bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive Fire Protection PFP Optimization in Offshore Topsides Structure
Authors: Sari Ali , Ramana Ekkirala , Dara Sepehr , Azimov Umid
Published: March 2016

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

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

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

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

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

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

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.
A Novel Approach for Estimating Continuous Matrix Permeability with Open-Hole Capture Spectroscopy Logs and Formation Pressure Tests
Authors: Guo Shusheng , Chen Jianghua , Gao Yongde , Li Ting , Shim Yen Han , Zhang Lei
Published: March 2016

For most conventional reservoirs, matrix permeability determines the rock's ability to transmit fluids. It is a crucial input for the operator's completion design. Unfortunately, direct measurement of permeability is hard to obtain through well logging. Traditionally, a continuous permeability log is estimated from other petrophysical properties derived from well logs, such as porosity. The porosity-to-permeability relationship is typically established from core measurements. The drawback of this method is that porosity alone is insufficient to characterize the full variability in permeability. Also, the application of this method is limited by availability of core measurements representative of the reservoir in question.

In this report, we examine a siliciclastic oil reservoir in South China Sea with interbedded sandstone and shale. In such reservoirs, heterogeneity in permeability exists at a small scale. In order to capture the full variability of such reservoirs, it is critical to obtain a continuous permeability curve of the rock matrix.

It has been shown previously that permeability can be accurately computed from surface area-to-pore volume ratio (k?). This ratio can be obtained from lithology weight fractions by associating a specific surface area (S0) with each lithology. In general, the S0 values for clean sand and carbonate are well defined and stable. However, S0 for clay depends largely on clay type and varies from sample to sample. Since clay has the most significant effect on permeability, it is critical to select the correct k? for clay in the model.

In modern logging programs, formation pressure tests are commonly included for reservoir characterization. By observing pressure behavior versus time in a pretest, one can obtain direct measurement of fluid mobility at discrete stations along the well. This mobility can be converted to permeability if fluid viscosity is known. We can then use these measured values to calibrate clay S0 in our permeability model. Here is the workflow:

Zone the well such that the clay type is consistent within each zone.

Using a univariate optimization routine, find the clay S0 that minimizes the difference between k? and permeability from pressure tests.

Plug the calibrated S0 for clay into k? model to compute a continuous permeability log.

The above method was validated using a set of LWD logs acquired while drilling and LWD pressure tests acquired while reaming.
Drilling Fluid Density Calculation Model at High Temperature High Pressure
Authors: Peng Qi , Fan Honghai , Zhou Haobo , Liu Jinge , Kang Bo , Jiang Wenlong , Gao Yuan , Fu Suiyi
Published: March 2016

Drilling fluid density is very sensitive to the variation of temperature and pressure, especially in deep water and high temperature/high pressure environment. As downhole environment is different from the environment at surface, there must be a difference of density under these two conditions. The accuracy of downhole density calculation is directly related to whether the true downhole hydrostatic pressure could be reflected or not. Drilling fluid could be compressed under high pressure as well as be expanded under high temperature conditions. This paper proposes two important relational equations based on isothermal compressibility and isobaric expansivity. One equation is the relationship between isothermal compressibility and pressure. In this case fluid's volumetric reduction under certain pressure increment could be obtained. The other equation is the relationship between isobaric expansivity and temperature. Similarly, fluid's volumetric increment with the increasing temperature could be gotten by this equation. Therefore the true hydrostatic pressure at downhole could be accurately described by solving these two equations. Experiment data results show that curves of isothermal compressibility with pressure and isobaric expansivity with temperature are both conformed to exponential form. Besides, there is a special set of temperature and pressure for a given drilling fluid. Under this special situation, the compressibility are exactly offset by thermal expansivity, then mud density remain unchanged. Field applications indicates that this density model can describe downhole hydrostatic pressure well at Northwest China and South China Sea. Through adjusting mud density by this model, the headache problem of shallow narrow mud density window formation at South China Sea is well overcome. In addition, the true downhole equivalent static density (ESD) is smaller than fluid density measured at surface in a HP/HT well of Northwest China, whereas the situation is just the opposite in a deepwater well at South China Sea. Undoubtedly, the analysis of downhole hydrostatic pressure is a key process in drilling engineering operations. Too often, failure to accurately monitor wellbore ESD can lead to high risk activities, such as excessive well costs and unscheduled trouble time. Consequently, the HT/HP density model proposed in this paper, which provides an effective way to deal with those problems, is worth applying and promoting.
Comparison between Quasi-Static Analysis and Dynamic Simulation for the Motions and Mooring Tensions of Floating Offshore Platforms
Authors: Lim D. , Kim Y. , Park B.
Published: March 2016

As the development of offshore oil well advances to deep sea, the platform/mooring lines coupled analysis in time-domain is required in estimating the design tension to consider the complex nonlinear effects in the dynamic responses of floating offshore structures. However, in the early design stage where a number of environmental conditions are dealt with, a simpler analysis method adopting the uncoupled and quasi-static analysis is still practical. In this study, the uncoupled, quasi-static analysis in frequency-domain and the coupled analysis in time-domain were compared to establish a basis of design analysis flow from former to latter. A semi-submersible platform was selected as a comparison model, and a reasonable agreement between the two analysis methods were identified.
Cost Saving of Implementing Virtual Flow Metering at Various Fields and Engineering Phases - A Case Study
Authors: Varyan R.
Published: March 2016

Many companies are actively seeking alternative ways to develop a new field and/ or extend the production of mature fields at lower cost during the current downturn in the oil and gas industry. Numbers of advanced technologies are considered to change the conventional way of developing fields such that Capital Expenditure (CAPEX) and Operational Expenditure (OPEX) can be minimized. One area of improvement is flow metering. Having the ability to monitor individual well flow rates continuously allows the operator to optimize the production and maximize the uptime. Traditionally this has been achieved by installing a multiphase flow meter on each well. For some fields, this option is not feasible mainly due to the initial cost.

Combining the simplicities, robustness, and low cost, Virtual Flow Metering Systems (VFMS) address those needs to provide operators an alternative flow metering solution. VFMS have been known as an alternative low cost flow metering solution that is being implemented and the benefits realized in the global oil and gas industry. Notwithstanding the technology has been in operations for more than 20 years in some regions, mainly in subsea production system, the capabilities and dependencies of this technology remains unfamiliar to many, particularly in Asia Pacific region. 

Case studies have been performed to assess the benefit of implementing VFMS at both subsea and surface production systems at different phases of field life. Potential saving on CAPEX is observed to be the highest when the flow metering solution has been considered since the early stage of engineering phase in green field subsea project (numbers of area for optimization is foreseen along with the estimated cost-saving). Implementation of a VFMS in brown field project can be done seamlessly and therefore eliminates the need of piping work and production shutdown.
The Design and Deployment of Open Hole Standalone Screens and Two Cased Hole Gravel Pack in Highly Deviated Well—A Case History with A Field in Malaysia
Authors: Ab Rasid Mohd Fakhrin , Mohd Zain Siti Nur Mahirah , Osuji-Bells Godwin Akujobi , Samuel Orient Balbir , Zabala Jose , Zainal Abidin Mohd Reduan , Noorizan Airin Basha , Gil Joel
Published: March 2016

This paper summarizes the challenges faced during the well completion design, planning and execution stages in the "Well-B" located on the "Field-A" offshore Malaysia. In addition, it highlights the modifications and techniques incorporated in the completion design to ensure that the well was delivered flawlessly in terms of HSE and quality.

At the initial planning stage, the proposal on this well was to complete two oil producer sands with active sand control methods, the upper zone with Cased Hole Gravel Pack (CHGP) and the lower zone with Open Hole Standalone Screens (OHSAS), this concept changed after the analysis of the logging while drilling (LWD) output, when the subsurface team decided to complete an additional zone (midzone) with a stacked Cased Hole Gravel Pack.

The well completion operation effectiveness on this well could have been affected by the following challenges: High deviationMultiple sand control techniques in one wellOperation and logistic challengesAdditional zone expected to be completed with the available inventoryLimited resources and time

The team incorporated several techniques into the original completion design to enable the effective execution of these three zones and achieving the overall well objective.

After the well was successfully completed, it became the first highly deviated well in the field with an open hole standalone screens in the lower zone and two cased hole gravel pack in the upper zones with a dual upper completion string.

This well completion will become the benchmark for planning, designing and deploying future wells with similar characteristics and reservoir conditions.
Ultrabroadband Acoustic Logging Tool for Deep Reading Formation Evaluation
Authors: Sun Baichun , Wang Ruijia , Li Wei , Jonathan Brenda Sue , Langley Bill , Wilson Glenn , Cheng Arthur
Published: March 2016

This paper introduces an ultrabroadband array sonic logging tool and related processing for wireline logging in both open and cased holes. The tool consists of six broadband monopole and dipole transmitters and 104 highly sensitive wideband receivers, enabling deep-reading formation evaluation in axial, radial, and azimuthal directions around the tool.

The transmitter drive pulses from the six broadband monopole and dipole transmitters are dynamically optimized and controlled to cover a large dynamic range in formation slowness. The low-frequency monopole source is designed for measuring Stoneley dispersion curves. A high-frequency monopole source array helps enable extraction of compressional slowness and arrivals that can generate enhanced radial compressional slowness profiles. These deep readings are then used to evaluate the formation in three directions around the sonic logging tool.

The orthogonal dipole sources help enable direct measurement of the shear slowness from the low-frequency flexural asymptotes without the need for dispersion correction. Real-time processing, including quality control of transmitter and receiver sensitivities, delivers high-quality compressional, shear, and Stoneley wave slowness. Subsequent post-acquisition answer products include formation compressional and shear slowness, shear anisotropy, and Stoneley reflections and permeability. Further interpretation of low-frequency compression waves helps enable measurement through high attenuation gas zones and also measure the true formation compressional slowness in very slow formations where leaky compressional modes are prominent. Also, shear slowness measurements through very slow formations allow improved seismic ties from mudline to depth.

This next-generation ultrabroadband array sonic logging tool allows for deeper reading and more comprehensive formation evaluation in cased and open holes. In addition to discussing the process for using the tool in wireline logging, this paper provides examples for logs of both slow and fast formations.
Journey to Success - Advancement of Coiled Tubing Drilling in Malaysia
Authors: Ooi Zhon Wei , Hamzah Nurul Ezalina , Ibrahim Zahidi , Fauzi Nurfaridah Ahmad , Pozdnyshev Maxim
Published: March 2016

Coiled Tubing Drilling (CTD) Technology was first implemented by Petronas Carigali Sdn. Bhd. (PCSB) in 2011 where 3 wells were successfully drilled via a pilot campaign. The rig-less technology allows through-tubing side tracking to be conducted from the existing completion. This approach provides access to marginal bypassed reserves, which otherwise would be uneconomical to be developed by conventional drilling. The entire project comprised plug and abandonment work, whipstock setting, window milling, drilling of the build & lateral sections and completion as per the well design.

The second phase of CTD project was successfully executed from June to December 2013 with all the three wells successfully drilled and completed as per the objectives. Different from pilot project modus operandi, Self-Elevating Workover Platform Vessel (SEWOP) also known as liftboat was utilized to assist the operation due to limited space and deck loading on the working platform. Such approach has minimized the platform modification required as well as significantly reducing the dependency of on good weather window. The self-propelled SEWOP option has proven to be a self-sufficient by providing the required deck space, accommodation and a stable platform in allowing the CTD operation to be carried out safely.

Highlights of the project was the successful drilling and completion of the world's first CTD multilateral well. Such strategy involved the drilling and completion of two separate targets from one mother bore with dual completion strings. In order to achieve the well objectives, the team was challenged with complicated well preparation work scope such as multiple stages of cementing job and accurate determination of the azimuth of the dual kick off points from the existing dual completions in order to avoid drilling collisions during side-tracking.

In addition, team has also managed to replicate the lessons learnt from the pilot project with 100% success rate in dual casing exit from the existing completion setup as well as conveying the completion to the target zone via CT through 3½" tubing with maximum inclination of 90 deg angle and dogleg ranges between 20–40 deg per 100 feet.

The second phase project utilized Reservoir Navigation System (RNS), Managed Pressure Drilling (MPD) and Rotary Steerable Motor (RSM) that optimized payzone drilled, improved drill-ability and smoothened long trajectory thus improving operational efficiency and success rate.

Despite multiple challenges, the project was able to be completed safely and successfully with all objectives met. The achievement was largely attributed to good teamwork, visible leadership, and constant support from management and effective communication between project team and service providers.

This paper discussed about the experiences, learning curves, challenges and lessons learnt of PCSB in making CTD technology viable and successful in offshore Malaysia.
The Zipangu of the Sea Project Overview: Focusing on the R&D for Simultaneous Deployment and Operation of Multiple AUVs
Authors: Kim Kangsoo , Tamura Kenkichi
Published: March 2016

This paper presents the overview of a R&D project "Zipangu of the Sea", focusing on the sub-R&D project supervised by National Maritime Research Institute of Japan. Consisting of 7 sub-projects, main object of the Zipangu of the Sea project is the development of core technologies required for exploring, investigating, monitoring, protecting, and developing benthic mineral resources. The project is a collaborative R&D conducted by national institutes, universities, and private companies in Japan. The NMRI of Japan leads a sub-R&D project of developing the system and strategy for simultaneous deployment and operation of multiple AUVs. In this sub-project, AUVs play a leading role as a cutting-edge undersea probe. Supervised by an USV, multiple AUVs form a fully-autonomous undersea survey unit. In this paper, we introduce a new benthic resource survey system consisting of multiple AUVs and an USV being developed by R&D association led by NMRI. Key technologies as well as hardware elements consisting of our system are also overviewed.
Downhole and Surface Vibration Measurement
Authors: Gao Wenkai , Dou Xiurong , Jia Hengtian , Peng Hao
Published: March 2016

Vibration measurement while drilling is very important. Real-time analysis of the vibration data can be used to evaluate the performance of the downhole tools and to identify the rocks. The paper briefly introduced the work principles, composition and application of the system.

The system is composed of near-bit vibration measurement tool, surface vibration detecting device, wireless transmitting system, signal processing and indicating software system. The downhole measurement system detects and processes the near-bit data, the result is sent to surface in real time, then operators can change drilling parameters in time if harmful downhole conditions are indicated, considering with the surface measurement.

This system has been extensively tested and proved to be effective in identifying the difference of breaking fossil coal and other rocks. Detail of the test and the method will be discussed in the paper. Especially in CBM drilling, the conventional electromagnetic resistivity or gamma measurement while drilling system mounts far away from the bit(more than 7m), however the ROP of CBM drilling is usually high, which lead to time lag and large deviation of trajectory. The use of near-bit and surface vibration measurement while drilling system can identify the seam top or floor as quickly as the bit contact the boundary, to increase drilling efficiency.

With the vibration measurement while drilling tool, the drilling efficiency can be remarkably improved. This paper will highlight the technical development and present helpful case histories and recommendations.
Mitigating Corrosion Under Insulation in a Gas Processing Facility 10 Years On
Authors: Biddle Ben
Published: March 2016

As is often the case when developing new technologies the first adopters are those who have a specific problem for which they are seeking a solution. This was the case in 2005 with a new, at the time, high temperature protective coating designed for use beneath insulation and in highly aggressive cyclic temperature environments between 40°C (104°F) to 260°C (500°F). The facility in question is a gas processing plan in South Australia and they had significant issues with corrosion on their propane treater units. This paper will review the circumstances of the application in 2005, detailing the corrosion mechanisms at work and the justification behind the selection of the then largely unproven new coating technology. It will then review the performance of the material over the course of its ten year service life concluding with a detailed review of its current condition. The paper then moves to the wider topic of coating development and specification with particular reference to developing test methods where robust methods are not yet known. The paper details the methodology used to create and validate a reliable test for coatings used in the prevention of CUI. With reference to the South Australian experience, the paper poses the question ‘how can new coating technologies be successfully developed and launched into a such a conservative market?', especially given the importance placed by customers around long term proof of in service performance.
Riser Support Structure for Support of Flexible Risers and Umbilicals
Authors: Rayappa J. W. , Christensen L.
Published: March 2016

Mid-water arches are often used for supporting flexible risers and umbilical's from floating structures onto seabed. If the structure needs to support a number of flexible risers and umbilicals located at a site which is prone to soil liquefaction during seismic conditions, then the selection of an appropriate foundation system and designing the super structure to suit the ground condition becomes a challenge and it is the behaviour of the foundation system that dictates the design of the structure.

The Ichthys Field located about 220 kilometres offshore from the NW coast of Western Australia in average water depths of 250 m is such a site. The Ichthys LNG Project Field development includes a large subsea Riser Support Structure (RSS) supporting up to 25 flexible risers and umbilicals in a "Fixed-S" configuration as they transition from the seabed to the semi-submersible Central Processing Facility. The RSS consists of two key components, namely a 130 m long arch structure and a steel tower with a suction foundation base. The total height above seabed of the RSS is 110 m with a total weight of 7300MT in air. The RSS has been conceptualized to suit the design, fabrication, installation and inplace operations. The RSS was installed using the conventional method of launching at site, self-upending and crane assisted lowering onto the seabed with a controlled flooding of tower legs and Auxiliary Buoyancy Tanks (ABT). The tower is anchored permanently to the seafloor by suction cans.

The objective of this paper is to present the key aspects of the concept and detailed design development of the RSS, including the innovative approach to the environmental and seismic conditions to avoid problems with due consideration of fabrication, transport and installation. The scope of this paper is limited to the RSS structure and will not cover the detail geotechnical foundations design aspects which are the subject of another paper.
Complex Subsea to Subsea Pigging Operations of Pipelines
Authors: Nesje P.
Published: March 2016

Objectives/Scope

Operators of subsea pipelines sometimes find advantages in performing subsea to subsea pigging operations. This type of pigging may be necessary in order to facilitate a specific field layout or concept. However, operational pigging and inspection pigging from subsea pig launchers to subsea pig receivers can create several design and operational challenges. These are identified and addressed in this paper.

Methods, Procedures, Process

Two main types of pigging operations are identified.

The main challenges are:

Results, Observations, Conclusions

The methods and the solutions that we have chosen to use in recent projects are described. The background information leading up to the decisions and choices taken will be discussed.

Special focus will be given to the importance of planning for any subsea operational and/or inspection pigging up front in the field layout and design phases, i.e. at the same time as the commissioning pigging is defined.

The need for a reliable and safe pig tracking management system will be addressed and our observations with respect to this issue will be included.

The specific advantages for the Subsea Automated Pig Launcher will be highlighted, a short list of these are:

Novel/Additive Information

This paper will present practical and sound solutions of how to perform subsea to subsea operational and inspection pigging in a cost effective and safe manner.

It will also highlight and explain the importance of planning for any subsea operational and/or inspection pigging up front in the field layout and design phase. This is often not a high focus element and this can result in very costly modifications later in the field life.
Systematic Qualification Test Procedure to Evaluate New CRA Material, 17-Chrome
Authors: Ong G. , Hassan H. S. , Ishak M. Faizatulizuddin , Ishiguro Y.
Published: March 2016

A new Oil Country Tubular Goods (OCTG) Corrosion Resistant Material (CRA) 17-Chrome (17CR) was introduced in late 2011. The corrosion resistance performance of such material was claimed to be comparable to a higher grade material of duplex stainless steel 22-Chrome (22CR) under a given aggressive corrosion environment. In addition to that, 17CR was expected to be significantly competitive and commands shorter delivery lead time compared to 22CR as it does not require cold-drawing process to achieve the required high yield strength. PCSB had evaluated this new material for one of its massive LNG development projects through a series of qualification testing. These LNG carbonate fields were highly corrosive with CO2 and H2S content up to 22 mol% and 140ppm respectively. Maximum bottom hole temperature anticipated was more than 180 degrees Celsius. Material selection for production tubing was therefore of paramount importance in such severe well condition to ensure that long term well integrity was not compromised with this newly developed material. Through the establishment of a multidisciplinary team, PCSB had established a set of rigorous qualification test procedure, fully aligned with industry standards to ensure that the identified risks were mitigated from both material and connection perspectives. This paper will describe the systematic approach that was used to evaluate the reliability of the new material with a premium connection under the defined worst case conditions; discuss the corresponding results which led to significant cost savings for the mentioned project.
Oilfield Microbiology: Detection Techniques Used in Monitoring Problematic Microorganisms Such as Sulphate-Reducing Bacteria SRB
Authors: Bennet Douglas G.
Published: March 2016

Microbiologically Influenced Corrosion (MIC) is a well-documented phenomenon that involves microorganisms and affects multiple industries with untold economic impact. The most well- known microorganisms within the oilfield, by far, are Sulphate-Reducing Bacteria (SRB). It is thought that through SRB respiration, corrosion of metals can occur. An exact figure for MIC responsibility in overall corrosion is currently unknown. However estimates of between 10-50% are not uncommon, when coupled with estimated costs of metal corrosion in developed countries to be between 2-3% of Gross Domestic Product (GDP), suddenly the cost implications of MIC gain significance. The technical and economic implications have gained recognition within the oil and gas industry within the last thirty to forty years and monitoring techniques to detect microorganisms and corrosion have progressed and developed through increased interest in microorganisms commonly found within the oilfield. As with human nature, the ability to predict the future, rather than deal with the consequence is a preferred approach, which is one of the main driver's to pro-active monitoring techniques for detection of microorganisms to help determine the risk of MIC to occur, rather than a reliance on rate of corrosion alone. This approach has led to increased research in to the subject of oilfield microbiology and development of modern molecular techniques, often borrowed from other industries such as medical microbiology, that have come to the fore recently. However a significant focus on cost saving practices within the oil and gas industry has a significant and direct impact on the type and frequency of monitoring applied (if any).

The objective of this review is to discuss and evaluate the available techniques and review the most common problems associated with microorganisms within the oil and gas industry. To determine effective monitoring practices in a practicable and economically viable manner to ensure monitoring can be carried out effectively, understood and evaluated while implementing control and mitigation strategies with confidence.
Sensitivity Study of Slug Induced Fatigue in Flow Line Spools
Authors: Ancian L. , Salanon R. , Agar M.
Published: March 2016

The fatigue generated by slugs in pipelines depends on the pipe structure, slug density, velocity and length. This research project sponsored by five operators and engineering companies assesses the influence of the main parameters mentioned above on pipeline vibration levels and predicts associated fatigue.

A 3D Finite Element Model of an existing pipe system is used to simulate the force generated by the passage of slugs. Gravity variations and impact forces at elbows are adjusted based on specific formulas and experimental results for a range of slug sizes and velocities. Resonance sources and effects are analyzed.

Fatigue damage is then computed using time-domain Finite Element software and a rainflow-counting algorithm. Finally, a detailed sensitivity study is performed to quantify the influence of cell length and velocity.

Results show that above a minimal slug length, a static equilibrium is reached. For slugs longer than this minimal length, the piping oscillates around a new equilibrium point until the liquid fills the pipe. For any given spool, the maximum fatigue generated by a slug is encountered at a slug velocity and length specific to the spool. The most significant new finding shows that this maximum fatigue non-linearly varies with the slug velocity, length and the pipe structure (elbow location, length of unsupported pipe, 3D routing). This is mainly due to the fact that the force generated by the liquid after the slug passage is in phase with an existing pipe oscillation generated at the entrance of the slug. This is important as until now, slug fatigue computation was based on average slug parameters, now recognized as not conservative.

The novelty of this new computation method is its ability to accurately predict the fatigue levels in a subsea spool. It also shows that the existing method taking into account mean slugs does not necessarily generate the worst-case scenario and that all the slugs expected to exist throughout the lifetime of the pipe system have to be considered.
Model Test for Crane Installation of Subsea Equipment in Deep Water
Authors: Nam B. W. , Kim N. W. , Hong S. Y. , Choi Y. M. , Kim J. W.
Published: March 2016

In this study, crane installation operations of subsea equipment in deep water are experimentally investigated. A series of model tests for the deepwater lifting operation were performed at Ocean Engineering Basin of KRISO. For the model test, an installation vessel with dynamic positioning system, and a crane system were introduced. Among various subsea equipment, a suction pile was examined. The objective of the model test is to observe the motion responses of the lifted object and the dynamic tension of the hoisting wire during deepwater lifting operation. Under various irregular wave conditions, the horizontal and vertical motion responses of the lifted object were examined. The dynamic tension of the hoisting wire were also evaluated under the different wave period and water depth conditions. Discussion is made on the effect of passive heave compeasator on the motion and tension responses.
Developing a Multiphase Reference Network to Support Well Optimisation & Flow Assurance
Authors: MacDonald Marc , Leonard Terri
Published: March 2016

The use of Multiphase flowmeters in the oil and gas industry has increased significantly in recent years. The technology is now widely utilised subsea for well optimisation and reservoir management with the drive in development toward use for fiscal allocation.

Currently, the lack of an established reference network, guidelines and standards – whereby the metering technology can be reliably evaluated and/or verified for their applications – is inhibiting further development. In addition, the intrinsic complexities associated with multiphase and multi-component mixtures result in a wide variation in flow patterns developing, including challenging slugging conditions which must be detected in order to avoid flow assurance issues and catastrophic damage to processing equipment. The impact of challenging flow regimes on metering performance must also be accounted for through further research and development.

This paper reviews the current theoretical methods for the determination of flow patterns as a function of field variables such as pressure, temperature, component fluid properties and velocities. Established flow pattern maps presented in the literature and commonly used in industry are evaluated using experimental data from NEL's multiphase flow facility.

The development of flow pattern maps and flow visualisation techniques is a key part in the development of a much needed reference network for multiphase flow metrology. This work is part of a wider €3M project with support from the EU, National Measurement Institutes, Universities, Operators, Multiphase Flow Laboratories, Vendors and Regulators.
The Importance of Early Water Detection and Water Salinity Measurement in Multiphase Production Systems and a New Measurement Technology That Addresses This Challenge
Authors: Hanssen Birger Velle , Lupeau Alexandre , Solheim Harald , Leong Yit Seng
Published: March 2016

Early water detection and on-line measurement of water salinity is important for many applications in multiphase and wet gas flow metering. Applications range from detecting formation water breakthrough for reservoir management and flow assurance purposes to updating water property input for multiphase flow meters. This paper addresses the value of early water detection and having knowledge of water salinity in an oil and gas production systems. It also presents a measurement solution to this challenge.

The development of an open-ended coaxial reflection probe for estimating water salinity in three-phase flow is described. The shallow sensitivity depth of the reflection probe, based on microwave technology, means that it is sensitive to the bulk electrical properties of the fluids in its close vicinity. The reflection probe works well for both the multiphase and wet gas flow conditions when placed in a liquid-rich location of the production flow line. This provides good salinity-estimate accuracy for the full range, from low to very high GVF. While a microwave transmission system will fail to measure salinity for many oil-continuous flows, the intermittent presence of water in the close vicinity of the reflection probe flush at the pipe wall helps achieve an accurate salinity estimate even at very low water fractions.

The extensive testing of this measurement probe will be presented and discussed.

The novelty of the new sensor technology is that it works over the full range of water-liquid ratios, independent of whether the liquid is in an oil continuous, transition, or water continuous phase.