Method for analyzing formation data from a formation evaluation measurement-while-drilling logging, tool

摘要

A method for analyzing data from a measurement-while- drilling (MWD) formation evaluation logging tool 10 which compensates for rotation of the logging tool (along with the rest of the drillstring) during measurement periods. In accordance with this method, the density measurement is combined with the measurement from a borehole caliper, preferably an acoustic caliper. The acoustic caliper can continuously measure the standoff as the tool is rotating in the borehole. If the caliper is aligned with gamma-ray source 12 and detectors 14, 16, it can determine the standoff in front of the detectors at any given time. This information can be used to separate the density data into a number of bins based on the amount of standoff. After a pre-set time interval, the density measurement can then be made. The first step in this process is for short space and long space densities to be calculated from the data in each bin. Then, these density measurements can be combined in a manner that minimizes the total error in the density calculation.