive agent, or time on the bond strength of composite to bovine enamel (α=0.05). Significant differences were found between the groups based on surface treatment (p&lt;0.01) or adhesive agent (p&lt;0.01), but not on time (p=0.19), with no significant interactions (p&gt;0.14). Phosphoric-acid etching of bovine enamel significantly increased the bond strength of the self-etch methacrylate and the silorane adhesives. The methacrylate-based adhesives had significantly greater bond strength to enamel than the silorane adhesive.
Effect of Cr3C2 content on the microstructure and properties of Mo2NiB2-based cermets
Authors: Xie Lang , Li XiaoBo , Zhang Dan , Yang ChengMing , Yin FuCheng , Xiao YiFeng 
Published: August 2015

Abstract
Four series of Mo2NiB2-based cermets with Cr3C2 addition of between 0 and 7.5 wt.% in 2.5 wt.% increments were studied by means of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffractometry. The transverse rupture strength and hardness were also measured. It was found that Cr3C2 completely dissolved in Mo2NiB2-based cermets. Cr3C2 addition improved the wettability of the Ni binder phase on the Mo2NiB2 hard phase, which resulted in a decrease in the porosity and an increase in the phase uniformity. The cermets with 2.5 wt.% Cr3C2 content showed relatively fine grains and almost full density. A high Cr3C2 content resulted in the formation of M
6C (M = Mo, Cr, Ni) phase. In addition, energy dispersive X-ray spectroscopy results showed that the content of Mo in the binder decreased with increasing Cr3C2 content. The cermets with 2.5 wt.% Cr3C2 addition exhibited the highest transverse rupture strength of 2210 MPa, whereas the cermets without Cr3C2 addition exhibited the highest hardness.
Interpolation, Projection and Hierarchical Bases in Discontinuous Galerkin Methods
Authors: Angermann Lutz , Henke Christian 
Published: August 2015

AbstractThe paper presents results on piecewise polynomial approximations of tensor product type in Sobolev-Slobodecki spaces by various interpolation and projection techniques, on error estimates for quadrature rules and projection operators based on hierarchical bases, and on inverse inequalities.
Local Multilevel Method on Adaptively Refined Meshes for Elliptic Problems with Smooth Complex Coefficients
Authors: Li Shishun , Shao Xinping , Si Zhiyong 
Published: August 2015

AbstractIn this paper, a local multilevel algorithm is investigated for solving linear systems arising from adaptive finite element approximations of second order elliptic problems with smooth complex coefficients. It is shown that the abstract theory for local multilevel algorithm can also be applied to elliptic problems whose dominant coefficient is complex valued. Assuming that the coarsest mesh size is sufficiently small, we prove that this algorithm with Gauss-Seidel smoother is convergent and optimal on the adaptively refined meshes generated by the newest vertex bisection algorithm. Numerical experiments are reported to confirm the theoretical analysis.
A Standards-Based Architecture Proposal for Integrating Patient mHealth Apps to Electronic Health Record Systems
Authors: Fontelo P. , Rossi E. , Ackerman MJ , Marceglia S. 
Published: August 2015

SummarySummary Background: Mobile health Applications (mHealth Apps) are opening the way to patients’ responsible and active involvement with their own healthcare management. However, apart from Apps allowing patient’s access to their electronic health records (EHRs), mHealth Apps are currently developed as dedicated “island systems”.Objective: Although much work has been done on patient’s access to EHRs, transfer of information from mHealth Apps to EHR systems is still low. This study proposes a standards-based architecture that can be adopted by mHealth Apps to exchange information with EHRs to support better quality of care.Methods: Following the definition of requirements for the EHR/mHealth App information exchange recently proposed, and after reviewing current standards, we designed the architecture for EHR/mHealth App integration. Then, as a case study, we modeled a system based on the proposed architecture aimed to support home monitoring for congestive heart failure patients. We simulated such process using, on the EHR side, OpenMRS, an open source longitudinal EHR and, on the mHealth App side, the iOS platform.Results: The integration architecture was based on the bi-directional exchange of standard documents (clinical document architecture rel2 – CDA2). In the process, the clinician “prescribes” the home monitoring procedures by creating a CDA2 prescription in the EHR that is sent, encrypted and de-identified, to the mHealth App to create the monitoring calendar. At the scheduled time, the App alerts the patient to start the monitoring. After the measurements are done, the App generates a structured CDA2-compliant monitoring report and sends it to the EHR, thus avoiding local storage.Conclusions: The proposed architecture, even if validated only in a simulation environment, represents a step forward in the integration of personal mHealth Apps into the larger health-IT ecosystem, allowing the bi-directional data exchange between patients and healthcare professionals, supporting the patient’s engagement in self-management and self-care.Citation: Marceglia S, Fontelo P, Rossi E, Ackerman MJ. A Standards-Based Architecture Proposal for Integrating Patient mHealth Apps to Electronic Health Record Systems. Appl Clin Inform 2015;6: 488–505http://dx.doi.org/10.4338/ACI-2014-12-RA-0115