Integration of two methods to realize deviated well VSP geophone orientation
Ma Zhi-xia1,2, Sun Zan-dong1
Lab for Integration of Geology and Geophysics (LIGG),State Key Lab of Petroleum Resource and Prospecting, China University of Petroleum, Beijing City, 102249, China
Abstract：In this paper two deviated well VSP geophone orientation methods,the polar plane method and the relative angle method,were analyzed. The former method utilizes polarization property of the direct wave to realize geophone orientation,while the later uses correlation property of the adjacent traces to conduct geophone orientation. By conducting orientation to forward simulated deviated well VSP 3C data and field deviated well VSP 3C data,the feasibilities,advantages and disadvantages for the two methods were validated. It is noticed that picking up first arrival of the direct wave is needed in the calculation for the polar plane method and the calculation workload is heavy. If the first arrival is not clear due to limitation in well-source distance,ignition conditions,and subsurface conditions,it will cause some difficulty in the first time's picking up,in addition,many time coordinate transformations are needed,and the estimation of rotation angle has to be done through angle scanning,so the whole process is too complicated. The calculation process for relative angle method needs to know the geophone's azimuth at first,and then the azimuth of the adjunct geophone can be calculated through the correction property of the picked-up signal of the adjunct geophone.The recursion processes of this method may cause the accumulated errors,but it is relatively simple in its implementation and the pickup for first arrival is not needed.The two methods were jointly used in the deviated VSP geophone orientation,so not only the workload decreased and efficiency raised,but also the reliable orientation results achieved,esfablising the solid foundation for the subsequent VSP processing.
马志霞, 孙赞东. 两种方法结合实现斜井VSP检波器定向[J]. 石油地球物理勘探, 2010, 45(5): 655-660.
Ma Zhi-xia, Sun Zan-dong. Integration of two methods to realize deviated well VSP geophone orientation. OGP, 2010, 45(5): 655-660.
