AN INTEGRATED APPROACH OF PETROPHYSICS AND ROCK PHYSICS MODELING USING 3D SEISMIC DATA OF DULJAN AREA, LOWER INDUS BASIN, PAKISTAN

Abstract

The lower Indus Basin has a huge significance and a great potential to produce oil and gas in Pakistan. To determine its hidden certainties, the present study on Duljan area has been carried out using advanced techniques of petrophysics, seismic inversion, and Rock physics modeling. The sands of Lower Goru have been assessed by utilizing a variety of seismic, well logs, core and field analysis that showed spatial heterogeneity in composition, making it difficult to discriminate between facies and the kind of fluid content present in the reservoir interval. In this study, 3D seismic cube has been used along with the data of two wells i.e., Duljan East-01 and Duljan Re-entry 01 well residing in that field to evaluate reservoir behavior. Seismic data has been used to delineate the sub-surface structure which shows that the horst and graben structures were formed by extensional tectonics in the area. C interval of Lower Goru Formation has been evaluated as clean intervals of considerable reservoir thickness by using Petrophysics. Elastic properties such as acoustic impedance, density and velocity from seismic data set have extracted by applying seismic inversion technique. This technique also has facilitated in the reliable interpretation of important geological and petrophysical boundaries in the subsurface by giving acoustic impedance contrast for both ‘A’ and ‘C’ intervals of the utilized wells. Computation of the set of modelled logs for the reservoir interval of Duljan area by using rock physics modeling. The rock physics modeling has used various input parameters i.e., lithology, porosity percentage or fluid content to evaluate reservoir interval. The resulted models for A and C interval of both wells have been shown good consistencies between measured and predicted properties for the zone of interest. The cross-plots generated by rock physics modeling clearly separated and distinguished the litho-fluid zones such as wet sand interval, gas sand interval and shaly units, with proper alignment which were not obvious by only using conventional petrophysical cross-plots.