Fractures Robots (FracBots) are underground IoT (internet of things) wireless sensor nodes designed to be deployed in oil/gas reservoirs to map hydraulic fractures (HF) and monitor in real-time main reservoir parameters including pressure and temperature in real-time. A significant amount of FracBots will be injected inside hydraulic fractures immediately after conducting the fracturing job to gain the required data. They will launch the network connectivity in a fashion of FracBot-to-FracBot to collect, exchange data and transmit it to the base station installed in the wellbore. FracBots technology employs the same concept of the wireless underground sensor network (WUSN), a very capable technology for the applications in hydraulic fractures network. However, developing such technology is exceptionally challenging due to many environmental complications. The main challenges are severe environment, size, and energy limitations which contribute heavily to destroying the quality of the underground wireless communication link. FracBots technology comprises a gateway, a base station (BS), and FracBots. The main role of the BS is to transfer power to FracBots for charging purpose, gather data from FracBots, and finally transmit data to a gateway that send them to a centralized computer for further processing. The function of FracBot nodes is to sense the required data, send it wirelessly among them in multi-hop fashion and then communicate data to BS.
This paper discusses the available wireless communication techniques including electromagnetic waves (EM) and magnetic induction (MI) wireless communication that might be suitable candidates for hydraulic fractures environment. They are compared in terms of the path loss model, path loss parameters, and the advantages and disadvantages of each technique. Moreover, we provide several simulations showing the importance of omnidirectional antenna and the effect of an alignment angle (between the axes of transmitter and receiver) on the path loss of the MI network. Also, we analyze the environmental effects on the path loss inside hydraulic fractures. After studying both EM and MI techniques in fractures environment. We found that the heterogenous environment stiffly influences the EM and MI communications inside hydraulic fractures in oil reservoirs. A hybrid solution that combines both EM and MI communication technologies will be very suitable for such an environment.