Fracture Prediction Based On OVT Domain Data

Sinian Dengying Formation of the G-M area is a deep Fracture-Cavern carbonate reservoir with a depth of more than 4500 m.In recent years the development practice in this area shows that has drilled more exploration wells and most of which have oil and gas show in the Dengying Formation,showing the G-M area Dengying formation has a good prospect of exploration.G-M area Sinian Dengying Formation reservoir by the late karstification of the transformation,strong heterogeneity,in the effective reservoir of fine description and distribution of the law there is a certain degree of difficulty.The developed multiple sets of normal faults is not only an important factor in the fractured reservoirs reconstruction but also a favorable channel for oil and gas migration.Cracks are of great help to oil and gas distribution.In development,controlled by Fracture-Cavern reservoir,single well production,recovery rate and the economic performance of oil and gas exploitation are affected by natural fractures.It is difficult to identify small-scale fractures and cracks in the method according to the conventional post-stack technique.On seismic data,it is more difficult to predict the density and azimuth of fractures by ordinary seismic data.In summary,the effective prediction of cracks in the area is difficult,and the yield of single well is obviously different in production.For the above difficulties,this paper focuses on:(1)On seismic data,the research work is carried out by using and analyzing the data of OVT(offset vector tile)pre-stack gathers,OVT domain offset can provide high quality OVT domain spiral gathers,retain more azimuth information,which facilitates azimuthal anisotropy analysis and fractures detection,and after the azimuth anisotropy correction can further improve the pre-stack offsets quality.(2)In the method of technology,adopt pre-stack and post-stack fracture comprehensive prediction,post-stack coherence and curvature technology can effectively identify large-scale fracture system,pre-stack azimuthal anisotropic fracture prediction techniques can semi-quantitatively predict fracture density and fracture orientation,use of adopt pre-stack and post-stack methodto achieve the purpose of comprehensive prediction of cracks.(3)To improve the development of single well production,recovery ratio and economy of oil and gas exploitation,by combining the tectonic characteristics of the area,reservoir prediction,oil and gas identification and comprehensive prediction results of fractures,to predict favorable oil and gas enrichment area,to guide the deployment of well location in the study area and improve the purpose of drilling a high-yield well.Based on the analysis and research on the existing data of the Sinian Dengying formation in the G-M area,the following information is obtained: the azimuth information of the pre-stack gather after OVT has a strong advantage in the prediction of the density and azimuth prediction of the fracture.And the correlation between the anisotropy intensity and the actual oil and gas distribution is strong.Multi method and multi parameters can effectively control the accuracy and reliability of prediction.The fracture is often associated with large faults.The post-stack method is effective in identifying the large fracture system,the pre-stack method recognizes the high fracture precision,and the combination of various methods can achieve better results.