Research On Multi-wave Field Forward Simulation Of Micro-seismic Model Based On Ray Tracing

The micro-seismic technology which has been widely used for monitoring the production performance in oilfield is gradually maturing nowadays. Compared with other seismic exploration technology, the Micro-seismic fracture detection technology has its own uniqueness which results in two difficult points during data processing and inversion: effective identification of wave field and effective establishment of velocity model. Only when both difficulties are solved will the final inversion results of micro-seismic be more accurate. The imaging for fracturing fracture is carried out by inversion of numerous micro-seismic events to study fracture properties. Based on micro-seismic model, the forward simulation has been done for multi-wave field information to analyze the characteristics of various waves and further instruct the micro-seismic data processing and modify the velocity model.The ray tracing method is a sort of approximate calculation method for wave field which has characteristics of rapid and efficient calculation, direct and clear ray path. It has been widely used in many fields, such as forward simulation, migration imaging,tomography and has achieved terrific results. Based on the principle of ray tracing, lots of research on ray tracing between two points have been done in this paper. Aiming at horizontal layered uniform motion model, curved layered uniform motion model and complex geological model, the corresponding ray tracing algorithms, such as the dichotomy, the improved dichotomy and micro-variable mesh algorithm, are scientifically designed to improve the computational efficiency and application scope greatly on the premise of original trial ray method. The error range and computational efficiency for each algorithm in this paper has been compared and verified. A proper algorithm is selected for different geological model in order to achieve fast calculation speed and high accuracy simultaneously. Some factors which mainly affect seismic amplitude, such as wave front divergence, absorption and attenuation, transmission loss, reflection loss, excitation conditions to receive and wave interference, are respectively taken into consideration on the basis of ray path tracing and are further researched. The ray path and ray time are respectively exhibited by ray tracing for this micro-seismic models and then forward simulation are carried out for multi-wave field three-component records.The results of models and application examples in this paper show that the improved dichotomy can achieve ray tracing for curved interface with high accuracy compared with the dichotomy. In the curved layered model, the improved dichotomy possesses higher calculation speed than the micro-variable mesh algorithm and could be applied in inversion. The notion of ultra-thin layer has been introduced into this paper during modeling and the refraction wave is taken into consideration for simulation on the premise of existing simulation for direct wave, transmission wave and reflection wave. The multi-wave field information by forward simulation is richer than before.