The paper deals with the application of nuclear physics methods in oil and gas detection, prospecting and production in the U.S.S.R.
Radioactive logging is being widely used in exploring oil and gas wells. In recent years, methods have been developed for neutron and gamma-gamma logging of wells, combined and simultaneous application thereof making it possible to determine with great accuracy the porosity of strata. For carbonate reservoir rocks, the above methods are the only ones which permit a quantitative appraisal of porosity.
The paper analyzes the basic methods, the equipment, the methods of exploration, and the principles of interpreting the gamma-gamma and neutron-neutron logging curves.
Neutron methods to determine the shifting of water-oil and gas-fluid contacts have found an ever extending application in the course of developing oilfields in the Soviet oil and gas industries. The methods of neutron logging and induced activity are employed for such purposes. The measurements are made in cased wells. Oil-bearing strata differ from water-bearing strata by higher intensity and smaller energy of gamma-radiation arising during the capture of thermal neutrons in the stratum.
Apart from this, smaller density of thermal neutrons has been observed opposite oil-bearing strata.
These peculiarities are related to the comparatively large cross-section of capture of thermal neutrons by chlorine nuclei. The position of water-oil contacts is more effectively determined by artificial activation of sodium and chlorine.
Radioactive isotopes are widely and successfully used in the U.S.S.R. oil and gas industries to define the technical condition of wells. Research has been carried out in recent years to use tritium for defining the movement of water beds.
Research is being condncted on an ever increasing scale to use artificial radioactivity for element analysis of rocks. Very interesting data have been obtained in investigations into the nature of radiometric anomalies over oil and gas deposits. It has been established that radiometric anomaly is a special case of geochemical anomaly inherent in oil deposits. This allows consideration of the radiometric method as a special case of the direct radiogeochemical method for detection of oil. Radiometric methods are bound to find a wider application particularly when intensive sources of neutrons (small-sized neutron breeders and neutron generators) also capable of operating under impulse conditions are available. The we of spectrometric equipment is highly promising.
Cette communication traite de l'emploi, en U.R.S.S., des méthodes de physique nucléaire pour la prospection et l'exploitation du pétrole et du gaz.
Le carottage radioactif est devenu
