Seismic and geomechanical characterization of Asmari formation using well logs and simultaneous inversion in an Iranian oil field

This paper presents a case study on the application of simultaneous inversion (SI) technique and well log analysis to accurately seismic-geomechanical characterization of Asmari formation in an Iranian oil field. To achieve this goal, a one-dimensional (1D) prediction of geomechanical properties such as Young's modulus (E), bulk modulus (K), shear modulus ([Formula: see text]), Poisson's ratio (PR), Vp/Vs ratio and brittleness (BRI) was first generated from the analyzing the well log data. In the next step, the spatial distribution of the geomechanical parameters in the reservoir area was predicted on the basis of the results of the simultaneous inversion. Lithological facies discrimination and fluid detection of the Asmari formation were performed using simultaneous inversion of pre-stack seismic data and conventional cross-plotting analysis of well data. To accomplish this objective, elastic and geomechanical parameters were cross-plotted against conventional petrophysical logs along with BRI, water saturation (Sw), gamma ray (GR), acoustic impedance (Zp), [Formula: see text], and lithology logs such as quartz and calcite volumes. As a result of this work, two reservoirs were identified in the Asmari formation: sandstone and carbonate. The carbonate reservoir consists predominantly of calcite and dolomite, with minimal shale content, while the sandstone reservoir is mainly composed of shale and contains less quartz. In addition, the carbonate section within the Asmari formation exhibits better reservoir quality due to lower water saturation and higher porosity compared to the sandstone zone. To determine the type of fluid in the Asmari formation of the studied oil field, LMR (lambda-mu-rho) scatterplots were employed in both well and seismic domains. The findings reveal that the sandstone reservoir in the Asmari formation is water-saturated, while the carbonate reservoir is oil-saturated. Furthermore, a gas cap is present at the top of the Asmari formation.