ANALYSIS OF THE MAIN FACTORS AFFECTING 4D CONVERTED-WAVE SEISMIC FEASIBILITY IN CO2 GEOLOGICAL STORAGE

摘要

The use of 4D converted-wave seismic exploration technology to monitor the safety of CO2 geological storage can fully exploit the characteristic insensitivity to fluids of shear waves to determine individual changes in reservoir pore pressure and fluid saturation. The suitability of 4D converted-wave technology for CO2 geological storage has yet to be assessed; therefore, it is necessary to analyze the feasibility of using 4D converted waves and the factors influencing their use. Based on actual geological data acquired from the Weyburn oilfield, this paper constructs a 4D converted-wave forward model based on well-logging analysis data and numerical simulation data. Using two-layer and wedge-shaped fluid substation models, we analyze the variation in reservoir elastic parameters and fluid parameters with CO2 injection and study the effects of reservoir pore pressure, fluid saturation, and reservoir porosity on 4D converted waves. Using the results, the feasibility of 4D converted waves is studied. The results show that an increase in reservoir thickness is beneficial for 4D converted waves. Changes in reservoir fluid saturation and reservoir porosity affect the results of 4D converted waves, while reservoir pore pressure plays a significant role in changes seen in 4D converted waves. This study lays a good foundation for subsequent interpretations of 4D converted-wave data.