Standard two-stage frac record. This pad was tagged with scandium, the proppant with iridium. In the standard log presentation, tracer curves appear in chronological order from right to left.
Three-stage frac tagging in a limited-entry perforated well. Note the formation breakdown did not always occur opposite the perforations. This is not atypical.
The Multiple Isotope Tracer Tool (MTT) gives you a clear analysis of your multistage stimulation—at the wellsite.
Schlumberger sharpens your evaluation of stimulation stages by discriminating between gamma ray-emitting isotopes with the MTT log. Because the tool can tell radioisotopes apart, we can track any downhole process that can be tagged with different isotopes. An important example is formation fracture evaluation. When your pad fluid is tagged with one isotope, and each proppant stage with others, a single wireline run can log independently the extent of the fracture and the degree of proppant placement. Since the MTT log is available in real time at the wellsite, you can make your evaluation immediately. If you need to treat again, you can do so and immediately recheck the results.
The MTT tool—discriminating between Y sources.
Gamma ray logs have long been used to estimate success of hydraulic fractures. Multiple isotopes, too, have been used to tag different stages of frac jobs, but interpretation has been complex and time-consuming.
The MTT tool has no such limitations. It detects gamma ray energies through 14 energy windows ranging from 180 to 3,000 keV. By means of the wellsite computer, the count/energy level relationships are integrated and used to identify the source isotope. As you see from the gamma ray energy distribution profiles below, finding these relationships amounts to finding the fingerprint. Isotope identification by the MTT log is virtually immediate.
Using laboratory-derived standard spectra, the detector also discriminates between isotopes in the formation and isotopes in the wellbore.
