Forward modeling of 3D induction logging tool in 3D borehole environment

Key words:  3D induction logging  three-coil array  apparent conductivity  bed boundary  borehole environment  drilling fluid  tool eccentricity  forward modeling

Abstract:

The influence of the bed boundary, borehole drilling fluid, invasion and the tool eccentricity on apparent conductivity of the three-coil array of a 3D induction well logging tool was analyzed. The results show that the apparent conductivity in the XX/YY direction can be affected more by borehole drilling fluid than the apparent conductivity in the ZZ direction. In the presence of invasion, the shift direction of the apparent XX/YY-direction conductivity is opposite to the ZZ-direction apparent conductivity. The borehole drilling fluid and invasion affect XZ/ZX-direction apparent conductivity mainly in the boundary. A decentralized tool will not affect the ZZ-direction apparent conductivity. When the tool is decentralized in the X direction, the apparent conductivity in the YY direction can be significantly distorted. But when the tool is decentralized in the Y direction, the effect on the apparent conductivity in the XX direction will be the maxmum.