Separating Upgoing And Downgoing And Multiwave Wavefield On3Dd-VSP

Since the birth of the three-dimensional and three-component VSP technologynow, geophysicists around the world are very concerned about its development.3Dtechnology is able to overcome the conventional VSP technology coverage angle limit,it can be a full range of observations of the formation surrounding the well. Thethree-component technology can receive various types of waves, it can get detailedreflect the various sections of the wells surrounding space, profiles and data volume.In addition, the3D3C VSP technology around the well structure high precision andaccurate imaging, it is used to study the anisotropy of the formation near the well, andcan fill the blank of surface seismic imaging.Although the3D3C VSP data processing and surface seismic data processing aremostly the same in principle, but it also has its own characteristics. For thesecharacteristics, this paper studies the geophone orientation, upgoing and downgoingwavefield separation and mulitwave wave field separation of the3D3C VSP data.(1) Change the direction of the three-component geophones variation with depth,two horizontal component of randomly oriented in the case of vertical wells, deviatedcase is more complex. So, firstly, for the vertical wells VSP data collection discussesthe correct rotational orientation of vertical wells, deduced the formula of coordinaterotation orientation; Secondly, according to the incline Data Acquisition detectorplaced, we can deduce the three components of the orientation of the formula in thiscase, and according to the energy characteristic to calculate the horizontal componentof the azimuth, we derive the rotational orientation of the formula; Finally, using thismethod, we calculated the reality of the3C data. We not only validate theeffectiveness and feasibility of this approach, and we got a good three-componentdata, it can be provided for subsequent processing of reliable data.(2)Original VSP data after a3C orientation, we get the correct verticalcomponent, the tangential component and the radial component. However upgoingand downgoing data obtained as well as P-and S-are mixed stacked together, thissituation is not conducive to imaging and geological interpretation. Therefore, we usedifferent depending on the speed and the polarization properties of the wave. We studied the wave field separation method: linear Radon transform, median filteringand polarization analysis.