Applications Of Lambda Rho And Mu Rho Inversion For Characterization Of Lower Goru C Sands

Abstract

The exploration and exploitation of hydrocarbons as the main source of energy is vital for the economy of any country. Every sedimentary reservoir requires a detailed analysis prior to extraction for optimal production. The main objective of this research is to find and spatially characterize the prospect zones in the sands of Lower Goru Formation in Gambat area, geographically located about 42 km south-west of the producing Sawan Gas field. The study for the structural interpretation and reservoir analysis of Gambat area has been conducted using 3D seismic data and well log analysis. Horizons have been marked along the formation tops based upon the seismic-to-well-tie. Time and depth contours maps have been generated for the formations of interest to analyze their spatial extension and regional structures. Model-based inversion has been applied to the 3D seismic data for estimation of acoustic impedance values. A regression line-based equation has been developed for the cross-plot of effective porosity and impedance values to spatially mark the distribution of effective porosity. Furthermore, the Lambda-Rho (λρ) and Mu-Rho (μρ) sections and their respective slices have been developed to analyze to fluid content and lithology within the zone of interest of the C interval. The seismic interpretation shows the presence of normal faults indicating the extensional regime. The petrophysical analysis indicates a zone of interest in the C sand interval of the Lower Goru Formation with shale volume of 39.4%, and effective porosity of 12.6%, and water saturation of 12.6% and hydrocarbon saturation is 87.4% This zone is spatially indicated by the low impedance values within the C interval from the results of the model-based inversion. Furthermore, the effective porosity distribution also indicates high porosities along the zone of interest throughout the interval. The borehole-derived porosity and the porosity values determined from post-stack inversion at the specified well locations are very close indicating the accuracy of the applied technique. The presence gas along the zone of interest is confirmed by the low λρ values with the moderate values of μρ depicting the presence of sand lithology