وارون سازي داده هاي لرزه اي سه بعدي پيش از برانبارش در يكي از مخازن هيدروكربني ايران براي تخمين مدول هاي ژئومكانيكي ديناميك

Estimation of geomechanical parameters including Youngʹs modulus, Poissonʹs ratio, brittleness index, an‎d rock hardness plays an important role in understan‎ding the mechanical behavior of rocks, assessing reservoir quality, an‎d designing drilling operations an‎d hydrocarbon field development. Since direct measurement of these parameters is only feasible at the wellbore location, the utilization of seismic data an‎d inversion methods as an effective tool for extending this information throughout the reservoir has gained particular importance. The objective of this research is to estimate geomechanical parameters using three-dimensional seismic data inversion before stack in the Hendijan field. In this study, following the preparation of seismic data, the velocity model was prepared using P-wave velocity logs corrected by check-shot data. Subsequently, angle stacks were generated an‎d a low-frequency model was constructed based on well information an‎d geological horizons. To perform inversion, statistical wavelets an‎d wavelets extracted from the well were compared with each other, an‎d considering higher correlation coefficient, the wavelet extracted from the well was selec‎ted for conducting model-based inversion. Subsequently, elastic parameters including P-wave impedance, S-wave impedance, density, an‎d P-wave to S-wave velocity ratio were estimated, an‎d based on these parameters, geomechanical properties including Youngʹs modulus, Poissonʹs ratio, brittleness index, an‎d Brinell hardness number were calculated. Validation of the results using well HD-06 data an‎d analysis of the correlation coefficient between real seismic data an‎d synthetic seismic traces demonstrated favorable correspondence of the inversion model with real data. Furthermore, the comparison of geomechanical parameters resulting from inversion with values calculated from well logs confirmed the appropriate precision of the model in reconstructing variations of mechanical properties of rocks. In particular, Youngʹs modulus an‎d Brinell hardness number possessed higher correlation, whereas Poissonʹs ratio exhibited greater dispersion due to higher sensitivity to seismic data quality an‎d resolution limitations. The results indicated that the Asmari formation possessed lower density an‎d impedance compared to underlying units an‎d from the perspective of elastic properties, offered more favorable conditions for reservoir development. The relatively high brittleness index (approximately 70 to 90 percent) an‎d appropriate Youngʹs modulus values (in the approximate range of 35 to 45 gigapascals) in this formation were indicative of the existence of natural fractures an‎d appropriate reservoir potential. In contrast, in the Jahrum-Pabdeh an‎d Gurpi-Illam formations, an increasing trend in density, impedance, an‎d P-wave to S-wave velocity ratio was observed, which demonstrated increasing rock compaction an‎d gradual deterioration of reservoir quality. The Kazhdomi formation also, with the highest Poissonʹs ratio (0.35 to 0.40) an‎d the lowest brittleness index (35 to 45 percent), accompanied by lower Youngʹs modulus (20 to 25 gigapascals) an‎d higher Vp/Vs ratio (1.85 to 1.95), exhibited ductile behavior an‎d was eva‎luated as an appropriate seal rock for maintaining reservoir pressure an‎d preventing fluid migration. In general, the results of this research demonstrate that three-dimensional seismic data inversion before stack is a reliable method for estimating elastic an‎d geomechanical parameters an‎d extending limited well information to the entire reservoir volume. The estimated parameters can be applied in lithology analysis, identification of fracture-prone zones, assessment of reservoir quality, an‎d planning of field development an‎d production operations.

محمد ابطحي فروشاني , حمزه صادقي سرخني

نادر فتحيان پور , عليرضا باغبانان