Flowline Systems Research Articles

Deep reinforcement learning-based preventive maintenance for repairable machines with deterioration in a flow line system

Deep reinforcement learning-based preventive maintenance for repairable machines with deterioration in a flow line system

Optimizing integrated lot sizing and production scheduling in flexible flow line systems with energy scheme: A two level approach based on reinforcement learning

Many production environments are faced with the need to simultaneously determine the planning of lot sizing and the scheduling of production sequences while ensuring cost minimization. This issue becomes even more complex when integrating multiple energy sources with the goal of a low-carbon economy. To address this challenge, this paper proposes an integrated lot sizing and flexible flow line production scheduling model under a time-of-use pricing scheme. In addition, the model takes into account conventional grid power, on-site renewable energy sources, and an energy storage system. The associated objective function is solved adopting a two-level approach to optimize energy costs while maintaining production throughput and meeting customer demand. The implementation relies on reinforcement learning capabilities to tackle complexity issues. The proposed approach is evaluated on a benchmark case and its results are compared with those obtained with First-In-First-Out heuristic, genetic algorithm and CPLEX. These results highlight the promising aspect of the proposed approach in terms of performance.

Potency of starch in hydrate inhibition in a field within Gulf of Guinea Using Aspen Hysys

Hydrocarbon industry is now moving from onshore to offshore environments in search of black gold, since the world’s energy demand is growing astronomically. Exploitation of this black gold in an offshore environment is quite very capital intensive but not exonerated from flow assurance and intervention challenges. This is due to the fact that the black gold is produced alongside with BSW, associated gas, without which the black gold will be termed dead oil; also, there is restricted accessibility in an offshore environment. The result of hydrate formation includes blockage of flow lines, plaguing downstream equipment and flow line’s appurtenances such as Valves, Tees, Elbows. The current methods of preventing hydrate formation by the industry are highly limited and the chemicals used are harsh to the ecosystem. This study investigated the potency of Starch from Manihot Esculenta in hydrate inhibition using Aspen Hysys V11.0. The performances of considered hydrate inhibitors in a modeled flow line system with diameter355.6mm, length of 12.095 km in deep water hydrocarbon field within the Gulf of Guinea, were based on actual condition and production data. The simulation results at 40% and 80% water cuts were plotted for both steady state and dynamic state using Mat lab. At steady state, simulation results disclosed that there will be no hydrate formation. However, at dynamic state, simulation results disclosed that hydrates will form. HCF’s pressure declines from 61bar to 40.52bar, 32.43bar respectively, for the different water cuts, in induction time of 240 minutes. Likewise, HCF’s temperature declined suddenly and sharply rose again indicating hydrate formations. Starch at 0.05, 0.1, 0.15, 0.2 mole fractions prevented hydrates from forming but best at 0.2 mole fractions. Starch was therefore, recommended for field-pilot test and further developed, utilized as an ecofriendly hydrate inhibitor.

Transfer function identification of a liquid flow-line pressure control system from simple relay auto-tuning

Accurate modeling of liquid flow systems is necessary for the effective operation of the plant under different conditions. The plant dynamics may change with time, and due to this, the operation may not be satisfactory. In this article, relay autotuning of a liquid flow-line is proposed. Well-known describing function approximation is utilized for the estimation of gain of relay used in a feedback loop to excite the plant to be identified. The expressions are derived for the identification of a class of overdamped second-order plus dead-time and first-order plus dead-time plant dynamics. The identification method tested on different standard systems shows that the proposed method has good identification accuracy. Therefore, the proposed identification method is applied to a liquid flow line pressure control system. The experimental results show that an accurate dynamic model is extracted using the proposed method with a minimal set of data from an obtained limit cycle oscillation. The measured quantities of the limit cycle are utilized in the derived explicit expressions for the identification of unknown variables of the dynamic plant model. A distributed process control system is utilized here as a standard industrial platform to design virtual relay and conduct the proposed autotuning. The efficiency of the modeling method is demonstrated through the comparison of Nyquist and relay response plots with the transfer functions obtained from the MATLAB system identification toolbox.

Integrated Production and Maintenance Planning for Flow Line Systems

Integrated Production and Maintenance Planning for Flow Line Systems

Optimization of Pipe Insulation Volume for a Subsea Production System

AbstractThe increasing of deepwater oil field developments brings a growing need for thermal management to prevent hydrate and wax formations in the subsea production system, due to the low environment temperature and long-distance transportation. Pipeline insulation coating is a typical strategy for thermal management. In a subsea production system, pressure, temperature, flowrate, and length of each flowline vary, leading to different thermal performances of the transported fluid. Therefore, the insulation coating should be carefully designed from the overall perspective to minimize the total material volume, thus reducing the cost. In this paper, an optimization model for the insulation material volume of a rigid subsea flowline system is proposed. Then, the best insulation thickness of each subsea flowline can be determined under given flow parameters and temperature requirements. The factor that defines the temperature drop from the riser base to the top termination is introduced and analyzed. There is a proper temperature drop factor associated with the insulation material volume for subsea flowlines, as well as a proper insulation capacity for the risers. This optimization model can define the subsea system insulation and provide reliable results for cost estimation.

A review on subsea process and valve technology

The world’s energy consumption continues to increase steadily. Fossil fuels (oil, natural gas, and coal) still comprise more than approximately 85% of the world’s energy consumption. Offshore oil field development and operation began by using platforms and ships, but oil producers and operators are looking for new and innovative ways to reduce production costs and improve recovery and production rates from reservoirs. As a result, subsea production solutions are becoming more popular. A subsea production system consists of subsea completed well(s), seabed wellhead(s), production tree(s), subsea tie-ins to flow line systems, and subsea equipment and control facilities to operate the well(s). The wellhead consists of the pressure-containing components at the surface of an oil and gas well that provide the interface for drilling, completion, and testing of the well, in addition to production equipment. Subsea manifolds are used to simplify the subsea system, minimizing the usage of subsea pipeline and risers while optimizing the fluid flow. Subsea valves, which are mainly ball or through conduit gate valves, are located on the trees and wellheads and designed based on API and ISO standards. They are made in exotic corrosion-resistant alloys to avoid different types of corrosion such as hydrogen-induced stress cracking, and should withstand high-pressure classes. These valves can be manual or actuator-operated with or without the help of a remote-operated vehicle. The subsea industry is shifting from hydraulic-type to electrical-type actuators for important reasons including reduced costs and faster operation. Newly designed subsea valves should pass strict qualification tests such as hyperbaric tests, endurance tests, and pressure and temperature cycle tests.

New Technology Enables Development of Norwegian Sea Field

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 29523, “New Technology Enables Development of Field in Norwegian Sea,” by Arne Skeie, Subsea 7, prepared for the 2019 Offshore Technology Conference, Houston, 6–9 May. The paper has not been peer reviewed. Copyright 2019 Offshore Technology Conference. Reproduced by permission. The Arfugl field is a gas condensate field located in the Norwegian Sea. Heat input into the flowline system is required during shutdown and potentially also during off-plateau production periods. A new enabling technology known as electrically heat-traced flowline (EHTF) will be used to enable system startup and shutdown and to maintain production fluids outside of the hydrate envelope during steady-state operation. Background EHTF is a pipe-in-pipe (PIP) system in which heating cables are used to heat the inner pipe. This enables even longer tiebacks and development of fields with challenging hydrate characteristics. The Arfugl field represents one of the first EHTF projects awarded. System Configuration Topside. The Arfugl field will be tied back to the Skarv floating production, storage, and offloading (FPSO) unit. A container module with a transformer will be installed on the FPSO. From the transformer, the required three-phase voltage can be taken out by a tap exchanger. The three phases are then routed through the swivel paths to the turret, where they are split into multiple triplets in a busbar box. One swivel path is also occupied by fiber-optic (FO) cable, which is used for digital temperature•monitoring. Umbilical. The triplets are routed from the busbar box though the dynamic and static umbilical to the subsea umbilical termination assembly (UTA). The UTA is located close to the inline power-inlet structure (ILPIS), which is the entry point for the power into the flowline. Electrical flying leads are used to connect the UTA to the ILPIS. The FO is also routed through the umbilical and connected to the ILPIS by flying leads. ILPIS. The ILPIS is shown in Fig. 1. The flying leads from the UTA are connected to wet-mate connectors on the roof panel. In addition to the flying leads for power, two dedicated flying leads for the FO are included. From the wet-mate connectors to the double barrier arrangement, the wires are routed through oil-filled hoses with overpressure. In the double barrier, the wires are routed through two penetrators; the first enters into a chamber with atmospheric pressure, and the second into the annulus, where pressure is lower than atmospheric pressure. Should one barrier begin leaking for any reason, there will always be an active second barrier. The ILPIS is located in the middle of the 20-km flowline. Flowline Cross Section. From the ILPIS, the wires are routed onto the inner pipe in a helix shape, which ensures that the wires do not experience excessive tension or compression during the reeling operation when the flowline is installed (Fig. 2). The inner pipe is a 10-in. pipe inside a 16-in. carrier pipe. Centralizers are also located on the inner pipe. The pressure is reduced in the annulus between the inner and outer pipe to improve insulation. Insulation panels are located on top of the heating wires. The insulation panels consist of a microporous material, which means that, when pressure is reduced, the voids in the material become so small that movement of air molecules is restricted, and thus insulation properties are improved.

Ethylene glycol injection for hydrate formation prevention in deepwater gas pipelines

The presence of hydrates in deepwater oil-gas-field operations is a fairly frequent issue. It is very important to have a hydrate management strategy for normal operation and while shutdown. The objectives of the work were to mitigate the hydrate formation in the deepwater operation conditions. This study analyzed the sensitivity of the hydrate compound formation process in flow line system with diameter 9.5" with a length of about 22 Km in deep water gas-field, based on actual condition and production rate assumption. Based on the simulation results for the actual production flow rate, hydrate is formed at a distance of about 17991 ft from the wellhead that is in the first segment of the well head to the Pipeline End Manifold (PLEM). For a higher production flow rate, hydrate formation occurs at a distance approaching the wellhead which is part of the first segment. This is because the temperature at the bottom of the deep-water is as low as 40 °F. The addition of MEG to prevent the formation of hydrate compounds was further investigated. Fluid flow modeling was performed under steady state with CH4 levels of about 87%, pressure of 1900 psia, 125 °F temperature and 85 MMSCFD production flow rate as the basic conditions. The data used in this research is taken from one of the deepsea gas field in Makassar Strait. Adding MEG dose of 0.175% mole, lowering the hydrate-forming temperature from 67.8 °F to 3.2 °F. Similarly, for increasing MEG doses, the greater the decrease in hydrate formation temperature. The addition of MEG dose of 0.175% mole at each production flow rate gives different working fluid temperature with hydrate formation temperature of 5.5 °F to 18 °F, so it is safe from the risk of hydrate formation.

Embedding Advanced Harmony Search in Ordinal Optimization to Maximize Throughput Rate of Flow Line

Flow line systems are production systems in which successive operations are performed on a product in a manner so that it moves through the factory in a certain direction. This work firstly formulates a flow line system as an integer-ordered inequality-constrained simulation–optimization problem and present a stochastic simulation procedure to estimate the throughput rate. The mathematical formulation and simulated procedure can be used for any distribution of processing rate and can be applied to high-dimensional problems. An approach that embeds advanced harmony search (AHS) in ordinal optimization (OO), abbreviated as AHSOO, is developed to find a near-optimal design of the flow line system to maximize the throughput rate. The proposed approach comprises three levels, which are meta-modeling, diversification and intensification. A radial basis function network is a meta-model to approximate the performance of a design. The proposed approach integrates the AHS approach for diversification with improved optimal computing budget allocation (IOCBA) for intensification. AHS favorably explores the solution space initially and moves toward exploiting good solutions close to the end. The IOCBA maximized the overall simulation efficiency for finding an optimal solution. The proposed AHSOO is tested on three examples. In the moderately sized example, simulation results reveal that the average best-so-far performances that were determined using PSO, GA and ES were 6.12, 9.65 and 8.53% less than that obtained using AHSOO—even after the former took more than 50 times the CPU time that was consumed by AHSOO upon completion. Analytical results reveal that the proposed method yields designs of much higher quality with a much higher computing efficiency than the seven competing methods.

A review of deepwater pipeline construction in the U.S. Gulf of Mexico–Contracts, cost, and installation methods

The offshore pipeline network in the U.S. Gulf of Mexico is the largest and most transparent system in the world. A review of deepwater projects in the region provides insight into construction cost and installation methods and the evolution of contract strategies. Pipeline projects are identified as export systems, infield flowline systems, and combined export and infield systems, and three dozen deepwater pipeline installations from 1980–2014 are described based on OTC/SPE industry publications and press release data. Export lines and infield flowlines are equally represented and many projects used a combination of J-lay, S-lay and reel methods with rigid steel, flexible line, and pipe-in-pipe systems. The average 2014 inflation-adjusted cost for pipeline projects based on OTC/SPE publications was $2.76 million/mi and ranged from $520 000/mi to $12.94 million/mi. High cost pipelines tend to be short segments or specialized pipeline. Excluding the two cost endpoints, the majority of projects ranged from $1 to $6 million/mi. The average inflation-adjusted cost to install deepwater pipelines in the U.S. Gulf of Mexico based on available public data is estimated at $3.1 million/mi.

Finding New Ground in Subsea Integrity Management

The oil and gas industry has moved into more extreme territories in recent years, sanctioning an increasing number of ultradeepwater projects that require the use of remote and long-distance subsea tiebacks as well as subsea processing systems. With the push to deepwater development, production has become more reliant on the integrity of subsea, umbilical, riser, and flowline (SURF) systems. Operators have been seeking more cost-effective ways to define and implement the inspection and monitoring methods needed to assess and manage the integrity of SURF systems. An operator-only joint-industry project (JIP) was launched to help enable an integrated approach to the integrity management of SURF systems and develop best practices.

Математическая модель распределения технологических операций по рабочим местам поточно-конвейерной системы

The problem of optimal allocation of jobs by work stations of flow-line conveyor system boils down to a class of extremum problems, which, in turn, can be narrowed down to discrete programming models. The paper offers a mathematical model designed to allocate operations for manufacturing certain product by flow-line conveyor work stations. The model is built with due regard to operations procedure limitations and can be used to design flow-line conveyor system for the purpose of parameters optimization.

Математический метод определения элементов структуры поточно-конвейерной системы дискретного производства

The author proposes a mathematical method for determining structure elements
 of discrete component manufacturing. Based on the information theory the
 author has developed a new formula for calculation of job numbers needed
 to the flow-line conveyor system.

Multi-agent reinforcement learning based maintenance policy for a resource constrained flow line system

This paper investigates the maintenance problem for a flow line system consisting of two series machines with an intermediate finite buffer in between. Both machines independently deteriorate as they operate, resulting in multiple yield levels. Resource constrained imperfect preventive maintenance actions may bring the machine back to a better state. The problem is modeled as a semi-Markov decision process. A distributed multi-agent reinforcement learning algorithm is proposed to solve the problem and to obtain the control-limit maintenance policy for each machine associated with the observed state represented by yield level and buffer level. An asynchronous updating rule is used in the learning process since the state transitions of both machines are not synchronous. Experimental study is conducted to evaluate the efficiency of the proposed algorithm.

English

A number of studies on effect of temperature on the flow characteristics of various fluids have been carried out. The aim of this work was to examine the flow characteristics of hexane upon the influence of temperature as well as the effectiveness response of orifice plate using pneumatic proportional control. Knowledge of the past on temperature impact as one aspect of the information set held by various scientific and a well established finding in engineering is that changes in composition can change the effect of temperature on the flow characteristics of hexane in a flow line system. The particular aspects of temperature impact on the research work highlighted are density, viscosity and pressure characteristics. The effect of temperature on flow characteristics of hexane was examined within the temperature range of 283 to 323 K and Bernoulli’s equation knowledge of the past was used in developing the model for this paper. The mathematical models developed were simulated using the numerical concept of polynomial expression of the best fit. The effects of temperature on the functional parameters were examined and proportional gain at various error range of E = 0.1 to 0.5 were considered during the investigation. These effects on the variation of the results were attributed to the temperature, flow characteristics of the hexane and its effectiveness on orifice plate using pneumatic proportional control.  Key words: Effect, temperature, hexane, effectiveness, flow characteristics, orifice plate.

굴삭기 부품 용접 자동화라인의 셀생산방식 적용을 위한 시뮬레이션 연구

Mixed model production system means that various products are manufactured alternately in a line, and it has become a popular system in the era of multi-product small-quantity production. However, in the mixed model production system using flow line, the unbalance among stations is not inevitable because the workloads of stations cannot be the same. Thus, flow line system has been replaced to cellular manufacturing system for reducing the loss of waiting due to the unbalance of stations. In this paper, we introduce the simulation case study of an automated welding line which produces the parts of excavator. The factory has considered replacing the mixed model flow line to the cellular manufacturing system based on FMC concept. The increase of production quantity is estimated about 26.7%, and the lead time is reduced more than 55%. Furthermore sensitivity analyses are conducted considering the changes of product-mix.

Moderately converging ion and electron flows in two-dimensional diodes

Flow of particles in diodes is solved selfconsistently assuming an approximated system of flow lines, that can be easily represented by an analytic transformation in a complex plane, with assumed uniformity in the third spatial direction. Beam current compression is tunable by an angle parameter α(0); transformed coordinate lines are circular arcs, exactly matching to the curved cathode usually considered by rectilinear converging flows. The curvature of flow lines allows to partly balance the transverse effect of space charge. A self-contained discussion of the whole theory is reported, ranging from analytical solution for selfconsistent potential to electrode drawing to precise numerical simulation, which serves as a verification and as an illustration of typical electrode shapes. Motion and Poisson equation are written in a curved flow line system and their approximate consistency is shown to imply an ordinary differential equation for the beam edge potential. Transformations of this equation and their series solutions are given and discussed, showing that beam edge potential has a maximum, so supporting both diode (with α(0) =/~ π∕3) and triode design. Numerical simulations confirm the consistency of these solution. Geometrical details of diode design are discussed: the condition of a zero divergence beam, with the necessary anode lens effect included, is written and solved, as a function of beam compression; accurate relations for diode parameters and perveance are given. Weakly relativistic effects including self-magnetic field are finally discussed as a refinement.

Optimal flow-line conditions with worker variability

When classical scheduling theory is applied to task sequencing problems, human characteristics are often not the primary consideration and their impact is often assumed away. In this paper, we examine the workforce scheduling problem in sequential flow line systems. We investigate the impact of within-worker and between-worker variability and discuss the selection of scheduling policies between fixed and work-sharing systems. The methodology includes human performance modeling with the objective to maximize throughput with general results with respect to productivity model. We are interested in determining and characterizing the optimal switching time between workers in work-sharing systems. A closed form solution is established in the case of two and three tasks with two workers. For a general number of workers and tasks we establish the maximum number of changes between assignments. We also establish a bound on throughput. Results allow one to solve workforce scheduling problems reduced complexity given the current set of bounds and conditions.

Working time evaluation in assembly lines

Assembly lines are special flow-line production systems which are of great importance in the industrial mass production. This paper introduces the deterioration effects in assembly lines that the aim of the developed mathematical model and the proposed genetic algorithm is to minimise the working time of a product in a cycle of assembly. Task deterioration means that a task processed later consumes more time than the same task when it is processed earlier. At the end several well-known examples are solved and the results proved that the deterioration will affect both cycle time and working time, simultaneously.