bluuebunny/crossref_metadata_2025 huggingface dataset:
Constitutive Model of TRIP600 Based on Rheological Theory
Authors: Sun Ji Quan , Niu Chuang , Yin Yan Jun , Teng Sheng Yang
Published: March 2016

TRIP steels are prone to crack during forming process, mainly because of the transformation of retained Austenite to Martensite, causing discordance between external force and deformation. The mechanical behavior of TRIP steels has conventional elastic and plastic deformation, as well as time-dependent viscous properties. So it is necessary to consider the effect of time to their deformation behavior during constitutive model building. The rheological model used in TRIP steels is not only to reveal the soft and hard phase properties accurately and reasonably by combination of different components but also to indicate the TRIP effect during deformation process by change and combination of coefficients of components. In this paper, rheological constitutive models for TRIP600 are adopted and discussed based on rheological theory, and finally the uniform constitutive equations under creep condition and stress relaxation are built.
Numerical Simulation of Multi-Pass Welding Temperature Distribution of Jacket Platform Assembly Using SYSWELD Software
Authors: Zhang Bo , Tao Han , Liu Cun
Published: March 2016

At present, the flame retardant system was adopted by Cnooc offshore oil engineering (Qingdao) co, LTD (COOEC) workshop ton class jacket platform, whose heat resistance temperature is no more than 80°C. The part of flame retardant area is burned by excessively high temperature and excessive on-site repair work at COOEC workshop due to reserved area of flame retardant is not accurate. In this paper the welding simulation software SYSWELD was used to analyze the temperature distribution of weld joint of typical assembly at workshop. The process parameters, material and model input parameters were adjusted by the field data feedbacks to obtain the optimized welding temperature distribution. The results show that the temperature distribution simulated by the SYSWELD was similar to the field actual measurements. The results of the temperature distribution of the weld joint give the accurate reserved area of flame retardant.
Effect of the Spinning Deformation Processing on Microstructure and Mechanical Properties of A356 Wheels
Authors: Liu Mao Wen , Xiao Wen Long , Xu Cong , Yamagata Hiroshi , Chen Jiu Xin , Zhang Jian Bin , Ma Chao Li
Published: March 2016

The influences of spinning deformation and heat treatment on microstructure and tensile properties of A356 alloy at different cooling rates were investigated in this study by optical and scanning electron microscopes. The results indicated that spinning deformation enhanced the tensile properties of the alloy due to the reduction of Si size and porosity percentage, especially in the samples with coarse microstructure. Heat treatment increased the strength while decreased the ductility of the alloy because of the precipitation of brittle Mg2Si in Al matrix. It is suggested that the spinning deformation processing is an effective technique to produce A356 alloy wheels with high mechanical properties.
Effect of Aging Treatment on Microstructure and Properties of Fe-26Mn-7Al-1.3C Austenitic Steel
Authors: Tan Zhi Dong , Song Ren Bo , Peng Shi Guang , Chen Lei , Wang Wei , Guo Ke , Wang Zhong Hong
Published: March 2016

The effects of different aging processes on microstructure and properties of Fe-26Mn-7Al-1.3C austenitic steel were investigated by mechanical properties testing, optical microscopy (OM). And scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and transmission electron microscopy (TEM) were also used to study the deposition, morphology and composition of the precipitates. The experimental results showed that after homogenized at 1050°C for 1 h, the best aging process was aged at 550°C for 2 h, then air cooled to room temperature. Through the best heat treatment process, some fine κ-carbides with a modulated structure ((Fe, Mn)3AlCx) were found to precipitate within the austenitic matrix, which significantly enhanced the austenitic matrix. Its best comprehensive mechanical properties were tensile strength of 789MPa, yield strength of 612MPa, impact toughness values (V-notch) of 168J/cm2, surface hardness of HB272. Nevertheless, as the aging time prolonged, the fine globular κ-carbides became coarse and grew along austenite grain boundaries and were harmful to mechanical properties of the experiment steel.
Torsion Failure Analysis of 0Cr17Ni7Al Precipitation Hardening Stainless Steel Wire
Authors: Chen Lei , Song Ren Bo , Yang Fu Qiang , Wang Yong Jin , Tan Zhi Dong , Guo Ke , Wang Zhong Hong
Published: March 2016

0Cr17Ni7Al is a precipitation hardening stainless steel, which combines the advantages of austenitic stainless steel and martensitic stainless steel. 0Cr17Ni7Al shows good corrosion resistance, excellent processability and high strength. This paper is mainly focused on the fracture morphology of 0Cr17Ni7Al wire during torsional deformation. Cracking mechanism and torsion failure reason is analyzed in detail. The results show that AlN inclusions are observed both in raw steel wire and fracture, the micro-cracks appear along the axial direction of the steel wire. The torsion strength is normally 2958MPa. but, the local stress of steel wire reaches up to5295MPa when a 0.4mm deep micro-crack locates on the surface of steel wire, and the local stress is obtained to 2953MPa around a 10μm AlN inclusion. Stress concentrating is caused by inclusions and micro-cracks, and the crack propagation lead to the torsion failure of steel wire when the local stress is beyond the torsion limit.
Effect of Rolling Process on Fatigue Property of 2A66 Aluminum-Lithium Alloy Sheet
Authors: Wang Xu Dong , Wu Yue , Li Jiong Li , Feng Zhao Hui
Published: March 2016

The effect of rolling process on the mechanical property and microstructure of 2A66 Al-Li alloy sheet was investigated. Three different rolling processes for 2A66 AL-Li Alloy Sheet were picked for fatigue crack growth test in T3. The results showed that enhancing the amount of deformation in the range of moderate or reducing the rolling step of rolling process will increase the fatigue crack growth rate.
Semi-Solid Moulding of AZ91D Magnesium Alloy
Authors: Xu Hong , Zhang Xin , Wang Chang Shun , Hu Jin Chuan , Wang Cheng , Liu Chang Hua , Zhang Wei Hua
Published: March 2016

AZ91D magnesium alloy is one of the most widely used magnesium alloys in the production of metal forming, which use the characteristics from liquid state to solid state of metal to form. The present status of the research and application of the semi-solid forming for AZ91D magnesium alloys at present was reviewed in this paper, including the microstructural characteristics, the thixotropic and rheological behavior, the forming process of semi-solid for AZ91D magnesium alloys and the mechanical properties of the parts made of semi-solid magnesium alloys. The developing prospects and the key points of the semi-solid forming for AZ91D magnesium alloys were forecasted, and the industrial application of the alloy were also discussed.
Research on Microstructure and Mechanical Properties Evolution of Rheocast and Thixocast 319s Aluminum Alloy
Authors: Du Kang , Liang Xiao Kang , Li Da Quan , Zhu Qiang
Published: March 2016

In semi-solid rheocast and thixocast industry, T6 heat treatment was one key factor to improve the mechanical properties of the castings. The microstructure evolution was closely influenced by heat treatment temperature and time. In this paper, the morphology change of eutectic silicon in semi-solid alloy during different heat treatment time was firstly observed. The changes of both roundness and aspect show that the silicon particles underwent fragmentation, coarsening and growing up processes during solution treatment. Then, the mechanical properties after stand T6 and T6 with higher temperature were compared. It may be concluded that the higher temperature doesn’t have obvious effect to increase the mechanical strength, but severe negative effect on the elongation. Finally, the incipient melting defect appeared in higher temperature T6 was proved and its relationship with elongation was analysed.
Corrosion Failure Analysis of a New L360 Pipeline
Authors: Su Xin , Wang Feng , Fan Yu Ran , Zhang Yan Chun , Chen Qing Lai
Published: March 2016

In this paper, the optical microscope, scanning electron microscope (SEM), X-ray Diffraction (XRD) and simulation test were utilized to study the corrosion failure of L360 pipeline. The results show that the corrosion pits distributed around the pipe inner surface. The pipe mechanical properties, chemical constituents and inclusions grade satisfied the requirements of the technical conditions. Inclusions were composed of Ca, S, Al and O. Corrosion products consisted of the Fe3O4, Fe2O3 and FeO (OH). The compositions of corrosion products within and around the pits were similar to the inclusions. Due to the combined effects of water and high pressure air sealed in the pipeline, the pits formed around inclusions, and developed into occluded cells which accelerating the corrosion and leading to the failure finally.
Influence of Deformation and Temperature on the Austenitic Stainless Steel Performance
Authors: Zhang Xue Tao , Xu Tong , Song Ming , Zhao Bo , Zhang Yi Liang
Published: March 2016

Austenitic stainless steels widely used in cryogenic pressure vessel construction, and heads are formed by cold or warm spinning and stamping. Because of large deformation at excessive circular arc and at the straight parts of head during fabrication, the possibility of damage in these two positions during service is very high. In order to solve this problem, the commonly used S304408, S30403, S31608 steel plates processed under different temperature, different deflection and deformation rate were comparative studied. The evolution of the microstructure and mechanical properties were investigated to quantify the driving characteristics of the martensitic transformation by temperature and mechanical deformation. Consequently, the intergranular corrosion resistance of different microstructure was studied. The results of the research provide valuable reference for the selection and the processing technology of the head steel. Meanwhile, this study also provides a simple method for estimating the material properties after forming.
Reduction Methods of Structure Models for Control System Purposes
Authors: Koszewnik Andrzej , Gosiewski Zdzisław
Published: March 2016

To design vibration control system for flexible structures their mathematical model should be reduced. In the paper we consider the influence of the model reduction on the dynamics of the real closed-loop system. A simply cantilever beam is an object of consideration since we are able to formulate the exact analytical model of such structure. As a result of reduction the model with low frequency resonances is usually separated from the high frequency dynamics because high frequency part of the model is naturally strong damped. In order to estimate dynamical system for control purposes in the paper we applied a few orthogonal methods such as: modal, Rayleigh-Ritz and Schur decompositions. As it is shown all methods well calculate resonances frequencies but generate different anti-resonances frequencies. From control strategy in point of view of the flexible structures these anti-resonances have significantly influence on the stability and dynamics of the closed-loop systems.
The Application of xPC Target Platform for a Circular Plate Vibration Control
Authors: Sierżęga Mariusz , Leniowska Lucyna
Published: March 2016

The goal of this work is to describe a control procedure that simplifies the implementation and improves the performance of feedback active control on a planar structure. The article presents a design, development and experimental verification of an active feedback vibration control system of circular plate with the application of xPC Target platform. Vibrations of the plate are measured using MFC sensors. The control input is applied to the plate by a MFC disk, attached to the plate in its center. The plate vibrations were excited by a loudspeaker or by a second MFC actuator placed at a certain distance from the center of the disc.The basic philosophy is the off-line identification of the best model for the controlled process [1] and the subsequent synthesis of the controller. There are many classical strategies that can be used when a mathematical model is available, for instance, poles allocation or optimal control (LQR), used also by the authors [2, 3]. This article proposes an approach to design an effective controller for vibration suppression of a circular plate with the use of the pole placement method. For the considered system a linear discrete model obtained by parametric identification method for the data measured in a separate experiment has been designated. This model was used to develop the 6-th order digital controller which was implemented on xPC Target platform. Before implementation of the chosen control law design on real plant the simulations in Simulink/Matlab were performed. In order to investigate the influence of the implemented controller on the plate vibrations suppression the 3D scanning vibrometer has been used. The obtained simulation and experimental results, corresponding to the developed active vibration control system have been presented, compared and analyzed.
Hybrid Simulation of Tracked Vehicle Suspension on Real-Time Environment
Authors: Kciuk Sławomir , Kielan Paweł , Mężyk Arkadiusz , Wilk Krzysztof
Published: March 2016

The work presents simulation method of dynamic properties used as assistance in the construction process of suspension systems for high-speed tracked vehicles. Special consideration has been given to the real-time coupling of virtual models with the dynamic response of actual elastic-damping elements of the vehicles. An original design method has been proposed. The method is characterized by the fact that each of the design stages are not performed sequentially, but are parallel to each other and that at each level, mutual coupling between the tasks of the design process occurs. The proposed simulation method using the dSpace system is based on the integration of virtual environment such as LMS Virtual Lab or MATLAB/Simulink with the actual object such as a damper, by means of dedicated input/output devices operating in real time. The method developed in the work allowed for an extension of the classic co-simulations, that is, simulations in two coupled virtual environments, to include an actual component or, rather – its dynamic – often non-linear – characteristic, its response to excitation. The method developed in the work allowed for an extension of the classic co-simulations, that is, simulations in two coupled virtual environments, to include an actual component or, rather – its dynamic – often non-linear – characteristic, its response to excitation.The developed test method and the computer programs have been verified by means of experimental measurements of the dynamic characteristics of the actual object during test-ground tests and in the laboratory. The obtained results of the simulations and experiments allow to confirm the validity of the assumed thesis, which has been included in the summary.
Study of Flow-Induced Vibration Phenomena in Automotive Shock Absorbers
Authors: Sikora Marian
Published: March 2016

The purpose of this study was to develop a model of the dynamic behavior of a hydraulic vehicle double-tube shock absorber. The model accounts for the effects of compressibility, valve stiction, inertia, etc. and can be suitable for use in the analyses on flow-induced pressure fluctuations in the device. The author highlights all major variables to influence the output of the shock absorber, and then proceeds by performing a series of simulations using the developed model. The model is demonstrated to operate well in the large amplitude and low frequency range as well as the small amplitude and high frequency excitation operation regimes. The results are presented in the form of time histories of pressures in each fluid volume of the damper, flow rates through the valves, piston rod acceleration and force. Fast Fourier Transform (FFT) graphs are presented, too, in order to identify major components of the pressure fluctuation phenomena in frequency domain.
Piezoelectric Generators in the Energy Harvesting Systems
Authors: Grzybek Dariusz
Published: March 2016

Piezoelectric generator is a device used to convert mechanical energy into electrical energy. The basic element of the generator is made from piezoelectric material in which electrical energy is created as a result of deformations caused by reactions of mechanical structure of the generator. The amount of obtained electrical energy depends mainly on the piezoelectric material used, construction of the generator as well as a type of the source of mechanical energy. Construction of the generator is adjusted to the type of the source of mechanical energy. In order to obtain electrical energy from mechanical vibrations, the most frequent solution is beam structure. Effective electric energy generation by the piezoelectric generators depends on the following main factors: piezoelectric material used, generator structure, electronic system of the control and storage of energy, and the generator size. Generated by piezoelectric generators electric energy, can be used to power of miniaturized electronic devices with low power supply demand. The goal may be monitoring of the structure or industrial processes in hardly accessible places or/and in systems requiring the use of a big number of sensors. It will make cutting the operating costs possible and allow to create the eco-friendly technology without waste discharged batteries.
Effect of Corrosion, Scale and Biocide Inhibitor on Residual Oil Saturation
Authors: Ali Mohammad A. J , AL-Quraishi A. , Kholosy S. , Al-Makimi A.
Published: March 2016

In most water injection projects, inhibitors are added to the injected water to protect the pipelines, facilities, and reservoir from corrosion, scaling, and bacteria growth. Most studies in the literature focus on the efficiency of inhibitors to prevent corrosion and scale, but very few discuss their effect on formation permeability and oil recovery.

Laboratory experiments on core samples were carried out and chemical additives to seawater were tested at different conditions to evaluate formation damage and residual oil saturation. Different solutions of combined scale, corrosion, and biocide inhibitors at concentrations of 0.5 and 1% were added to seawater.

Formation damage was studied using core samples at full water saturation and showed permeability decline up to 75% due to suspended solids formed from the interaction between the inhibitors and dissolved salts in water. Oil recovery was measured using core samples at full oil saturation. Residual oil saturations varied between 24 to 70% depending on the type and concentration of inhibitors. An increase in the concentration of a single inhibitor yielded a reduction in oil recovery. However, for mixture of inhibitors, the relationship becomes complex. A linear model developed to predict residual oil saturation from inhibitor concentration and an optimum concentration of the mixtures minimizing permeability reduction and residual oil saturation was defined.
220°C Ultra-Temperature Fracturing Fluid in High Pressure and High Temperature Reservoirs
Authors: Liwei Wang , Wen Zhai , Bo Cai , Yongjun Lu , Xiaohui Qiu
Published: March 2016

X basin was located in the eastern China with diverse types and complex structures, is dominated by algal dolomite. The formation charactristers are summarized as following: high temperature from 180 °C to 230°C(quick acid reaction) and ultra-low porosity and permeability(less than 10% and 0.1md), high in-situ stress(>90MPa), high leak-off and because of natural fracture networks which making fracture encounted many problems. This paper presents a new type of synthetic anionic terpolymer gelatinizer and the related influencing factors were studied including a new polymer and a new crosslinking. During the development process of synthetic polymers, the monomer selection, synthesis processes and other conditions directly affect temperature resistance capability of the polymer fracturing fluid. Furthermore, the optimal reaction conditions of polymer thickener with high temperature resistance capability are acquired through "single-factor method", obtaining high temperature polymer thickener with certain temperature resistance capability. Moreover, the temperature resistance, shear resistance and gel breaking performance of cross-linked fracturing fluid were also investigated which shear viscosity was retained more than 150 mPa.s at 220 °C sheared at 170s-1 for 120min. The pilot and production of polymer gelatinizes was carried out and the results showed that new polymeric fracturing fliud system overcomes the thermal limitations of traditional guar. The post-fracturing rate is encourge with 80m3/d oil and 10×104m3/d gas, respectivity. The new fracturing fluid provides a new way to improve production in HTHP reservoirs.
A Novel Oil-Water Separator Design Based on the Combination of Two Flow Resistance Mechanisms
Authors: Wang Xiaoqiu , Zeng Quanshu , Wang Zhiming , Guo Xiao , Zhao Yanlong
Published: March 2016

Numerous oil wells, especially in their middle-late periods, are becoming less economic due to the high lifting costs and reduced recoveries. The downhole oil-water separation (DOWS) system is aimed to lower the production cost, reduce the environment impact, and enhance the oil recovery. However, current separators are of either poor separation effects or poor separation efficiencies.

In this paper, a novel oil-water separator design is proposed based on the combination of two different flow resistance mechanisms and pipe serial-parallel theory, with the restrictive path restricting the heavier water, while the frictional path impeding the more viscous oil. Based on the combination of the flow pattern transformation criterion, homogenous model, two-fluid model, and pipe serial-parallel theory, a unified model of oil-water two-phase flow is developed to predict both the flow rate and water content distributions in different paths, which is then compared with the computational fluid dynamics (CFD) results. Unlike the CFD results, each path has a specific flow rate and water content, and as a consequence, specific flow regime and flow pattern.

Both the CFD and model results show that the flow distributions in different paths of the separator will be adjusted automatically according to the fluid's property, while the model can also predict the water content distributions at the same time. And the average relative error for flow distribution is 17.71%, while that for water content distribution is 32.66%. Specifically, oil, being more viscous, mainly takes the restrictive path; while water, being heavier, tends to take the frictional path instead. To sum up, this autonomous function directs oil and water to different paths, hence oil and water is well separated.
Feasibility of Thermal Oil Recovery Processes in Offshore Heavy Oil Reservoirs: Simulations and Experiments
Authors: Sun Xiaofei , Zhang Yanyu , Chen Huijuan , Duan Xuewei , Hu Wentao , Zhang Xiansong
Published: March 2016

The Bohai Bay Basin is located in the eastern part of North China. Within it lies one of the largest offshore heavy oil deposits in China, roughly 4 billion tons of oil in place. In order to recover sufficient heavy oil at economical rate within limited lifetime of the production platform, CNOOC launched cyclic steam stimulation (CSS) and multi-component thermal fluid (MCTF) huff and puff process on offshore oilfields in Bohai Bay. However, thes processes realize recovery factors less than 15%, which implies that >85% of the oil remains in the ground after the processes become uneconomic to continue operation. Therefore, the incentive is strong for the development of appropriate follow-up techniques that will maximize the recovery potential of and profitability from these offshore heavy oil reservoirs in Bohai Bay, China.

A series of experiments were conducted to test thermal conductivity of unconsolidated sandstones, heavy oil-water and heavy oil-steam relative permeabilities used in thermal simulations. The effects on these parameters of temperature, pressure and heavy oil viscosity were also studied. Furthermore, reservoir simulations were conducted to guide the design of oil recovery processes for three heavy oil reservoirs with a range of in situ oil viscosities from 342 to 926 mPa·s by comparing different operating strategies, including steam flooding, hot water flooding, and MCTF (high pressure steam, CO2 and N2) flooding. The experimental results of the thermal conductivity varied from 0.385 W/ (m °C) to 0.488 W/ (m °C) under systems and temperatures used in this study. Higher temperature are beneficial to decreasing residual oil saturation and increasing water and oil relative permeabilities, which is the main mechanism for thermal recovery method to enhance oil recovery. The simulation results show that, for lower viscosity heavy oil, MCTF flooding as a follow-up process achieved much better performance compared to steam flooding and hot water flooding operation. However, for intermediate and higher viscosity heavy oil, steam flooding was found to be more effective.
Development and Application of Ultra-High Temperature Drilling Fluids in Offshore Oilfield Around Bohai Sea Bay Basin, China
Authors: Mao Hui , Qiu Zhengsong , Xie Binqiang , Wang Zaiming , Shen Zhonghou , Hou Weichao
Published: March 2016

It is known that ultra-high temperature drilling fluids are still quite a challenge to drilling engineering. When bottomhole temperatures exceed 200°C, the design and formulation of drilling fluids can present a host of problems. Drilling fluids destabilize under such extreme conditions, possibly causing wellbore instability, well control problems, and ultimately loss of the well. Drilling buried hill hydrocarbon reservoir in offshore oilfield around Bohai Sea Bay Basin in China has often resulted in failure to reach desired objectives. Bottomhole temperatures up to 220°C, however, the pressures requiring drilling fluid weights just to 1.04 to 1.10 g/cm3 equivalent place severe limitations on the performance of drilling fluids and often contribute in failure to reach the desired drilling objectives. Polymers as viscosifying agent that control rheological properties and fluid loss create major challenges for drilling fluid performance and stability when temperatures over 200°C are reached. Additionally, the gelation of drilling fluids containing low solids content and high fluid loss can become difficult to control under ultra-high temperature conditions. Both of these issues are compounded when the ultra-high temperature is coupled with a requirement for low drilling fluids density. The wildcat well NP3-81 and NP3-82 were drilled in this offshore oilfield around Bohai Sea Bay Basin on January 2014. TD of 6066 meters and 6037 meters were attained, respectively. Both of the bottomhole static temperatures were exceed 220°C and the pore pressure was 1.04 to 1.10 g/cm3 equivalent. Logs were run to bottom without incident and drilling fluids related problems and the primary drilling objectives achieved. The success is attributed to the new technology, fit-for-purpose drilling fluids and rigorous pre-well planning. The paper describes the laboratory development and field application of a new technology of environmentally acceptable and seawater discharged drilling fluids designed for ultra-high temperature environments, highlighting the viscosifying agent which has excellent ultra-high temperature resistance and salt resistance viscosifying property, thermal stability and thermo sensitive characteristics. The apparent viscosity retention rate of novel viscosifier after aging at 220°C after 16 h were 90.81% and 95.95% respectively and the EC50 value was 15.529×104 mg/L in both fresh water based drilling fluid and salt-water based drilling fluid. Field application data shows that this new polymer viscosifying agent could play a critical role even though at harsh conditions such as ultra-high temperature and low density drilling fluids system which decreasing daily performance maintenance problems at the expense of the large consumption of fluid additive including conventional sulfonate copolymer.
The Flow-Field and Sand Retention Characteristics of a Full-Scale Sand Screen for Gas Field Deployment
Authors: Wong C. Y. , Wu B. , Solnordal C. B. , Yang W. , Zamberi M. S. A. , Shaffee S. N. A. , Johar Z. , Jadid M.
Published: March 2016

In order to gain a better understanding on fluid and sand flow around and through a stand-alone-sand (SAS) screen, a scouting study on the flow-field and sand retention characteristics of a full-scale 5.5" OD sand screen was conducted. The velocity flow-field around a horizontal 1-metre long sand screen within a clear acrylic cylinder was investigated in air using state-of-the-art laser diagnostics experiments with complementary computational fluid dynamics (CFD) simulations. The flow-field in the annular space was interrogated by a 2D Particle Image Velocimetry (PIV) technique. CFD using standard solution techniques for dilute particle flows in air employed over 20 million elements to capture the fine details around the individual components in the screen shroud. The sand retention and pressure drop characteristics across the same sand screen were similarly conducted in the same flow loop. At the toe of the screen, some of the flow entering the base pipe also entered the annular space. The inflow from the base-pipe continues to contribute to the annular flow which builds up in magnitude towards the heel of the screen. As the flow approaches the heel of the screen, the annular flow is forced to re-enter the base-pipe via the screen. This phenomenon is observed in the PIV experiments and the CFD simulation results, albeit with minor differences. However, evaluation of the velocity range and span suggest that the CFD results are reasonably validated by the experimental data. Further tests on the sand retention and plugging characteristics of the screen demonstrated that the screen responds differently to low concentrations of coarse, medium and fine sands. Taken together, these provide field engineers some insight into the screen characteristics and behaviour when deploying such screens in the field. When validated with physical data, CFD is a reliable engineering tool to assess the complex single phase flow phenomena occurring in downhole completion equipment where it may not be economically viable to simulate in field conditions. The sand retention work on a 1-metre long full bore screen also provides a reality check for the screen when subject to low concentration of sand loading, which alters the pressure drop requirements and sand retention capability of that screen. For the first time, the annular flow in a full-sized sand screen has been measured in the laboratory using 2D Particle Image Velocimetry. The results provide supporting evidence to confirm the annular space flow features obtained in the CFD simulation results and provides some insight into the behaviour of annular flow around the sand screen.
A Decision Support Framework for the Technical and Economical Optimisation of the Supply Chain and Project Scheduling for Oil and Gas Projects Under Uncertainty – A Case Study Approach
Authors: Katterbauer Klemens
Published: March 2016

Supply chain optimization and optimizing the construction and field development schedule of oil and gas projects has become quintessential for energy companies in order to cope with changing economic situations, avoid cost overruns and delays in starting production. While the construction process and the individual tasks of it are determined in the planning stage and encounter only limited changes, the economic environment, the duration of tasks and other outside factors, such as the weather, are subject to strong uncertainty and hence this uncertainty needs to be taken into account in the planning and supply chain management process for oil and gas projects. We present a new framework for the integration of technical and economic uncertainties for optimizing the supply chain and the project schedules. Furthermore, we also integrate the option to establish regional distribution center facilities in order to route equipment and material through these facilities to the projects. The operations decision framework was then examined on a realistic test case in the northern Eurasian region where we performed a scenario based optimization in which certain transport links may break down due to either political, environmental or other reasons, affecting both the links as well as the duration of the project schedules. The results outline the importance of taking into account the uncertainty in order to create a sustainable value generating supply chain and project scheduling methodology. Furthermore, the results indicate that while robustness is critical, the establishment of a larger number of regional distribution center facilities is not necessitated in order to maintain robustness and minimize cost. Finally, given the target completion date, the framework delivers a schedule that with almost certainty leads even in various event scenarios to an in-time schedule.
Rheology and Temperature Dependency Study of Saraline-Based Super Lightweight Completion Fluid
Authors: Amir Zulhelmi , Jan Badrul Mohamed , Wahab Ahmad Khairi Abdul , Khalil Munawar , Tong Chong Wen
Published: March 2016

One of the effective alternatives to minimize this perforation-induced formation damage is by application of underbalanced perforation. Fluid systems with very low density could be used to perforate reservoirs in underbalanced pressure conditions that virtually eliminate or minimize fluid invasion and damage along perforation tunnels. To respond in the needs of such fluid, Saraline-based super lightweight completion fluid (SLWCF) was formulated from glass bubble, stabilizing and homogeneity agent. This paper focuses on a rheological and statistical evaluation of Saraline-based SLWCF and its effect on operating temperature. Eight rheological models, namely the Bingham plastic, Ostwald-de Waele, Herschel-Bulkley, Casson, Sisko, Robertson-Stiff, Heinz-Casson, and Mizrahi-Berk, were used to describe the rheological behavior of the fluid. Based on the results, rheology of the fluid was best represented by both the Sisko and the Mizrahi-Berk models. Furthermore, it is also found that the viscosity of Saraline-based SLWCF was more dependent to temperature changes at low shear rate. The Arrhenius activation energy for the fluid to flow was also found to be decreasing with shear rate and their relationship can be expressed with a power law equation.
Produced Water Management – The Challenges Faced
Authors: Ariaratnam G. D. , Roth N. J.
Published: March 2016

In this paper we will discuss the factors that influence the strategy for produced water treatment and disposal. Various aspects of the produced water treatment plant will have an impact on the water quality achieved, for example operational parameters such as interface levels, differential pressure ratios, flowrates, pressures, temperatures, etc. The required specification for either discharge or reinjection is a key factor in determining the process equipment and chemicals that are needed for the separation process. For injection, the water quality that needs to be achieved is often more stringent as there are limitations on solids loadings and particle sizes as well as oil concentrations.

In this paper we will review a detailed case study that was conducted offshore in the UK North Sea. This site was struggling to achieve the water quality needed for reinjection. The work conducted quantified the key areas that were causing the process problems and explored options such as optimising existing separation equipment as well as maximising chemical efficiency.

The case study will highlight how the overall process performance was improved once the oily water separation challenges faced were identified and understood. Improved water quality was achieved by enhancing the chemical dose rates for one chemical and eliminating the use of another chemical as well as optimising several operating parameters for different parts of the treatment process. The overall work led to reduced operation costs and reduced production time whilst ultimately achieving water quality within the required specification without affecting the export oil quality.
High-Resolution Seismic Stochastic Inversion as a Direct Input for Reservoir Modelling
Authors: Xin Chen , Wei Xiao-dong , Li Yan-jing , Cui Yi , Ma Yingzhe , Yan Xiao-huan , Xia Yaliang , Wang Guan , Wang Xiaotian
Published: March 2016

Three-dimensional (3D) reservoir models are best created with a combination of well logs and 3D seismic data. However, the effective integration of those results in the reservoir modeling was not easy due to limited seismic resolution. With the increasing quality of seismic data and widely application of new methods, High-resolution seismic stochastic inversion volume was used as a direct input to reduce the uncertainty of the reservoir model in this paper.

Through the past years study, workflows were developed which use the high resolution seismic stochastic inversion as a direct input for reservoir modeling. The workflows mainly include three steps. The first step is target processing. Wavelet transform was applied to achieve noise elimination and resolution improvement. Base on the High-resolution seismic data, the second step is seismic stochastic inversion. After the process of time-depth conversion, the high resolution 3D data from seismic stochastic seismic inversion and well logs data were used to reservoir modeling as a direct input.

Experiment results show that noise elimination and resolution improvement achieved by using wavelet transform brings desirable convenience, high efficiency and good fidelity. The seismic response of sand reservoir in the high resolution seismic section becomes clearer than the seismic data before target processing, and matched with the well log interpretation. As the seismic stochastic inversion process is controlled not only by the acoustic impedance features, variographic model, and histogram, but also by high-resolution seismic data, the possible number of solutions is reduced, thus decreasing the nonuniqueness of the solution. The seismic stochastic inversion results were multiple 3D volumes with the same horizontal resolution of the seismic and with the vertical resolution, which is matched with the well data. The reservoir model base on the high-resolution 3D data from seismic stochastic inversion and well logs data will reduce the uncertainty greatly, especially in the area Where reservoir exhibits strong heterogeneity. A postmortem is presented showing a successful well that were better explained by this model result based on data existing before the well were drilled.

With the increasing quality of seismic data, and the progress of target processing, seismic stochastic inversion and reservoir modeling technology, the high-resolution seismic data will play more and more important role in reservoir modeling. High-resolution seismic stochastic inversion as a direct input for reservoir modeling will reduce the uncertainty of model greatly.
Study of the Effects of Wettability Changes on Three-Phase Flow in Porous Media Through Pore Network Modelling
Authors: Raman Aarthy , van Dijke Marinus I. J.
Published: March 2016

The increased reliance on CO2 sequestration and Enhanced Oil Recovery techniques such as tertiary gas injection or WAG for oil field development has necessitated an in depth analysis of three-phase flow in porous media for reservoir modelling and production enhancement techniques. Prediction of three-phase flow phenomena requires a sound understanding of the fundamental flow physics in water-wet, intermediate and oil-wet rocks in order to derive physically robust flow functions, namely relative permeability and capillary pressure curves.

A new pore-network model for rocks with arbitrary wettability employing the thermodynamic oil formation and collapse criteria was developed and successfully validated by Al Dhahli et al. in January 2013. This model has been used in the current study to assess the influence of network extraction methodologies, wettability alteration after ageing and capillary effects on multiphase flow characteristics at pore level. Also, the study aims to understand the effects of capillary height functions on flow phenomena. These analogies are successfully illustrated for the Berea sandstone network models.

The flow functions for pore-network analyses were subsequently imported to a reservoir model so as to carry out pore to reservoir scale integration. Flow function normalization and de-normalization were performed with respect to the flowing fluid saturations. This aided in better curve interpolations and fewer curve smoothening. Consequently, curve interpolations based on flowing saturations are suggested for three-phase pore- to reservoir scale integrations in future analyses.

Pore network extraction and flow modelling has contributed to a paradigm shift in today's reservoir modelling approach. However, these applications are presently being limited to research level only and pore scale modelling is still in a relatively nascent stage. Near reservoir conditions such as intermediate wettability, variable flow functions and reservoir heterogeneity form a part of future work in this subject. Further study in this field can delineate dynamic properties of the reservoir, bringing the industry one step closer to effectively recovering immobile/trapped fluid from brown field reservoirs.
Zonal Water Injection for Offshore Highly-Deviated Wells
Authors: Sun Fuchao , Pei Xiaohan , Liu He , Zhang Yusheng , Song Xianmin , Hu Huili
Published: March 2016

Water injection is an effective way for maintenance of reservoir pressure, realization of high and stable oil production and improvement of oilfield development efficiency. Actually, it is a major way for oilfield development in China. Artificial island oilfields are often developed through highly-deviated wells. Existing water injection technologies feature a low pulling and running success ratio of downhole nozzles and pose difficulties in flowrate testing and adjustment, which can hardly meet the needs of zonal testing and adjustment of highly-deviated wells in offshore and artificial island oilfields. This paper proposes a concentric zonal water injection technology for highly-deviated wells. The technology adopts a concentric testing and adjustment scheme, wherein testing instruments and downhole regulators adopt concentric connection with a high connection success ratio for highly-deviated wells. Downhole regulator adopt a bridge channel design that can effectively eliminate the influence of interlayer interference and enhance the efficiency of testing and adjustment. Zonal flowrate is adjusted by adopting an eccentric valve design featuring small loss under fully closing state, small adjustment torque and more easy to adjust. Collected testing and non-collected testing are compatible to meet the requirements of low flowrate. Online packer seal test by cable is realized, ball sealing can be monitored, and all seal checking operations can be completed at one time. In order to achieve long-term continuous monitoring for zonal after-nozzle pressure, an equipped zonal pressure monitor is developed for acquiring long-term continuous data during water injection used for reservoir analysis. During testing and adjustment, online direct reading of multiple parameters (such as zonal flow, pressure and temperature) of any layer can be achieved together with the automatic testing and adjustment without pulling and running operation, which dramatically improves the efficiency of testing and flowrate adjustment. So far, field tests have been made for 14 wells with a maximum hole deviation angle of 59.4°. The flow testing error is less than 5%, and the time for packer seal checking, zonal testing and flowrate adjustment is less than 1 day. Comparing with existing technologies, this technology is of the characteristics of high efficiency of testing and adjustment, high accuracy, low cost, etc.
The Benefits of Detailed Global Analysis Modelling for the Installation of Flexibles, Umbilicals, and Rigid Pipelines
Authors: Jones Chris
Published: March 2016

Global analysis is required when installing flexibles, umbilicals and rigid lines in order to plan the operation and establish safe working environmental limits. Recent advances in modelling software and computing power mean that it is now feasible to model these operations in significantly more detail than has been previously considered. This paper provides an overview of the level of detail which can now be achieved, highlighting various operations which can be modelled and demonstrating how this can reduce risks as well as optimising operability during installation.

The paper focuses on the following areas: modelling techniques, modelling of offshore deck handling operations, and modelling the installation of a Pipeline End Termination (PLET). These case studies are used to highlight the benefits of detailed modelling in reducing risks for the actual operation offshore, in particular by studying the dynamic response as the equipment is installed, and how this relates to the accurate definition of a safe sea state limit. In the past, due to the high level of complexity, these operations have been engineered through the use of standardised calculations or through simplification of the modelling. Comparisons between the simplified and detailed analysis are made, highlighting the differences and the increased accuracy of results which may be obtained, showing areas where offshore installation may be executed more safely. Models are also be compared against the reality of the offshore installation to confirm the validity of the techniques described.

This provides an overview of the level of detail which can now be achieved with the following benefits:

Capturing critical motions which may have been previously missed due to over-simplification Modelling new stages of the operation which could not previously be covered

This will ultimately help to reduce risks as well as optimise operability during installation.
Laboratory Investigation on CO2 Foam Flooding for Mature Fields in Western Australia
Authors: Xu X. , Saeedi A. , Zhang Y. , Liu K.
Published: March 2016

Quantities of mature oil fields in the North West (NW) Shelf of Western Australia are characterized by high water cut and poor productivity, which makes them potential candidate for Enhanced Oil Recovery (EOR). In recent years, CO2 foam flooding has been widely recognized as a promising EOR method in terms of its outstanding ability to increase swept volume as well as improving the displacement efficiency.

In this paper we present the experimental investigation on the feasibility of applying CO2 foam flooding in mature oil fields in Western Australia. A procedure was firstly developed to screen ideal foaming agents at reservoir condition; furthermore, core flooding was performed to optimize operation parameters such as injection mode and volume ratio of aqueous phase to CO2.

The results demonstrate: 1) among a number of commonly used surfactants, AES exhibited the highest foambility and stability; 2) by adding 1.2% additive triethanolamine and 1500ppm polymer (AVS) into 0.5% AES solution, the stability of CO2 foam would be improved significantly without affecting the foamability considerably; 3) the foam stability increased with foam apparent viscosity; 4) the ultimate recovery of direct injection of foam was 7.72% and 4.09% higher than that of co-injection of solution and gas and surfactant-alternating-gas respectively; 5) under optimal flow rate and volume ratio of aqueous phase to gas phase, the oil recovery could go up to 30.05% after the water flooding.

Through systematic and thorough research, CO2 foam flooding has been shown to be a viable and effective EOR method assisting in maintaining the production in mature oil fields in the NW Shelf of Western Australia.