Seismic Quantitative Interpretation of a Gas Bearing Reservoir - From Rock Physics to Volumetric

A complete well-seismic integration project was successfully performed in a gas field located in the Lower Magdalena Basin, Colombia. The reservoir level corresponds to a laterally limited, mixed clastic turbidte system (laminated, shaly sands) which makes prospect identification and delineation difficult. The study can be divided in three phases: well log analysis, seismic analysis and interpretation/integration. Well log analysis included petrophysical volumetric estimation and rock physics modeling. Seismic analyses included gather conditioning and pre-stack simultaneous inversion. The interpretation/integration phase pulled together the results from the phases described above. Based on the rock physics modelling and the rock physics template, there is a clear separation between gas shaly sands and other facies (wet shaly sands and shales) in the Poisson’s ratio vs. P-impedance domain. During the interpretation phase, seismic inversion attributes guided by the rock physics information made it possible to separate the shaly gas sands in order to identify new prospective areas in the field. New successful wells were drilled, validating the workflow.