bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimizing Additional Stabilization Requirements of an Existing Pipeline
Authors: Teh Thiam Chuan , Nitchov Tony , Selvam Rajendran , Panambur Sandeep , Mahmoud Abdel Hakim , Qazi Muhammad , Tjahyono Sindhu , Dai Keyang 
Published: March 2016

Abstract
In order to increase oil production, an oil field operator undertook a field expansion program which required the construction of additional satellite platforms and several new artificial islands as centres for future drilling and oil production facilities. As a result of these newly constructed islands, wave and current conditions within the surrounds became more severe. Some sections of the existing pipelines in the vicinity of the new artificial islands were identified to no longer satisfy DNV-RP-F109 Generalized Method's stability criterion of pipe lateral displacement for less than ten (10) times the diameter. This resulted in the need to employ additional stabilization measures for these affected sections. As a consequence of the high costs associated with these measures and the inherent conservatism in the use of small allowable displacements as a failure criterion, a dynamic analysis using finite element method was used to assess the pipeline displacement and the structural integrity responses during a storm duration. This paper details the use of such dynamic analysis to optimize the additional stabilization requirements for one of the pipelines in the field. The results demonstrate that significant cost savings for the operator could be achieved using this method.
Assessment of Nonlinear Roll Damping and Hydrodynamic Loads on Extended Bilge Keels for FPSO/FLNG
Authors: Kim Sungeun (Peter) , Seah Robert 
Published: March 2016

Abstract
Bilge keels are commonly installed on commercial ships and FPSO/FLNG units to effectively mitigate roll motions. Accurate predictions of the roll damping and hydrodynamic loads are critical for the structural design of the bilge keels. In this paper, model tests and Computational Fluid Dynamics (CFD) are employed to investigate the nonlinear roll damping and hydrodynamic loads on the bilge keels. Roll decay tests and CFD simulations are carried out for a FPSO vessel to estimate the roll damping and drag coefficients of the bilge keels with extended depths. Also seakeeping model tests and CFD simulations are carried out to estimate the hydrodynamic loads on the bilge keels in regular beam waves. From this study, it is found that the drag coefficients of the Ikeda formula (1976) and Sarpkaya & O'Keefe (1996), originally developed for wall-bounded plates, can substantially under-predict the drag loads on the bilge keels attached to a FPSO vessel without considering a velocity increment factor. This paper presents the first part of the Joint Development Project (JDP) between ABS and Chevron to develop the procedures for the strength and fatigue assessment of bilge keels for FPSO/FLNG units.
Infinite Conductivity Horizontal Borehole Assumption: Applicability & Quantification of Error
Authors: Abo El Seoud M. A. , Alnuaim S. A. , Shoukry A. E. 
Published: March 2016

Horizontal drilling technology is advancing rapidly day after day. That is due to the much higher productivity of horizontal wells relative to vertical wells. However, the paycheck of drilling a horizontal well is also higher. Therefore, the productivity of a horizontal well not just needs to be estimated whatsoever, but the estimation has to be reliable enough. As a faulty-estimated productivity shall result in a faulty economic feasibility of drilling this well, and may cause huge economic losses.
Several types of models discussed the productivity of horizontal wells. Analytical models (ex. Furui) are the most common to use because they are easy to use. Nevertheless, this easiness comes at the expense of the infinite borehole conductivity assumption, which does not account for any pressure drop along the lateral length of the well. This assumption causes severe errors in some situations. On the other hand, semi-analytical models (ex. M. Tabatabaei and A. Ghalambor) couple reservoir inflow with wellbore outflow to estimate the productivity of horizontal wells.
This paper concentrates on showing the value of production rate error resulting from using Furui's model applied on published data of three wells, the error in rate is calculated based on the M. Tabatabaei and A. Ghalambor's model which is assumed to yield the right rate. First, a MATLAB code was developed to implement the M. Tabatabaei and A. Ghalambor's model. Then, after matching the code results with the rates of the 3 wells mentioned in the original work of M. Tabatabaei and A. Ghalambor, sensitivity studies were made on all the reservoir and production parameters in both productivity models. They were to show the effect of changing each parameter on the production rate error. The analysis of results showed that the error comes from a combination of parameters with different weight factors.
A productivity error correlation is the output of the second part of this paper. The correlation is developed by non-linear regression on the results of the sensitivity runs as inputs, and the errors as the output. A neural network model was also developed, using the same inputs, to confirm the reliability of the developed correlation. The correlation could be used to get a rough estimate of the actual production rate of a horizontal well, as well as judge the validity of the infinite borehole conductivity models.
Analysis and Improvement of Calculation Method of Riser Top Tension in Deepwater Drilling
Authors: Meng Wei , Yang Jin , Gao Deli , Hu Nanding , Tong Gang , Deng He , li Lei , Zhao Yihui , Liu Zhengli 
Published: March 2016

Abstract
Top tension plays an important role in stability of riser system. Either excessive or insufficient value of it tends to cause negative effects on risers' proper function and then pose a threat on drilling operation. But there is no unified calculation method about the setting value of riser top tension. Therefore, the purpose of this paper is to establish a calculation method of riser top tension that both meets the requirements of theory and engineering.
The improved method is based on the theory of effective axial force in tubing mechanics. It considers the requirement of risers stability and over-pull force to lower marine riser package (LMRP) in field drilling operation. Take three deepwater wells in South China Sea as examples. Utilizing finite element analysis software ANSYS to model the riser, subsea wellhead and conductor systems respectively, then exerting the calculated top tension and environment load, the analysis results can be used to check the accuracy of the proposed calculation method.
After analyzing the related methods proposed by American Petroleum Institute[1] (API) and Institute of French Petroleum[2] (IFP), it is found that both of them have their limitations. The former one only concentrates on stability but ignores the over-pull force required by LMRP in field operation. The latter one takes the requirement of overpull into consideration though, it regards this force as effective tension rather than true tension. According to the related theories of tubing mechanics, the effects of true axial force and effective axial force on the riser mechanical behavior is analyzed. The results show that, the bottom tensile force to LMRP is determined by true axial force, and the risers' stability depends on effective axial force. Through the force analysis of risers which simultaneously bear the inside and outside pressure, the correspondent mechanical model was established, and a new calculation method of top tension was derived, which modifies the deficiencies of algorithms proposed by API and IFP. The accuracy of this method is verified by the values if field operating and numerical simulation of ANSYS.
The novelty of this method is to propose a calculation method of riser top tension that could improve the deficiencies of API and IFP and meet the requirement of stability and bottom over-pull force to LMRP in field operation.
Passive Fire Protection PFP Optimization in Offshore Topsides Structure
Authors: Sari Ali , Ramana Ekkirala , Dara Sepehr , Azimov Umid 
Published: March 2016

Abstract
Structural integrity assessment and fire response analysis of offshore topsides structures focus on protecting topsides primary structural steel, hydrocarbon equipment supports, secondary steel along the primary escape routes, pressurized hydrocarbon pipes and vessels from damage and fracture due to pool and jet fires, and providing safe escape routes for emergency evacuation of the personnel during a specific period of time. In order to achieve these purposes, it is very critical to apply sufficient amount of Passive Fire Protection (PFP) on the topsides structural steel members, pressurized vessels and piping to supplement active fire protection systems like deluge, foam systems, etc. On the other hand, excessive use of PFP on the structure results in considerable additional cost and extra added dead load to the structure.
Simplified and conservative approaches are available to estimate the extent and amount of the PFP on the offshore structures. However, the main concern with simplified approaches is that they can lead to over-application of the PFP resulting in substantial increase in the topsides weight. These methods may also result in under-estimation of the required amount of PFP, which can compromise the topsides structural integrity. With the use of advanced engineering analysis and knowledge of critical load path, an optimized PFP scheme can be developed that would maintain the structural integrity of the structure and also provide sufficient escape time for personnel during fire. The risk-based approach for PFP scheme development and optimization is introduced in this paper. In this method, ductility level fire response analysis is discussed, which is coupled with the probability of failure and probability of escalation to estimate risk to individual, asset, environment, etc. The ductility level analysis accounts for material and geometric nonlinear behavior of steel and load redistribution when heated members are over-utilized. The risk-based method is compared against the conventional method of PFP optimization using ductility level analysis recommended by API RP 2FB. It was concluded that using the risk-based approach can result in a significant reduction in the amount of required PFP.
Dropped Object Assessment of Subsea Assets and Pipeline Protection System
Authors: Sari Ali , Azimov Umid , Nguyen Hieu 
Published: March 2016

Abstract
In offshore drilling operations, accidental loads such as dropped objects pose a high potential threat to human safety, asset integrity, environment as well as reputation and business of the operator. A safe design of offshore exploration and production facilities for accidental collisions requires the risk assessment of such accidental events. This paper proposes the methodology to assess such risk. For the frequency assessment part of the risk, the paper proposed an extended version of the approaches outlined in industry guidelines such as DNV-RP-F107. For the consequence analysis, it has been demonstrated that advanced analysis method is capable and suitable for understanding the response of structures to accidental loadings, not only to remove conservatism inherent in simplified approach but also to assure a safer and economical design. Furthermore, this paper has demonstrated that by accounting for fluid-structure and structure-soil interactions, more detailed insight can be obtained of the response of the subsea pipeline protection system that otherwise could be easily missed without consideration of the fluid and foundation and can lead to ineffective design and connection details.
Seismic Modeling and Imaging Using Wave Theory for Fault and Fracture Identification
Authors: Yasir Bashir , Ghosh Deva Prasad , Moussavi Alashloo Seyed Yaser , Sum Chow Weng 
Published: March 2016

Abstract
Illumination of discrete transmissivity structures such as faults or fracture zones prior to exploration offers substantial benefits for all phases of field development. We have established a new way of seismic imaging through diffractions study using reflection seismology. A subsurface geological model is developed for highly productive field located in southern part of Malay Basin. Finite difference modeling is used for generating synthetic seismic data. Both velocity and density model is used for explanation of wave propagation intimate the subruface from side to side one-way and two-wave wave propogation. One–way wave equation migration methods are tested to image the faults in synthetic seismic section of Malay Basin and they are able to image the complex structure such as faults and fracture prevailing in the model.
Temperature Increase Behavior of Multi-Annuli in Subsea Wells
Authors: Liu Jinge , Fan Honghai , Liu Wenke , Hu Hangjian , Zhang Qunhai , Chen Xiaolong , Gao Yuan , Han Fuxin 
Published: March 2016

Abstract
Annular pressure buildup (APB), caused by fluid thermal expansion in confined annuli of high temperature (HT) subsea wells, can lead to some serious accidents such as casing failure or tubing collapse, especially during the starting production within hours. Thermal expansion in the sealed annulus contributes to more than 80% of APB. To predict annular temperature accurately is the key to calculate APB. This paper presents a semi-steady state model to predict multi-annular temperature. The new model presented not only taking the amount of annuli difference in various depths into account but also the friction energy effects of formation fluid flowing in the tubing. The simulation result describes the temperature distribution in various depths of different annulus. The simulation results show that the temperature increase in the multi-annuli can be as high as 30°C on an average.
Accurate Production Logging in Deviated Gas-Liquid Producer Wells
Authors: Gok Ihsan M. , Thanh Tung Huynh , Khunaworawet Tanawut , Mukerji Parijat , Kim Young Sig , Lee Jongyong , Sun Dongsu , Van An Phan 
Published: March 2016

Abstract
Production logging tools (PLTs) are used to evaluate downhole flow profiles under flowing and shut-in conditions before taking any well intervention decisions. Interpreting conventional centre- weighted production logging data is more complicated in deviated wells due to more complex flow behavior such as recirculation. Downflow of the heavy phase along the low side of the pipe occurs due to significant shear between the light and heavy phases, resulting in recirculation phenomena. A pipe centered conventional spinner tries to average the velocities of the phases passing through the swept area of the blades, but generally returns a velocity that is too low if not actually negative. A poorly centralized spinner often tends to indicate downflow due to the recirculation of the heavy phase. This paper shows how eccentered multi-spinner technology delivers accurate results for multiple phases in deviated wells where conventional spinners do not perform reliably.
An advanced PLT provides discrete velocity and hold-up measurements: five spinner velocity points and six pairs of water and gas hold-up points. This technology was initially designed for production logging in horizontal wells exhibiting stratified flow regime. It is also shown that multi-spinner measurements can be used to characterize recirculation behavior in deviated wells. To obtain quantitative fluid influx moving upwards, a new approach was used to calculate the average velocity without including the spinners immersed in recirculation zones. Individual phase hold-up was then calculated using a linear hold-up averaging technique from discrete hold-up measurements across the pipe interval.
Reliable results were obtained using this approach in deviated wells from both under shut-in and flowing conditions of low flow rate where a low mixture velocity and high slip velocity coexist. Recirculation poses serious problems when fluid velocity is low in the pipe. Typical example of this is PLT data acquired under shut-in condition. Generally, crossflow characteristic were missed in such wells and depleted zones cannot be identified. Two data sets acquired under flowing and shut-in conditions are discussed extensively. Downhole flow rate results were compared with surface flow rate measurement and an acceptable match was obtained between two rate measurements. In addition, the importance of selective performance analysis (SIP) was also shown.
Development of World's First Corrosive Hostile Environment (CHE) Gun System
Authors: Lavery Joshua , Hoelscher Chris , Harive Kevin , Quaden Roy 
Published: March 2016

Abstract
The quest for oil and natural gas reserves is taking the industry to areas where production was previously considered uneconomical. Floating liquefied natural gas (FLNG) is a technology that allows for the production, liquefaction, storage, and transfer of liquefied natural gas (LNG) at sea, removing the requirement for pipelines, reducing development costs, and unlocking new remote fields for production.
The Prelude natural gas field was discovered in the Browse Basin in Western Australia, by a major operator in 2007, with the additional Concerto field discovered nearby in 2009. The combined gas fields have around 3 trillion cubic feet of liquids-rich gas. The development strategy was the Prelude FLNG facility.
The Prelude FLNG facility is supplied with gas from 7 near horizontal wells, completed with 7-in. production tubing.
One of the well completion challenges faced was related to the sand face completion strategy. Formation evaluation studies determined that the optimum sand face completion for Prelude was cased and perforated. The challenge was perforating 600 m of near horizontal interval in underbalanced conditions in one trip, followed by an immediate well cleanup to the Mobile Offshore Drilling Unit (MODU) via a well test facility, thereby maximizing perforating tunnel cleanup efficiency and optimizing recovery of perforating debris during the well cleanup.
Various options were considered, from multiple coiled tubing runs to tubing-conveyed perforating (TCP) shoot and pull operations, but all had drawbacks and were not able to achieve the previously mentioned underbalanced perforating and well cleanup requirements.
This led to a perforating strategy whereby a 600 m TCP gun string was deployed across the reservoir and dropped off. The completion fluid at this stage was already a base oil, which would generate the desired underbalance during the perforating event later. Gun deployment was followed by installation of the 7-in. production tubing and completion assembly. Only after completion installation and testing were the guns pressure activated from surface and the well cleaned up immediately through the well test facility.
The 600 m spent gun string will remain in place across the reservoir section for the well lifecycle through to final abandonment. While leaving perforating gun strings downhole is not an uncommon occurrence in the industry, the mildly sour downhole environment on Prelude introduces a corrosion risk for traditional mild steel gun systems, which has the potential to lead to gun degradation with corrosion particles being produced up the well leading in turn to potential well and facility operability issues. To avoid this specific risk, the operator worked with the service company to develop the world's first corrosive hostile environment (CHE) TCP perforating gun system.
Severe Formation Damage Due to Solids Invasion in Inclined/Horizontal Wells With High-Permeability Zones
Authors: Aljabbar Muhammad Ihsan , Rizkiaputra Ricko 
Published: March 2016

Abstract
High-gravity solids (HGS) invasions via microfractures and large openings is known to cause a severe formation damage. A HGS invasion model is presented by using unsteady-state mass transfer as its basis for calculations for inclined and horizontal wells. Results are compared to previously published studies for an invasion that is limited to vertical wells.
The model developed considers wells inclination, mud rheology, filtration rate, effective contact area, pore sizes, effective pore reduction, solids particle size and the nature of formation pore throat. This model created to determine the effect of inclination, invasion impact, penetration length, magnitude of the productivity loss that is related to some particular scenarios with high accuracy and stability.
The HGS invasion model is compared to the similar earlier models or studies that are published or commercially available, which is limited to the vertical well system. Five wells at the same observation depth and similar formation characteristics are simulated, with different inclinations of 0°, 30°, 45°, 60°, and 90°. The most significant new finding is that the invasion depth and the damage is increased consistently with the increase of inclination, and the invasion impact is strictly limited to the size of the openings such as pore throat and fractures. This is important because the higher solids invasion rate leads to higher formation damage, PI reduction, completion problems, insoluble solid plugging, and formation testing difficulties. Minimizing solids invasions are important because it always increases the formation damage to the pay-zone. The HGS invasion model is capable to solve solids invasion calculations for entire sections of an inclined well as well as the damage that accompanies in the simplest way possible with better visualization.