# US 2019/0170897 A1 · Non-Radioactive Tracers to Evaluate Fracturing Procedures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170897 A1 - Document ID: US20190170897A1 - Status: Published application - Kind: A1 - Application number: 15/831,081 - Filed: 2017-12-04 - Published: 2019-06-06 - Earliest claimed: 2017-12-04 - Assignees: Carbo Ceramics Inc. - Applicants: CARBO Ceramics Inc. - Inventors: Qianmei Zhang; Harry D. Smith - Web page: https://patentgrep.com/patent/US20190170897A1 ## CPC - E21B 43/267: reinforcing fractures by propping - E21B 43/26: by forming crevices or fractures - E21B 47/11: using tracers; using radioactivity - G01V 5/102: {the neutron source being of the pulsed type} - G01V 5/108: {the neutron source being of the pulsed type} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) ## Abstract A method for evaluating induced fractures in a wellbore includes obtaining a first set of data in a wellbore using a downhole logging tool. A first proppant is pumped into the wellbore, after the first set of data is captured. The first proppant includes a first tracer that is not radioactive. A second proppant is also pumped into the wellbore, after the first proppant is pumped into the wellbore. The second proppant includes a second tracer that is not radioactive, and the second tracer is different than the first tracer. A second set of data is obtained in the wellbore using the downhole tool after the first and second proppants are pumped into the wellbore. The first and second sets of data are compared. ## Claims ### Claim 1 A method for evaluating induced fractures in a wellbore, comprising: obtaining a first set of data in a wellbore using a downhole logging tool; pumping a first proppant into the wellbore, after the first set of data is captured, wherein the first proppant comprises a first tracer that is not radioactive; pumping a second proppant into the wellbore, after the first proppant is pumped into the wellbore, wherein the second proppant comprises a second tracer that is not radioactive, and wherein the second tracer is different than the first tracer; obtaining a second set of data in the wellbore using the downhole tool after the first and second proppants are pumped into the wellbore; and comparing the first and second sets of data. ### Claim 2 (depends on 1) The method of claim 1, wherein the downhole logging tool comprises a pulsed neutron logging tool. ### Claim 3 (depends on 1) The method of claim 1, wherein the first set of data, the second set of data, the comparison of the first and second sets of data, or a combination thereof comprise: borehole sigma data, formation sigma data, detector count rate data in different time windows after neutron bursts, ratio data of count rate changes in different time windows after the neutron bursts, elemental yield data of the first tracer, the second tracer, or both, or a combination thereof. ### Claim 4 (depends on 1) The method of claim 1, wherein the first tracer includes an element selected from the group consisting of gadolinium, boron, and samarium, and wherein the second tracer includes a different element selected from the group consisting of gadolinium, boron, and samarium. ### Claim 5 (depends on 1) The method of claim 1, further comprising determining, based on the comparison of the first and second sets of data, that the first proppant is present in formation fractures proximate to a first set of perforations in the wellbore, and the second proppant is present in formation fractures proximate to a second set of perforations in the wellbore when an elemental yield of the first tracer increases proximate the first set of perforations, the elemental yield of the second tracer increases proximate the second set of perforations, or both. ### Claim 6 (depends on 1) The method of claim 1, wherein comparing the first and second sets of data comprises comparing detector count rate changes between the first and second sets of data in an early time window after neutron bursts. ### Claim 7 (depends on 6) The method of claim 6, further comprising determining, based on the comparison of the detector count rate changes, that one of the first and second tracers comprises boron and is present in first formation fractures when the detector count rate decreases proximate to a first set of perforations adjacent to the first formation fractures. ### Claim 8 (depends on 7) The method of claim 7, further comprising determining, based on the comparison of the detector count rate changes, that the other of the first and second tracers comprises gadolinium or samarium and is present in second formation fractures when the detector count rate increases proximate a second set of perforations adjacent to the second formation fractures. ### Claim 9 (depends on 1) The method of claim 1, wherein comparing the first and second sets of data comprises comparing detector count rate changes between the first and second sets of data in a late time window after neutron bursts. ### Claim 10 (depends on 1) The method of claim 1, wherein comparing the first and second sets of data comprises computing a ratio of a detector count rate change in an early time window after neutron bursts relative to the detector count rate change in a late time window after the neutron bursts. ### Claim 11 (depends on 10) The method of claim 10, wherein the ratio is positive in the presence of boron, and negative in the presence of gadolinium or samarium. ### Claim 12 (depends on 1) The method of claim 1, further comprising pumping a third proppant into the wellbore, wherein the third proppant comprises a third tracer that is not radioactive, and wherein the third tracer is different from the first and second tracers. ### Claim 13 (depends on 1) The method of claim 1, further comprising determining, based on the comparison of the first and second sets of data, that the first proppant is present in formation fractures proximate to a first set of perforations in the wellbore, and the second proppant is present in the formation fractures proximate to a second set of perforations in the wellbore when: proximate to the first set of perforations: a borehole sigma increased, a formation sigma increased, a detector count rate in an early time window increased, the detector count rate in a late time window decreased, an elemental yield of the first tracer increased, or a combination thereof; and proximate to the second set of perforations: the borehole sigma increased, the formation sigma increased, the detector count rate in the early time window decreased, the detector count rate in the late time window decreased, or a combination thereof. ### Claim 14 (depends on 1) The method of claim 1, wherein the first proppant comprises a first plurality of particles, the second proppant comprises a second plurality of particles, and the average size of the first plurality of particles is different from the average size of the second plurality of particles. ### Claim 15 (depends on 1) The method of claim 1, wherein the first proppant comprises a lead-in portion, and the second proppant comprises a tail-in portion. ### Claim 16 A method for evaluating induced fractures in a wellbore, comprising: pumping a first proppant into the wellbore, wherein the first proppant comprises a first tracer that is not radioactive; pumping a second proppant into the wellbore, simultaneous with or after the first proppant is pumped into the wellbore, wherein the second proppant comprises a second tracer that is not radioactive, and wherein the second tracer is different than the first tracer; obtaining a set of data in the wellbore using a downhole logging tool after the first and second proppants are pumped into the wellbore; and analyzing the set of data to determine locations of the first and second proppants in formation fractures. ### Claim 17 (depends on 16) The method of claim 16, wherein the analyzing of the set of data comprises: determining elemental yields of the first and second tracers; determining that the first proppant is present in the formation fractures proximate to a first set of perforations in the wellbore, and the second proppant is present in the formation fractures proximate a second set of perforations in the wellbore when the elemental yield of the first tracer increased proximate to the first set of perforations, the elemental yield of the second tracer increased proximate to the second set of perforations, or both. ### Claim 18 A method for evaluating gravel packs or frac packs in a wellbore, comprising: pumping a first proppant into the wellbore, wherein the first proppant comprises a first tracer that is not radioactive; pumping a second proppant into the wellbore, simultaneous with or after the first proppant is pumped into the wellbore, wherein the second proppant comprises a second tracer that is not radioactive, and wherein the second tracer is different than the first tracer; obtaining a first set of data in the wellbore using a downhole logging tool after the first and second proppants are pumped into the wellbore; and analyzing the first set of data to determine locations of the first and second proppants in a gravel pack region in the wellbore, in induced formation fractures, or both. ### Claim 19 (depends on 18) The method of claim 18, further comprising: obtaining a second set of data with the downhole logging tool prior to pumping the first and second proppants; and comparing the first and second sets of data to determine locations of the first and second proppants in the gravel pack region in the wellbore, in the induced fractures in the formation, or both. ### Claim 20 A method for evaluating induced fractures in a wellbore, comprising: obtaining a first set of data in a wellbore using a downhole tool; pumping a frac fluid and a proppant into the wellbore simultaneously, after the first set of data is captured, wherein the frac fluid comprises a first tracer that is not radioactive, and wherein the proppant comprises a second tracer that is not radioactive; obtaining a second set of data in the wellbore using the downhole tool after the frac fluid and the proppant are pumped into the wellbore; and comparing the first and second sets of data to determine locations of the frac fluid the said proppant.