Research On The Application Of Model Forward Modeling In Constructing Graphs

There are rich petroleum resources in Southern margin of Junggar Basin,which is one of strategic substitute area for petroleum exploration of Xinjiang oilfield.In the early stage,the oil and gas fields have been found in middle and upper assemblage of the area.In order to further expand exploration results,the structures in lower assemblage of deep layer become important research fields in this area.Because of the effect of both variable surface relief and complex subsurface structure,the quality of seismic data is relatively poor and the velocity are severely changeable in both vertical and lateral.There are only 3 wells drilled to deep layer,it is difficult to confirm the structural feature accurately.For confirming piedmont complex structure feature,we have used composite seismic-geological modeling technology,varying velocity mapping by seismic velocity building with drill constraint and so on.These methods have played a good role to improve the accuracy of deep structure map.In some cases,there is a false structural appearance in the time domain data,so seismic velocity mapping can't confirm the structural feature accurately.There are multiple solutions on the areas underlying high dip angled strata in depth migration data,so how confirm the structural feature is the key factor in the oil-gas exploration of lower assemblage of deep layer in this area.On the basis of widely absorbing previous research achievements and techniques,this paper has explored emphatically the method how use forward modeling to confirm and verify the structural feature.It has summarized a process of structure mapping technical that use seismic time domain data to do varying-velocity mapping and use forward modeling to verify.It has summarized a process of interpretation scheme optimization on the poor imaging area of prestack depth migration data.All the methods have increased the accuracy of confirming the structure greatly in lower assemblage of deep layer.The steps of confirm the structural features by the method as follows:1.Make seismic data interpretation base on a reasonable seismic-geological modeling;2.Preliminary confirm the structure use the results got from varying-velocity mapping of time domain data or depth domain data interpretation;3.Build a high accuracy forward model to simulate wave-field of the structure.Then iterating the model until the profile of forward modeling is in keeping with actual seismic profile.At this time,we think the forward model can well reflect the real structural features;4.Basing on the results of forward modeling,we correct the result of structural mapping.The method of varying-velocity mapping and forward modeling verification technology to complex structure summarized by the study can well meet the requirement of confirming the complex piedmont structure feature.The technology is an originative solution of the problems as following:1.Confirm how much the abnormal velocity body influence the structure feature underlying it;2.Quantify the high dip angle structure plane offset;3.Confirm interpretation scheme of the high dip angle structure.By the study,we have summarized the method of varying-velocity mapping and forward modeling verification technology to complex structure.We have further optimized the research ideas and research methods of the varying velocity mapping work.It has improved the accuracy of confirming structure in complex structure in Southern margin of Junggar Basin.This method has been applied in many areas,and have got a well result.The real drilling data have validated the rationality of structures features.This method has provided a more reliable structural maps for the petroleum exploration and played an important role in the petroleum exploration in Southern margin of Junggar Basin.