Nodal land seismic acquisition: The next generation
Within the last two years six new land seismic nodal acquisition systems have been launched, a pace unmatched even during the oil boom of the late 2000s/early 2010s. Any acquisition system that utilizes recording instrumentation that does not incorporate cables is often referred to as a nodal system. Some instruments, however, are beginning to blur what initially appears to be a clear boundary. For example, the U-Node system from Seismic Instruments utilizes a node that records data from up to 24 different channels that can then be stored locally or transmitted via Wi-Fi to a central system. The reduction in cabling, which is usually cited as the core advantage of nodal recording, is therefore limited to the backbone connecting the central recording system to the field recording units. In this paper we will concentrate on nodes that are designed to record data from a single point and are thus typically limited to six or fewer channels. Over the history of nodes there have been six major categories developed (listed roughly in the order of their introduction): 1. Delayed data – Data is stored on the node and then transmitted after each shot, or stacked series of shots, is completed. 2. Remote-controlled – data is recorded internally but recording is initiated via radio messages. 3. Remote-synchronized – data is recorded continuously but the timing signal is issued via radio. 4. Real-time data – Data is transmitted in real-time. 5. Real-time QC – Status and or quality control data is transmitted in real-time. 6. Blind – the node records data internally and does not provide status or QC information in real-time. In this article we look at how nodal systems have evolved over the last 50 years. We begin with a historical overview starting from the early 1970s finishing in 2015. We then introduce the latest nodal systems and look at the implications of their use for seismic survey acquisition logistics. Finally, we will discuss the implications of these new systems and make some suggestions about where future developments should lie.