Comprehensive Prediction Of Carbonate Fractured Reservoirs By Post-stack Seismic Attributes

The target work area is located in Tahe oilfield.This oilfield has formed a complex fault structure system due to many large tectonic movements in the geological-historical period,such as the Caledonian period,Hercynian period and the Himalayan period.After karstification in the late Caledonian and Hercynian period,Ordovician carbonate rocks formed the extremely complex fractured systems.The main reservoirs are Ordovician carbonate fractured reservoirs,and the holes are the main reservoir spaces and the fractures are the channel connecting those reservoir spaces.With the continuous development of oil and gas reservoirs,more of the remaining oil and gas are stored in fractures,so it is more and more important to identify the geological structure of the stratum in the target area.For the whole oil and gas exploration and development,it is of great significance to predict faults and fractures in target area by classification and to identify the spatial distribution and internal structure of the fractured and cavern reservoirs better in the stratum.In this paper,I based on the previous research to characterize the formed fracture and hole units in the target work area.In order to predict faults and fractures for grading better,I have used the multi-scale coherence based on Curvelet transform and threedimensional multi-scale body curvature attributes combined with a variety of seismic attributes and made some improvements,then the method of fault and fracture prediction in target area by classification was formed.Compared with the original traditional methods,the improved methods have better recognition effect for discontinuous anomaly information in the stratum when applied to the actual data,because the multi-scale coherence and multi-scale body curvature have the ability to identify different scales.The identification method of single seismic attribute has higher requirements on seismic data,and it is often difficult to fully describe all kinds of abnormal information in the stratum.In the actual process,according to the abnormal information that need to be characterized,I compared the results of different seismic attributes,and then used the better results for comprehensive prediction by post-stack seismic attributes.A method for identifying the fracture units and the meandering channels was obtained firstly,and finally a method for detecting large,medium and small faults or fractures of different scales in the target area was formed.According to the actual situation of the target area,this paper and combines a variety of seismic attribute methods for the comprehensive prediction work by poststack seismic data.The applied multi-scale coherence and multi-scale body curvature attributes of ant bodies and their maximum likelihood bodies have achieved initial results in identifying geological anomalies of different sizes and shapes.And the method flow was formed that is suitable for the target area to predict the faults and fractures by classification,which provides ideas and references for the more detailed description of the reservoir space of different types of carbonate fractured reservoirs.