EEI Inversion for Detection and Mapping of Sweet Spots in Tight Gas Glutenites - An Example from Northeastern China

Tight gas glutenite of low permeability exhibits reservoir properties very similar to those of tight gas sandstone, with sweet spots occurring under similar conditions. The sweet spots detection poses a challenge to seismic methods due to low porosity and the stiff framework of tight rocks. In this project, the scheme of extended elastic impedance (EEI) inversion was used to detect sweet spots in tight glutenite bodies of formation A from an oilfield in northeastern China. It is found from the petrophysical study that Poisson’s ratio is a good indicator of gas-bearing reservoirs of relatively high porosity. The EEI curve tuned to Poisson’s ratio with the optimum angle Chi is highly correlated with Poisson’s ratio itself, but changing in sign. Therefore, the EEI volume estimated from AVO inversion can be used to detect sweet spots characterized by higher EEI values. Our results show that detected sweet spots mainly controlled by sedimentary facies are consistent with gas production data.