A New Nuclear Logging Method to Locate Proppant Placement in Induced Fractures

Traditional proppant placement evaluation in hydraulically induced fractures utilizes detection of radioactive (R/A) tracers such as iridium 192, scandium 46 and antimony 124, which are manufactured in nuclear reactors, and then shipped to the wellsite and pumped downhole with the frac slurry. Although this technique has proven useful, it involves environmental, safety, and regulatory concerns/issues. Recently a new technology has become available that offers a viable alternative to radioactive tracers. The new technology utilizes a non-radioactive ceramic proppant that contains a high thermal neutron capture compound (HTNCC). This high thermal neutron capture compound is inseparably incorporated into each ceramic proppant grain during manufacturing in sufficiently low concentration so as not to affect proppant properties. The non-radioactive tracer proppant (NRT) is detected using standard pulsed neutron capture tools (PNC) or compensated neutron tools (CNT), with detection based on the high thermal neutron absorptive properties of the tagged proppant relative to other downhole constituents. Monte Carlo modeling data and several field examples presented in this paper demonstrate the viability of both the PNC and CNT proppant detection technologies.