R. J. S. Brown and C. H. Neuman
Chevron Oil Field Research Company, La Habra, California
ABSTRACT
A second-generation Nuclear Magnetism Log (NML) has been available on a limited basis for several years and will soon be available generally. We present here a series of computations and signal displays which help to show the nature of NML signals in general as well as to show the response to particular formation, hole, and tool conditions. Such processing of digitally recorded signals enables improved accuracy and bed resolution over that presented with the raw log. Various kinds of noise or disturbances are displayed in forms readily identifiable.
The treatment of drilling mud filtrate to eliminate NML signal from the brine phase in the invaded zone is described. Logs are shown as recorded before and after invasion of treated mud filtrate. This treatment causes the NML signal to correspond to residual oil only, enabling accurate and relatively inexpensive measurement of residual oil.