The Research On Computing Method Of Through Casing Resistivity Logging Response

With the perpetual deepgoing of oil-field exploitation, there is an increasing number of cased borehole, and so many of these cased boreholes have went into the intermediary and later stage of exploitation which require dynamic reservoir monitoring and evaluation of oil remaining. Therefore, more and more people pay attention to through casing resistivity(TCR) logging, and TCR logging has huge development potential. In this paper, computing method of TCR logging response is researched, at the same time, the impact of various factors on logging response is analyzed. It is of great significance for the development of TCR logging and its instrument.In this paper, modified transmission line equation of TCR logging response is calculated through the adoption of a recursive matrix method, and the material reseach of TCR logging including the deduction of theoretical computing method, calculation through programming, response analysis and research of affecting factors is conducted. Main results of this paper is acquired as follows:Firstly, traditional transmission line equation is deducted and modified, considering the reflection of multiple contact bed along radial direction of formation in its coefficient, for formation model with axial direction into a layered, radial step change, potential distribution of cased well could be given. Secondly, a recursive matrix method which is used to solve the modified transmission line equation is deducted. This algorithm is in favor of little calculated amount, programming easily, no overflow and so on. The TCR logging response could be calculated conveniently through using this method. Thirdly, computing program used for calculating TCR logging response is written by the platform of Fortran power station4.0, the logging response plot on the condition of different formation can be described. Lastly, according to analyzing and discussing the impact of various factors such as surrounding rock, cement mantle and inequable casing on logging response, this research presents considerable reference merit in terms of further explanation and evaluation of the formation.