Hydraulic Transients Induced by Pigging Operation in Pipeline with a Long Slope

Pigging in pipelines basically performs operations for five reasons including cleaning the pipe interior, batching or separating dissimilar products, displacement, measurement, and internal inspection. A model has been proposed for the dynamic simulation of the pigging process after water pressure testing in a long slope pipeline. In this study, an attempt has been made to analyze two serious accidents during pigging operation in 2010 by the model which is developed by the method of characteristic (MOC) by Wylie et al. (1993) and the two-phase homogeneous equilibrium vaporous cavitation model deveoped by Shu (2003) for vaporous cavitation. Moreover, simulation results of the third operation show good agreement with field data from the previous field trial. After investigation, it was showed that the impulse pressures produced during collapse of a vapor cavity result in severe damage of tubes

Leak Detection in Long Pipelines Systems

Leakage in any fluid distribution network or conveying systems results in consumption of resources and time, and its impacts affect the on the environment and the profits for any asset owner. Moreover, a sufficient and applicable leak detection system, especially, in the oil/gas industry, comes at a high cost and time consuming, sometimes affects the system’s productivity. Because of its simplicity and encouraging results from the theoretical, experimental and real field tests, the water hammer phenomenon promises shows great benefits. This work has tried to utilise the routine transient events, raising the pump flow rate, to detect the leak. Also, it attempted to draw on some successful theoretical techniques, the cross-correlation and its second derivative, to apply on a real field system. To achieve that, some theoretical and experimental stages had to be carried out first. The real system was scaled theoretically to form a laboratory apparatus, so it could be fitted in a Contaminant Ingress into Distribution Systems (CID) laboratory at the University of Sheffield. The leak approach was tested by means of a numerical code for this design before construction of the rig. Then, the experimental rig was completed and the data collected from it. In the real field system, the shortage in the data frequency is an obstacle to applying the approach. The researcher’s colleagues tried their best to improve the data acquisition system to meet the requirements. Although the improvement made to the system in terms of the time precision was impressive, the sample frequency increment was under the desirable level. The signal analysis approach was worked as expected theoretically, empirically the results were limited. Some trials were conducted to enhance the signal features. Later, some issues were raised and clarifications were added

Modeling of Pipeline Transients: Modified Method of Characteristics

The primary purpose of this research was to improve the accuracy and robustness of pipeline transient modeling. An algorithm was developed to model the transient flow in closed tubes for thin walled pipelines. Emphasis was given to the application of this type of flow to pipelines with small radius 90° elbows. An additional loss term was developed to account for the presence of 90° elbows in a pipeline. The algorithm was integrated into an optimization routine to fit results from the improved model to experimental data. A web based interface was developed to facilitate the pre- and post- processing operations. Results showed that including a loss term that represents the effects of 90° elbows in the Method of Characteristics (MOC) [1] improves the accuracy of the predicted transients by an order of magnitude. Secondary objectives of pump optimization, blockage detection and removal were investigated with promising results

Flow assurance and multiphase pumping

A robust understanding and planning of production enhancement and flow assurance is required as petroleum E&P activities are targeting deepwaters and long distances. Different flow assurance issues and their solutions are put together in this work. The use of multiphase pumps as a flow assurance solution is emphasized. Multiphase pumping aids flow assurance in different ways. However, the problem causing most concern is sand erosion. This work involved a detection-based sand monitoring method. Our objectives are to investigate the reliability of an acoustic sand detector and analyze the feasibility of gel injection as a method to mitigate sand erosion. Use of a sand detector coupled with twin-screw pumps is studied under varying flow conditions. The feasibility of gel injection to reduce slip and transport produced solids through twin-screw pump is investigated. A unique full-scale laboratory with multiphase pumps was utilized to carry out the experimental tests. The test results indicate that acoustic sand detection works in a narrow window around the calibration signature. An empirical correlation for predicting the twin-screw pump performance with viscous fluids was developed. It shows good agreement in the practical operational limits – 50% to 100% speed. The results indicate that viscous gel injection should be an effective erosion mitigation approach as it reduces slip, the principle cause of erosive wear. To correlate the performance of viscous fluid injection to hydroabrasive wear, further experimental investigation is needed

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

MODELING OF FLOW INSTABILITY IN DEEPWATER FLOWLINES AND RISERS: A CASE STUDY OF SUBSEA OIL PRODUCTION FROM CHINGUETTI FIELD, MAURITANIA

Chinguetti a deepwater oil field development offshore Mauritania is experiencing a rapid decline in its production that resulted to severe flow instability or slugging in flowlines and risers of its subsea oil production system. Slugging initiates oscillations and puts field operator in a demanding situation to manage and control flow instability. It is crucial to have a model to describe flow instability issues in live field conditions. Apparently, there is no applicable model to represent flow instability in deepwater operations. Current available data that represents flow instability in flowlines and risers in live field conditions has not been published in any literature. The available data is mostly from laboratory controlled conditions or laboratory scale ideal condition. Model using laboratory conditions has limited capability that cannot be used to assess severity of slugging. A study was undertaken in which integrated production system of the Chinguetti wells, flowlines and risers were developed using the OLGA transient multi phase flow simulator. Field validation was performed by tuning the models to match field pressures and phase flowrates and instability in the systems. The impact of various changes in operating conditions on the flow instability was examined by simulating the models that included changes in well routings, gas lift injection rates and location of injection points, riser and wellhead choke openings. The severity of flow instabilities for the different operating conditions was categorized by the degree of fluctuations in liquid arrival rates and the characteristics of its liquid slugs, length and frequency. Results from field implementation of the recommended changes in operating conditions indicated improvement in flow stability and oil recovery. From the study, a methodology has been developed to assess the severity of slugging and strategies to mitigate flow stability and productivity in the flowlines and risers ofChinguetti oil production system

Transient Mobilisation of Pipe-Wall Adhered Material in Drinking Water Distribution Systems

Discolouration, an aesthetic indicator of drinking water quality, affects approximately 6.7 million customers annually in the UK and is perceived to mask other water quality failures. Existing management techniques cannot explain all of these discolouration failures. Therefore, understanding the processes and forces that lead to discolouration is crucial. Material associated with discolouration is mobilised from the pipe wall when its adherence strength is exceeded by imposed hydraulic forces. Transient events generate significant dynamic forces, yet, there is currently little conclusive evidence exploring their influence on mobilisation of material. This study aims to determine, for the first time, if transient forces can mobilise of material adhered to the pipe-wall, which cannot be mobilised by steady state flows at the same initial or final conditions. An innovative, rigorous laboratory experiment was designed to test this aim. Replicated adhered material was created using magnetic particles inside the pipe and an electromagnet external to the pipe, so that controlled current through the electromagnet quantified adherence force experienced by the magnetic particles. Hydraulic steady state and transient tests, for a range of flow rate and pressure conditions, were conducted to determine the current at which mobilisation occurred. A key contribution of this research was the confirmation that valve closing and valve opening transients cause mobilisation of adhered material, where steady state cannot. This is substantial finding, particularly for valve closing transients as the steady state force reduces during the valve movement. Mobilisation must be due to the dynamic forces generated by the transient. An observationally driven analysis led to development of a function to capture the magnitude of the hydraulic force generated during transients. The one dimensional function was termed the ‘Peak Dynamic Force’ and begins to quantify transient induced forces that lead to mobilisation of pipe-wall adhered material. The work presented within this thesis is unique in that it consistently isolated transient forces and quantified their mobilisation ability. This dynamic ability has theoretical and practical implications, and could ultimately lead to the development of effective management strategies for improving drinking water quality

Towards The Development of Biosensors for the Detection of Microbiologically Influenced Corrosion (MIC)

Corrosion is one of the biggest concerns for mechanical integrity of infrastructure and infrastructural components, such as oil refineries, bridges and roads. The economic cost of corrosion is typically estimated to be between 1 to 5 % of the gross national product (GNP) of countries, of which the contribution of microbiologically influenced corrosion (MIC) is estimated to be between 10% and 50%. Current state-of-the-art approaches for detecting MIC primarily rely on ex-situ tests, including bacterial test kits (bug bottles); corrosion coupons, pigging deposits analysis and destructive analysis of MIC affected sites using SEM, TEM, and XRD. These ex-situ measurements do not capture the complexities and time sensitivities underlying MIC. This is owed to the fact that the proliferation of the microbial contamination is a dynamic and rapid process, and any delay can prove expensive as it is estimated that once the biofilm formation takes place the amount of biocides needed is magnitude of orders more as compared to when the bacteria are in planktonic form. Additionally, the field environment is a complex biotic and abiotic environment which is often difficult to replicate even in high fidelity laboratory models. Hence a real-time/pseudo real-time method of detection would greatly help reduce the costs and optimize biocide-based mitigation of MIC. To overcome the above-mentioned shortcomings associated with the state-of-the-art; this work is aimed at the development of a sensor substrate whereby highly specific detection can be carried out in the environment where the corrosion exists, in a real-time/pseudo real-time basis. More specifically, the research is aimed at the development of sensors based on a nanowire matrix functionalized with biomolecules which can perform this specific and real-time detection of MIC in the pipeline environment. Here, the detection of MIC is based on the binding of specific biomolecules causing MIC to organic molecules anchored on top of the nanowires. These sensors also need to be inexpensive (made of low-cost, earth abundant materials), have low power consumption, and robustly deployable. The primary component of the detection platforms are copper oxide nanowire arrays (CuONWs with lengths of 25 to 30 m, 50 to 100 nm in diameter) and silicon nanowires arrays (SiNWs with lengths of 5 to 8 m, 45 to 100 nm in diameter). They are synthesized using facile and scalable techniques and are selected for their robust electrical and mechanical properties. Electrochemical degradation studies of the NWs were performed in 3.5 wt. % NaCl solution and simulated produced water using polarization and electrochemical impedance spectroscopy (EIS). The NWs systems showed robust resistance to degradation despite higher surface area (as compared to bulk counterparts), and both diffusion limitations and charge transfer resistance was observed on the analysis of the impedance response. The ability to immobilize a variety of moieties on the nanowire platforms gives them the ability to detecting a wide variety of MIC biomarkers. The Biotin-Streptavidin (SA) complex was used as a proof of concept to test the viability of the NW arrays as a substrate for sensing. A custom test bed was built for the functionalized NW thin films, and cyclic voltammetry studies revealed a stable current response with time for 10nM and 10,000 nM SA concentrations. The use of different probes such as aptamers to larger immunoglobulin probes provides the flexibility to detect the full spectrum of biomarkers. The development of these next generation sensor platforms along with the methodologies employed to stabilize them and assemble them into functional devices are explored in detail in this dissertation