Primary Study Of Rvsp Data Drocessing Of Seismic Exploration While Drilling

Seismic while drilling has rapidly developed,as a new downhole seismic technique in recent years. It use the vibrationgs produced by a drillbit while drilling as a downhole seismic energy source to do RVSP exploration. Seismic while drilling surveys are acquired whithout any downhole instrumentation. It means there is no interruption to drilling, no lost rig time and no risk to the borehole while the seismic data are being acquired. These characteristics offer a method by which borehole seismic data can be acquired, processed and interpreted while drilling. Subserface conditions ahead of the drill bit can be predicted at any time during drilling without tripping out of the hole and seismic data are available at the well site for real-time drill decisions. Furthermore, it can reduce the drilling risk and improve the efficiency of drilling.In the exploration process of SWD,signals generated by the drill vibration directly from the location of vibration transmitted through the formations to the ground (direct wave),or reflected from the formation boundaries below the bit and then transmitted to the ground (reflection wave),also and be transmitted along the drill string to the drill string up top (the precursor signal).Using the signal received by precusor controller on the dring sting as the drill-bit signal,get the driect wave and the reflect wave received by the geophone array on the ground,then we get the SWD records.SWD data processing can be roughly divided into two phases:the first is transformation from initial datas into seismic profiles, including data de-compile, signal to noise separation, correlation, superposition, phase correction and real time reflection correction, this stage is often referred to as drilling seismic signal processing. The processing result obtained is equivalent to RVSP seismic profiles. The second is RVSP processing on the data after signal processing. including the first break picking, velocity analysis, wave field separation, deconvolution, transform the corridor stack,and CDP-tansform. In the actual treatment process, there is no strict dividing line between the two phases because some processing steps can exchange the order.The main contents of this paper is doing RVSP processing on seismic datas obtained after the signal processing. Processing on numerical forward modeling datas as the main content, testing the feasibility process and applied in the actual data, the final record is the common geophone record's superposition CDP profile, and then compare with the surface seismic data profiles.