3D Seismic Prestack Inversion for Predicting Fracability Attributes - A Case Study in North Kuwait

The recent exploration focus in Kuwait has expanded from finding conventional, structural traps to unconventional reservoirs. One of our target reservoirs in the study area of North Kuwait is the Najmah Formation. The Najmah reservoir is mainly unconventional, organic-rich shale, a highly fracture-enhanced reservoir. Historically, our exploration focus has been on the 4-way closures with indication of fracture zones. To explore for hydrocarbon potential in low structural areas with less natural fractures, there is a need to map the fracability of the unconventional reservoir. This abstract describes the workflow for a prestack simultaneous inversion, to estimate seismic fracability volumes using mainly the LambdaRho vs. MuRho crossplot method. Detailed well tie analysis was carried out for wells with petrophysics and rock physics editing applied. Stable wavelets were obtained for the simultaneous inversion. The inversion results (P-Impedance, S-Impedance) were quality checked by comparing to well impedance logs, and the results are reasonable. Seismic fracability attributes (LambdaRho, MuRho) were computed using P-Impedance and S-Impedance as input. The thickness of brittle Najmah shale was estimated, and the exploration area was highlighted, targeting thick organic-rich shale for potential application of the hydraulic fracturing technique.