Microseismic Data Inversion Based On Ray Theoretical ForwardModeling

With the maturity of the microseismic theory, it is more widely used. Inthispaper,somecharactersofmicroseismicrecordarediscussedaccordingtothe microseismic ray theoretical model. The algorithms of two mediummodels (the layered homogeneous medium model and the complicatedmedium model) are proposed in the microseismic ray theoretical model. Asthe cumulative error in the computer calculation is relatively obvious, thesubvariable grid method is adopted in order to make the calculated resultsaccurate. Because it is very important to pick the first arrival in themicroseismic data, the energy ratio constraint tendency picking method isused to pick the first arrival and it is proved well both in the modelverification and in the actual data. Based on the source location in theforward model, the required model is inversed. By virtue of the characters ofthe microseismic data, the strata are sliced by the datum velocity calibratedby the heterotypic wave moveout. And the interval velocity of each layer isinversed. Then an approximate horizontal layer medium modeling method isproposed. The result shows the modeling problem in actual data relativelywell is solved. It can be concluded that the flow chart of the microseismicinversion includes the forward modeling, the initial model establishment, thefirst arrival picking, the actual model inversion and the last source locationinversion.Theresultscansatisfytheactualdemandprovedbythemodeldataandtheactualdata.