Claudio Soligo Camerini

Autonomous system for oil pipelines inspection

Abstract Maintenance of oil pipelines is an issue of great concern for oil companies. Any possibility of leakage must be detected before the leakage occurs and a preventive action should be taken in order to avoid losses of oil and ecological disasters. One of the main causes of oil pipelines leakage is the corrosion of the bottom part of the pipeline due to accumulation of water and other corrosive substances. One of the methods used to check the conditions of the oil pipelines is the running of a data acquisition device through all the length of the pipeline (that can be km) to gather information about the corrosion and its position inside the pipeline. This device is commonly referred to as pig. The Brazilian oil company, PETROBRAS, wanting to have the technology of such device to detect corrosion in their oil pipelines proposed to the Department of Mechanical Engineering of the Escola Politecnica da Universidade de Sao Paulo a joint project to the development of a pig that could run uninterruptedly in long oil pipelines gathering corrosion data for the preventive maintenance of their oil pipelines. The result of the project was the development of an ultrasonic pig with 16 ultrasonic transducers with on-board energy system and acquisition and storage systems. Also, comprised in the presented solution was the development of a software to analyze the collected data and give the position of the corrosion spots along the pipeline. This paper presents in detail the implementation and design issues related to the development of the ultrasonic pig. Also, some experimental data will be shown as confirmation of the effectiveness of the developed system.

Monitoring of flexible oil lines using FBG sensors

Thorough the last two decades, oil and gas reservoirs discovered and developed in deep and ultra deep waters have continuously posed challenges to petroleum exploration and production activities in offshore basins. Maintaining optimum flow rates of oil and gas from subsea wellheads to surface processing facilities demands new technological solutions for petroleum companies operating in such frontiers. Integrity assurance of structures, equipment, and flow lines plays a major role in maximizing offshore production systems availability while at the same time keeping safety, operational, and environmental risks at minimum levels. In this scenario, implementation of permanent health monitoring solutions must take into account the environment of oil and gas production facilities, where installations in hazardous classified areas require explosion and fire-proof instrumentation. In this context, optical fiber sensors offer an attractive alternative to electrical sensing technologies, which, until now, have been the primary choice by maintenance personnel at offshore production units.

A robot for offshore pipeline inspection

The robot presented in this paper was designed to find damages to the external sheath of offshore pipelines. The pipeline section subject to inspection is known as “riser” and connects the pipe running on the seabed to the production facility at the platform or “floating production, storage and offloading” ship (FPSO). When compared to the current tools used to perform this work, the main advantage of this robot is to be able to execute the inspection without umbilical cable or operator assistance. The vehicle, called Autonomous Underwater Riser Inspection robot (AURI), uses the pipeline for guidance. A closed feedback loop control system is used to maintain constant speed during the mission. Several sensors provides multiple return conditions for safe operation, such as maximum depth, maximum time or maximum distance. The robot is suited to carry different inspection devices (payloads). The payload for the first prototype consists of four cameras which provide 100% coverage of the external pipe surface. All robot vessels were designed to support up to 100 Bar of pressure, allowing the vehicle to reach a maximum depth of one thousand meters. This paper presents the general concepts of the robot as well as results from the tests in a pool, including some hydrodynamic parameters of the vehicle.

New Techniques for Integrity Management of Flexible Riser-End Fitting Connection

As the operation water depth for flexible risers increases, the stress level in these structures also increases. This higher load, associated with stress concentration close to end fitting, can induce fatigue damage in tensile armors at riser top section. Progressive rupture of wires due to fatigue, which may be accelerated by corrosion, is an important indication of deterioration in riser-end fitting connection, and has become a typical failure mechanism for flexible riser top section. In order to mitigate the progression of these damages, apart from the inspection program and the surface monitoring procedures already implemented, techniques for the early detection of failure mechanisms at the riser-end fitting connection, specially at the tensile armors, are under development. This paper describes and evaluates these techniques, such as visual torsion monitoring, detection through acoustic emission of tensile armor wire rupture, electromagnetic tensile armor stress measurement and monitoring through optical fiber sensor extensometers, as well as reports the results obtained from field experience.Copyright

Flexible riser monitoring using hybrid magnetic/optical strain gage techniques through RLS adaptive filtering

Flexible riser is a class of flexible pipes which is used to connect subsea pipelines to floating offshore installations, such as FPSOs (floating production/storage/off-loading unit) and SS (semisubmersible) platforms, in oil and gas production. Flexible risers are multilayered pipes typically comprising an inner flexible metal carcass surrounded by polymer layers and spiral wound steel ligaments, also referred to as armor wires. Since these armor wires are made of steel, their magnetic properties are sensitive to the stress they are subjected to. By measuring their magnetic properties in a nonintrusive manner, it is possible to compare the stress in the armor wires, thus allowing the identification of damaged ones. However, one encounters several sources of noise when measuring electromagnetic properties contactlessly, such as movement between specimen and probe, and magnetic noise. This paper describes the development of a new technique for automatic monitoring of armor layers of flexible risers. The proposed approach aims to minimize these current uncertainties by combining electromagnetic measurements with optical strain gage data through a recursive least squares (RLSs) adaptive filter.

Circumferential SCC in Pipeline Due to Land Creeping

This paper describes the analyses performed in a circumferential rupture that occurred in a pipeline crossing a high slope region in the Southern part of Brazil. The pipeline was made of API 5L-X46 steel, coal tar coated, and has been in operation since 1977. The failure occurred after a period of heavy rains and was clearly associated to land creeping. The fracture occurred in parent metal 2770 mm away from the nearest circumferential welding. This fracture initiated in an approximately 3×70 mm external surface crack. Besides, several secondary parallel cracks were detected at a 6 o’clock position.Copyright

Ultrasonic measurement of micrometric wall-thickness loss due to corrosion inside pipes

Pipelines are subject to wall-thickness loss due to corrosion along time. Ultrasonic pulse-echo techniques are widely used for thickness measurement achieving a high resolution. However, the precision of measurement is highly dependent on temperature and on the ultrasonic system. This work presents the temperature correction strategy of an ultrasonic measurement system to obtain one micron accuracy, in a pipeline corrosion long-lasting monitoring. The proposed technique is based on the fact that the coupling layer has a constant thickness during a long period of time (year) and can be used in the same way as a thermometer to compensate the changes in the ultrasonic velocity. The variation of time of flight in the coupling layer can relate to the variation of time of flight in the pipe wall to construct a correction polynomial. This function compensates the variation on propagation velocity and thermal expansion. The results are experimentally evaluated using an array of eight ultrasonic transducers (5 MHz, 10-mm diameter) operating in pulse-echo mode with a water coupling layer. Long term corrosion tests were conducted using an electrolytic bath along ten months. Good agreement was found between the theoretical corrosion rate and the results of the ultrasonic measuring system.

Optical profilometer using laser based conical triangulation for inspection of inner geometry of corroded pipes in cylindrical coordinates

An axis-symmetrical optical laser triangulation system was developed by the authors to measure the inner geometry of long pipes used in the oil industry. It has a special optical configuration able to acquire shape information of the inner geometry of a section of a pipe from a single image frame. A collimated laser beam is pointed to the tip of a 45° conical mirror. The laser light is reflected in such a way that a radial light sheet is formed and intercepts the inner geometry and forms a bright laser line on a section of the inspected pipe. A camera acquires the image of the laser line through a wide angle lens. An odometer-based triggering system is used to shot the camera to acquire a set of equally spaced images at high speed while the device is moved along the pipe’s axis. Image processing is done in real-time (between images acquisitions) thanks to the use of parallel computing technology. The measured geometry is analyzed to identify corrosion damages. The measured geometry and results are graphically presented using virtual reality techniques and devices as 3D glasses and head-mounted displays. The paper describes the measurement principles, calibration strategies, laboratory evaluation of the developed device, as well as, a practical example of a corroded pipe used in an industrial gas production plant.

Autonomous Underwater Riser Inspection Tool

The inspection of the vertical section of an offshore pipeline, known as the riser, plays a critical part of any integrity management program. This section connects the pipe that runs on the seabed to the production facility, be it a floating platform or a FPSO. Hanging from the platform over deep waters, risers are subject to very extreme operating conditions such as high loads and underwater currents. Corrosion, fatigue, abrasion and damages caused by stray object collisions are factors that must be taken into account, so that oil and gas production are not compromised. A flexible pipeline, a well engineered solution used in most riser installations, provides high reliability while requiring little maintenance but, in spite of advances in project and installation, the inspection of riser pipelines is an immature field where technology has not yet met the user’s demands. In the search for better riser inspection techniques, a project was started to design a new inspection tool. The basic concept consists of an autonomous vehicle, the Autonomous Underwater Riser Inspection tool (AURI), that uses the riser itself for guidance. The AURI tool can control its own velocity and is suited to carry different types of inspection devices. The first AURI prototype is designed to perform visual inspection with an built-in camera system, covering 100% of the external riser surface. The AURI can reach water depths up to a thousand meters. It was built with several embedded security mechanisms to ensure tool recovery in case of failure and also to minimize chances of damage to the pipeline or other equipment. It uses two electrical thrusters to push it along the riser. The mission is set to a maximum depth to be inspected and is considered complete when one of the following conditions is met: (1) maximum pressure on depth sensor is reached or (2) the length of the run is achieved or (3) maximum mission duration is exceeded or (4) maximum allowed tilt is detected by the inclinometer. Thanks to its positive buoyancy, the AURI will always return to the surface even if the electronics fail or the batteries get exhausted. This paper presents the first AURI prototype as well as the preliminary test results.© 2010 ASME

Pipeline Inspection Operations With Geometric Pigs: Campos Basin Main Results

The increasing use of geometric pigs in the last five years has significantly contributed to the quality of pipelines in construction, as well as to geometric defect detection, assessment and identification, improving pipeline maintenance and overall quality. Geometric pigs with advanced built-in electronics allow precise defect sizing, helping pipeline integrity analysis. This paper presents actual anomalies detected by geometric pigs through comprehensive assessment and anomaly identification.Copyright