The Thermal Decay Time Log – A Description of Its Benefits and Interpretation in Canada


J.J. Edgson,

4th Formation Evaluation
Symposium of the Canadian Well Logging Society in Calgary, May 9-10,



The TDT has been in Canada since Feb- ruary, 1969 and has shown the ability to aid the oil industry in defining formation fluid contacts. This through-tubing pul- sed neutron device has helped define oil- water, gas-oil and gas-water contacts, transition zones and water coning in Alb- erta and Saskatchewan to date. The part- icular tool under discussion has the abil- ity to be run under dynamic conditions.