Developments in Nodal Data Acquisition in the Transition Zone and Shallow Water

Single-sensor seismic nodes enable cost-effective seismic data acquisition at the high spatial receiver density demanded to meet current seismic data imaging quality requirements. Large-scale seismic onshore surveys very often include transition zone (TZ) areas of varying size and water depth. These areas include tidal zones, river estuaries, marshes, swamplands, and beaches, etc. This is particularly the case as the O&G industry looks to secure the efficiencies of infrastructure-led exploration (ILX) to develop new finds close to existing infrastructure which is often in coastal areas.

A primary challenge for onshore nodes is their dependence on GPS timing signals, which cannot be received when a node is submerged. On the other hand, Ocean Bottom Nodes which do not rely on GPS for timing synchronisation are not practical and too costly for deployment in TZ environments. The use of deployment methods for modern nodes similar to those used for the first generation of cable-free recording systems enables seamless data acquisition from land to shallow water. Thus, avoiding both unnecessary omissions in onshore surveys due to inland water bodies and bridging the gap from the onshore to marine data acquisition. The authors discuss various deployment methods, with examples from recent successful 3D surveys.