Floating Production Storage And Offloading Research Articles

Effects of structural congestion and surrounding obstacles on the overpressure loads in explosions: experiment and CFD simulations

ABSTRACTAn experimental and numerical study was undertaken to identify the characteristics of overpressure loads in offshore platform models subject to hydrocarbon explosions, with a focus on the structural congestion and surrounding obstacles. A large-scale (one-half) test model of a FLNG (liquefied natural gas floating production storage and offloading unit) topside structure was used for the experiment. Computational fluid dynamics (CFD) were used to calculate the overpressure loads in explosions with varying degrees of structural congestion. The overpressure loads tended to be more significant with the increase in structural congestion because the ventilation of exploded gas was retarded due to the obstacles presented by congested structural elements. Also, the overpressure loads with the surrounding structures are much larger than those without them. Details about the test database are documented to provide a useful reference for other researchers to validate numerical and theoretical methods.

Artificial Potential-Based Adaptive ${{H}_{\infty }}$ Synchronized Tracking Control for Accommodation Vessel

Combining with artificial potential field and robust $H_\infty$ methods, the neural network (NN)-based adaptive synchronized tracking control is proposed for accommodation vessel (AV). The control task is to drive AV synchronous tracking floating production storage and offloading (FPSO). For finishing the task, NN is employed to approximate the unknown nonlinear dynamics of AV; $H_\infty$ method is to guarantee the system states of AV robust to exogenous disturbances; artificial potential method aims to produce the attractive and repulsive forces to assist AV maintaining desired distance with FPSO so that the gangway connecting both AV and FPSO is operated smoothly. Finally, it is proven that the proposed control scheme can guarantee that all error signals of the tracking control are Semi-Globally Uniformly Ultimately Bounded (SGUUB) and AV can synchronously track FPSO to desired accuracy. The simulation results further demonstrate the effectiveness of the proposed method.

“Vaguely Right or Precisely Wrong?”: Making Probabilistic Cost, Time, and Performance Estimates for Bluefield Appraisal

Summary We conducted a practical case study that aims at estimating the shapes and parameters of probability distributions for key cost, time, and activity performance inputs required by a risk, resource, and value simulator to conduct a stochastic valuation of a new exploration asset. We analyzed a sample of 73 shallow offshore fields in Australia retrieved from a global field-by-field database that includes reserves, production profiles, financials, valuation, breakeven prices, ownership, and other key metrics for global oil and gas fields, discoveries, and exploration licenses. The reviewed facilities concepts include 40 steel platforms, 2 concrete gravity-based developments, 10 projects with extended-reach drilling, 4 floating production, storage, and offloading (FPSO) vessels, and 17 subsea tiebacks. The aggregate capital expenditure (Capex) of projects in the sample during 1965–2015 is USD 99.1 billion (in nominal terms), which is commensurate with the total asset size of the Australian offshore petroleum industry. We estimate probability distributions for all full-cycle parameters required to generate Monte Carlo Capex, operating expenditure (Opex), and production profiles. In particular, these include facility Capex per unit peak, development-phase duration and scheduling rules, drilling expenditures per barrel of oil equivalent (BOE), cost of exploration and appraisal wells, Opex/Capex ratio, abandonment cost ratio, fraction of hydrocarbons produced yearly at plateau, fraction of hydrocarbons remaining at end of plateau, terminal production rate, and fraction predrilled wells. Most of the aforementioned were found to be log-normally distributed. The paper illustrates a practical application of a simple, yet robust, work flow relying on real industry data to assess the value, risks, and uncertainties of an exploration prospect. It can be seamlessly extended to other basins because of a rich coverage of the online field-analogs database.

Sustainable Building Blocks for Cost-Effective Deepwater-Field Development

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 181707, “Truly Sustainable Building Blocks for Deepwater-Field Development: Need for Strategy Redefinition in a Persistently Low-Oil-Price Scenario?,” by Francesco Beltrami, Energo Engineering, and Kevin Hansen, Granherne, prepared for the 2016 SPE Annual Technical Conference and Exhibition, Dubai, 26–28 September. The paper has not been peer reviewed. To survive the current economic scenario, the deepwater industry needs to rethink the way projects are carried out. This paper reviews clusters of information that will be termed “building blocks” for deepwater-field-development planning, discussing how they are currently used and exploring more-affordable, but technically robust, alternatives. Building Blocks Advantages of Building Blocks. The use of conceptual “building blocks” during concept definition and concept selection is not new; they have been used in field-development planning for more than 3 decades. The field-development building blocks are a very versatile and powerful tool and are relatively simple to define and to use. They may be tailored to the case under investigation, providing a higher-level view or more-detailed insight, and can enable rapid generation of several development options. They also offer the possibility of producing simplified sketches representing field-development options (Fig. 1). The key components of a future offshore field development are represented by predefined, project-specific building blocks that are combined in a methodical way (often automated) to generate multiple development options to be further ranked and screened. A typical building block is the type of host required in an offshore-field development. Multiple alternatives are possible, such as the floating production, storage, and offloading (FPSO) vessel; the semisubmersible; the spar; the tension-leg platform; and other fixed or floating platforms. Even a limited number of initial building blocks can generate a remarkable number of field-development options. To manage the potential complexity of the building-block approach, the quantity and type of building blocks to be used are generally defined in an early stage of the project. Specific building blocks may be added to ensure that project challenges are addressed properly. Building blocks may be purely qualitative or may provide some quantitative information. In some cases, there might be multiple combinations of technical and nontechnical features for a single building block. In some geographical areas, the FPSO would necessarily have to be disconnectable; this requirement would affect the definition of the building blocks to be used.

Vortex Induced Vibration of Subsea Umbilicals: A Case Study of Deep Offshore Nigeria

This study involved using typical Joint North Sea Wave Project (JONSWAP) based Umbilical design of lengths 3044m, 3215m, 4481m and 2873m clamped to Floating Production Storage and Offloading (FPSO) unit in Deep Offshore Nigeria at water depth of 2000m. Relevant metOcean data was used to simulate the environmental conditions. The process was simulated using different wave spectra on OrcaFlex software. JONSWAP spectra results for Umbilical-1 to Umbilical-4 at near-surface current (End A: 850m) showed a Transverse Vortex Force (TVF) range of 0.0115 – 0.018kN/m; 0.009 – 0.0149kN/m; 0.006-0.014kN/m; 0.0048 -0.009kN/m, respectively. For Ochi-Hubble spectra, the corresponding TVF range obtained include: 0.004 - 0.0305kN/m; 0.004 - 0.028kN/m; 0.003 - 0.027kN/m; 0.003 - 0.0232kN/m, respectively. JONSWAP spectra showed maxima (t, TVF) values of (0.013, 0.018); (0.012, 0.0149); (0.008, 0.014); (0.0074, 0.009) from Umbilical-1 to Umbilical-4, respectively. With the Ochi-Hubble spectra, maxima (t, TVF) values were (0.018, 0.0305); (0.016, 0.028); (0.013, 0.027); (0.0141, 0.0232) for Umbilical-1 to Umbilical-4, respectively. Hence, maxima (t, TVF) values were greater for Ochi-Hubble than JONSWAP. Simulation plots indicate that adjusting the peakedness parameter (γ) of the JONSWAP spectra does not give the required accuracy for this region. Therefore, using a JONSWAP based Umbilical design in Ochi-Hubble environment like Offshore Nigeria shows higher vortex induced vibration (VIV) at near surfaces leading to higher TVF, and higher fatigue damage tendency.

Sloshing in a Horizontal Cylindrical Tank Subjected to Pitching Excitation and Damping Effects by Perforated Plates

Natural gas is relatively clean, and its demand is currently increasing. In most cases, gas fields are located at the bottom of the sea. Therefore, floating production, storage, and offloading (FPSO) systems are now attracting considerable attention. This paper is related to the dynamical design of a FPSO system; in particular, it focuses on the free surface elevation induced by the waves in a horizontal cylindrical and axisymmetric liquid vessel with end caps. In this study, the theory of the wave height and resonant frequency in a horizontal cylinder subjected to pitching via external excitation is developed. Then, a theory taking into account the effect of perforated plates is introduced. A special discussion is made with regard to the number and location of the perforated plates and the effect of a partial opening in a perforated plate on the damping. Finally, the experimental data of resonant wave heights up to the third mode are shown in comparison to the theoretically derived results.

A comparative assessment of approximate methods to simulate second order roll motion of FPSOs

Ship shaped FPSO (Floating Production, Storage and Offloading) units are the most commonly used floating production units to extract hydrocarbons from reservoirs under the seabed. These structures are usually much larger than general cargo ships and have their natural frequency outside the wave frequency range. This results in the response to first order wave forces acting on the hull to be negligible. However, second order difference frequency forces start to significantly impact the motions of the structure. When the difference frequency between wave components matches the roll natural frequency, the structure experiences a significant roll motion which is also termed as second order roll. This paper describes the theory and numerical implementation behind the calculation of second order forces and motions of any general floating structure subjected to waves. The numerical implementation is validated in zero speed case against the commercial code OrcaFlex. The paper also describes in detail the popular approximations used to simplify the computation of second order forces and provides a discussion on the limitations of each approximation.

Structural Response of Blast Wall to Gas Explosion on Semi-Confined Offshore Plant Topside

Since gas explosion is the most frequent accidental event occurring in the oil and gas industry, all safety-related critical elements on the topside of offshore platforms should retain their integrity against extreme pressure demands. Although considerable effort has been devoted to develop blast-resistant design methods for offshore structures, there remain several issues that require further investigation. The duration of the triangular-shaped blast design pressure curve with a completely positive side is usually determined by the absolute area of each measured transient pressure response, using the flame acceleration simulator (FLACS). The negative phase pressure in a general gas explosion, however, is often quite crucial, unlike gaseous detonation or TNT explosion. The objective of this study is to thoroughly examine the effect of the negative phase pressure on structural behavior. A blast wall for a specific floating production, storage, and offloading (FPSO) topside is considered as an exemplar structure for blast-resistant design to focus only on overpressure because there is no drag pressure in this type of obstacle. Gas dispersion and explosion simulations were carried out using FLACS, while LS-DYNA was used in the nonlinear transient finite element structural analysis.

Practical example of data integration in a PRM environment, BC-10, Brazil

Deepwater developments always represent a huge capital investment, and this is especially true when the field in question is instrumented with Permanent Reservoir Monitoring (PRM). These massive financial outlays demand optimum efficiency to maximize the return on investment. This means taking full advantage of the value in the large volumes of time-lapse seismic data collected. In this paper, we examine enhanced workflows and solutions for optimizing the utility of Permanent Reservoir Monitoring data in a deepwater setting. We do this by fully integrating these data into our subsurface models and decision making in a rapid, thorough, and quantitative fashion. Parque das Conchas (BC-10) represents a major milestone in the development and commercialization of Brazil’s deep water. The project consists of several distinct small-to-medium-sized fields in the Campos Basin that allow for phasing. The fields have been developed using subsea wells and manifolds, all of which are connected to a centrally located floating production, storage and offloading (FPSO) vessel, the Espirito Santo (Figure 1). The Espirito Santo FPSO, which has a processing capacity of 100,000 barrels of oil equivalent per day (BOE/d), was built by SBM in Singapore and delivered to Brazil in late 2008 being moored in around 1800 m of water. The double-hulled FPSO’s design required significant power and heat delivery systems to drive the seabed lift equipment and process the heavy crudes. This development is the first of its kind based on full subsea oil and gas separation and subsea pumping. This system uses 1500-horsepower underwater pumps – each equivalent to a Formula One engine – to drive oil and a small quantity of gas to the surface.

Innovative inspection techniques for ultra deepwater drillships and other floating O&G production assets saving costs, enhancing safety, while assuring operational availability and asset integrity

The Hull Inspection Techniques and Strategy (HITS) Joint Industry Project (JIP), a subgroup of the Floating Production Storage and Offloading (FPSO) Research Forum, called for new methods to be developed that enhance safety, reduce costs and support the assurance of integrated asset management. Hull integrity is critical to enhancing safety and operational effectiveness for production operations, particularly for high-value assets. Good hull integrity requires accurate, relevant hull-inspection data of the internal structure, isolation valves, moonpools, external appendages and positioning systems. Current methods use divers or remotely operated vehicles (ROVs); this often disrupts drilling operations and, in the case of divers, is a high but managed risk. HITS JIP called for methods to minimise diver and man intervention in confined spaces. This has now been achieved on several assets while on station, operational and on-hire by an innovative method of conducting inspections from within the hull and using advanced techniques to inspect critical isolation valves, moonpool high-stress areas, thrusters and hull appendages. Aligning internal and external structural inspections optimises operational availability further and is achieved by means of class-approved ‘long-term inspection plans’ that align the ‘underwater’ scope with other hull inspections and spreads the work over several 5-year cycles. As well as safety enhancements, benefits include over 70% persons on board (POB) reduction on diver under water inspection in lieu of drydocking (UWILD) operations, minimising downtime and operational impact, and high-value inspection data. Further advances in hull inspection have also been proven that eliminate man entry of confined spaces for inspection of ballast and other tanks.

Coordinated weathervaning control of two surface vessels in a tandem configuration

During a tandem offloading operation between a floating production storage and offloading (FPSO) unit and a connected shuttle tanker (ST), the control of the relative position and heading between two vessels is crucially important, since large relative motion may cause serious accidents such as collision or hose disconnection. Dynamic positioning (DP) systems can be used to control the motion of the vessels during the operation. Among various DP control strategies, weathervaning control enables each vessel to be oriented toward the direction of the mean environmental force induced by wind, wave and ocean current so as to improve the operational safety and reduce the overall thruster power consumption. This study proposes a controller design for DP in the task space of the vehicle dynamics that allows for weathervaning control without explicit measurements or accurate estimation of environmental disturbances. A coordinated control scheme assuming a reliable communication channel between two vessels is also introduced to ensure the safety of the vessels and continuous oil transfer by suppressing excessive relative heading changes under significant environmental disturbances. Numerical simulation results for several DP control scenarios under different control settings and environmental conditions are presented.

SLAYING THE DRAGON—THE STORY OF ONE FPSO, 20 VIETNAMESE OPERATORS AND 3 CONCRETE MIXERS

End of life of a floating production, storage and offloading (FPSO) facility requires a lot of planning and management. One of the major challenges is the issue of decontamination and waste management. Waste disposal is a very sensitive subject and with agreements like the London Protocol and differences in legislation between countries, it has the potential to become a major stumbling block. Radiation safety is something not often on the mind of an FPSO operator. The planning and layout of such a vessel and its processing plant have usually not gone through any as low as reasonably achievable process during design. Planning the decontamination of such a vessel should start long before the actual decommissioning date. Performing regular vessel cleanouts and radiological profiling of the plant can be beneficial in the end. Finding a workable solution in getting naturally occurring radioactive material contaminated waste out of the vessels and tanks and effectively reducing the waste volumes for end of life clean-up is very important.

Physical modelling of wave scattering around fixed FPSO-shaped bodies

FPSO (Floating Production Storage and Off-loading) vessels used for offshore oil and gas production are operated in deep water, often at locations which experience severe wave loading. This paper reports on laboratory experiments on a series of simplified FPSO-shaped bodies, with the aim of understanding more about the wave-structure interaction, particularly the generation of scattered waves. These tests were carried out in the Ocean Basin at Plymouth University’s COAST Laboratory where the effects on the wave-structure interaction of model length, wave steepness and incident wave direction were investigated. All three models had semi-circular ends, separated by a box section for the 2 longer models. Input waves were based on focused wave groups generated using NewWave with an underlying JONSWAP spectrum. A general phase-based harmonic separation method was applied to separate the linear and higher-harmonic wave components of the free-surface elevation surrounding the bodies, and of relevance to the assessment of wave loads. Close to the bow of the model, the highest amplitude scattered waves are observed with the most compact model, and the third- and fourth-harmonics are significantly larger than the equivalent incident bound harmonic components. At the locations close to the stern, the linear harmonic is found to increase as the model length is decreased, although the nonlinear harmonics are similar for all three tested lengths, and the second- and third-harmonics are strongest with the medium length model. The nonlinear scattered waves increase with increasing wave steepness and a second pulse is evident in the higher-order scattered wave fields. As the incident wave angle between the waves and the long axis of the vessel is increased from 0° (head-on) to 20°, the third- and fourth-harmonic scattered waves reduce on the upstream side. These third- and fourth-harmonic diffracted waves should be considered in assessing wave run-up for offshore structure design, and may be relevant to the excitation of ringing-type structural responses in fixed and taut moored structures.

Experimental study on the hydrodynamic behaviour of an FPSO in a deepwater region of the Gulf of Mexico

As offshore oil and gas exploration moves progressively toward greater water depths, it becomes more challenging to predict the environmental forces and global responses of floating production storage and offloading (FPSO) systems and the dynamic behaviour of the mooring lines and risers. The validation of complex numerical models through scale model experimental testing is restricted by the physical limits of the test facilities. It is not feasible to install the equivalent full length mooring lines and riser systems and select an appropriate scale model for reducing the uncertainties in the experimental test programme for deepwater and ultra-deepwater conditions. The combination of an appropriate scale FPSO model with a suitable level of equivalent effect reduced depth using a hybrid passive truncated experimental methodology for the mooring lines and risers is a practical approach.Following recent discoveries, FPSO has been proposed for a portion of the planned development in the southern Gulf of Mexico (GOM) in water depth ranging from 1000 to 2000m. Based on a scale model and a hybrid passive truncated experimental method for mooring lines and risers, this paper investigates the global response of an FPSO, as well as the dynamics of mooring lines and risers in the context of prevailing environmental conditions for field development in a specific deepwater location in GOM. The experiments revealed that the main horizontal motion response of the FPSO (surge) under non-collinear loading condition is almost two-times that of the collinear loading condition. The mooring lines in the non-collinear condition are more sensitive to the dynamic response and risers appear to have an important influence on the low frequency damping.

Sapinhoÿ Field, Santos Basin Presalt: From Design to Execution and Results

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 26320, “SapinhoÁ Field, Santos Basin Presalt: From Conceptual Design to Project Execution and Results,” by J. Turazzi Naveiro, SPE, and D. Haimson, Petrobras, prepared for the 2015 Offshore Technology Conference Brasil, Rio de Janeiro, 27–29 October. The paper has not been peer reviewed. This paper presents the development of SapinhoÁ field, covering the fast-track transition and decision-making process, from appraisal to conceptual and basic engineering of the SapinhoÁ pilot project and on to its subsequent execution, highlighting the challenges, lessons learned, and results. Even though, at the time, several uncertainties about developing presalt areas were present, a fast-track strategy was chosen. A pilot project was seen as a means to provide valuable information for the remaining development of SapinhoÁ and other fields in the presalt cluster. Introduction The SapinhoÁ field is in Block BM-S-9 at the central portion of the Santos Basin (Fig. 1). The water depth is approximately 2140 m, and reservoir depth lies between 5000 and 6000 m, with salt-layer thickness up to 2 m. The main objectives of the SapinhoÁ pilot were to evaluate the production and injection behaviors in a carbonate reservoir of microbial origin and obtain information and provide technology development so that those could be used for the remaining development of the presalt cluster. This information would be useful to Define the best recovery method to be applied in future projects Define the best exploitation strategy Optimize location, geometry, and number of wells Evaluate reservoir hydraulic communication Estimate vertical and horizontal permeability Project Engineering: Concept Overview Production-development plans consisted of the installation of a chartered floating production, storage, and offloading (FPSO) vessel in the field’s south area; a well-construction campaign; a subsea gathering system; and gas-export-pipeline installation.

Cost-Optimized FPSO Mooring Design Via Harmony Search

A mooring system optimization program has been developed to minimize the cost of offshore mooring systems. This paper describes an application of the optimization program constructed based on the recently developed harmony search (HS) optimization algorithm to offshore mooring design which requires significant number of design cycles. The objective of the anchor leg system design is to minimize the mooring cost with feasible solutions that satisfy all the design constraints. The HS algorithm is adopted from a jazz improvisation process to find solutions with the optimal cost. This mooring optimization model was integrated with a frequency-domain global motion analysis program to assess both cost and design constraints of the mooring system. As a case study, a single-point mooring system design of floating production storage and offloading (FPSO) in deepwater was considered. It was found that optimized design parameters obtained by the HS model were feasible solutions with the optimized cost. The results show that the HS-based mooring optimization model can be used to find feasible mooring systems of offshore platforms with the optimal cost.

Applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures

In design and operation of floating offshore structures, one has to avoid fatigue failures caused by action of ocean waves. The aim of this paper is to investigate the applicability of WaveWatch-III wave model to fatigue assessment of offshore floating structures. The applicability was investigated for Bluewaters’ FPSO (Floating Production, Storage and Offloading) which had been turret moored at Sable field for half a decade. The waves were predicted as sea-state time series consisting of one wind sea and one swell. The predicted waves were compared with wave data obtained from ERA-interim and buoy measurements. Furthermore, the fatigue calculations were also carried out for main deck and side shell locations. It has been concluded that predicted fatigue damages of main deck using WaveWatch-III are in a very good agreement regardless of differences in predicted wind waves and swells caused by differences in wave system partitioning. When compared to buoy measurements, the model underestimates fatigue damages of side shell by approximately 30 %. The reason for that has been found in wider directional spreading of actual waves. The WaveWatch-III wave model has been found suitable for the fatigue assessment. However, more attention should be paid on relative wave directionality, wave system partitioning and uncertainty analysis in further development.

E&P Notes (August 2016)

E&P Notes (August 2016) A New Reality for Training and Safety Technology Trent Jacobs, JPT Senior Technology Writer If you were at the Offshore Technology Conference in Houston this year you may have noticed the increasingly popular trend of exhibitors using virtual reality (VR) headsets to engage with attendees. The unique visual and immersive qualities that make these devices such great marketing tools are also what some in the oil and gas industry say make them such powerful training tools. VR technology has come a long way since its clunky ancestors were first introduced in the 1990s. Thanks to high-resolution screen technology and powerful gaming engines, the latest generation has been deemed by the techno-experts as ready for prime time. Equally important, VR has become affordable; some of the high-end devices now sell for only a few hundred dollars. This confluence of capability and cost is why Vincent Higgins left his job as a senior-level industry consultant to become the founder and chief executive officer of Optech4D. The 4-year-old Houston-based startup develops custom training programs that recreate oilfield and facility environments inside the VR devices. Ohio Study Tries To Pin a Number to Earthquake Risk Trent Jacobs, JPT Senior Technology Writer Research and development firm Battelle is working on a new induced-seismicity study that aims to help wastewater disposal well operators in Ohio stay on the good side of state regulators. Expected to be completed later this year, the company says the study will be the first to quantify a disposal well’s potential to cause an earthquake. Concern over disposal wells in Ohio was brought to the fore when a series of earthquakes jolted residents of Youngstown, Ohio, in late 2011. A disposal well near downtown was assigned responsibility for the tremors and regulators responded by shuttering that well along with several located nearby— the scenario Battelle is hoping its study can prevent from happening again. Twenty-Year Effort Brings Only Two FPSO Vessels to US GOM Joel Parshall, JPT Features Editor The floating production, storage, and offloading (FPSO) vessel is the world’s most widely used floating production system, with 218 units worldwide installed or on order. Yet, despite the United States offshore industry’s major advance into remote, deepwater projects, there are only two FPSO vessels in the US Gulf of Mexico (GOM). Speaking to the Rice Global Engineering and Construction Forum at Rice University in Houston in June, floating systems consultant Peter Lovie, who has worked on FPSO-related projects for more than 2 decades of a 50-year engineering career, gave a close-up view of the persistent effort to bring FPSO facilities to the US gulf. His talk was titled “2016 and Two FPSOs in the US GOM: The Twenty-Year Saga.” An FPSO vessel produces oil through onboard wells or is connected to subsea producing wells and in some cases receives oil from nearby production facilities. The vessel stores the produced oil in its hull and offloads the oil to tankers that station themselves next to the FPSO vessel, load the oil, and carry it to market. By offloading to tankers, FPSO facilities can avoid the need for oil pipelines connecting to shore and their major installation costs, although some FPSO units do connect with pipelines. Shell Stays Committed to Shale Opportunities Joel Parshall, JPT Features Editor Shell has reaffirmed its commitment to the shale business and views it as a growth opportunity moving into the 2020s, Executive Vice President for Unconventionals Greg Guidry told members of the media in a presentation on 20 June in Houston. Following its recent acquisition of BG Group, Shell has set the strategic priorities for its portfolio in a framework of three time horizons: cash engines of today, growth priorities (2016 and beyond), and future opportunities (2020 and beyond). Guidry noted that shale is in the last group. While some other portfolio choices offer better prospects in the current price environment, shale has “material value upside,” Guidry said. “We have a path to profitability, and we are managing exposure. …. We have the choice to activate shale with the right pricing.” Shell’s current shale production is just less than 300,000 BOE/D.

A liquid distribution model for a column with structured packing under offshore conditions

A liquid distribution model for a packed column with structured packing under offshore conditions is proposed. In this paper, permanent tilt and dynamic roll motion were selected as representative offshore conditions for the proposed model, considered to be the most severe offshore conditions. The proposed model is composed of an intersection network model with a liquid split algorithm. Parameter estimation was performed for the proposed model using published experimental data to adjust the parameters in the liquid split algorithm for the considered offshore conditions. A comparison between the liquid distribution of the proposed model and that of literature data was also presented. Using the adjusted parameters and proposed model, the main characteristics of liquid distribution under offshore conditions were investigated. In addition, the effects of column diameter and packed height on liquid distribution were studied. The results obtained from the proposed model could be the basis for the design of an absorption column installed on a buoyant platform like a floating production storage and offloading (FPSO) unit.

Dynamic analysis of turret-moored FPSO system in freak wave

Freak wave is the common wave which has significant wave height and irregular wave shape, and it is easy to damage offshore structure extremely. The FPSOs (Floating Production Storage and Offloading) suffer from the environment loads, including the freak wave. The freak waves were generated based on the improved phase modulation model, and the coupling model of FPSO-SPM (Single Point Mooring) was established by considering internal-turret FPSO and its mooring system. The dynamic response characteristics of both FPSO and SPM affected by the freak wave were analyzed in the time domain. According to the results, the freak waves generated by original phase modulation model mainly affect the 2nd-order wave loads. However, the freak waves which are generated by random frequencies phase modulation model affect both 1st-order and 2nd-order wave loads on FPSO. What is more, compared with the irregular waves, the dynamic responses of mooring system are larger in the freak waves, but its amplitude lags behind the peak of the freak wave.