Using modern processing technology to improve signal to noise ratio, a Perth basin 3D land case study

Abstract

The processing of two 3D land Perth basin seismic survey gave us the opportunity to apply and test some of the modern processing technologies available. The technologies we explore through those examples take place in the early steps of processing, later in the sequence before imaging and at the imaging level itself. For each of the steps we performed comparisons with more conventional technologies. Especially with land data, often acquired with poor signal to noise ratio, it is important to remove noise in the early phases of the processing sequence. Groundroll in particular needs special attention as the characteristic features of Groundroll (low frequency, highly energy) noise in the data can hide near offset reflection data that contains important signal. In this article we review a new adaptive method for Groundroll attenuation that could potentially better attenuate noise and at the same time better preserve signal. 3D land datasets are also often characterized by a wide range of azimuths being present in the data. This differs from most 3D marine acquisitions that are (with the exception if multi and wide azimuth surveys) mostly acquired in a narrow azimuth fashion behind the boat even with the presence of a wide array of streamers. Those wide azimuths represent a challenge for conventionally sorted data regularization prior to imaging. In this article, we analyze the results of using offset vector tile (OVT) gathers regularization and OVT gathers in the imaging process against the more conventional offset volume method. Finally, the use of Controlled Beam Migration (CBM) is compared to a more conventional Kirchhoff imaging process. Controlled Beam migration has often been used to image steep dips and provide multi arrivals in extremely complex environments. However in relatively low signal to noise ratio environment like the Perth basin we have seen in the second case study that this imaging technique could potentially bring better results than the conventional Kirchhoff.