Nuclear well logging methods in the modifications ofcarbon-oxygen log and 3-sondes spectral pulsed neutron log

Currently, in the Russian well-logging market there are practically no borehole tools to determine the current oil and gas saturation of the reservoirs in small diameter cased wells. In the complex of nuclear geophysical well logging techniques, new TsSP-3INGKS-76 tool is discussing. It is specially designed to meet the challenges of monitoring the development of oil and gas reservoirs in small diameter cased wells, widely represented by the sidetrack wells and liners.
Materials and methods
1. Determination of the current oil and gas saturation of the reservoir in wells, cased column with the more than 110 mm diameter, were carried out by the standard complex of nuclear geophysical methods, including the carbon-oxygen log (C/O-log), the twosondes pulsed neutron-gamma ray log and spectral gamma ray log. Equipment: TsSP-C/O-90, TsSP-2INGK-43m, TsSP-GK-C-90 digital borehole tools, respectively. 2. Determination of the current oil and gas saturation of the reservoir in wells, cased column with up to 86 mm diameter, were carried out by the 3-sondes spectral pulsed neutrongamma ray, spectral gamma ray, neutron activation logging methods. Equipment: TsSP-3INGKS-76 digital complex borehole tool.
Results
In the complicated technical and geological conditions (small diameter wells, low or arbitrary mineralization of reservoir water), without the possibility of C/O-log recording, for the first time the current oil and gas saturation is estimated based on the integrated use of the following parameters: fluids mineralization and neutron activation of oxygen. The effectiveness of the new method was provided in the course of experimental work on the oil fields in the Perm region.
Сonclusions
The developed method of estimating the current oil saturation of reservoir in cased wells of small diameter, implemented in TsSP-3INGKS-76 complex borehole tool and special software, can be used as a promising direction for further development of nuclear geophysical methods for production wells logging.