We offer a technology for reservoir identification and porosity, oil/gas saturation coefficients and hydrocarbon content determination by 2NNKt+SNGK-Cl neutron methods complex.


Oilsaturation determination is realized by “chlorine deficit” in oilsaturated reservoir in comparison to watersaturated, gas-saturation determination is realized by “density deficit” in gas-bearing reservoir in comparison to oilbearing and waterbearing.

Features and Advantages

• lithology determination;
• reservoir identification and porosity coefficient determination according to 2NNKt, NGK-60 methods;
• oil/gas-saturation coefficient determination in cased wells;
• hydrocarbon content determination in cased well reservoir;
• oilbearing interval identification, watered by fresh waters in cased wells;
• free-salined salinity zone identification at the expense of column seal failure by mineralized waters, injected in oilbearing beds in order to provide bottom-hole pressure in cased wells;
• washing fluid saline filtrate penetration interval identification in reservoir beds with low formation water mineralization;
• washing fluid fresh filtrate penetration interval identification in reservoir beds with high formation water mineralization;
• identification of intervals with residual gas-saturation in open hole.

This technology is performed by SPRK digital radioactive spectral logging tool for several measurement methods: SNGK spectral neutron-gamma-ray logging, 2NNKT dual-sonde epithermal neutron logging and NGK-60 method is realized when registing capture gamma-rays of thermal neutrons with energy up to 500 keV. At Customer’s demand the equipment may also include natural gamma-spectral method (GK-S). The equipment is developed by OAO NPP VNIIGIS together with ZAO NPF GITAS. The downhole tools diameters 90 and 48 mm provide through-tubing surveying.

2NNKT and NGK-60 geological-geophysical characteristics completely answer the nuclear logging equipment properties. This provide the continuity of porosity methods. In that case the technology is applicable in oil-and-gas field development monitoring.

Besides, SNGK method provides understanding of rock material composition effects on the oil-and-gas saturation coefficient, that improves the reliability of the reservoir saturation nature determination.

The technology was successfully tested in different geological-technical well conditions of Kazakhstan, Ural-Volga region, Western Siberia oil/gasbearing province, China and also including directional/horizontal well logging conditions.

PAO NPP VNIIGIS and AO NPF GITAS provide equipment delivery and render service on geological problems solving with the provided technology.


Hydrocarbon saturation character and content determination in reservoir according to SNGK-Cl, 2NNKt and C/O logging method complexes