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Oil Well Monitoring by Ultra-wideband Ground Penetrating Synthetic Aperture Radar
Blekinge Institute of Technology, School of Engineering.
2012 (English)Independent thesis Advanced level (degree of Master (Two Years))Student thesis
Abstract [en]

Radar has been used for remote sensing and surveillance for decades. Nowadays radar remote sensing and radar surveillance is used for many different things in the modern society. Radar can sense objects or environments from very long distance. Electromagnetic radar waves can work where and when light cannot. This unique ability of radar made remote sensing techniques available in research and in industrial applications. Radar can operate in any climate and any time of the day. Using ultra-wideband (UWB) pulses for radar in combination with synthesizing apertures, which is so called synthetic aperture radar (SAR), enables radar to produce high resolution images in both range and azimuth directions. The work presented in this thesis uses SAR for oil well monitoring. SAR is seen as a good candidate to follow oil well changes in time by means of maintenance. Other methods to perform this task have been introduced and implemented but they are not able to produce high resolution images from the oil well. Using SAR for oil well monitoring provides high resolution images of oil well walls in order to detect the asphaltene or bitumen. The resolutions of images can be enhanced by using UWB signal and SAR processing. Asphaltene and bitumen are the heavy components of crude oil and capable of blocking the porous media in oil well. The porous media is called damaged material when its holes are blocked by asphaltene or bitumen as it cannot pass the oil any more. A decrease in oil production is the consequence of this phenomenon. If these materials can be detected at very beginning stages of formation, addition of solvent at the location of the detected materials can be very helpful for oil well maintenance. This thesis is divided in to two parts. The first part focuses on SAR processing whereas the second one aims at antenna design and fabrication to work in a ground penetrating synthetic aperture radar (GPSAR) system. In the first part, an oil well model based on the measured electrical properties of common oil well materials is introduced. SAR processing is then applied to the oil well model to reconstruct SAR image of the oil well. The resulting SAR image is shown to provide high resolutions so that different materials can be distinguished. In the second part, a modified TEM horn antenna for SAR is designed, simulated and fabricated. The antenna is customized to work in oil media. A new profile model for the TEM horn antenna is proposed that modifies the antenna radiation pattern in the design. The antenna measurements are shown to be in agreement with the simulated results.

Abstract [sv]

Oil well monitoring is very important for the oil and gas industry. Therefore in this thesis, a new ultra-wideband (UWB) ground penetrating radar (GPR) system for detection of near wellbore formation damage is introduced. The proposed GPR uses ground penetrating synthetic aperture radar (GPSAR) and a new developed transverse electromagnetic (TEM) horn antenna to increase GPR image resolution. The work has therefore been divided in two parts of synthetic aperture radar (SAR) processing of ground penetrating data and TEM horn antenna design as UWB transceiver for this system. In the first part GPR data is processed with SAR to achieve better horizontal resolution. The results show that the combination of GPR and SAR is a good solution to achieve high resolution images in both range and cross range (directions of the oil well axis). This method is very beneficial in borehole radar imaging where use of a big antennas to achieve high resolution in cross range direction is not feasible. In the second part of thesis, a TEM horn antenna is designed that fits into the oil well. A new profile for TEM horn antenna is introduced to remove the ripples and dips in antenna mainlobe radiation pattern which is normally a problem with this type of UWB horns. The designed antenna is simulated and fabricated and the measurement results fully verify the simulation results. Future work will be on extracting materials electromagnetic properties like dielectric constant and loss tangent by invers scattering techniques from the recorded data by the GPSAR system. This work would be very interesting for companies who are working on geology and underground material investigation. In future work the antenna design will be very important since the antenna is one of the most critical parts of UWB radar systems. Therefore, investigations of antenna impulse response enhancement and antenna performance estimation will be made.

Place, publisher, year, edition, pages
2012. , 73 p.
Keyword [en]
Ground penetrating radar, Synthetic aperture radar, Ultra-wide-band radar, Ultra-wide-band horn antenna
National Category
Signal Processing Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:bth-3797Local ID: diva2:831109
Available from: 2015-04-22 Created: 2012-08-29 Last updated: 2015-06-30Bibliographically approved

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