The identification of intervals receiving proppant and accurate assessment of near wellbore fracture height are valuable in evaluating and optimizing stimulation strategies. Propped frac height evaluation in hydraulic fractures has typically involved the detection of radioactive tracers added to the proppant during treatments. However, as environmental regulations regarding this technique have tightened, and with increased scrutiny by the public and regulatory bodies of the oil and gas industry in general and hydraulic fracturing in particular, the need for an alternative to radioactive tracers has become critical.
A novel technology for identifying intervals receiving proppant and determining fracture height utilizing a non-radioactive detectable proppant has been recently introduced. The technology has found global acceptance and has proven to be a robust and accurate method of locating proppant in the near wellbore region with standard logging techniques. In addition to eliminating the health, safety and environmental concerns with radioactive tracers, this new method also provides a permanent indication of the proppant location near the wellbore. Unlike traditional radioactive tracers which must be logged before the radioisotopes completely decay, this new method allows investigation of the proppant pack many months or years in the future, which would provide critical information during remedial or redevelopment work that would not be possible with conventional approaches.
A review of the current state of regulatory impediments to the use of radioactive tracers in key producing regions around the world is discussed highlighting the need for an alternative diagnostic technology. The technology utilized in the application of the non-radioactive detectable proppant is described and comparisons to other fracture diagnostic technologies are presented. Several case histories are shown which illustrate various applications of the technology in regions around the globe. These case histories include applications performed in the Middle East and North America.
In addition to identifying proppant location and fracture height, this technology can be used in other applications such as the evaluation of gravel pack quality.
If the current trends in regulatory actions related to hydraulic fracturing continue, it is anticipated that the use of radioactive tracers will be restricted to fewer and fewer locales. At the same time the importance of reliable fracture diagnostics for optimization of hydraulic fracturing both from a well performance and cost control standpoint remains extremely important.