Research on Influencing Factors of New Over-drill Collar Azimuth Array Lateral Instruments

  • Liu Jichun, Wu Dong, He Quan, Deng Rui


This paper presents an innovative small diameter azimuth array lateral logging electrode system. The special electrode structure allows the instrument to pass through the drill collar, reducing the number of downhole in the instrument. Measurement curves and resistivity images of four different depths of investigationcan be obtained simultaneously in one measurement. This instrument has the ability to detect formation boundaries in a horizontal well environment. By comparing the results of 3D finite element simulation with the simulation results of third-party software, the accuracy of the simulation results is verified, which lays a solid foundation for the subsequent study of the investigation characteristics and environmental impact of the instrument. In low invasion mode, the instrument can investigate a maximum depth of 2.24 meters. The correction of the depth focus mode under different wellbore sizes does not exceed 10%, which is less affected by the wellbore environment. As the eccentricity of the instrument increases, the measured response value of the 0-degree azimuth electrode gradually increases, while the measured response value of the 180-degree azimuth decreases. The farther away from the well wall, the smaller the measured response of the instrument. The resistivity imaging features of the instrument at four different depths of investigation can be used for the indication of the layer interface and the orientation of the target layer. In the horizontal well environment, when the contrast of the two-layer formation resistivity is greater than 10 times, the edge detection capability of the instrument can reach more than 1 meter.