bluuebunny/crossref_metadata_2025 huggingface dataset:
Operability in Design - Fast, Flexible and Economical Design Tool for Subsea Gas Compression Design and Verification
Authors: Storvik Marit , Irmann-Jacobsen Tine Bauch , Bakken Asbjørn
Published: June 2014

The introduction of subsea gas compression systems in a network of wells and flowlines has increased the complexity and number of design elements, each with their individual effects on the total production system. As we move into deeper water, longer flowlines, colder environment and marginal field developments, the need for correct design decisions early in the project become even more important. To maximize the economics of a subsea development, it is important to understand how the technology selection impacts performance, risks, costs and ultimately the attractiveness of subsea compression. In the quest to ensure the operability of such a system, it is vital to address the complete production system from wells to topside. All design elements that affect the upstream or downstream conditions should be included to identify their influence on the overall production; temperature, pressure, capacities and sizes of main process elements on the station (e.g. compressor, scrubber, cooler, pump), process control and flow assurance issues such as hydrate formation, flow regimes, wax deposition, corrosion, erosion and vibrations. It is also important to simulate all operational scenarios over the life of the field.

In order to define a model that provides the most realistic system response, it is vital that realistic inlet and outlet conditions of the compression station are used. In practice this often implies using the reservoir conditions and arrival conditions at receiving facility as boundary conditions.

This paper presents an operability design process including an Engineering Simulator tool that has been developed to include the full production system from reservoir to receiving facilities. This provides a powerful means to screen design alternatives to identify the optimal field solution and subsea compression station design in a fast, flexible and cost efficient way. An example case is described, and highlights from the results of using the operability design process and engineering simulation tool are shared.
Challenges of Lowering a Live Subsea Buried Gas Pipeline by 6m
Authors: Thusyanthan N. I. , Williams K.A.J. , Selwood T. , Smith P. , Jegandan S. , Robert D.J.
Published: June 2014

There are hundreds of kilometers of subsea pipelines around the world, forming a network for the extraction and transportation of oil and gas products. When near shore subsea pipelines cross shipping channels to ports, these pipelines can limit the size of the ships that enter the port. This is because the shallow burial depth of the existing pipeline can prevent any additional dredging required to deepen the shipping channel to accommodate larger vessels. An attractive solution under such circumstances is lowering the pipeline section throughout the width of the channel so that the channel can be deepened. The option of shutting the line down or installing a re-routed new line has cost implications. However, the alternative of lowering a pipeline while it is fully operational has engineering risk, operational challenges and the offshore industry is not very experienced in such projects. This paper presents a case study of such a key project where a 16" gas pipeline was successfully lowered from -3 m to -9m below the seabed whilst fully operational. The live gas pipeline was crossing a shipping channel and was buried at 3m below seabed. In order for the port to expand and allow bigger vessels to enter the port, the shipping channel needed to be deepened. Thus the pipeline was required to be lowered a further 6m for a stretch of 350m where the pipeline crosses the shipping channel. The lowering operations had to be carried out whilst the pipeline was fully operational as it was a 70km pipeline with key supply. This paper presents detailed overview into engineering challenges and operational issues faced on the project. The paper discusses all the stages of the project, risk assessments; integrity assessment for pipeline lowering; geotechnical assessment of trench stability; detailed pipeline lowering stress assessment; pre-operational planning; pipeline survey and pipeline lowering operation; post lowering integrity assessment. The pipeline lowering was successfully completed to meet the project requirement after 14 lowering passes. This successful lowering of a live gas pipeline by 6m is considered to be world's first such lowering. Recommendations on how a pipeline lowering project should be approached, assessed and executed are presented in this paper.
Improved Temperature Performance PolyArylEtherKetone Polymers for use in HPHT Conditions
Authors: Chaplin A. , Clemensen Patrick , Duckworth C. , Warmington K.
Published: June 2014

Polyaryletherketone polymers have proven performance with 30 years of experience in Oil and Gas applications due to their excellent creep resistance, wear and chemical resistance under high pressure, high temperature (HPHT) conditions; increasing the reliability of oilfield equipment and extending the life of equipment in the ever more challenging oilfield environment. An example application is back-up rings used to prevent extrusion of the elastomeric seal materials under high differential pressures. Current PolyArylEtherKetones, in reinforced formulations, can typically withstand temperatures in excess of 260°C (500°F) and 20, 000 psi. In more demanding HPHT conditions, there may be a requirement for a polymer with a capability of over 288°C (550°F) and 30, 000 psi.

A new semi-crystalline PolyArylEtherKetone polymer has been developed, with the aim of meeting this requirement, whilst also showing good resistance to aggressive chemicals likely to be encountered, such as sour gas. The polymer has a glass transition temperature of approximately 200°C (390°F) at ambient pressure and a melting point of approximately 400°C (750°F). It is semi-crystalline and has good retention of modulus above Tg. PVT data was used to construct a Tg versus pressure plot, indicating a Tg of 288°C (550°F) at 30, 000 psi. The new polymer was found to have significantly enhanced Creep/Compression performance at 260°C (500°F) compared to an existing PolyEtherEtherKetone (PEEK) formulation. After exposure to sour-gas at high temperatures (1000 hours at 175°C / 350°F, gaseous), retention of mechanical properties was good with 90% tensile strength retention.

In summary, an improved temperature performance PolyArylEtherKetone polymer that retains its performance advantage under HPHT conditions in a chemically aggressive environment, has been developed. This has the capability to further extend the opportunities for use of polymers in increasingly challenging HPHT environments, in applications such as seal back-up rings.
Wet Deck Slamming Analysis of Twin-Hulled Offshore Ship in Irregular Sea Waves
Authors: Lubeena R. , Gupta Vinay Kumar , Agrawal Madhusuden
Published: June 2014

In ship hull design, it is important to predict the seakeeping parameters like ship motions, vertical accelerations, wave impact loads, deck wetness, etc. when the ship is subjected to waves. According to the ABS Guide for Building and Classing High Speed Naval Craft (HSNC 2007) slamming impact load is one of the most critical factors for the scantling design of hull structures[7]. Accurate prediction of wave impact loads requires solution of three problems. First one is the prediction of wave kinematics, second one is the prediction of the pressure and viscous forces and the third one is the prediction of ship motion during the wave impact.

This paper focuses on the wet deck slamming analysis of twin-hulled offshore ship in irregular sea waves and proposes a Computational Fluid Dynamics (CFD) solution using Volume of Fluid (VOF) method and Six Degrees of Freedom Model (6DOF). Irregular waves were modeled using JONSWAP wave spectrum. The wave profile obtained from the numerical simulation was validated with analytical results. The wave impact load and the hull motions depend on many factors, such as sea state, ship speed, draft, wave heading angle, hull structure, ship loading condition etc. In this paper, we have analyzed the wet deck slamming for a survival condition with sea state of significant wave height of 9m with two different ship loadings and two different ship speeds. CFD analyses were also carried out for calm sea conditions with different ship loadings. The heave and pitch motion of the ship in wave conditions are compared with calm sea conditions. The ship motions, vertical accelerations, pitch velocities and the wet deck slamming pressures are compared for the two ship loadings and two ship speeds. This paper describes these results in detail.
Offshore Tandem Loading of LNG – from Idea to System Approval
Authors: Eide Joergen , Haakonsen Rune , Oya Tor Vidar , Frohne Christian
Published: June 2014

The paper describes the background and design approach used to develop and qualify a LNG transfer system to be used for tandem loading between a LNG producer (FLNG) and an LNG carrier (LNGC), specifically in harsh environments. Although tandem loading of crude oil is being performed worldwide every day, such operations are always challenging in harsh environment. Transfer of LNG between two large vessels is even more challenging, as the standard rubber hoses used in Crude Oil transfer operations no longer can be used due to the product's low temperature. The core issues in LNG tandem loading are;The suitability and qualification of the hose/flexible pipeThe marine operations and vessel motions in relation to Dynamic Positioning systemsThe mechanical design of the loading system

The development of the Offshore Cryogenic Transfer system (OCT) has been based on proven technology wherever possible, not only for components but also for procedures. The OCT System can be an enabler for the development of large offshore gas fields or stranded gas using FLNGs in combination with LNGC's, specifically for harsh environment applications. Several LNG transfer system solutions have been put forward over the past decades, either based on specific transfer ideas or individual product proposals. Of these, the OCT System is the only Tandem LNG Transfer System that has been awarded a system approval by DnV according to RP A 203 / EN 1474–3, as far as is known. The system approval depends on the approval of the main sub-systems according to EN 1474–2; the pull-in and connection, the connectors and the transfer hose/pipe itself.

There are significant challenges involved in offshore LNG transfer between floating units. The following five critical technology areas all need to be successfully addressed and solved in the development and qualification of an LNG loading system:Safe operation of two large vessels during the final approach, connect, loading and disconnection phasesThe performance / operating life / safety features of the flexible cryogenic pipes for LNG transferThe design of the flexible pipe manipulating arm / A-frame storage system on the FLNGDesign of the pull-in and connect system in the bow of the LNG carrierQualification of the sub-systems and overall solutions according to EN 1474–2 and EN 1474–3

An LNG transfer system is inherently more complex than crude oil loading due to the requirement of a return gas path. That means that minimum 2, possibly 3 hoses/pipes needs to be connected to the bow of the LNGC instead of the single rubber hose as used in crude oil transfer systems. These subjects are elaborated in more detail in the following sections.
Developing a mechanical earth model using tectonic deformation coefficients in Ceuta VLG-3676 field, Maracaibo basin, Venezuela
Authors: Vásquez Vladimir , Lobo Carlos , Bois Axel-Pierre , Boutin Hugo
Published: June 2014

Reservoir Eocene C/VLG-3676 of Ceuta field, one of the major reservoirs in Maracaibo lake basin, is characterized by operational challenges that prevent its optimal production. Drilling is challenging and requires large mud-weights to reach target. In order to optimize drilling and completion operations, a geomechanical study was launched to develop a Mechanical Earth Model (MEM) and use it to improve well trajectory, mud-weight programs, and perforation strategies. The methodology followed when developing this MEM was:data audit and well selection;tectonics and structural-setting analysis;drilling-event analysis;mechanical-stratigraphy definition;rock-property evaluation;pore-pressure estimation;in-situ stress determination;wellbore-stability evaluation;mud-weight window determination; and

optimal well trajectory computation. The three most interesting features of this paper are:the analysis of more than 200 tests performed in laboratory on Eocene "C" cores that shows a very high degree of damage of the cored material;a new in-situ stress field determination method based on tectonic deformation theory; anda stress regime that changes from normal in the Miocene at shallow depths (200–5000'), to strike-slip and reverse in the Eocene at depths greater than 10,000'. This last result is of great importance for producing reservoirs in this area, as it not only impacts the evaluation of optimum mud-weight windows, but also well trajectories and perforation strategies.
Squall Wind Elevation/Gust Factors and Squall Coherence
Authors: Santala Markku J. , Calverley Mark , Taws Sarah , Grant Hazel , Watson Andrew , Jeans Gus
Published: June 2014

A squall is a strong transient wind event generated by a convective storm. Though squalls are an operational concern over a wide range of latitudes, they are typically only design events in tropical areas. At this time, there are no widely accepted elevation and gust factors for squalls that are appropriate for engineering purposes. No specific guidance is given on squall gusts in the present API or ISO standards. The nature of wind squall events is fundamentally different than that of high latitude non-cyclonic storms and tropical cyclones which are presently the only types of wind events specifically addressed by API and ISO standards. Such factors are needed for squall events so that measurements made in different ways may be converted into homogeneous databases at specified elevations and gust intervals such that they can be analyzed in an unbiased way. Such factors are also needed to convert squall criteria values at a specified elevation or gust interval to a relevant elevation and interval required for the engineering of a specific structure or appurtenance.

The West Africa Gust (WAG) joint industry project JIP was formed to better understand the nature of wind squall extremes offshore West Africa. The WAG JIP has concluded its third and final planned phase. The first phase of WAG focused on developing regional return period extreme value estimates of squall winds. The second and third phases of WAG focused on understanding the temporal and spatial nature of squall gusts in the context of the requirements needed for offshore engineering. Results were based on an offshore multi-anemometer array set up by the third phase of the JIP (WAG3) offshore West Africa.

In this paper, expressions for wind gust elevation profile and gust factors are presented for squall winds over water. Coherence of longitudinal variations in squall winds is compared to the expressions for non-squall winds presently in API and ISO standards. The results presented herein will lead to an improved treatment of squall events for offshore engineering applications.
Remote Hydrocarbon Sampling Skid
Authors: Fowkes Mick , Bryson Kenneth , Ferguson Hugh
Published: June 2014

As the need to exploit offshore oil and gas deposits in increasingly challenging environments increases, the economic development and safe operation of technologies has become more critical.

The requirement to sample and establish the characteristics of produced well fluids has been long established in order to provide:Fluid composition and flow data for each wellReservoir management philosophyFiscal allocation

Traditional methods for sampling and testing of wells employed the use of a dedicated subsea test header, pipeline, or riser connected to test separators and individual single phase flow meters located on a surface production facility. But as production has moved to deeper water, Multi-Phase Flow Meters (MPFM) have been introduced to monitor or meter individual well production, prior to a production manifold combining the production from several wells for onwards transport in a single riser or flowline. Since reservoir and well fluid characteristics alter over their life cycle, it is essential that MPFM be recalibrated to account for this to ensure their continued accuracy.

Subsea 7 has developed and operated an ROV deployed Remote Hydrocarbon Sampling Skid capable of taking separate samples from up to eight individual wells in a single dive. During operation and recovery the temperature and pressure of the samples is maintained to prevent the sample coming out of phase and prevent hydrates forming in the sample or skid pipework. On recovery the sample bottles are removed from the skid and transported ashore for analysis to allow calibration of MPFMs and for fiscal allocations to be determined.
High Pressure Flexibles Pipes – Knowledge and Qualifications at 15 kpsi, 17.5kpsi and 20 kpsi Design Pressure
Authors: Deheeger Antoine , Bernard Gary , Secher Philippe , Estrier Pascal , Félix-Henry Antoine
Published: June 2014

Recently and particularly in the Gulf of Mexico, High Pressure reservoirs discoveries in ultra-deep water and deep formations were made. While the drilling rigs and well intervention vessels were traditionally fitted with 15 kpsi equipments, a growing number of rigs are now being upgraded to operate beyond 15 kpsi.

For more than 30 years now, Technip has been providing under Coflexip® trademark 15 kpsi rated flexible pipes qualified to API 16C and API 7K and is now moving toward 20 kpsi ratings.

At the same time, progress is continuously made in flexible riser technologies to enable service of production, water injection & gas injection in ultra deep water with maximum pressures up to 20 kpsi.

In this paper, Technip track record for 15 kpsi jumpers and production risers will be shown and the challenges to reach higher pressures will be explained. Along with the information provided, the reader will be guided through technological innovation in High Pressure domain. The document will cover flexible pipe armor layers design, end-fittings, dynamic behavior and High Pressure / High Temperature interactions.

Full scale testing performed to qualify 15 kpsi production risers designed to API 17J for operation in Gulf of Mexico will be detailed. To take further the understanding of High Pressure products, a focus will be made on the design and qualification performed on 4? internal diameter 20 kpsi rated well intervention lines already in-service in the Gulf of Mexico.

In the end, technical solutions and associated ongoing qualification testing to achieve 6? ID production risers for 130°C/17.5 kpsi and 150°C / 20 kpsi design temperature and pressure will be presented.
Field Development using Semisubmersible Floating Production System with Steel Catenary Risers in Western Australia Harsh Environment
Authors: Mansour Alaa M. , Bhat Shankar , Pasala Dharma , Kumar Dhiraj
Published: June 2014

Semisubmersible Floating Production System (Semi-FPS) with Steel Catenary Risers (SCRs) is an attractive field development solution worldwide, and especially so in deeper water of Western Australia. However, SCR design is challenging in the offshore Western Australia environment due to severe cyclonic environments and persistent swells.

This paper presents a comparison of three different field development alternatives that use Semi-FPS with SCRs in deepwater Western Australia. These alternative solutions are conventional semisubmersible hull design with Steel Lazy Wave Riser (SLWR), deep draft semisubmersible hull design with conventional SCRs and a novel semisubmersible hull design with conventional SCRs.

The study considers a typical wet tree development for a gas field with a new build Semi-FPS host facility in 4,000 ft (1,220 m) water depth. 10-inch production and 16-inch export SCRs are considered in this study. Feasible riser designs are developed for each alternative solution.

Numerical results are presented to compare the performance of the three hull designs. Project Execution Plan (PEP) and the identified risks and risk mitigations associated with the novel hull design have been addressed in this paper.

Finally, differences in the hull, mooring and SCR total installed cost (TIC) as well as project execution schedule for the three alternative solutions are summarized and presented. The paper concludes with a comparison of the three Semi-FPS hull- riser choices along with a summary of the relative benefits and risks.
Safe Blind Flange Removal in Live and Congested Areas
Authors: Low Mitchel , Cameron John , Farstad Roger , Ferreira André Braz
Published: June 2014

The first campaign of an EPCIC (Engineering, Procurement, Construction, Installation and Commisioning) contract was a diver-less intervention to remove a blind flange under a live operational FPSO (Floating Production Storage, and Offloading vessel) turret located in a harsh North Sea environment. This was achieved by the design and build of a bespoke tool: The BFRT (Blind Flange Removal Tool).

Interfaced directly with the Remotely Operated Vehicle (ROV), the ROV docks the tool onto the flange and then controls its rotation around the flange, cutting the twelve bolts using a saw blade attached to a feeding arm. Completion of the next operation, to install a Bend Stiffener Connector (to be connected to the blind flange, enabling a riser pull-in), was very much dependent on the success and offshore feedback from the first campaign.

The initial concept was based on previous offshore experience and in-house design of rotational cutting tools. This paper will outline some of the technical challenges in creating the tool and how the use of advanced modeling software, practical onshore testing, operator feedback, and previous project experience contribute to the final delivery.
Hybrid Split VFD Poses to Significantly Extend Subsea Processing Tieback Distance
Authors: Voight Richard
Published: June 2014

Oil and gas operators are developing subsea production systems at greater and greater distances from their respective hosts in deepwater basins worldwide. Many of these subsea systems have the potential to include subsea boosting systems (pumping and/or compression) in these installations, which presents the need for significant amounts of AC power to be delivered over these increasing distances. Recent experience and subsequent investigation has shown that the required AC power can be delivered efficiently and cost effectively to these installations via an innovative system approach involving a split of the major components of a typical Variable Frequency Drive (VFD) system, locating the AC/DC conversion equipment at the host facility where power is generated, locating the DC/AC conversion equipment on the seabed, in proximity to the subsea boosting equipment, and connecting the two via a DC transmission cable.

Through utilization of DC power transmission, we expect to eliminate the reactive power issues and line harmonics issues associated with AC transmission. Innovational approaches such as this one will make these installations more practical and cost effective, and open the door to even further capability.
Technological Issues Related to the Identification of Submerged Prehistoric Sites
Authors: Keith Matthew , Evans Amanda M.
Published: June 2014

Late Pleistocene and early Holocene landscapes exposed during the last glaciation have since been inundated by rising sea levels, resulting in their submergence and often subsequent burial by sediment accretion. On the outer continental shelf (OCS) in the northwestern Gulf of Mexico (GOM) the formerly exposed landscape coincides with the presence of Paleoindian and Early Archaic human populations in the region. Unlike submerged prehistoric sites in other parts of the world the emphasis in the northwestern GOM is not on artifacts or even sites, but rather on the identification of the landscapes in which archaeological sites would have been located prior to sea-level rise. The first step in identifying and verifying these features, and any subsequent sites, consists of geophysical remote sensing, especially acoustic profiling, to identify subseafloor horizons and depositional events considered conducive for human habitation. This paper will look at current methods for identifying prehistoric sites on the GOM OCS, challenges faced in identifying prehistoric sites using the most prevalent technologies, and will briefly explore alternate technologies that are available or in development that could improve our current capabilities.
Managed Pressure Drilling Probabilistic Risk Analysis: An Illustration
Authors: Zan Kun , Bickel J. Eric
Published: June 2014

In this paper, we present a quantitative risk analysis tool designed to enable operators to quantify and communicate the potential safety benefits of managed pressure drilling (MPD). Building on the 2008 DOI MMS report "A Probabilistic Approach to Risk Assessment of Managed Pressure Drilling in Offshore Applications" (MMS 08), we construct a probabilistic risk analysis model. This model is based on specifying deviations and their cause-consequence relationships. Particular attention is given to deviations that may be mitigated by managed pressure drilling (MPD) operations.

Specifically, we illustrate the use of influence diagrams (IDs) or Bayesian networks (BNs) to assess the risk benefit of MPD. One important benefit of our work is the presentation of MMS08 using IDs, which are a much easier method of communicating complex probabilistic models. MMS08, while quite detailed, lacked many important assessments that would be required to calculate the probability of a well control incident (WCI), which was define as a kick. We supplement this missing information by making several assumptions. These assumptions limit the applicability of the analysis we present here, but not the underlying models and methods.

In the case we analyze, causes vary widely in terms of how much they contribute to the risk of a WCI. This suggests that using our tool to focus on the most important risk drivers could pay large dividends. In terms of the risk characteristics of MPD, three of our top ten risks could be addressed by MPD. Eliminating all of the risks that could be addressed by MPD reduced the probability of a WCI by 22% in our illustrative example.
Installability of Umbilicals
Authors: Pereira Miguel , Ramar Pandia Raj , Dixon Mark
Published: June 2014

Offshore umbilical systems are essential for transmitting power and signals required to operate subsea facilities. In particular, umbilicals are made of a large number of elements with different engineering materials to accommodate constantly increasing requirements from oil and gas industry for production in deep waters and subsea processing. Often offshore umbilicals are installed using a reel lay or a carousel method and hence they are subject to large bending, axial and crush loadings during the installation process.

In order to guarantee the structural integrity and installability of umbilicals during the installation process, umbilical manufacturers have to carry out a detailed structural analysis of the umbilicals. Such an analysis requires a deeper understanding in the structural mechanics of complicated cross sections subjected to various loadings. This increases the cost and manufacturing time of the umbilicals. This paper will present a simple method to carry out a detailed three dimensional finite element analysis of the umbilicals which will help to define safe installation limits such as the minimum reel/carousel/sheave(s) radiuses, maximum installation tension and tensioner crush operating loads.

A 3 Dimensional Umbilical Simulation Tool, known as 3DUST has originally been developed by DeepSea (Dixon and Zhao, 2008), now a McDermott subsidiary. 3DUST is capable of three dimensional modelling of umbilicals and consists of pre-processing and post-processing features. Using the pre-processing feature, a modelling input deck with different materials, geometries, boundary conditions of any umbilical can be generated. This input deck is compatible with Abaqus finite element analysis software. Once the input deck is analysed, the post-processing feature can generate results with the installation capacity such as bending, axial load, crush load and ovality of the umbilical analysed, which can in turn be used to determine the adequacy of the reel lay or carousel system of the installation vessel.

The paper will demonstrate the use of 3DUST for the installability analysis of an example umbilical with original analysis carried out for providing solution to an installation challenge of the umbilical. The paper will also present the results of the example umbilical obtained from 3DUST.

A particular significance of the paper is not to demonstrate the computational mechanics involved in the analysis of umbilicals, but to address key challenges in the structural mechanics of the umbilicals and to simplify the umbilicals' analysis method by using 3DUST, a knowledge based system with capabilities including suitable finite element meshing of geometries, material assignments, defining boundary conditions and presenting relevant results. It is noted that this method has been applied to many deepwater umbilicals in West Africa, Golf of Mexico and Brazil.
On the Development of an Enhanced Method to Predict Asphaltene Precipitation
Authors: Vargas Francisco M. , Garcia-Bermudes Miguel , Boggara Mohan , Punnapala Sameer , Abutaqiya Mohammed , Mathew Nevin , Prasad Sudha , Khaleel Aisha , Al Rashed Mariam , Al Asafen Hadel
Published: June 2014

Asphaltene precipitation and subsequent deposition is a potential problem in oil production because the significant costs for wellbore cleaning and the associated production loss. To better understand the mechanisms by which asphaltenes precipitate and deposit, in this work we present experimental evidence that supports the idea that precipitation and aggregation of asphaltenes is a multi-step process, where the former is driven primarily by thermodynamics whereas the latter is driven by kinetics. Under this multi-step mechanism, asphaltene precipitation is a fully reversible process. On the other hand, from the precipitated phase, subsequent aggregation and aging leads to the formation of more solid-like structures. Furthermore, we also present experimental results that suggest that the currently available commercial technologies to detect asphaltene precipitation (i.e. NIR spectroscopy and High Pressure Microscopy) might not be appropriate to detect the exact point of asphaltene precipitation, but instead they give a combined reading of precipitation plus aggregation. For this reason, the results obtained using these methods are very sensitive to the depressurization rates. The better understanding of the asphaltene behavior has enabled the development of an enhanced modeling approach based on the Perturbed Chain version of the Statistical Associating Fluid Theory equation of state (PC-SAFT EOS), which is used to predict the precipitation of asphaltenes at reservoir conditions and requires fewer simulation parameters than previous methods. A case study is presented in which our modeling technique was proven useful for the detection and correction of inconsistencies in experiments done using a bottom-hole sample at reservoir conditions.
Modeling the Properties of H2S - CO2 - Salt - Water Extreme Environments
Authors: Springer Ronald D. , Wang Peiming , Anderko Andrzej
Published: June 2014

To address the need to predict the properties of fluids in severe environments in the oil and gas industry, a comprehensive thermodynamic model has been developed for mixtures containing H2S, CO2, H2O, and selected salts. The model is based on the previously developed Mixed-Solvent Electrolyte (MSE) framework, which combines an equation of state for standard-state properties of individual species, an excess Gibbs energy model, and an algorithm for solving phase and chemical equilibria in multiphase systems. The standard-state properties are calculated from the Helgeson-Kirkham-Flowers equation whereas the excess Gibbs energy is expressed as a sum of a long-range electrostatic interaction term expressed by a Pitzer-Debye-Hückel equation, a virial coefficient-type term for interactions between ions and a short-range term for interactions involving neutral molecules. The model has been parameterized using critically evaluated phase equilibrium data for various binary and ternary subsystems of the H2S – CO2 – H2O – Na – Ca – Cl system and has been validated for temperatures ranging from 0°C to 300°C, pressures up to ~3500 atm and salt concentrations up to solid saturation. Furthermore, it reproduces chemical speciation in acid gas – brine systems as exemplified by the accurate prediction of pH. Because of its capability of predicting pH and activities of solution species, the model can serve as a foundation for studying metal – environment interactions in severe oil and gas environments.
International Boundary Disputes: An unfinished tale of Geology, Technology, Money, Law, History, Politics and Diplomacy
Authors: Andersen Niels , Bekker Pieter , Bishopp David , Nassif Toufic , Nordentoft-Lauridsen Sune , van de Poll Robert
Published: June 2014

This paper provides an overview of the history of global maritime boundary issues, mechanisms to resolve boundary disputes, and the economic potential that can be unlocked by coastal States through the exploitation of hydrocarbons trapped in areas currently unavailable for exploration and production operations.

Vast hydrocarbon reserves are tied up in areas, either underlying waters greater than 200 nm offshore or disputed by coastal States. In the former case technology in the form of deepwater drilling has made testing the potential feasible, whilst in the latter case many of the 311 or so areas in dispute are able to be tested and developed using conventional techniques.

Anything that appears to show a sovereign entity ceding control of land or sea to another country inevitably takes on a high profile in the countries concerned, which in the worst case can lead to armed conflict. It is a credit to those States that subscribe to the principles of the United Nations Charter and the United Nations Convention on the Law of the Sea ("UNCLOS") that they have reached agreement on how the economic potential trapped in disputed areas may be divided or shared.

High-profile, high-stakes disputes relating to offshore oil and gas deposits underscore the importance of the modern law of the sea, and international law generally, to the peaceful settlement of boundary disputes affecting the energy industry. Yet boundary disputes form an overlooked area of investment risk management in the energy sector.

This paper will introduce the technical and legal principles behind the solutions reached by States and will highlight some of the areas with the greatest hydrocarbon potential that have yet to be exploited as well as the areas of risk that require mitigation before investors will advance risk capital.
Advances in Power Feedthrough Connector Technology for HP ESP Applications
Authors: Nicholson J.A.
Published: June 2014

Emerging deep-water fields in the Gulf of Mexico pose significant challenges for the deployment and operation of subsea tree ESP systems where reliability is crucial to the economic viability of the fields. Key challenges include high initial reservoir pressures (13, 500psi), 1–2yr natural flow start-up conditions without effecting electrical integrity, 5yr MTBF for the ESP system after start-up of the pump, high horsepower pumps (1200hp), restricted space at the tree interface and the need for integrated power and controls to the pump system as examples. One of the main system components is the power feedthrough connector through the wellhead. This component has to be deployed into the wellhead as part of the Cable Hanger assembly through a marine riser and then subsequently connected to the tree Cap assembly remotely in up to 10,000ft of water depth.

For effective well control the connector systems have to maintain pressure barrier seals for the life of the well in a 15kpsi rated tree. In addition the connector system has to maintain electrical integrity under high voltage conditions and be able to be mated together consistently within the confines of the tree system. Increasing qualification standards by operators pose even greater challenges to the connector vendors as standards are driven higher.

This paper presents the latest connector technology developed by OneSubsea to meet the extreme challenges and needs of HP ESP applications in the GOM.
Ultra-High Strength Proppant Developed for Deep, Offshore Completions
Authors: Palisch Terry , Duenckel Bob , Wilson Brett
Published: June 2014

As the industry has moved to the development of deeper reservoirs, drilling and completion equipment have undergone significant upgrades to allow for the successful exploitation of these higher pressure, higher temperature applications. Similarly, no conventional proppant can provide the required conductivity at the 20, 000 psi closure stresses (and higher) anticipated in the formations such as those found in the Lower Tertiary of the deepwater Gulf of Mexico. With the development of these reservoirs, whether in the GOM or other offshore applications, there now exists a gap in downhole proppant performance and technology.

This paper will document and present the results of years of research prompted by deepwater GOM operators, resulting in a new proppant that has been developed specifically to meet these challenges. The step change advancements achieved by this new proppant will be presented, including technology improvements in both raw materials and manufacturing process. It will present unique proppant properties regarding shape, sizing and strength, never before seen in conventional proppants. The end results is a proppant which exhibits twice the baseline conductivity of any conventional proppant at these high stresses, and provides additional advantages with increased durability and longevity. Extensive laboratory testing has been completed to demonstrate the superior performance in harsh conditions, and will be presented.

The paper will also review the potential applications for this product, which should result in increased production rates, superior EUR, lower erosivity and reduced equipment wear. Field applications are being evaluated and will be discussed.

This paper should be beneficial to all engineers and technologists currently working in the deep, high stress offshore environments of the GOM's Lower Tertiary or comparable applications.
Deepwater Methane Hydrate Gravel Packing Completion Results and Challenges
Authors: Terao Yoshihiro , Duncan Mike , Hay Bill , Dang Le
Published: June 2014

The world's first subsea gravel packing for methane hydrate was conducted and production test successfully executed in the eastern Nankai Trough area off the coast of central Japan in March 2013. Methane hydrate formations all over the world promise huge energy reserves on the earth to permafrost zones in the Polar Regions, and formations within several hundred meters from the seafloor of an ocean. The formation and shallow depths create an assortment of issues that must be addressed to successfully produce this resource. The gas production from methane hydrate formation is different from conventional oil and gas formations in terms of the mechanism and the phenomena, since low temperatures, high pressures environment, and physical properties change in the formation as methane hydrate dissociation. It is important to overcome the above issues for methane hydrate production.

During the planning process, studies were completed to review the formation particle size, the low-temperature effects on tools, circulating temperature issues, the erosional considerations and potential subsidence of the formation. Various experienced processes were used and testing completed to prove the integrity of the system that utilized several nonstandard pieces of equipment and procedures. Vigorous preplanning, experienced personnel and onsite expertise enabled the people and equipment to be prepared for the procedure allowing successful variations. Post-job analysis and review of how the various products and services worked together will enable further success in the future.

This paper discusses the application of vertical open hole gravel packing in a methane hydrate production well from a floating-rig environment in the eastern Nankai Trough area off the coast of central Japan. It reviews the pre-planning process, the equipment selection, procedure recommendations and the on-job decision-making that enabled the successful flow testing.
Restricted-S Riser Configuration for Ultra-Shallow Water Projects
Authors: Dencker Claus
Published: June 2014

The design of dynamic riser systems in connection with floating production units operating in shallow water generally results in rather complex configurations using combinations of buoyancy elements, clump weights, tethers, anchors, and special arrangements of rigid and/or flexible structural members. These often complicated systems can be difficult to install, they may require an extended seabed lay-out area and the operation of these complex systems can be associated with a relatively high risk profile. Thus there is an incentive to develop reliable shallow water systems for harsh environmental conditions which do not have the above draw-backs.

This paper describes the development of a novel dynamic riser system (Restricted-S System) intended for use in extremely harsh ultra-shallow water applications as for example offshore Malaysia and Vietnam with a water depth of 50m or less. The Restricted-S System was developed by NOV Flexibles in connection with a FPSO field project and comprises a well-known mid-water arch (can be either fixed or dynamic) in a restricted position such that it always will be in front of the FPSO vessel bow. This special feature allows the gutter system on the arch to be positioned relatively high in the water column resulting in a significant flexibility of the riser system. In particular, this configuration enables the riser system to survive in harsh environmental conditions with large vessel offsets and large vessel pitch motions.

The detailed design of the Restricted-S System will be described including the development of a special stiffness cover for the dynamic flexible risers resulting in a highly versatile system for ultra-shallow water fields thus enabling the development of challenging prospects with special high wave-height to water-depth ratios. The dynamic analyses of the Restricted-S concept will be compared to model test results thus demonstrating its superior capabilities compared to other configurations. Finally, the leanings from the successful field installation of the Restricted-S System will be addressed.
Advances in Predicting Pipeline Embedment Based on Assessment of Field Data
Authors: Bruton D.A.S.
Published: June 2014

This paper reviews the current methodology for assessing pipeline embedment against field data, where embedment levels were under-predicted leading to an unconservative design. An updated model is provided for predicting pipeline embedment. One important principle behind this new approach is to define the operative soil strength, based on reconsolidation of the remoulded soil beneath the weight of the empty pipe during the intervening period between laying and flooding. This approach is based on pipeline embedment data from the field, which has demonstrated that soil around the pipe can become fully remoulded during installation. Therefore, embedment in the flooded condition should be assessed using an operative strength from reconsolidation, rather than the intact strength, which is current practice. This paper also provides current equations that improve the prediction of embedments over one-half diameter, by proposing methods to take account of the increasing buoyancy with depth, the reducing influence of heave mounds and modified penetration resistance at deeper embedments.

Pipeline embedment is a fundamental input to the assessment of pipe-soil interaction, which is the largest uncertainty faced in the design of pipelines subject to lateral buckling and walking phenomena. However, pipeline embedment is notoriously difficult to predict due to the inherent uncertainty of the installation process. Improving the prediction of pipeline embedment is critical to reducing the range of predicted pipe-soil responses in design.

A current project has compared high quality observations of pipeline embedment from an earlier phase of the same field development, against predicted embedments using more recent, high quality soils data from parallel pipeline routes, including fully remoulded soil strength from cyclic penetrometer testing. While current design approaches were under-predicting embedment levels, leading to a potentially unconservative design; this updated methodology provided a much-improved match to actual embedment data. The revised model was successfully verified against measured levels of pipeline embedment and is now being used for the design of future pipelines in the area, with improved certainty and easing of the design challenge.

Under-predicting pipeline embedment could be critical to design integrity. The methodology presented in this paper has the potential to improve assessments of embedment and avoid unconservative pipe-soil responses on future developments.
Art, Science, and Engineering of Managing Offshore Field Development Economics and Risks
Authors: Chaudhury Gautam , Whooley Alan
Published: June 2014

Decent profit margins enjoyed by the oil industry are mainly due to inexpensive wells of the past. Exploration, development, and production costs have escalated to a level where small to medium size offshore fields are challenged to be economically developed. Each opportunity comes with its own unique constraints requiring adaptive and flexible applications from a variety of processes and systems. The art of field development engineering requires linking interactive and integrated flow of information, best practices, lessons learned, and risk management across all disciplines. This starts with reservoir evaluation and development through surface facilities and transport systems, and production management. Further considerations include finance, procurement and contracting strategy, equipment standardization, and decommissioning. Success of economically challenged field development depends on an experienced team with deep understanding of each respective domain and appreciation in interfacing disciplines. Such a team using a systematic approach challenging each constituent system and process in the field development procedure chain will help identify an optimum development plan.

In this paper, the strategy, technology, and step changes necessary for successful development of economically challenged fields are identified. The inter-dependence between sub-surface, drilling and completion, and surface facilities including production and operations are established in relation to cost, safety, and risk management. This paper will discuss a systems approach for prudent selection of all surface facilities and drilling and completion design taking due account of reservoir uncertainty.

The primary focus of this work is deep water fields of Gulf of Mexico (GOM) with strong analogs for application in other regions of the world including regional socio-political impact. High level discussion on the main drivers of the selection of deep water platforms, subsea architecture, and risers are presented.