Polarization Characteristics Of Terahertz Waves In Shale

There are abundant shale gas resources with great economic value in China.The development and research of shale is of great significance for oil and gas exploration.With the increasing difficulty of unconventional oil and gas exploration,the study of shale dielectric properties,anisotropy and functional properties is also of great significance to shale exploration.In this thesis,the dielectric properties,optical properties and functional properties of shale have been studied.The anisotropy of invisible layered shale was explored by using Oblique Incident Light Reflection Difference(OIRD)technology combined with deep learning algorithm.The terahertz(THz)wave polarization characteristics of shale were explored by using THz spectrum technology,and its modulation amplitude was improved by various means.The following research results have been obtained:1.The internal defects of organic polymer materials were characterized by THz technology combined with intelligent algorithms.The mechanism of THz wave polarization characteristics was clarified in simulated shale core.The uneven THz absorption along vertical and parallel directions of the bedding structure led to the polarization characteristics of simulated core.2.Potassium feldspar had half wavelength and one wavelength THz wave phase delay at 0.51 and 0.94 THz,respectively.The THz wave birefringence effect of potassium feldspar was resulted from he bedding structure in THz band and the refractive index difference in s and p directions of THz wave.3.The anisotropy of recessive bedding shale was characterized by OIRD technology and convolution neural network algorithm.The THz wave polarization characteristics of shale were affected by the thickness.The largest modulation amplitude of THz wave occured in 1.2-1.4 mm shale.The structure and inorganic mineral composition plaied main role in THz wave polarization characteristics of shale.4.A new method for the detection of trace organics—thermal THz spectroscopic analysis technology(TTA)was proposed.The mechanism of improving the THz modulation performance was clarified in high-temperature pyrolysis shale.The pyrolysis of organic matter and inorganic minerals in shale converted large particles into small particles,which changed the scattering type of THz wave in shale.A multi-layer structure was produced after the pyrolysis,which also led to the improvement of modulation performance.5.The THz wave polarization characteristics of shale can be improved by electric field regulation and the THz wave time delay modulation amplitude can be significantly improved.The shale was briefly polarized under an electric field,resulting in the decrease of its refractive index.Thus the relative time delay was reduced and the transmission capacity of THz wave was improved.