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The Forward Modeling Of Three-Dimensional Borehole-to-Surface Logging Technology

Posted on:2010-01-15Degree:MasterType:Thesis
Country:ChinaCandidate:Y ZhangFull Text:PDF
GTID:2120360275986447Subject:Earth Exploration and Information Technology
Abstract/Summary:PDF Full Text Request
The research of infused water distributing and remaining oil is a hot shot to high water cut producer in the industry of oil gas, also a hard nut. As one of main logging technologies in the world, three-dimensional borehole-to-surface logging technology is a valuable method, which can provide reliable basis for tapping the remaining oil, promote substantially success rates of finding efficient wells in the exploration process, finally to optimize development program and promote oil recovery. Forward modeling is a good way to get surface potential, the forward modeling of borehole-to-surface is actually computing potential distribution through the parameters of underground medium, such as conductivity, resistivity. In this paper, the forward with borehole-to-surface is studied and becomes the basis of inversion.For vertical line source, the total potential is usually divided into normal potential and abnormal one because of voltage singularity in source. Normal potential produced in homogeneous half-space is calculated by analytic method. While for abnormal potential produced by underground anomalous body, Finite Difference Method (FDM) is used based on differential equation of abnormal potential. Further, the total potential is calculated and the forward is realized. The efficiency with direct method to solve the linear equation Aφ=S formed during FDM calculation process is quite slow, in which A is a large sparse band symmetric matrix. Accordingly, Incomplete Cholesky Conjugate Gradient (ICCG) is introduced in this paper, it converges more quickly while requires less memory.To indicate potential distribution produced by underground anomalous body, models such as layer cake model are calculated in this paper. It is an initiation to introduce dipping bed model and sphericity model in this paper, then maps formed with FDM calculation are exhibited. It shows that forward modeling of this paper is fast in convergence and accurate, also images potential distribution more precisely, being the foundation of further inversion and providing constraints.
Keywords/Search Tags:three-dimensional borehole-to-surface logging, Finite Difference Method (FDM), forward modeling, Incomplete Cholesky Conjugate Gradient (ICCG)
PDF Full Text Request
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