Oil Well Monitoring by Ultra-wideband Ground Penetrating Synthetic Aperture Radar

Abstract: 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.