Real Time Inversion and Field Test of LWD Azimuthal Electromagnetic Waves Based on Quasi-Newton Method

In order to determine the formation interface azimuth and distance by using the data measured by LWD azimuthal electromagnetic wave resistivity logging instrument using the quasi-Newton inversion algorithm. The objective was provide a decision-making basis for geosteering, an accurate and reliable inversion method must be used. For the LWD azimuthal electromagnetic wave resistivity logging instrument, an application model of geological guidance has been established and simulated its response characteristics. By studying the quasi-Newton inversion algorithm and process, the Jacobian matrix was obtained with less calculation cost in the inversion process, which greatly speeds up the inversion. At the same time, the correctness and accuracy of this algorithm were verified by using the theoretical inversion model including both single interface and a double interface strata model. The field test of Well Cao-XX in Shengli Oilfield showed that the real-time inversion results were consistent with the imaging display of azimuthal electromagnetic wave resistivity and also with the drilling/completion/logging results in later stages. This inversion method can meet the requirements of real time geo-steering by efficient and accurate calculation of azimuthal electromagnetic wave resistivity.