ABSTRACT

Orienting core and gathering downhole orientation data, such as paleocurrents or fractures, has always been a challenge in the petroleum industry and academia. Downhole core orientation while drilling is expensive, time consuming, and not always accurate. Nowadays, microresistivity logs are run in many boreholes and can easily be used for orienting conventional core of all sizes and many shapes (whole, slabbed, or plugged). The only requirement is a facies or lithologic change with a sharp contact visible in both core and microresistivity log. Downhole logging tools can thus provide a quick and inexpensive way to orient conventional core. A simple mechanical goniometer can then be used to measure foresets of cross-stratification for paleocurrent analysis. Mechanical goniometers have the advantage of being more robust than their electronic counterparts, and measurement errors are within a reasonable margin. Using this setup, paleocurrents from core were commonly found to be more precise than those generated digitally from microresistivity logs.