Seismic surveys using autonomous Ocean Bottom Nodes (OBNs) are becoming an increasingly popular technique to acquire reservoir imaging data. Sonardyne’s acoustic navigation and data telemetry technology can be used to support all stages of these operations. When deploying and recovering nodes, their position can be accurately determined using Ranger 2. During data collection, Sonardyne’s wireless, high-speed acoustic communications technology uploads status data to the surface enabling operators to check that each node is functioning correctly.

Installed on the surface vessel, the Ranger 2 USBL (Ultra-Short BaseLine) positioning system tracks the position of the ROV deploying each node and also the node basket from where the nodes are withdrawn. As the ROV places each node on the seabed, a highly accurate position fix for the ROV and therefore the node, is recorded.

Ranger 2 builds on the simplicity and reliability of Sonardyne’s popular Ranger 1 system but adds support for the latest sixth generation (6G®) acoustic instruments and Wideband®2 signal architecture. 6G systems offer higher precision acoustic ranging, faster data telemetry and hardware that is easier to set-up and operate even in the most challenging subsea operating environments.

Transfer of node quality control (QC) information is performed using a low-power acoustic modem attached to each node. These modems communicate with a local subsea data collection transponder anchored several metres above the seabed. Multiple transponders form an acoustic network that autonomously hops the QC data, and on command, uploads it to a waiting surface vessel located anywhere within the survey area. Once received, the status monitoring software shows each node’s operating status. A ‘traffic light’ display allows operators to check the status of the entire node network and identify problems at a glance.