Structure Interpretation And Exploration Target Selection In Daijiaping Area Zhenjing Block

The Chang 8 Reservoir in Yanchang Formation Daijiaping Area is the complex subtle reservoirs of lithologic or low amplitude structural, which has features of low porosity, low permeability, poor physical and strong heterogeneity. We have invested a lot of efforts in lithologic reservoir exploration in the past, but there are still many issues unresolved by the limits of seismic exploration and seismic instruments, These factors have seriously restricted the depth and breadth of comprehensive geological research and exploration target evaluation.Fine structural interpretation and Seismic reservoir prediction technology is a strong support for the exploration of subtle reservoirs, especially for tapping old oil resources in China, we need more precise interpretation results and reliable hydrocarbon detection to provide reference basis for well deployment. The reliability of seismic structural interpretation and reservoir prediction is based on seismic data,3-D seismic acquisition in Zhenjing block has been carried out in recent years, Which has been covered in main exploration area and has improved the resolution of seismic data, furthermore it has created the conditions for 3D fine structure interpretation and reservoir prediction. This study has taken full understands of the structure and trap’s characteristics, which is based on 3D fine structure interpretation, and in order to carrying out reservoir prediction, this method is mainly for analyzing the sand’s body distribution in study area by using reservoir prediction technology of attribute analysis and seismic inversion method. This study has maked full use of seismic interpretation and reservoir prediction method, and combined with petrophysical properties of sandstone reservoirs, in order to identifying lithologic traps and tight reservoirs based on 3D seismic data. The ideas of this study are as follows:first studing reservoir characteristics of log-seismic responses, and delineating favorable development zones of lithological traps by mature reservoir prediction method. Then taking combined studies of log-seismic (including attribute analysis, seismic inversion, etc.)-geological interpretation, which is based on the theory of seismic lithology and the study of log-seismic responses. In order to predict lithologic traps, and analysis tight sandstone reservoirs or fractured reservoirs, at last taking comprehensive evaluation for traps and favorable exploration targets. Practice has proved that, The development of 3D fine structure interpretation and reservoir prediction method research can optimize target trap and increase potential reserves, which has very important practical significance for Chang 8 Reservoir Daijiaping Area.This study focuses on the object of Chang 8 unit Yanchang Formation, the main contents of the study include:(1) 3D Fine Structure InterpretationFor one thing, we carry out seismic data quality analysis; for another thing we get synthetic seismogram calibration of Chang 8 unit Yanchang Formation, and then establish connection seismic profile and cross-well backbone sectional to determine the relation between the seismic reflection layer and geological interface, in order to build up the construction of the 3D interpretation of the control network backbone area; We take fine contrast explanation of objective layer in Yanchang Formation by taking comparison of seismic reflection interpretation, tracking continuous or unconformity interface, and identifying the structure, which are under the control of backbone structural interpretation.(2) Study on Structure and Fracture CharacteristicsWe establish the study area’s average velocity field for time-depth conversion and preparing the structural map of 81 and 82 unit reflections by 3D Fine Structure Interpretation; On the other side, we carry out multi attributes (Body attributes, structure attributes along the layer, energy attenuation attributes and so on) and seismic interpretation for fault interpretation, in order to study the fracture characteristics in the region, which has take fully understand of the ability of small fault recognition by forward modeling method.(3) The Seismic Prediction of Complex ReservoirWe should analysis the log response characteristics of tight sandstone reservoir and fractured reservoir, and find out the variations of reservoir’s elastic parameters, in order to determining the favorable reflection characteristics of reservoir and developing detailed attribute analysis and seismic inversion schemes for tight sandstone reservoir. On one hand, we should study on the prediction of sand qualitatively and determine the distribution of favorable reservoir by the extraction of multi parameters or multi attributes.On the other hand, we take hydrocarbon detection of favorable reservoir and delineat oil range by post stack seismic inversion.(4) target selection and comprehensive evaluationWe prefer favorable exploration targets, and evaluate them by the prediction results of complex reservoir, and in order to summarize a geophysical method of predicting complex sandstone reservoir that is based on logging and seismic data.