UNITE cableless system and its real-time capabilities

Land recording systems are composed of many receiver-points connected by cable to a central unit for synchronization, real-time transmission and quality control of the seismic data. With the growing amount of channels in use and the exploration of frontier areas cable systems may become less productive. In difficult access or environmentally sensitive areas, they are complemented or replaced by cableless systems (D. Mougenot, First Break, February 2010). Such systems are not new, but they used to be expensive and quite difficult to synchronize using conventional radio antennas. Since 2005, with the availability of low cost low power consumption GPS chips used for synchronization, cableless systems have become more affordable and reliable. Today, they offer a cost effective alternative to the cable systems in some areas. In the Americas, the use of cableless systems is growing very fast while in other countries like China, India, Russia and the Middle East their use is still in infancy. One of the reasons is that the oil companies are still reluctant to perform acquisition without having the benefit of the (near) real-time data transmission, like they used to have with the cable systems. Therefore, the challenge to further expand the market share of cableless systems is to provide them with some real-time capabilities as made it possible by the use of the WiFi technology. The UNITE cableless system as developed by Sercel was the first to include both GPS and WiFi capabilities. Depending on client requirement, the contractor can select a totally blind acquisition in which the Remote Autonomous Units (RAU) are continuously recording GPS-time-stamped data that will be recovered later on. This assumes a very high reliability of the equipment. More often than not, the client feels more confident when it is possible to control some of the RAU's located around a WiFi antenna to check in real-time GPS synchronization and seismic data quality. For particular operations like to record the micro-seismicity during a frac job, it may be even necessary to get all data in real-time via a Mesh network. Thanks to its flexibility in the data recovery, Sercel UNITE can easily adapt to all requirements. In addition, it offers a large choice in sensor configuration and battery autonomy.