Terahertz Channel Modeling of Underground Sensor Networks in Oil Reservoirs Mustafa Alper Akkaş *‡ , Ian F. Akyildiz † and Radosveta Sokullu * ‡ This work was completed during his stay in the Broadband Wireless Networking Laboratory * Department of Electrical & Electronic Engineering Ege University Bornova IZMIR 35100 TURKEY Email: {alper.akkas, radosveta.sokullu}@ege.edu.tr † Broadband Wireless Networking Laboratory School of Electrical and Computer Engineering School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA Email: {akkas, ian}@ece.gatech.edu Abstract— Future enhanced oil recovery technology requires wireless sensor networks to effectively operate in underground oil reservoirs. In this case, the millimeter scale sensor nodes with the antennas at the same scale have to be deployed in the confined underground oil reservoir fractures. This necessitates the sensor nodes to be operating in the THz frequency range. In this paper, the propagation based on electromagnetic (EM) waves in the Terahertz band (0.1-120.0 THz) through a crude oil/water mixture and soil medium is analyzed in order to explore its applicability in underground oil reservoir assessments. The developed model evaluates the total path loss and the absorption loss that an EM wave experiences when propagating through the crude oil/water mixture and soil medium. Our results show that sensors can communicate successfully for distances up to 1 centimeter and we have determined the existence of two transmission bands, in which the path loss is below 100 dB. Among those, the frequency window, which provides best performance, determined as 70 to 85 THz. Different path and absorption loss schemes considered, which suggests that the 70 to 85 THz band is suitable for sensor communications in a medium of crude oil/water mixture and soil. Keywords: - Terahertz Band; Channel Model; Electromagnetic Absorbance; Crude Oil; Water I. INTRODUCTION Due to its high energy density, easy transportability and relative abundance, oil has become the world's most important source of energy since the mid-1950s. Petroleum is also the raw material for many chemical products, including pharmaceuticals, solvents, fertilizers, pesticides, and plastics; the 16% not used for energy production is converted into these other materials. Petroleum is found in porous rock formations in the upper strata of some areas of the Earth's crust. There is also petroleum in oil sands. Known oil reserves are typically estimated at around 190 km 3 (1.2 trillion barrels) without oil sands, or 595 km 3 (3.74 trillion barrels) with oil sands. Consumption is currently around 84 million barrels (13.4×10 6 m 3 ) per day, or 4.9 km 3 per year. Which in turn yields a remaining oil supply of only about 120 years, if current demand remain static [1]. Figure 1. System architecture of the wireless sensor network for oil recovery The typical oil well illustrated in Fig. 1 is created by drilling a hole into the earth with an oil rig. A steel pipe is placed in the hole, to provide structural integrity to the newly drilled wellbore. Holes are then made in the base of the well to enable oil to pass into the bore. Afterwards, an underground explosion makes a medium of 3-D hydraulic fracture with the size about 100m*3m*1cm (length * height * width). From one hole, water and carbon dioxide is pumped periodically to remove to oil to the ground. Finally, a collection of valves is fitted to the top in order to regulate the pressures and control the flows. As a promising approach to increase the oil recovery factor, deploying sensing agents in the 3-D hydraulic fracture of oil field can enable real-time oil reservoir monitoring by providing comprehensive sensing measurements such as pressure, temperature, oil saturation and fluid type. As illustrated in Fig. 1. The underground sensor network for oil recovery consists of a base station (data sink) located at the wellbore and a large number of wireless sensor nodes deployed in a uniformly distributed manner in the fracture of the oil reservoir. Since the 978-1-4673-0921-9/12/$31.00 ©2012 IEEE Globecom 2012 - Ad Hoc and Sensor Networking Symposium 543