Application of Seismic-Resistivity Conversion to Reservoir Characterization: An Advanced Study

Denny M.F. Mendrofa¹*, Ahmad Naveed², and Richard Hayward^1
1Premier Oil, Indonesia
²Premier Oil, UK
*[email protected]

In the last decade, several formulations for reservoir characterization have been introduced that involve optimizing the seismic amplitude information associated with various types of pre and post stack seismic data. The purpose of all such techniques is to predict, away from control points, for example reservoir fluid or petrophysical properties by calibrating seismic amplitudes. This presentation describes a method for converting acoustic impedance to resistivity with an example of its application to real data. The method utilized the seismic amplitudes of near-offset stacked data to predict fluid type in saturated rocks. The resulting predicted resistivity distribution was then compared to the observed resistivity in blind wells by constructing a resistivity section. It is based on Gassmann theory that the shear wave relatively does not change as significantly as compressional wave when a small portion of gas replacing water in a porous rock. We inferred that the acoustic impedance generated from nearly normal-offset seismic data was taken to represent fluid composition, whilst the elastic impedance in the mid and far offset seismic data is less influenced by fluid content. In this study, we applied the conversion formula (Mendrofa, 2006) to a shaly sand gas reservoir to study the lateral reservoir and hydrocarbon distribution with a satisfactory result of quantitative Resistivity and Net pay volumes. In addition, given a sufficient resistivity contrast, we see a potential for this technique to discriminate between oil and brine by its use in classifying the resistivity cut-offs for gas, oil and brine.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain