bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wax Deposition Study in a Cold-finger System with Model Oil
Authors: Fan Kaifeng , Huang Qiyu , Li Si , Zhao Dan 
Published: October 2015

Abstract
Wax deposition problem occurred during crude oil production and transportation process is a hot one and has brought huge economy losses around the world. This paper focused on the mass and heat transfer process during wax deposition with cold-finger experiments by method of differential scanning calorimetry (DSC) and gas chromatography (GC). Two sets of experiments with 15 °C and 20 °C temperature difference were conducted using the model oil with wax content of 10 wt. % for 120 h. During each experiment, the wax-solvent mixtures at two radial positions of two horizontal planes and deposits are sampled for DSC and GC analysis.
The dissolved wax content gradient of the wax-solvent mixture at the same height is from the tank wall to the cold-finger, which is just opposite of its temperature gradient. As the diffusion proceeds, the total proportion of wax with carbon numbers of nC21~nC39 gradually decreases near the tank wall, but increases near the cold-finger. Furthermore, compared with the initial wax-solvent sample, the absolute mass ratios of wax molecules heavier than nC31 become greater in the deposits under 15 °C and 20 °C temperature difference, while the mass ratios of those lighter than nC32 decrease. This variation trend indicates that under this cold-finger temperature, heavy wax molecules continually diffuse into the deposition layer and meanwhile light wax molecules are displaced out of the deposition layer. The nC32 is the critical carbon number (here we defined the carbon number from which can deposite on the cold-finger as the critical carbon number) heavier than which the wax molecules can deposit in this condition.
This paper intensely analyzed the wax molecule distribution conditions from the view of heat transfer and mass transfer theories. It will undoubtedly promote the investigation of wax deposition mechanisms of waxy crude oil.
Application of Cellulose Nanofiber as Environment-Friendly Polymer for Oil Development
Authors: Kusanagi K. , Murata S. , Goi Y. , Sabi M. , Zinno K. , Kato Y. , Togashi N. , Matsuoka T. , Liang Y. 
Published: October 2015

Abstract
Cellulose nanofiber (CNF) is a biodegradable material. It can be obtained from natural cellulose through simple process; TEMPO oxidation. Its suspension in water shows high viscosity by the entanglement of fibers each other, owing to its high aspect ratio and the balance of electrical repulsion and hydrogen bond between fibers. In addition, it can regain its viscosity after shearing, which seems to be efficient polymer for E&P industry. In this study, we conducted the next core flooding experiments; polymer flooding and profile modification, and evaluated the applicability of CNF as environment-friendly polymer for EOR process. For the polymer flooding, Berea sandstone core of 145 mm in length and 1 inch in diameter was first prepared to be the residual oil saturated condition by the enough volume of water flooding with the API brine. After that, the 0.1 wt% CNF suspension was injected. As a result, additional oil was recovered, but the differential pressure between inlet and outlet of the core reached 5 MPa when 0.9 PV of the CNF suspension was injected. For the profile modification, we introduced high permeability column of 16 mm in diameter along the center of the sandstone core axis by packing and sintering glass beads. First, the core was saturated by the oil and the primary water flooding with the API brine from upstream was carried out until no more oil was recovered. Second, pure water for pre-flash, the 0.4 wt% CNF suspension and cross-linker solution of AlCl3 were injected successively from downstream for gel blocking inside high permeability zone. After the gel treatment, the secondary water flooding was carried out, and it improved oil recovery from 13.3 % to 24.3 %.
We could confirm the ability of CNF suspension to control mobility owing to its viscosity, and to make bypass in low permeability zone by blocking up easy channel when cross-linked with aluminum ion. However, we got the results that the CNF suspension shows poor injectivity because filtration occurs in the sandstone core during injection.
Experimental Investigation of Crude Oil Emulsion Physicochemical Properties and Demulsifier Dosage Prediction
Authors: Alomair Osamah , Alqabandi Salman , Malallah Mariam , Alajmi Amer 
Published: October 2015

Abstract
One of the common methods of reducing or eliminating the emulsion is the use of different chemical demulsifiers depending on the type of crude oil and water cut. This method is widely used in Kuwait Oil Company (KOC) at wellheads and gathering centers (GC). However, some wells have practice increases of demulsifier dosage as a result of increase in water content. Consequentiality, KOC initiated a program for optimization of chemical consumption for water/oil emulsion separation in the surface facilities at West Kuwait. As a result, of one year oil field statistical analysis of crude oil emulsion collected data. The results indicate that there are four oil wells of a different physical property could be very helpful for our study. Such properties include emulsion viscosity, size of water droplets, surface active materials, resin to asphaltene ratio (R/As), emulsion temperature. Over and above the demulsifier efficiency and dosages were evaluating using the calculated emulsion separation index (ESI) and interfacial tension measurement. As a result the oil field laboratory test indicates that the viscosity of emulsion increases to at least from 12 to17% of its original value based on dry condition. The average droplet size distribution near to (1–10) μm was highly effect on emulsion stability. Moreover the emulsion behavior was linked closely to the film form around the water droplets that are believed to result from the adsorption of high-molecular-weight polar molecules (asphaltene) and fine inorganic solids. There surface-active behavior that makes them good emulsifiers. Also it was found there are a consistent relationship between emulsion stability and relative resin to asphaltene content R/As for all four of the field samples under study. The crude oil of high emulsified water, near 30%, contains low (R/As, 0.84). However, as resins to asphaltene ratio increased the emulsion become unstable and emulsified water decrease up 9 %. This relationship could be used as the method to indicate the more likely oil field areas of strong emulsions and the suitable practical methods for treatment. Also from the well head operating conditions collected data; emulsion temperature, well head pressure, salinity of emulsified water and IFT. From the laboratory bottle test and oilfield crude oil emulsions data. The demulsifiers dosage was predicted using the proposed empirical model. In addition it could be used as a good tool for the new or the incumbent demulsifier evaluation.
A Self-Adaptive Surrogate-Assisted Evolutionary Algorithm for Well Placement Optimization Problems
Authors: Sayyafzadeh Mohammad 
Published: October 2015

Abstract
Finding an optimal well placement scenario is a complex and computationally intensive problem. The major computational cost is associated with the numerical reservoir simulation which should be executed for the fitness evaluation of each scenario. For such problems, a robust optimization algorithm is required. Population-based algorithms are powerful, but computationally demanding, optimizers. Surrogate-assisted algorithms have been developed to reduce the CPU-time of these optimizers, by substituting the original fitness function (OF), partially or completely, with an approximation function (AF), often known as proxy or surrogate.
in these algorithms, a model management strategy should be implemented to use the OF effectively and minimally, during the optimization process, fn this study, a self-adaptive model management strategy is developed, in which two surrogates are required. The first surrogate approximates the fitness function landscape, and the second one estimates the fidelity of the first surrogate over the search space (uncertainty map). According to the estimated uncertainty, the probability of using the OF is calculated for each individual, and then the algorithm stochastically decides to use the OF or AF. A heuristic fuzzy rule is applied to define the range of probability values in each evolution-cycle, based on the average fidelity of the second surrogate. The proposed technique is installed on a genetic algorithm, and two artificial neural networks are used as the proxies, which are trained online.
The robustness of the proposed algorithm is analyzed using a semi-synthetic reservoir model, PUNQ-S3. The outcomes are compared with the results achieved by two common algorithms, a typical (unassisted) genetic algorithm, and an offline-learning surrogate-assisted genetic algorithm. The comparison indicates that the proposed method can reduce the computational costs up to 48%. This surrogate-assisted algorithm may enhance the applicability of population-based algorithms in well placement optimization problems, by reducing the associated computational costs.
Advances in Mooring Integrity Management
Authors: Wales Stuart , Lee Tim , Carra Chris , Potts Andrew E. 
Published: October 2015

Abstract
Mooring Integrity Management has gained much interest in recent years as the failure rate for FPS mooring systems has been found to be significantly higher than expected. Existing mooring integrity management practices have not provided adequate protection against such failures. This paper provides an overview of recent advancements in the understanding of fundamental degradation mechanisms applicable to mooring systems and improvements to mooring system integrity.
Advancements in the understanding of mooring system degradation mechanisms will be explored through reviews of recent Joint Industry Projects (JIPs) that have looked at corrosion mechanisms for chain and wire rope, as well as remaining life assessment for corroded chain links. Recent advances in understanding of wire rope birdcage formation and degredation will also be presented.
Improvements to the approaches to management of mooring integrity will be provided by an overview of the DeepStar® supported industry study that has developed Model Guidelines for Mooring Integrity Management (MIM) for permanent mooring systems (AMOG, 2013). These Model Guidelines serve as the foundation for future implementation of risk-based inspection planning for mooring systems. The framework for a risk-based inspection program can be used by the operator to meet the risk profile of the individual facility as well as corporate and regulatory guidelines. The guidelines identify the required practices at each stage of the mooring system life cycle in order to minimize the risk of degradation mechanisms arising from design, construction, installation and operations practices.
Fundamental to the reliability of this methodology are the means to estimate the long-term degradation processes, such as corrosion, wear, fatigue and constructional disturbance, and the commensurate reduction in residual strength capacity and degraded fatigue endurance. The former of these aspects has been the subject of two JIPs, which have advanced the understanding of corrosion and wear processes (SCORCH JIP) and the commensurate reduction in strength and fatigue endurance (Chain FEARS JIP). The latter, constructional disturbance, is the subject of a proposed JIP, leveraging observations of degredation with numerical techniques.
This paper summarizes significant contributions to the understanding of the key causes of mooring component degradation and improved techniques for the effective management of mooring system integrity.
A Case Study on the Successful Application of Solids Lubricants in Directional and Horizontal Drilling Operations to Reduce Torque and Drag and Improve ROP in One of the Carbonate Oil Reservoirs
Authors: Mohammadi Mojtaba Kalhor , Nowtarki Koroush Tahmasbi 
Published: October 2015

Abstract
Current advancements for the development of oil and gas reservoirs require drilling directional and horizontal wells. Besides the technology for drilling directional and horizontal intervals, drilling fluids play an important role to reach the target. Conventionally, liquid lubricants including mineral and vegetable types have been used to reduce the torque and drag during directional drilling. As the result, high torque and drag was observed during drilling in rotation and sliding mode. This limits required sliding from plan and decrease ROP with the possibility of stuck pipe.
This paper reviews the application and the use of different types of solids lubricants in drilling fluids during drilling directional and horizontal intervals as an operational experience. Drilling fluids rheological properties were monitored and the effects of applying these solids lubricants was the reduction of torque and drag values. In addition, lubricity factor of the filter cake has been measured during drilling by using a lubricity meter to be kept in the proper range by changing the type and concentration of solids lubricants in the drilling fluids. All the data including torque, drag, lubricity factor, solids lubricants concentrations and ROP have been recorded versus depth to benchmark drilling performance.
Finally, application of different types of solids lubricants have been approved and showed ROP improvement especially during sliding mode in hard carbonate rocks in the reservoir. No stuck pipe has been recorded during the drilling of horizontal sections. In addition, liners were run successfully without any problem to the target.
Aquifer Deep Diversion Agent for Deep Reservoir Conformance Control
Authors: Meng Xianxing , Haron Raja Noorlyana , Li Mingyuan , Maarop Nurisman , Lin Meiqin , Yang Zhihao 
Published: October 2015

Abstract
Premature water encroachment or early water breakthrough is a common problem in the industry. Ever increasing water cut will reduce oil recovery, decrease well's productivity and increase the cost of produced water handling. Conventionally the only solution to tackle aquifer dominant encroachment is to introduce a water shut-off chemical in the producer to stop water from coming in. However this solution has its own limitations and tackles the problem via zonal isolation that can also be achieved mechanically in many cases. In this paper a novel deep reservoir conformance control technology for aquifer is studied. The main characteristic of the chemical used in this technology is its ability to propagate deep into the reservoir for effective constriction and diversion of aquifer channels without the risk of near wellbore blockage. Aquifer Deep Diversion Agent (ADDA) is a form of solution with viscosity similar to water and is only soluble in the water phase. It aggregates once it contacts with high salinity aquifer water and is absorbed on water wet rock to form a microscopic constriction which creates diversion. Its strong adsorption on the rock surface will ensure strong and stable constriction. Its fail safe mechanism includes its inability to absorb on oil wet rock and it does not aggregate when it contacts with oil thus it will not impair the performance of oil bearing zones and the oil inflow performance. ADDA is readily mixed with water and, due to its similar viscosity to water, it has the same mobility as water that enables it to flow easily in the reservoir. Subsequently ADDA which is predesigned to trigger at a certain salinity and ion content and will only flocculate when it meets with saline aquifer water with the properties specific to the targeted reservoir to constrict the water path. Consequently, the aquifer water will be diverted into lower permeability zones resulting in an increase in mobilization of bypassed oil and a decrease of water cut. Unlike other technologies, ADDA is tailored according to the reservoir properties and particularly aquifer salinity. The size of molecular aggregation and its rate of aggregation can be designed in the lab based on specific ion composition in aquifer water.
Development and Application of Continuously Mixing Seawater-Based Fracturing Fluid System
Authors: Gao Ying , Shi Yang , Zhou Fujian , Xu Minjie , Yang Xianyou , Xiong Chunming , Han Xiuling 
Published: October 2015

Abstract
The fracturing operation on offshore-platform is limited by high transportation cost of fracturing equipments and other materials, load capacity of platform and other aspects. To overcome these difficulties, a seawater-based fracturing fluid system is developed, which can realize continuously mixing operation on offshore-platform. There are several characteristics for this fracturing fluid system: ① The most commonly used hydroxypropyl guar gum (HPG) is taken as a thickener, and this system is characterized by mature technique and wide application. ② Chelating agent is needless for this fracturing fluid system, so cost will be reduced greatly. ③ Instant dissolving of thickener is achieved through adding instant additive to realize continuous-mixing. ④ Cross-linking technique of seawater-based fracturing fluid is developed: a weak-alkaline pH-buffer SC-150 for seawater mixing and the matching multipoint organic boron - zirconium composite crosslinker GM-7010 are developed. This fracturing fluid system with better temperature-resistance and shear-resistance can meet general requirements of water-base gel fracturing fluid.
This seawater-based fracturing fluid system is featured by instant dissolving, easy preparation, etc., which has been successfully applied in the fracturing operation of low-permeability offshore reservoir in South China Sea. The pilot well was shut-in because of no production before fracturing treatment. 770m3 fracturing fluid 74m3 proppant are successfully injected during fracturing operation, and 20m3/d stable production is obtained after treatment.
Transient Flow Behavior of Horizontal Wells, Pressure Drawdown, and Buildup Analysis
Authors: Odeh A. S. , Babu D. K. 
Published: October 2015

ABSTRACT
Four flow periods may occur during the transient behavior of a horizontal well. Drawdown and buildup equations describing the flow behavior of each of the four flow periods are given. Methods for analyzing data obtained from testing the well to determine permeability anisotropy in the drainage volume of the well, as well as the skin factor, are presented. The calculation procedures are illustrated by examples.
Experiences with Pumping Well Testing
Authors: Kabir C. S. 
Published: October 2015

ABSTRACT
This work embodies our recent experiences with pumping well testing using the acoustic method. Three areas of testing are examined here: first, computation of changing liquid density throughout the liquid column at every time step; second, interpretation of the test using simultaneous downhole pressure and flow-rate data; third, static and dynamic response of the acoustic device.
An algorithm is developed to incorporate the gas/oil mass transfer effect (solubility) so that accurate gas velocity and in turn improved liquid density in the annulus can be computed. The effect of gas solubility is to reduce the gas volume and hence the total downhole volumetric flow-rate (BHF), without affecting bottomhole pressure (BHP) significantly. Transient interpretation improves when the gas solubility is accounted for.
A review of some of the wellbore hydrodynamic models and correlations is attempted in this study. The Godbey-Dimon hydrodynamic model is modified to simulate the moving liquid-column during a buildup test.
Transient interpretation of many field tests indicates that long-duration wellbore storage is the dominant feature in all cases. In general, the use of BHF together with BHP aids early-time interpretation. However, in pumping wells, complexity in well/reservoir flow and uncertainty in early-time-rate estimation do not allow the benefit of such analysis in every situation. Hence the need arises for long shut-in times in many cases. Nonetheless, the examples show that the acoustic method does produce interpretable quality data.
Field examples are used to examine both the static (accuracy) and dynamic response (resolution) of the acoustic device. The available literature suggests that the acoustic method can faithfully reproduce the absolute static bottomhole gauge pressure. This study shows that the results from dynamic tests (buildup) compare very favorably with those from downhole measurements.
Single-Trip Tubing-Conveyed-Perforating, Production Testing, and Pressure Buildup Testing in Nonflowing Wells
Authors: Barnes J. A. , Swafford C. V. , Snider P. M. 
Published: October 2015

ABSTRACT
Procedures and tools have been recently developed to perforate, obtain a flow test, and record a downhole shut-in pressure buildup in oil wells which are not able of flowing to surface. For these tests, tubing conveyed perforating guns, downhole recording pressure gauges, and a hydraulic jet pump assembly with a specially designed blanking sleeve are run in the well. The well is perforated underbalanced and subsequently allowed to clean up by flowing until it dies. The blanking sleeve is then hydraulically shifted open, and the well is tested for an extended period using reverse flow jet pump lift. After completing the flow test, a pressure buildup with a downhole shut-in is acquired. The perforating, flow testing, and buildup are all obtained on a single trip with the workstring. Some advantages of the system are:
Accurate flow rates and water cuts are determined prior to completing the well. Multiple trips with the workstring are not required and rig time requirements are minimized. The well is not killed between perforating and flow testing. All equipment and operations are pressure actuated, eliminating the risks and costs associated with wireline operations. The bottomhole shut-in provides high quality information to evaluate additional stimulation benefits.
Managers' Strategic Reporting Judgments in Audit Negotiations
Authors: Brown-Liburd Helen , Wright Arnold M. , Zamora Valentina L. 
Published: October 2015

SUMMARY
Prior research has largely characterized audit negotiations as a dyadic relationship between auditors and managers. However, the Sarbanes-Oxley Act (SOX) substantially enhances the audit committee's oversight responsibilities for the financial reporting and auditing processes. Thus, negotiations post-SOX may be viewed as a triadic relationship that now involves the audit committee with the authority to scrutinize audit negotiations. Consistent with auditors considering their relative bargaining power and expectations of counterpart behavior, Brown-Liburd and Wright (2011) find that auditors are most contending when the audit committee is strong and the past relationship is contentious. We extend Brown-Liburd and Wright (2011) by examining the joint effects of these factors on managers' pre-negotiation judgments. We posit that rather than mirror auditor behavior, managers make different judgments because they have a different perspective and set of incentives than do auditors. Prior research suggests that managers are more flexible, more accurately determine their counterpart's goals and limits, and are more likely to use certain negotiation tactics than auditors. Further, managers have incentives to maximize the current outcome while maintaining their firm's reporting reputation. As such, managers will be less aggressive in responding to a contentious past auditor relationship, particularly in the presence of a strong audit committee that may ask difficult questions and potentially intervene against their favor. However, managers will act more aggressively to capitalize on a cooperative past auditor relationship, particularly in the presence of a weak audit committee that is passive or persuadable. To examine these two boundary conditions, we conduct an experiment with 137 experienced CFO/controllers. We find strong evidence supporting our expectations that managers act as if both the audit committee and the auditor jointly play important roles in ensuring high financial reporting quality.
JEL Classifications: M41; M42.