Seismic Response Analysis Of Deep Sag-clastic Reservoirs Based On Petrophysical Modeling

After years of exploration and development in China's oil fields,most shallow reservoirs have been proven and exploited.However,the demand for oil has not decreased,but has increased.As a result,the exploration and development of deep clastic rocks has become an inevitable trend.Clastic rock exploration has become one of the key exploration targets of oil fields.The influence of compaction,pressure dissolution and cementation on the deep sagclastic reservoirs result in a large deviation between the various types of petrophysical parameters calculated in the actual collected seismic data and the reservoirs.These factors constrain the prediction accuracy of the deep sag-clastic reservoirs.This paper relies on the clastic reservoir in the central depression of a basin in the west.There is a clastic rock deep belt in this area.The effects of pressure and the presence of thin-layer structures and thin interbedded structures make rock physics modeling difficult in the region.This paper summarizes the geological features of clastic reservoirs,compares the commonly used petrophysical modeling methods,and finds the most suitable modeling method for deep sag-clastic reservoirs.Established a dry rock model that considers the effects of pressure,and do fluid replacement on this model.The effects of rock physical parameters such as pressure,porosity and saturation on rock elastic parameters are discussed.The log data is combined with the petrophysical model to predict the missing shear wave velocity.The difference between reservoir and surrounding rock is clarified,and a petrophysical prediction template based on the characteristics of the study area was established.Firstly,a targeted geophysical model is established.AVO analysis is carried out by reflectivity forward modeling to investigate the effects of sand-ground ratio,inter-layer number and layer thickness on reflection characteristics.Then,a geologically significant geophysical model is established,and the effects of saturation,porosity and pressure on the reflection characteristics are analyzed by finite difference forward modeling.Combined with logging data to verify the correctness of previous analyses.After research,a variety of predictive quantities with various influencing factors are obtained,and the influences of rock physical property parameters,uneven distribution of rock pore fluids,and pore fluid type changes on rock elastic modulus are obtained.The influence of the ratio,the number of layers and the thickness on the reflection characteristics of the interbed structure,and the influence of saturation,porosity and pressure on the reflection characteristics of different geological structures are analyzed.