VSP Standardized Process And Interpretation In Shunbei Area

The distributed hydrocarbon in Shunbei area of the Tarim basin is controlled by large-scale deep strike-slip faults.Due to multi-stages tectonic evolution and subsequent karst reformation,Shunbei faulted-karst reservoirs were finally forged.For carbonate reservoirs,caverns and fractures are the main reservoir spaces,and the fractures also serve as the dominating channels for oil and gas migration.Therefore,in seismic exploration,it is particularly significant to accurately identify the faults,the spatial distribution of fractured-vuggy and characterize the inner structure of fractures.However,limited by the exploration environment of the desert surface and the strong heterogeneity of deep reservoirs,the ground seismic can not meet the subsequent development.We have acquired the VSP logging in this area.And as a result of the advantages of high-resolution and high signal-to-noise ratio(SNR)for VSP exploration,the description for the regional stratigraphic characteristics and the fractured-vuggy is more accurate.To meet the requirements of amplitude preservation and high-precision.Based on the data of zero-offset VSP in this area,this research focuses on the standardized workflows of VSP operations and the associated principles,selecting appropriate parameters,and establishing quality constraint criteria.The applicated technology of VSP interpretation has further described the structure of stratigraphical velocity and the characteristics of absorption and attenuation.The combination of pre-drilling VSP and surface seismic data that used for geological horizon calibration to achieve fine horizon calibration and delineate the reflection characteristics inside the formation.Finally,the parameters extracted from the VSP data were conducted to improve the quality of the surface seismic imaging profile.By high-resolution and accurate inversion to predict the spatial distribution of fractured-vuggy and favorable areas of reservoirs.What's more,the prediction result is confirmed by geological data.Through the above-mentioned work and research,the following results and acknowledges have been achieved for the VSP logging in the Shunbei area:1.The changing trend of the VSP layer velocity and Q value in the Shunbei area has a clear dividing line.The results show that the layer velocity and the Q value change trend are related and consistent.2.Using the VSP layer velocity to make a Synthetic seismic record,the results have a good correspondence with the ground seismic calibration;comparing synthetic records and ground seismic data,VSP has a higher resolution capability.3.Using the parameters extracted from the VSP data could significantly improve the accuracy of ground seismic profile imaging.Making full use of high-frequency information can further identify and characterize the characteristics of carbonate fractures and cavities.