Field Application of a New Proppant Detection Technology

Abstract

Abstract Traditional proppant placement evaluation in hydraulically induced fractures has utilized detection of radioactive tracers pumped down hole with the proppant. We are proposing new methods for proppant placement determination. The proppant placement determination method described in this paper eliminates down hole placement of radioactive materials. A thermal neutron absorbing compound is inseparably incorporated into a ceramic proppant during manufacturing in sufficiently low concentration that it does not affect proppant properties. Proppant is detected using standard compensated neutron tools or pulsed neutron tools, with detection based on the high thermal neutron absorptive properties of the compound relative to downhole constituents. Specifically, proppant is detected using after-frac compensated neutron logs combined with corresponding before-frac logs. Increased thermal neutron absorption by the compound reduces count rates in the near and far detectors, with approximately the same percentage reduction observed in each detector, leaving the N/F ratio unchanged. One detection method utilizes a comparison of before-frac log count rates and after-frac count rates, with reduced after-frac count rates observed in zones containing proppant. A second detection method, especially useful when formation gas saturations change, involves only the after-frac log. Since the near to far detector count ratio is unaffected by proppant, after-frac count rates predicted from the ratio will also be unaffected. These computed/synthetic count rates will be greater than the observed after-frac count rates in intervals containing proppant. This paper will describe the results of applications of the new detectable proppant in wells in South Texas and Wyoming. The location of the detectable proppant was determined from analysis of before-frac and after-frac compensated neutron logs.