bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Cutting Parameters on Tool Life: Case Study Twist Drill
Authors: Vaghefpour Hossein , Dahar Ali , Zabeh Kobra
Published: April 2015

This study discusses the relationship between various parameters of drilling and cutting tools using an analytical model is developed for predicting life and wear of twist drills by a temperature dependent friction law. The model permits the continuous determination of the cutting forces along the cutting lips and chisel edge which can be combined with the dynamics forces of the initial penetration and the chip evacuation forces in drilling .The approach is based on representing the cutting forces along the cutting lips as a series of oblique elements. Similarly, cutting in the chisel region is treated as orthogonal cutting with different speeds depending on the radial location. The chip flow is determined by the assumption that the friction force on the tool face is collinear to the chip flow direction. The contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on the tool wear were predicted. The model permits to predict the chip flow direction, the contact length between the chip and the tool and the temperature distribution at the tool–chip interface. Using the thermo-viscoelastic model and the temperature friction law, the tangential forces, friction coefficient and contact length on the cutting element as a function of radius, for different feed rate and cutting speed, are obtained. The proposed model results are compared with experimental results and good agreement is obtained.
Numerical Simulation of Solidification Processes of Copper Alloys by Vacuum Continuous Casting
Authors: Chiang Chen Hsueh , Cheng Chien Tzu
Published: April 2015

A numerical simulation method is used to analyse the microstructure evolution of 8-mm-diameter brass (70wt%Cu30wt%Zn) rods during the vacuum continuous casting (VCC) process. The macro-and micro-scale coupling method is adopted to develop a temperature field model and a microstructure prediction model. The effects of casting parameters, including casting speed and pouring temperature, on the shape of the solid-liquid (S/L) interface and solidified microstructure are considered. Simulation results show that the casting speed has a large effect on the shape of the S/L interface and grain morphology.
The Simulation of Laser Cleaning of Magnetic Head with Different Temporal Pulses
Authors: Rungcharoen Narongpun , Wannapapra Mongkol , Pijitrojana Wanchai
Published: April 2015

Nowadays, hard disk drives (HDD) technology are being developed continuously in order to increase the capacity, and reduce the size of HDD to meet user requirements. To increase the capacity which is equivalent to increasing read/write ability, the flying clearance must be reduced. Current new HDD models show that the fly height is lower than 0.3 μm. If the height of a particle or contamination is higher than 0.3 μm, the magnetic head will scratch the magnetic disk surface. However the process of cleaning in the HDD industry cannot remove particles with size smaller than 0.3 μm [1]. Therefore laser cleaning is selected first because this method can remove small particles [2]. and it does not damage the magnetic head. This research compares the range of temperature needed for cleaning the magnetic head between two types of heat source’s profile. The technique used is the heat transfer by finite element: FEM[3]. This technique provides an important factor of the laser cleaning method that increases the efficiency of particle removal. It is also a non-destructive method for cleaning the surface of the magnetic head slider.
Effect of Thick Wall on Transport Profile inside Pipeline Using Computational Fluid Dynamics Simulation
Authors: Rukthong Wanwisa , Weerapakkaroon Wichapun , Wongsiriwan Ungkana , Piumsomboon Pornpote , Chalermsinsuwan Benjapon
Published: April 2015

Heat transfer between convection and conduction near the pipeline wall was considered in laminar transient flow operation using developed computational fluid dynamics model. The governing equations were employed to investigate the effects of wall thickness, wall thermal conductivity and wall surface heat transfer coefficient on transport profile using statistical experimental design. A good agreement between numerical model and commercial software suggests that the proposed numerical scheme is suitable for simulating the transport profile in pipeline and predicting the phenomena for any other conditions.
Mathematical Modeling of the Drying Process of Chrome Shavings
Authors: Beltrán-Prieto Juan Carlos , Long Nguyen Huynh Bach Son , Kolomazník Karel
Published: April 2015

This paper described the mathematical modeling of chrome shavings drying by performing a microscopic balance for water content to describe the unidimensional transfer of water within the solid at a certain temperature. The deterministic model was solved using Laplace transformation and separation of variables methods in order to determine the average free moisture content at different intervals of time during the drying period. Agreement was observed between both, experimental and modeling data. The effective diffusion coefficient of water molecules during the drying of chrome shavings in a tunnel dryer was determined to be 5.8 x 10-6 m2/h.
Suppression of Thermocapillary Effect in Evaporating Thin Film of Micro Heat Pipes
Authors: Lim Elaine , Hung Yew Mun
Published: April 2015

This paper presents a theoretical study on the flow mechanism of different types of working fluids incorporated with Marangoni effect in a microelectronics cooling device. It is known that surface tension gradient effect or thermocapillary effect can be induced by temperature gradient which leads to the thermocapillary flow. By adding a small quantity of alcohol into the pure working fluid, the characteristics of surface tension can be altered without changing other thermo physical properties of the working fluid. A theoretical model is employed to focus on the suppression of thermocapillary effect in evaporating thin liquid film. The study reveals the fluid flow mechanism of a working fluid can be altered with thermocapillary effect. Thermal performance of microelectronics cooling devices can also be enhanced by utilizing aqueous solution as the working fluid.
First Principles Calculations on Cu-Doped TiO2
Authors: Mahmood Waqas
Published: April 2015

The electronic and optical properties of tetragonal rutile TiO2 are investigated by first principles calculations using plane-wave pseudopotentials. Generalized gradient approximation proposed by Perdew-Burke-Ernzerhof (GGA-PBE) is employed with Vanderbilt’s ultrasoft pseudopotentials (USPs) for the geometry optimization. The cutoff energy 380 eV and Monkhorst-Pack (MP) grid of size 5 x 5 x 8 is used to study the electronic properties of TiO2. Besides, the optical properties of TiO2 are studied using a mesh size of 9 x 9 x 9. A periodic supercell of size 2a x 2b x 2c is created and a single Copper (Cu) atom directly substitutes the titanium atom. The geometry is optimized at cutoff energy 440 eV with MP grid of size 3 x 3 x 8 and a denser k-points mesh of size 6 x 6 x 6 is used for the investigation of optical properties.
Development and Property Evaluation of Chilled MMC Prepared with LM25 as Matrix and SiO2 (Glass) Particulates as Dispersoids
Authors: Suresh R.
Published: April 2015

Main objective of the present work is to investigate the effect of dispersiod content and the effect of chill on the mechanical properties of chilled MMC with LM25 as matrix and SiO2 as dispersoid. Investigation is carried out to evaluate Ultimate Tensile Strength (UTS), Fracture toughness, Hardness, and microstructure of chilled aluminum matrix and Glass particulate composite. The glass (SiO2) particles ranging from 30-to100µm were chosen as dispersiod and added, ranging from 3to 12wt% in steps of 3%. The composite was prepared by stir-casting technique and poured into the sand molds incorporated with non-metallic and metallic chills. Test result showed that this MMC was greatly influenced by the dispersiod and chills. Fracture toughness & UTS of the composite are found to depend on the wt% of the dispersiod and chilling medium. It is observed that chill has influenced hardness of the composite. Volumetric heat capacity (VHC) of the chill is found to increase the amount of heat absorbed. Microstructure analysis has reveled uniform distribution of the dispersiod, which results in improved properties of the particulate reinforced metal matrix composite.
Prediction and Determination of Weight and Lycopene Contents of Stored Tomatoes (Lycopersicon esculentum)
Authors: Sunmonu Musliu Olushola
Published: April 2015

The need to develop empirical model equations that describe the changes in the nutritional compositions of stored tomatoes under different environmental conditionsA study was carried out to predict and determine the weight and lycopene contents of stored tomatoes. Three sets of four different types of passive evaporative cooling structures made of clay and aluminium were designed and constructed as part of the study. One set consists of four separate cooling chambers. Two cooling chambers were made with aluminium container (cylindrical and square shapes) and the other two were made of clay container (cylindrical and square). These four containers were separately inserted inside a bigger clay pot inter-spaced with clay soil of 5 cm (to form tin-in-pot, pot-in-pot, tin-in-wall and wall-in wall) with the outside structure wrapped with jute sack. The other two sets followed the same pattern with interspacing of 7 cm and 10 cm, respectively. The set with 7 cm interspace served as the control in which the interspace soil and the jute sacks were constantly wetted at intervals of between 2 to 4 hours depending on the rate of evaporation with water at room temperature. The 5 cm and 10 cm interspaced soil were constantly wetted with salt solution (sodium chloride) at the same interval to keep the soil in moist condition. Freshly harvested matured tomatoes (globe variety) were used for the experiments and the temperature and relative humidity inside the cooling chambers were monitored daily . The weight, lycopene contents, bacterial and fungal counts of these produce were determined at intervals of three days for a period of sixteen days. Mathematical models (using essential regression software package) were developed to predict the weight and lycopene contents of the stored produce at various conditions considered in the study. By substituting different values of predictor variables into the model equations, the expected values of weight and lycopene contents of stored tomatoes were predicted. Further analysis was done using a paired sample t-test using SPSS 16.0 computer software package to show the level of significance between the mean of observed and the predicted values for all the models developed. The mathematical models developed are reasonably accurate to predict the storability of fruits and vegetables in passive evaporative cooling structures.
Analyses of Deteriorating Old Masonry Buildings; Characterisation of Materials for Establishment of their Compatible Repairs
Authors: Makunza John K. , Kumaran G. Senthil
Published: April 2015

Most of the Governmental and religious building structures in Rungwe district are masonry structures built during the German East Africa period. These structures are deteriorating despite of various efforts on their repair intervention using modern cements and paints. This paper studies the types of mineral binders used, composition and physical characteristics of these in-situ mortar materials for the purpose of deciding on their appropriate compatible repair materials. Field observations and investigations, laboratory materials testing and review of the literature showed that the in-situ mortar materials constituted of sub-hydraulic lime mineral binders to natural sand (1:3) mortars. Currently there are no producers of hydraulic lime in Africa and a limited production worldwide. Mix design and analysis of locally available hydrated lime plus pozzolana natural sand (1:3) mortar material have shown compatibility in chemical and major physical properties and characteristics with the substrate in-situ hardened sub-hydraulic masonry mortars. Therefore use of these repair mortars is recommended for compatible repairs to these masonry structures and as a regional alternative to cement based materials for low rise masonry structures.
Importance of Material’s Dynamic Stress Intensity Factor Calculation in the Design of High Strenght Structures
Authors: Javed Raja Ahsan , Zhu Shi Fan , Jiang Feng Chun
Published: April 2015

The researchers and scientists have concluded that material dynamic fracture properties must be considered during the design stage of the modern structure. The dynamic stress intensity factor is very important in understanding of material dynamic behavior. Keeping in view the importance of the materials dynamic stress intensity factor: an efficient and reliable numerical-analytical procedure is developed for calculation of dynamic stress intensity factor. For this, three-dimensional model of a Modified Hopkinson Pressure Bar (MHPB) and a specimen is modeled and analyzed with the ANSYS software. Transient dynamic analysis technique is used for simulation of load-variations as a function of time. As an output of analysis, values of load point displacement and Crack Mouth Opening Displacement (CMOD) are obtained. These values are substituted into two different analytical formulas for calculation of a dynamic stress intensity factor. The results obtained are compared with previous published results, and a good agreement is found.
Reservoir Zonation - A Novel Approach: Use of Core Derived K-Ø-Swirr Relationship to Define Reservoir Rock Types (RRTs)
Authors: Choudhary A. , Thapliyal S.
Published: April 2015

Rock typing is an essential reservoir characterization tool to reflect the spatial variation in initial fluid distribution and flow behavior characteristics. Rock typing techniques are generally based on porosity-permeability relationships to establish the types of rocks present in the reservoir. These techniques lack in effective segregation of reservoir into definite number of zones/rock-types with clear boundaries. This results in a non-unique rock-typing scheme with arbitrary number of RRTs depending on data manipulation. Moreover, these RRTs do not correspond to separate J-function curves due to negligence to water saturation term. To overcome these problems, a new approach for reservoir zonation is developed which has been tested in a few off-shore sandstone reservoirs.

This paper illustrates a robust method of rock typing using a new theoretical development and mathematical formulation. The method integrates irreducible water saturation term with modified Carmen-Kozney equation using a proposed pore-throat dependent water saturation function [Swirr = exp (-art)]. The generalized porosity-permeability-saturation equation [K = AØ3(lnSwirr)B] thus derived is fitted on the Routine Core Analysis (RCAL) data for division of reservoir section into different layers having unique coefficient-exponent set (A, B) representing RRTs.

Application of this method resulted in an effective RRT scheme as evident from the unique coefficient-exponent sets as well as separate J-function curves. The unique porosity-permeability-saturation relationship existing for each RRT has been thus obtained from the RCAL data. This relationship can be used as an efficient tool for reservoir zonation. Reservoir zonation algorithm, analysis results and validation procedures are discussed using field examples.

Reservoir characterization is the key to improve reservoir performance prediction and recovery optimization. This paper presents a novel approach to effectively segregate the reservoir into definite number of RRTs using only RCAL data. This work also presents a theoretically derived K-Ø-Swirr relationship based on pore scale attributes. Irreducible water saturation, being an eminent parameter describing the internal architecture of the rock, is included in formulation and derivation of a theoretical framework to address classification of RRTs.
Settling of Wax Particles in Near-Gelling Systems Under Quiescent Conditions
Authors: Golchha Abhishek , Sarica Cem , Venkatesan Rama
Published: April 2015

During a shutdown of crude oil production from offshore fields, the trapped fluid inside the riser and flowlines starts cooling down, triggering the precipitation of the dissolved wax particles when the temperature drops below the Wax Appearance Temperature (WAT) of the mixture. This work aims to study the settling tendencies of precipitated wax under quiescent conditions when the final temperature of the crude oil is below its WAT but above or near its pour point.

An experimental test facility was designed and constructed to simulate subsea cooling of crude oils under quiescent conditions. A series of experiments were carried out with different model oils and wax concentrations to study gravity settling. Moreover, modifications were made to an existing hindered particle settling model and its application to wax settling scenarios was assessed by comparing the results obtained thereof with the results obtained experimentally.

The results obtained from the experimental runs show that gravity settling can be appreciable under certain operating conditions and fluid properties. It was observed that waxy model oils which have pour point (PP) temperatures above the surrounding ambient temperature tend to form gels as the fluid temperature decreases below the PP during the quiescent conditions. However, in cases where the pour point is close to or below the surrounding ambient temperature, precipitated wax particles may have a tendency to settle under gravity instead of gelling up. The results also portray the effect of wax concentration on the settling behavior. Understanding the behavior of precipitated wax particles in quiescent conditions under the influence of gravity in different systems of varying wax concentrations can help in identifying and remediating operational difficulties associated with wax precipitation during shutdown.

The effect of gravity on wax particles in vertical pipelines during shutdown has not previously been studied much and the settling phenomenon in such situations is not well-known. Due to the effects of changing temperature, particle shape and other factors, gravity settling of wax particles in such systems is different from other systems where a particle is settling in a fluid under gravity. This work provides some input on certain key aspects of this phenomenon.
An Experimental Study on Effects of Static CO2 on Cement under High-Pressure/High-Temperature Conditions
Authors: Aiex Cristina , Campos Gilson , Deshpande Abhimanyu , Chiney Abhinandan , Patil Sandip , Ravi Kris
Published: April 2015

Downhole CO2 in the presence of water forms carbonic acid, which reacts with cement. Some of the final products are water soluble and are leached out. This could cause loss of long term mechanical integrity of the cement sheath, among other issues. Hence, long term prediction of cement sheath carbonation is important to help ensure the cement system designed for CO2 environments creates and maintains zonal isolation throughout the life of the well.

This paper discusses a series of long term tests performed to better understand the effects of CO2 on cement quantitatively. CO2 downhole generally falls within two categories dry CO2, which is a result of carbon capture and sequestration (CCS) activities, and wet CO2, which accounts for naturally formed CO2. Cement samples are tested under downhole conditions of high-pressure/high-temperature (HP/HT) in two different environments supercritical CO2 and carbonic acid, which represent the two different types of CO2 present in the wellbore, respectively. Different types of cement blends have been used in the study to understand the effects of cement composition on corrosion caused by CO2.

Cement samples were periodically withdrawn from the autoclaves to test for transient permeability, compressive strength, Brinell hardness, and chemical composition (X-ray diffraction [XRD], inductively coupled plasma [ICP] tests, pH indicator testing, and thermogravimetric analysis [TGA]). All of the samples were tested for a total of one year. It was observed that chemistry played a very important role in determining how resistant the cement is to attack from CO2.

This study helped provide clear insight into a method that can be used for testing different cement blends for long-term integrity under varying corrosive environments. Knowing the performance of particular cement chemistry under downhole conditions provided considerable benefit in terms of understanding long term integrity of the cement sheath.
Effective Launch and Recovery of Autonomous Underwater Vehicles
Authors: Jamieson J , Wilson L
Published: April 2015

The introduction of autonomous underwater vehicle (AUV) technology in the Oil and Gas arena has and continues to demonstrate significant advantages in offshore underwater operations. One key aspect the "launch and recovery", of AUV operations has the potential to limit the full advantages of the technology being realized.

The current mitigation relies heavily on vessel operations during the launch and recovery procedure. This limitation does not fit the original vision set out as a key AUV service, that is to reduce the reliance on a support vessel enabling cost savings and flexibility to deploy when required. This could ultimately limit the effectiveness that the Autonomous Underwater Vehicle technology can deliver.

This paper will discuss operational issues related to current launch and recovery methods; including weather limitations; surface, mid water and seabed launch & recovery methods; typical vessel operational constraints and the AUV system requirements.

Further to this, the method developed by Subsea 7 to launch and recover its hovering Autonomous Inspection Vehicle (AIV) to the seabed using a dedicated basket will be discussed. A change in approach, the system is designed to meet the needs of the vehicle and vessel operations. The system combines well understood and commonly used offshore package handling practices with the advanced autonomous technology to resolve the launch and recovery issues once and for all.
Improving Seismic Reservoir Characterization With Broadband Seismic
Authors: Mesdag P.R. , Schakel M.D.
Published: April 2015

Broadband acquisition and processing technology has revolutionized seismic acquisition and interpretation. The revolution is not complete however, as we continue to explore how broadband can affect our efforts towards reservoir characterization. In particular, we see the ultimate benefits for reservoir properties with unprecedented bandwidth and accuracy through simultaneous AVO inversion. When performing inversion on broadband seismic data there are some particular properties that need to be considered in different steps of the process. Additionally, careful thought has to be given on how to use inversion QC's to indicate the value of broadband seismic in the inversion stage. We will show some results from our initial experiences in this area.
Subsea Processing versus Host Selection: An Imperative Correlation
Authors: Anikpo A. , Beltrami F.
Published: April 2015

Subsea processing (SP) technologies and host facilities are distinct building blocks in offshore oil and gas field development; they can be regarded as complements or alternates depending on the given scenario. This paper will present a unique insight into these scenarios including applicable interactions. It will highlight the key parameters in this rarely investigated correlation which influence concept selection and full field development (FFD). The paper will also shed some light on key FFD drivers such as reservoir size and (qualitative) economics.

This paper is based on thoroughly conducted secondary research covering 72 past, present, and potential-future related projects around the world. A multidisciplinary approach leveraging expertise in field development, topsides and subsea processing was developed to highlight the trends and possible future applications.

The study reveals a direct correlation between subsea processing systems and host selection which plays a vital role in concept feasibility studies and full field development. Numerous subsea processing parameters have been considered during this study and a few have shown significant effects on host selection - reservoir size, water depth, field typology, etc. The generated trends reveal interesting winners and losers for various technical configurations, including a slight technology limitation dependence on geographical region. Although it may be possible to predict future applications of subsea processing technology and optimize designs based on the host's interaction with the subsea processing system, the market uncertainties still remain high; nevertheless, recommended areas of focus are presented in this paper based on identified gaps. There are not many publications on this subject; therefore some of the observations presented in this paper are novel.
Implementing Constructability in Brownfield Projects: A Case Study
Authors: Salem Amir G. , Le Normand Olivier
Published: April 2015

A number of new developments based on floating production and storage facilities have suffered set-backs or been shelved due to escalating Capital Expenditure (CAPEX), increased top-side weight and complexity, and increasingly demanding regulatory requirements. Subsea tie-backs, and brownfield upgrades of floating facilities present operators with investment alternatives in their deepwater acreages while new technologies and improved business models are developed to lower cost and improve efficiencies. In this context, constructability offers an effective tool to influence project cost and schedule. As such, efforts to implement constructability in offshore oil and gas projects will set the stage for well-defined Exploration and Production (E&P) strategies while restoring confidence in the profitability and ultimately the safety of these developments.

This paper presents a case study of implementing constructability program in the deep-water Gulf of Mexico (GOM) for a brownfield subsea tie-back development. Project constraints such as regulatory requirements, metering, field proximity, production capacity, weight limitation, bed space, shutdown, commissioning and start-up etc, are identified and investigated in details. Measures to minimize offshore work, and hot work are presented. Tools utilized in the design phase such as 3D laser scanning technologies in conjunction with CAD systems and field verifications are discussed. Contracting strategies and fabrication yard selection process are explored.

Constructability parameters for the offshore campaign for hull piping and SCR/umbilical pull-in are outlined with goals to minimize offshore heavy lift and transport, diving operations, winch capacities and deck strengthening requirements. Additionally, riser installation methods and hang-off hardware are explored. Simultaneous Operation (SIMOPS) matrix development philosophy for the offshore campaign is proposed with focus on safety and uninterrupted production. The case study selected herein is for a Semi-submersible currently in production. Emphasis is given to effective work packages and job card development for effective offshore operations. Management of Change (MOC) processes are discussed. The findings and conclusions of this work are extended to other offshore production facilities. A road map extrapolating the outcome of this study is presented with the goals of implementing constructability as an effective tool for brownfield production floater development subject to risks of cost and schedule overruns.
Exploring the Benefits of Wellhead Fatigue Monitoring
Authors: McNeill Scot , Agarwal Puneet , Kluk Dan , Bhalla Kenneth
Published: April 2015

This paper examines the benefits achieved through fatigue monitoring of wellheads. As an introduction, conservatisms in analytical predictions of wellhead fatigue life are cited. In addition, considerations for increasing wellhead fatigue resistance are reviewed along with recent wellhead fatigue monitoring developments.

The architecture of both stand-alone, battery-powered monitoring systems and real-time monitoring systems are examined. The capabilities and limitations of each respective system are discussed and the overall value-added to drilling and production systems is summarized.

Wellhead monitoring systems have been deployed in several drilling and production operations with high fatigue demand, where loading from waves, rig motions or VIV is particularly intense. As a case study, results are examined from a wellhead monitoring campaign in an environment characterized by deep water and high-currents, where fatigue was driven by VIV. The measured vibration and current data are illustrated and the correlation is investigated. Important features of the wellhead fatigue damage rate trend are discussed. Fatigue life consumption tracking demonstrated that operations could safely continue, despite the arduous current conditions.

The wellhead monitoring methods discussed herein result in real-time or rapid turn-around of valuable fatigue life consumption information, enabling informed decisions to be made in adverse conditions. In a larger sense, measured data also serves as a benchmark for analytical model calibration activities, reducing the known conservatism in stress and fatigue in future deployments.
Performance Testing of an Integrated, Subsea Compact Separation System with Electrocoalescence for Deepwater Applications
Authors: Olson M.D. , Grave E.J. , Juarez J.C. , Gul K.
Published: April 2015

ExxonMobil Upstream Research Company (EMURC) recently completed a subsea technology development and qualification program which included performance testing of an integrated, subsea compact separation system with electrocoalescence for ultra-deepwater applications. To the authors' knowledge, this was the first time that an electrocoalescer had been tested with a gravity-based, compact separator (e.g., a Pipe Separator).

One challenge often seen with conventional gravity separators is the formation and build-up of stable emulsion layers, mainly associated with the processing of medium and heavy oils. In an earlier test program, the Pipe Separator, the primary oil-water separator in the subsea compact separation system, performed well; however, emulsions that were not separated in the main pipes of the Pipe Separator tended to accumulate in the outlet section. There, the emulsion layer then had to either flow out of the oil outlet (penalty on the oil quality) or the water outlet (penalty on the water quality).

The medium and heavy oil trials were particularly challenging, especially at lower water cuts. In order to achieve the desired oil and water qualities, the total liquid flow rate through the system had to be reduced. To overcome this limitation, additional trials were performed later with a compact electrocoalescer, the Compact Electrostatic Coalescer (CEC™) supplied by Fjords Processing (formerly Aker Process Systems), which effectively coalesced dispersed water droplets in the oil-continuous feed into larger droplets such that they could be separated easier in the downstream Pipe Separator. The results from the additional trials demonstrated that electrocoalescence enhanced the oil-water separation performance of the integrated system at flowing and operating conditions that would have otherwise been very challenging. This paper presents a summary of the results from these additional trials.

The cost of developing and deploying a subsea separation system is significant; and therefore, it may not be economical if the system is unable to achieve a sufficient capacity. The design of subsea processing systems is often a balance between what is practically achievable under the module size/weight constraints, and what production rate is required for project economics. By understanding, with confidence, the maximum liquid handling capacity of the integrated system with electrocoalescence, technical risks could be minimized, and a future subsea separation project could become more attractive. As such, the results from this test program may be of interest to operating companies considering similar technologies or future subsea separation projects.
The Cylindrical Hull Concept for FLNG Application
Authors: Odeskaug Lars
Published: April 2015

Cylindrical hulls are currently in use for FPSOs, drilling rigs and accommodation units. The objective of this paper is to describe how the cylindrical hull concept now has been developed to also be applicable to FLNG.

To provide a more stable and economical hull configuration, the use of a cylindrical hull as a platform for the gas pre-treatment and liquefaction plant has been studied and generically developed using advanced analytical design tools. The behavior of the cylindrical hull has been model tested and a significant amount of data is also available from the cylindrical FPSOs in operation. The cylindrical hull has significantly less pitch and roll motions than a conventional ship shaped hull, and eliminates the need for a turret and swivel. Hence it provides a stable platform for the process plant and and has the potential to enhance project development and operations.

The cylindrical FLNG concept is a further development of the proven cylindrical FPSO design. The hull meets the requirements of the International Gas Code and has been developed to accommodate both SPB and Membrane cargo containment systems.

The hull has double sides and bottom, and the ballast tanks are in the double sides. There are three decks, main deck, intermediate deck and the process deck.

Utility and safety equipment, such as lifeboats, water-makers, heat exchangers, etc. are located on the main and intermediate decks. The gas pre-treatment and liquefaction plant along with power generation and living quarters are on the process deck.

For offloading a novel development using an L-shaped DP assist vessel is proposed. This allows for loading of standard LNG Carriers at a safe distance from the FLNG in seastates of Hs 4m.

The L-shaped unit is a specially designed vessel that attaches to the LNG carrier and guides it during approach and departure and keeps the LNG carrier at a safe distance of 150 – 200 m from the FLNG during the offloading operation.

The cylindrical FLNG in combination with the novel offloading technology for offshore LNG transfer offers a safe, reliable and cost efficient solution to the emerging FLNG market.
Optimization of Submarine Pipeline Routes Considering Slope Stability
Authors: Rocha Djalene Maria , Cardoso Carlos de Oliveira , Borges Ricardo Garske , Baioco Juliana Souza , Silva Coutinho Daniel da Costa e , Albrecht Carl Horst , Jacob Breno Pinheiro
Published: April 2015

Submarine pipelines have been extensively employed to transport oil or gas from offshore petroleum exploitation activities. To ensure an efficient and expedited pipeline project, a computational tool based on Evolutionary Algorithms is employed to optimize submarine pipeline routes. Different evolutionary optimization methods could be applied, but this study focuses on the Genetic Algorithm (GA). In this tool, each candidate route is evaluated with several criteria incorporated in an objective function, obeying the relevant aspects to be considered in the route design such as: pipeline length, bathymetric data, obstacles, etc. Slope stability verification is also important in landslide risk areas in the pipeline route design context. Thus, this study evaluates the influence of these factors on a representative scenario route configuration. The case study results indicated the slope stability importance in the best route selection. Moreover, the computational tool provides more accurate results, avoids route interpretation mistakes, and ultimately minimizes the huge costs associated with submarine pipeline instalation and operation. Additionally, the slope stability assessment computational costs are low, which indicates the feasibility to incorporate them in the optimization tool.
Application of Sand Control and Stimulation Technology with Fiber Fracturing on Unconsolidated Deepsea Sandstone Reservoir
Authors: Shi Y. , Gao Y. , Zhou F. , Yang X. , Xiong C. , Liu X. , Han X. , Liao Y. , Peng J.
Published: April 2015

To meet the challenges from an unconsolidated, deep sea sandstone reservoir, this paper developed a stimulation and sand control method through fiber fracturing. The key points of the technology are as follow: (1) This paper developed instantizing guar gel fracturing fluid system based on seawater, which can be online mixed with in-situ seawater. Transport of fresh water will not be required for the new system, and the application of new fluid can save platform space. (2) The fracturing design was optimized with orthogonal analysis method to improve the stimulation effect. (3) Fill fiber and resin proppant into hydraulic fracture to form an artificial screen, preventing the fine sand production.

This method had been applied in a low-perm unconsolidated deep sea reservoir. Before the fiber fracturing, the pilot well was shut off because of no production. After treatment, the production reached to 20m3/d, and no sands were found in produced liquid.
Standardized Offshore Wellhead Platforms for Optimized Offshore Execution
Authors: Samuel Johnson , Al-Dossary Ghassan H. , Raja Abid
Published: April 2015

An improvement in the engineering, procurement and fabrication of offshore facilities was needed to support the Crude Production Program. The standardization of wellhead platforms was initiated by Saudi Aramco with the intent of developing a design suitable across all of its offshore oil fields. This resulted in the introduction of an innovative, standardized offshore wellhead platform design. The newly designed wellhead platform structure has an optimized layout to handle current and future operational requirements. The standard design using a 3D model was used repeatedly, eliminating the need for a customized design.

The standardized design enabled the advanced procurement of bulk materials and long lead equipment to support the fabrication yards for efficient execution of the offshore workload. This reduced the lead time for all new offshore platforms. As a result, the delivery of the supporting structures ("jackets") based on the standard design was also improved, which supported the drilling program.

The standard design allowed the implementation of Long Term Agreement (LTA) contracts with unit rates resulting in an optimized schedule and cost savings. This approach allowed the Offshore Program to secure the scarce offshore resources in the region exclusively. This provided an opportunity for Saudi Aramco to develop an inKingdom fabrication yard, which has already delivered numerous projects.

The standardized design eased fabrication procedures and assisted the contractor to fabricate multiple platforms in parallel tracks based on similar designs. As a result, the transportation and installation procedures were simplified and made applicable for multiple facilities with optimization leading to a reduced installation schedule.
Offshore Well Integrity Management with MPD Tools and Technology
Authors: Hannegan Don , Mahmood Azfar
Published: April 2015

Important key performance indicators of offshore well integrity management include mitigating drilling hazards without inducing others and maintaining control of the well in the process. Offshore applications of Managed Pressure Drilling (MPD) tools and technology have been steadily increasing over the past decade primarily for these reasons. Its growing acceptance has been influenced by drilling prospects deemed to be un-drillable with conventional circulating fluids systems for safety, economic, and/or technical reasons, increasing recoverable reserves in the process. MPD's pristine onshore well control track record is now being recognized as a safer way to drill a growing number of offshore prospects that could not be drilled with a conventional open-to-atmosphere mud returns system4.

There are four variants of MPD practiced offshore; Constant Bottomhole Pressure (CBHP), Pressurized Mud Cap Drilling (PMCD), Returns Flow Control (RFC-HSE), and Dual Gradient Drilling (DGD). CBHP for drilling in narrow, shifting or relatively unknown safe mud weight windows, PMCD for drilling in severe to total loss zones, RFC-HSE to augment safety systems and methods when drilling with an otherwise conventional fluids program, and DGD for reducing equivalent mud weight (EMW) when drilling depleted formations from shallow water rigs and eliminating gross overbalanced conditions when drilling from deepwater rigs8.

Over the past decade, key enabling tools have been developed to enable the safe and effective practice of MPD on all types of offshore rigs and water depths; marine series rotating control devices, MPD automated control systems, MPD hydraulic flow modeling, MPD well control matrix, etc. Early kick and loss detection is a flagship capability, as well as ability to conduct formation integrity and leak-off tests more frequently than industry norm by doing so while drilling, quantify and virtually eliminate ballooning3, closed-loop cementing, and managed pressure wellbore strengthening, all of which represent state-of-the-art well integrity management capabilities.

Whether it be in shallow water, deepwater, or ultra-deepwater, a growing number of otherwise promising prospects are deemed un-drillable with conventional circulating fluids systems. The industry has already drilled the majority of the available ‘easy’ wells with drilling hydraulics whose root principals were developed over a century ago. MPD is poised to become the next ‘conventional’ way to drill in marine environments within the next decade. This presentation will illustrate to the offshore drilling industry, regulatory and stakeholders why that is expected to be the case.
Risk Evaluation Methods of Gas Hydrate When Shallow Strata Drilling in Deepwater Area
Authors: Xu Yuqiang , Guan Zhichuan , Xu Chuanbin , Zhang Hongning , Zhang Huizeng
Published: April 2015

Natural gas hydrate often occurred blocking BOP and resulting in other accidents when drilling in deepwater, particularly in shallow strata. So this paper's objective is to establish risk evaluation methods of gas hydrate when shallow strata drilling in deepwater area. With comprehensive consideration of gas hydrate equilibrium conditions and borehole temperature and pressure field, we established method for prediction of gas-hydrate formation region in the shallow strata of deepwater drilling and method for prediction of gas-hydrate formation region when shallow drilling in deepwater area. On this basis, with comprehensive consideration of hydrate formation processes and its factors, we established the qualitative risk evaluation method of gas hydrate based on expert scoring method, meanwhile, established the semi-quantitative risk evaluation method of gas hydrates which takes the influence weight of multiple factors into account and based on Analytic Hierarchy Process. Through the analysis, shallow layer drilling in deepwater area has greater risk in natural gas hydrate than deep drilling. The example shows that: The level of hydrate formation risk near the subsea wellhead and the lower part of conductor is highest; Identification of shallow gas, gas hydrate strata identification, risk level within the predicted gas hydrate formation region as well as the water depth and geothermal gradient, etc. have most influence weight of gas hydrate when shallow strata drilling in deepwater area, we can according to this and combine the actual situation to optimize the design and construction of drilling, thus reduce or avoid the risk.
Subsea Power Supply Based On Submarine Propulsion Technology
Authors: Frühling C. , Schiemann M.
Published: April 2015

The paper reports on the development of electrical subsea power generation and storage systems based on non-nuclear air independent submarine propulsion technologies. Proven submarine technology represents a promising base for innovative and high-performance subsea solutions. Reliable and cost efficient electric power supply can be regarded as one of the most important factors for the successful development and operation of future subsea facilities. Long step outs, large water depths and remote locations without topside infrastructure pose challenges to cable based solutions. Submarine technologies can help to overcome these issues. Within the scope of the paper, an overview of conventional (non-nuclear) military submarine propulsion technology and its perspectives to be applied for civil subsea power supply systems is given. The outlined technologies include diesel-electric propulsion, lead and lithium ion batteries, and air independent propulsion (AIP) systems. For the latter, fuel cells and closed cycle diesel systems are described. The present work highlights the potential of such technologies to be applied as an energy supply for subsea systems. A modular concept is presented which is applicable for water depths up to 3000 m. It consists of battery components to satisfy large intermittent power demands as well as AIP modules which will be able to offer moderate base loads. This way, tailored hybrid battery/AIP solutions can be created which fit the needs of specific stationary and mobile subsea appliances. The concepts can easily be scaled in power and energy.
Geological Interpretation of Mass-Transport Complexes in the Gulf of Mexico: The Benefits of Integrating Borehole Geology, Borehole Geophysics, and Reservoir Engineering
Authors: Zimmermann Eric , Guzman Carlos , Vercher Mike , Hewitt Stan , Kumar Anish , Mahnke Michael , Mishra Vinay K. , Ruiz Elizabeth , Charmelo Nellyana
Published: April 2015

The deepwater Gulf of Mexico is one of the most actively explored deepwater basins in the world, with hundreds of wells drilled to date. However, although much knowledge has been derived from extensive drilling experience, the Gulf's geology offers many surprises. In general, if the horizons of interest are not located subsalt, then seismic-derived attributes can provide a reasonable understanding of the subsurface geology. In practice, the deepwater Gulf of Mexico geology is sufficiently complex that technology such as borehole imaging, borehole seismic data, and pressure and fluid sampling need to be included in the well evaluation to complement the surface seismic interpretation. Incorrect subsurface interpretations impact the drilling and well placement decisions to result in additional well and facilities costs.

In an example from the Gulf of Mexico, the sub-seismic-scale geological interpretations from borehole image data and high-frequency vertical seismic profile (VSP) reflection data were integrated with state-of-the-art lower frequency surface seismic data. The dip and image data obtained from the borehole imager, VSP, and surface seismic appeared to be contradictory when individually considered; however, a careful evaluation of the data reconciled the differences and provided a more complete picture of the subsurface. The example demonstrates how the combination of these different borehole data types was able to identify cycles of high-energy mass-transport deposits followed by relatively lower energy phases of sand deposition.

The impact of geological deformation affects the geological interpretation and the connectivity and types of fluids present in the reservoir. Pressure and fluid analysis from formation testing data confirmed nonlinear relationships at different depths, which were analyzed for implications to the reservoir.

In the challenging geology of the deepwater Gulf of Mexico, geological analysis based on only one kind of data often leads to incomplete understanding of the reservoirs, and that, in turn, can lead to ineffective field development plans. Integrating surface seismic, borehole seismic, borehole geology, and reservoir pressure and fluid data is essential for better understanding Gulf of Mexico deepwater reservoirs, especially in regions of complex geology.