Prediction of reservoir properties using the RDQ crossplot workflow

We develop the rotated distance and quadrant (RDQ) crossplot, an innovative alternative to conventional amplitude variation with offset (AVO) analysis using amplitude versus gradient (AB) crossplots. This new display is made possible through the integration of the distance and quadrant trace attributes and offers significant advantages over traditional methods. The RDQ crossplot reduces shale data point overprinting on the wet and gas sand clusters, better separates the lithology and pore fluid points, and analyzes all seismic trace samples. Unlike AB crossplots, which require the specialized processing and conversion of seismic amplitudes, the RDQ workflow uses readily available near and far partial-stack seismic sections as input, expediting the AVO analysis. An AVO catalog of well-log suites and their synthetic modeled seismic traces are used to develop and test new theories, revealing linear trends in RDQ crossplot displays that correlate with the variations in thickness, porosity, lithology, and pore fluid. A new seismic trace attribute, DQ⊖px, is derived from the RDQ crossplot and used to delineate fluid types and augment lithology predictions better. We determine a DQ⊖px seismic display for a dim spot, an AVO class 1 sand model, revealing a hydrocarbon fluid contact not visible on stack seismic sections. In addition, a Signed Half Isochron preconditioning filter is introduced to distinguish between sand and shale lithologies. The RDQ workflow and crossplot represent a significant advancement in seismic AVO interpretation and reservoir characterization, allowing for the earlier integration of geology, petrophysics, and basin properties.