CPG

Abstract:

The electromagnetic propagation (EMP) measurement frequently acquired with logging-while-drilling (LWD) tools in high-angle wells is sensitive to geometrical effects that can mask the true formation resistivity. Less commonly used, the LWD laterolog measurement is sometimes perceived as providing data too shallow to give a true formation resistivity (Rt). Both EMP and Lateralog effected by invasion, rate of penetration, time after drilling, thickness of reservoir.

The experience gained by comparing EMP and laterolog resistivities in several wells helped to verify that laterolog resistivities have better axial resolution and suffer less from polarization and geometrical effects than do EMP measurements. Due to their shallower depth of investigation, laterolog measurements are also less sensitive to the resistivity of adjacent layers than is EMP resistivity.

Presented actual examples to demonstrate that the laterolog can provide a superior resistivity measurement for formation evaluation than the does the EMP LWD tool.