Interpretation of borehole logging data by use of theoretical models for the nuclear probes used
The report describes the development of a log interpretation program, based on logs from four nuclear tools. For each of these tools a theoretical model is developed. The model of the neutron porosity tool is based on one-dimensional, three-group diffusion theory, that of the gamma density tool is based on one-dimensional, five group modified diffusion theory, that of the pulsed-neutron, capture-gamma tool is based on one-dimensional, Fermi-age theory and that of the natural gamma tool on two or three-dimensional numerical integration and the use of built-up factors. The four models are incorporated into a computer program, Nulip. This program uses as input the experimental data of the four tools at each depth value. From this input the program calculates the water/oil, the gas and the matrix volume fraction as a function of depth. Also the volume fraction of clay and sand of shale layers may be obtained. The computation is performed by use of iteration and the computing time is about six seconds for each depth value. An example of the use of the program on actual field data is presented.
Bibliographic Reference: EUR 12534 EN (1989) 51 pp., FS, ECU 5
Record Number: 199010248 / Last updated on: 1994-12-01
Original language: en
Available languages: en