Measuring Thermal Neutron Capture Cross Sections of Formation Brines


C. E. Rinehart, Exxon Production Research Co.,
J. Weber, IRT Corp.

5th Formation Evaluation
Symposium of the Canadian Well Logging Society in Calgary, May 5 – 7,



A recently-developed neutron absorption cell measures the thermal neutron absorption cross sections of formation brines (E ). This is one of the parameters needed for interpreting pulsed neutron decay logs. Generally, E is estimated from the salinity of the brine. ~ometimes it can be measured in a large tank with a logging tool, but this requires several hundred gallons of the brine. With the neutron absorption cell, this measurement can be made on a sample as small as one gallon, with a precision of 0.1 percent, in less than 5 minutes.