Wide Azimuth Data - How To Maximize Their Value for a Tight Gas Play, Onshore Oman

Petroleum Development Oman LLC is increasingly focusing towards tight plays as conventional hydrocarbon plays have become more mature. Amin reservoir is such a play consisting of alluvial sandstones with high net-to-gross but low porosity. However, one of the key wells within the area has encountered high overpressures with good porosity and prompted a quantitative interpretation study to identify sweet spots for drilling and to map out fracture networks.

This paper is divided into two sections. Part I discusses the conventional deterministic AVO inversion and part II describes the application and interpretation of the near offset Rüger equation and simultaneous azimuthal inversion. The outcome from part I resulted into a predictive porosity map, confirmed by a blind well. Therefore, the porosity map is used to guide the porosity distribution in the static model. Another attribute is a Poisson’s ratio map providing additional information about the rock matrix of the reservoir and possible fractures within. Results from part II are encouraging and confirmed by surrounding wells but qualitative. More intriguing is the comparison between Poisson’s ratio and tangential weakness. Low Poisson’s ratio in combination with increased tangential weakness could indicate better fraccable reservoir. To support this observation, more calibration data is currently being acquired.