MODELING AND SIMULATION OF A PERPETUAL PIGGING MECHANISM

Demands in oil and gas industries on reliable quality of inspection in pipeline operation is increasing throughout the year, although intelligent PIGs are more capable than simpler conventional counterparts, they still have several setbacks such as cannot clean throughout the pipeline while inspection and only can move in several distance in a single flow. Pipeline is the most important medium to transport crude oil and gas to the terminal. In order to maintain the efficiency of the transportation, Conventional PIG is the best solution that can act as a pipeline cleaner and also Intelligent PIG as a pipeline inspector to detect any corrosion and leakage. A proper research work has been made, an improvement in which a prototype of an Intelligent PIG is developed with respect to the benchmarked of the pipeline crawler drive mechanism to clean and inspect throughout the oil and gas pipeline on entering and leaving the pipeline from a single exit. This project is aimed to develop the assembly of a CAD-based model of an experimental intelligent PIG drive mechanism and simulate to show that the PIG model is able to travel in both contra-flow and in-flow direction based on the research work that has been made. CATIA software was used to review and developed the CAD-based model assembly on changing all constrains to meet the specific requirements. Meanwhile, for simulations using DMU Kinematics was used to demonstrate the movement of the PIG drive mechanism in a pipeline using a suitable joints and constrains. The final outcome of this project is a demonstration of the experimental PIG crawler drive mechanism CAD-based model assembly are correctly develop with the suitable constrains and shows that the PIG travel in the pipeline on bot

Development of a novel autonomous robot for navigation and inspect in oil wells

This paper proposes a novel robotic system that is able to move along the outside of the oil pipelines used in Electric Submersible Pumps (ESP) and Progressive Cavity Pumps (PCP) applications. This novel design, called RETOV, proposes a light weight structure robot that can be equipped with sensors to measure environmental variables avoiding damage in pumps and wells. In this paper, the main considerations and methodology of design and implementation are discussed. Finally, the first experimental results that show RETOV moving in vertical pipelines are analyzed

Automation and Control Architecture for Hybrid Pipeline Robots

The aim of this research project, towards the automation of the Hybrid Pipeline Robot (HPR), is the development of a control architecture and strategy, based on reconfiguration of the control strategy for speed-controlled pipeline operations and self-recovering action, while performing energy and time management. The HPR is a turbine powered pipeline device where the flow energy is converted to mechanical energy for traction of the crawler vehicle. Thus, the device is flow dependent, compromising the autonomy, and the range of tasks it can perform. The control strategy proposes pipeline operations supervised by a speed control, while optimizing the energy, solved as a multi-objective optimization problem. The states of robot cruising and self recovering, are controlled by solving a neuro-dynamic programming algorithm for energy and time optimization, The robust operation of the robot includes a self-recovering state either after completion of the mission, or as a result of failures leading to the loss of the robot inside the pipeline, and to guaranteeing the HPR autonomy and operations even under adverse pipeline conditions Two of the proposed models, system identification and tracking system, based on Artificial Neural Networks, have been simulated with trial data. Despite the satisfactory results, it is necessary to measure a full set of robot’s parameters for simulating the complete control strategy. To solve the problem, an instrumentation system, consisting on a set of probes and a signal conditioning board, was designed and developed, customized for the HPR’s mechanical and environmental constraints. As a result, the contribution of this research project to the Hybrid Pipeline Robot is to add the capabilities of energy management, for improving the vehicle autonomy, increasing the distances the device can travel inside the pipelines; the speed control for broadening the range of operations; and the self-recovery capability for improving the reliability of the device in pipeline operations, lowering the risk of potential loss of the robot inside the pipeline, causing the degradation of pipeline performance. All that means the pipeline robot can target new market sectors that before were prohibitive

Wax removal using pipeline pigs

The deposition of paraffin wax solids in pipelines and risers represents a continuing challenge to flow assurance in offshore installations. Wax deposits reduce product throughput, requiring increased energy expenditure to re-establish flow levels. In severe cases, wax deposits can completely block a pipeline. Preventative solutions to the problem such as pipeline insulation, active heating of pipes or chemical dosing with wax inhibitors are not always economically viable, so mechanical removal using a device known as a 'pig' remains an economical solution to the problem of wax removal. A pig is a cylindrical tool that is driven through the pipe by the flow of product, scraping deposits from the pipe wall as it travels. Despite the importance of pipeline pigging to the oil and gas industry, the effectiveness of pigs in removing wax is poorly understood and it is this problem that is addressed by this thesis. One of the first necessities in undertaking this work has been to define the mechanical properties of wax deposits. This has required critical analysis of published material on the subject of wax deposition along with practical experimentation to create representative models of wax deposits that require mechanical removal from pipelines. Previously, studies of wax removal using pigs have assumed the mechanics of the process to be adequately represented by uniaxial compression or simple shear load models. In this work wax removal is analysed using the orthogonal cutting model. This provides a more accurate description of the process as it includes the effect of material after yielding (the chip) on the net wax removal force. Experiments were designed to allow testing of the validity of the orthogonal cutting theory to the pigging process under a variety of conditions. An original contribution from this work is through experimental and theoretical results that are given context through comparison with established metal cutting theory. Through experimentation a specific cutting energy is obtained for wax removal. The results of the wax cutting experiments have identified particular differences between wax cutting and metal cutting regarding the homogeneity of chip formation. These observations have important implications in predicting wax removal forces using mechanical removal tools. Although the affect of removed wax chips on pigging forces has been neglected in theory, it is well known in practice. The fluid used to drive cleaning pigs is often used to produce a jet radiating centrally from the front of the pig intended to blast wax chips away from the pig body, avoiding formation of a 'plug' of wax ahead of the pig. In this study a novel variation of this process in the form of an annular bypass jet is experimentally studied. A semi-empirical model of wax removal using an annular bypass jet has been developed and empirical constants obtained to allow prediction of removal rates for different waxes under various conditions. The new model introduced here allows balancing of pig velocity with wax removal velocity so that a non-contacting wax removal system is obtainable. The bypass-jetting model has been validated using a full-scale trial of the process by industrial sponsors

Design and Motion Planning of a Wheeled Type Pipeline Inspection Robot

The most popular method for transporting fluids, and gases is through pipelines. For them to work correctly, regular inspection is necessary. Humans must enter potentially dangerous environments to inspect pipelines. As a result, pipeline robots came into existence. These robots aid in pipeline inspection, protecting numerous people from harm. Despite numerous improvements, pipeline robots still have several limitations. This paper presents the design and motion planning of a wheeled type pipeline inspection robot that can inspect pipelines having an inner diameter between 250 mm to 350 mm. The traditional wheeled robot design has three wheels fixed symmetrically at a 120° angle apart from each other. When maneuvering through a curved pipeline, this robot encounters motion singularity. The proposed robot fixes the wheels at different angles to address this issue, allowing the robot to stay in constant contact with the pipe's surface. Motion analysis is done for the proposed and existing robot design to study their behavior inside the pipeline. The result shows that the proposed robot avoids motion singularity and improves mobility inside pipelines. 3d printing technology aids in the development of the proposed robot. The experimental tests on the developed robot inside a 300 mm-diameter straight and curved pipeline show that the robot avoids motion singularity

MODELING AND SIMULATION OF A PERPETUAL PIGGING MECHANISM

Demands in oil and gas industries on reliable quality of inspection in pipeline operation is increasing throughout the year, although intelligent PIGs are more capable than simpler conventional counterparts, they still have several setbacks such as cannot clean throughout the pipeline while inspection and only can move in several distance in a single flow. Pipeline is the most important medium to transport crude oil and gas to the terminal. In order to maintain the efficiency of the transportation, Conventional PIG is the best solution that can act as a pipeline cleaner and also Intelligent PIG as a pipeline inspector to detect any corrosion and leakage. A proper research work has been made, an improvement in which a prototype of an Intelligent PIG is developed with respect to the benchmarked of the pipeline crawler drive mechanism to clean and inspect throughout the oil and gas pipeline on entering and leaving the pipeline from a single exit. This project is aimed to develop the assembly of a CAD-based model of an experimental intelligent PIG drive mechanism and simulate to show that the PIG model is able to travel in both contra-flow and in-flow direction based on the research work that has been made. CATIA software was used to review and developed the CAD-based model assembly on changing all constrains to meet the specific requirements. Meanwhile, for simulations using DMU Kinematics was used to demonstrate the movement of the PIG drive mechanism in a pipeline using a suitable joints and constrains. The final outcome of this project is a demonstration of the experimental PIG crawler drive mechanism CAD-based model assembly are correctly develop with the suitable constrains and shows that the PIG travel in the pipeline on bot

An inertial two-phase model of wax transport in a pipeline during pigging operations

Pig in pipelines performs operations for cleaning the pipe interior and internal inspection. In the past few years many 1D models have been developed to simulate the process because of their reduced computational cost; however, they rely on simplifications which are not always valid. In this paper, the results of a three-dimensional (3D) numerical investigation of the interaction between a waxy-oil and a dynamic sealing pig in a pipeline are presented. The results are obtained at a reduced computational cost by using a moving frame of reference, and an “injection” boundary condition for the wax deposited on the wall. The effect of the temperature and the wax particles’ size has been investigated. The 3D results show the structure assumed by the debris field in front of the pig. In particular, a lubrication region at the bottom of the pipe, whose dimensions are temperature dependent, is shown. This information cannot be deduced from 1D modeling. The influence of the oil on the mixture viscosity and the internal bed dynamics are discussed. This work provides insights into the interaction between the debris field in front of the pig and pipeline hydraulics

Design characteristics of a pipe crawling robot

This thesis deals with the design characteristics of a pipe crawling vehicle which utilises a unique, innovative and patented drive system. The principle of the drive system is simple. That is, if a brush is inserted into a pipe and its bristles are swept back at an angle, then, it is easier to push the brush forwards through the pipe than it is to pull it backwards. Thus, if two brushes are interconnected by a reciprocating cylinder, then, by cycling the cylinder, it is possible for the vehicle to "crawl" through the pipe. The drive mechanism has two main advantages. The first is the ability of the bristles to deflect over or around obstacles, thus, the vehicles can be used in severely damaged pipes. Secondly, the drive mechanism is able to generate extremely high "grip" forces, thus, the vehicle has a high payload to weight ratio. This "simple" traction mechanism has subsequently been proven to be extremely capable in significantly hostile environments, for example, nuclear plants and sewers. The development of the vehicle has resulted in brushes being considered as "engineering" components. This thesis considers the forces present when a brush moves forward through a pipe, further, it also considers the forces present if the brush is required to grip the walls of the pipe. A "simple" cantilever model has been developed which predicts the force required to push a brush forwards through the pipe. A second model has been developed which predicts the forward to reverse or "slip" to "grip" ratio of a brush, for given functional conditions. This model is deemed satisfactory up to the onset of bristle buckling. The experimental program determined three factors, they were, the force required to load a brush into a pipe, the force required to push a brush forward through a pipe and the reverse force a brush could support prior to failure. It can be concluded that this vehicle, through its tractive capability arid environmental compliance, is able to traverse irregularly shaped pipes. Ultimately, this allows tooling to be transported and used at previously unobtainable positions within such pipes

Development of techniques for detection and dissolution enhancement of mineral deposits in petroleum pipelines using ultrasound.

Scale formation in petroleum pipelines causes progressive flow reductions, leading to large production losses and operating costs. The composition and thickness of the scale deposits vary widely, but with present technology they cannot be accurately quantified or monitored. Remedial treatments such as chemical de-scaling etc. are therefore largely based on guesswork, which can lead to expensive chemical wastage and production shutdowns. This project is intended to address some of the above problems using ultrasonic techniques. Work presented in this thesis branches out into two main areas of interest, namely: (a) developments concerning location of deposits from both top-side and down-hole locations; and (b) developments relating to enhancement of scale removal, using ultrasound. With regard to top-side scale detection, the major challenge in this work was to develop a technique by which acoustic signatures are synthetically generated, which can be used with the techniques previously developed for pipeline inspection. This required the determination of a suitable type of transducer and the study of its radiation characteristics in developing comprehensive mathematical models for artificially generating reference echoes. The model allowed the first three multiple echoes (in steel objects) to be computed for given test parameters. Close agreement of the synthesised echoes with practical measurements was demonstrated with good repeatability. An essential requirement for the detection of deposits in down-hole is the accurate alignment of the test probes with respect to the pipe-wall. In this regard, a novel technique for remote alignment of the transducers was successfully formulated. It is based on identifying symmetrical properties of the signals received from the test probe itself when scanned around the correct angular position with respect to the target. However, through extensive practical measurements, it was found that an important requirement for applying this technique is to know in advance whether a particular combination of probe, target diameter and separation distance would give satisfactory angular resolution. Extensive practical examination of these factors showed that no general conclusion can easily be drawn with respect to this requirement. Therefore a mathematical model was successfully developed, which would predict the suitability of given probe/target parameters. It has been reported in previous studies that ultrasonic irradiation could greatly enhance the chemical dissolution of localised deposits during de-scaling operations. In this regard, a major challenge was to improve the efficiency of power transducers radiating into confined spaces at elevated temperatures. That required the study of radiation characteristics of ultrasonic power transducers and compensation techniques to regain loss of efficiency at elevated temperatures. Alternative types of transducers - based on flexural-horn designs - were also investigated and their relative merits presented. Significant findings related to the performance variations of ultrasonic transducers and transmission cables at elevated temperatures have been made. After examining the transducer efficiency drop with temperature, a closed-loop compensation strategy was proposed for maintaining optimal performance. The matching requirements of the cables transmitting power from top-side to down-hole power transducers were also investigated as part of optimisation of ultrasonic power output. From this study it was found that, within the temperature range of interest, the cable in itself does not require changes to the matching requirements as the environmental temperature fluctuates. However, it was noted that the transducer impedance changes rapidly with temperature and therefore a unified compensation strategy incorporating both cable and transducer impedances was proposed as a better solution. Overall, the main objectives of the project concerning pipeline scale detection were well achieved, namely: (a) modelling of a suitable type of ultrasonic transducer to synthesise the reference multiple echoes to aid top-side scale detection; and (b) development of a remote sensing technique for ultrasonic probe alignment in downhole pipes. With regard to dissolution enhancement, techniques for enhancing power output of ultrasonic transducers to aid dissolution enhancement of scale deposits have been determined. Further work includes the improvements to software algorithms developed and hardware integration to achieve the expected performance of the techniques presented