Improving the vibrator ground force on unconsolidated ground surfaces in Middle East desert environments

Abstract

Seismic vibrators have become the preferred sources for land seismic exploration. The objective of the vibrator is to transmit a known and spatially stable source wavelet so that any variations in seismic reflection data can be used to estimate the rock properties and geometries of subsurface geology. Unfortunately, the spatial variation of the ground surface can impact the vibrator performance. Field tests have revealed that the vibrator ground force decreases dramatically on unconsolidated sandy surface conditions, and the effect increases as the vibrator shakes toward high frequencies. A theoretical study is provided to explain this repeatable phenomenon that is independent of vibrator source control systems. Moreover, a practical solution, “BP control,” remedies this reduction in ground force over unconsolidated surfaces, especially sand, by introducing a new effective baseplate weight factor into the vibrator source controller. Field test results illustrate an increase in vibrator ground force at higher-frequency conditions over unconsolidated sand when implementing this new effective baseplate into the vibrator source controller. This increase in ground force may improve the recoverable bandwidth and lead to higher-resolution seismic images when encountering these surface conditions.