Rock Physics ‐ Modeling impact of pore fluid, lithology and depth on AVO signatures

Abstract

Summary Elastic properties of rocks are strongly dependent on local geology and can significantly vary within the same sedimentary basin. Both depositional environment and burial history are two critical factors that control the elastic properties of the subsurface rocks, and knowing the impact of these factors on the seismic response may increase our ability to predict hydrocarbon accumulations. The variation of reflection coefficients with source-to-receiver spacing in multi-offset seismic data, known as AVO, often contains critical information about the lithology and the pore fluid in the subsurface. In this paper, we discuss rock properties analysis of sands and shales in a deep water setting and the use of trend based rock physics modeling approach to model the clean sand, pure shale and shaly sand log response. Moreover, practical aspects of AVO modeling given both, a shalesand interface as well as log data and model response will also be discussed. The expected AVO response as a function of lithofacies, pore fluid, burial depth as well as the AVO approximation used in predicting the AVO response will be the focus of this discussion. Six wells from deep-water Angola are the basis for this work with the goal of assisting exploration activities in the area.