Seismic source comparison in Surat Basin, Queensland

Abstract

Onshore Oil and Gas exploration activities are increasingly moving toward environmentally sensitive and urbanised areas. Site access, work permits and approvals are becoming increasingly complex for seismic exploration within such areas. Seismic industry is evolving new technologies for conventional and unconventional seismic sources to accommodate the special challenges for exploration within sensitive areas; without compromising data quality and even stepping further to improve imaging quality of the acquired seismic data. Deployment of a seismic source type (dynamite, vibroseis, or weight drop) and seismic source effort is directly related to the environmental/access requirements, surface conditions and the geophysical/geological framework of the survey area. Decision making on seismic source efforts, i.e. source type/size, number of units, source array, etc. requires comprehensive testing and evaluation at the project's start-up stage to optimise the seismic source. Historically, seismic source efforts are biased toward deploying the highest possible efforts that is economically viable and logistically practical. In many cases, a higher seismic sources effort doesn't necessarily produce a superior seismic data quality. Seismic data acquisition parameters testing such as signal to noise ratio, frequency bandwidth, imaging depth, resolution, offset ranges and source strength are usually the driving factors when deciding on the seismic source for a particular survey. Planning and implementing data acquisition parameters testing for a survey needs to address geophysical implications, in addition to the feasibility factors of the operation such as survey duration that impact the economics of a project. This case study shows the methodology, analyses and results of seismic source optimisations from 2D and 3D seismic exploration programs in Australia for conventional Vibroseis and synchronised electromagnetic impulse source 'onSEIS'. Seismic signals from these surface sources were also compared with existing dynamite seismic data.