1. Field Application of a New Proppant Detection TechnologySPE 146744Robert J. Duenckel, SPE, CARBO Ceramics, Inc. Harry D. Smith, Jr., Consultant William A. Warren, Chesapeake Energy Corp.Abram D. Grae, Shell Western E&P, Inc.

2. Outline Overview of New Proppant Detection Technology Basic Downhole Neutron Physics Principles Proppant Identification Using CNT or PNC Logs Field Examples Conclusions/Summary 3. Proppant Detection TechnologiesPurpose:Determine which perfs took proppant and quantify near wellbore frac heightCurrent Technologies RA tracers added to proppant slurry Temperature logs - cooling indicates fluid entry Sonic log - Fracture indicatorNew technology Proppant itself is detectable Non-radioactive - no storage, handling, flow back, half-life or otherradiation-related issues 4. New Proppant Detection Technology Incorporate into the proppant a high thermal neutron capture compound(HTNCC) The presence of the HTNCC in the proppant will alter the response of acompensated neutron (CNT) or pulsed neutron log (PNC) Methods to determine the presence of proppant utilizing the CNT or PNChave been developed The presence of the HTNCC does not alter any of the physical properties ofthe proppant (crush, density, etc.) 5. Basic Downhole Neutron Principles Fast neutrons emitted in a logging tool are slowed to thermal energyprimarily by hydrogen in the borehole and formation Thermal neutrons diffuse in the formation and borehole and can becaptured by downhole nuclei, followed by the emission of capturegamma radiation The thermal neutron population is detected in most compensatedneutron (CNT) logging tools. Capture gamma radiation is detectedin pulsed neutron capture (PNC) logging tools 6. Basic Downhole Neutron PrinciplesThe presence of a High Thermal Neutron Capture Compound (HTNCC)in the proppant will: reduce thermal neutron and/or capture gamma ray count rates indetectors in CNT and PNC logging tools increase the formation (FM) and/or borehole (BH) thermal neutroncapture cross-sections computed using PNC tools. 7. Compensated Neutron (CNT) Logging Tool Continuous AmBe neutron source employed Tool contains two or more He3 thermal neutron detectors Count rates in each detector are recorded and the count rate ratio is computed The ratio of count rates in the detectors is sensitive to porosity but is very insensitive to borehole changes 8. Proppant Identification with CNT 9. First Method of Proppant Identification Using CNT or PNC Logs Obtain a before-frac CNT (or PNC) log across the potential zones to befractured, extending the logged interval to include non-fractured zones Conduct a hydraulic fracturing operation with the HTNCC tagged proppant Run after-frac log across same interval as in before-frac log Normalize count rates across the logged interval if required due to changingborehole conditions or if a different tool or source is used Count rate decreases (or capture cross-sections increases) in theafter-frac log relative to the before-frac log indicate the presence of proppant 10. Field Example 1XXY TaggedProppantYY 11. N/F Ratio Unaffected byPresence of HTNCC Proppant Changes in N/F ratio with porosity4.543.5N/F Ratio32.52No Fracture CEP w/ 0.4% HTNCC1.510.500 5 10 15 202530 35404550Formation Porosity3 3/8 tool, 8 bh, 5.5 cemented casing 12. Development of a Method of Proppant Identification Using After-Frac Log Only The N/F ratio is insensitive to tagged proppant A functional relationship between the N/F ratio and theobserved count rate is developed in zones outside of thefractured intervals This relationship can be used to predict count ratesthroughout an after-frac logged interval, including intervalspotentially containing tagged proppant 13. Second Method of Proppant Identification Using After-Frac Log OnlyI. Run an after-frac CNT log across an interval of the well including the fractured zones and zones outside the interval where fracturing is anticipatedII. Develop relationships between after-frac detectorcount rates and the N/F count rate ratio. 14. Second Method of Proppant Identification Using After-Frac Log Only (continued)IV. Using this N/F vs. count rate relationship compute ratio-based after-frac count rates across the logged interval.V. Compare the observed after-frac count rates with after-frac count rates computed from the N/F ratio.VI. Decreases in observed count rates relative to ratio-basedcount rates indicate the presence of tagged proppant. 15. Field Example 2Additional tagged proppantX (after Sg correction)XTaggedXproppant 16. Field Example 3XTagged proppant(using before and 1st after-frac logs)XTagged Sg proppant(between (using only after-frac2nd after-frac logs)Xlog) Additionaltagged proppant(after Sg correction)X 17. Conclusions / Summary New techniques to locate proppant in induced fractures have been developedwhich utilize a non-radioactive high thermal neutron capture cross-sectionmaterial tagged within each proppant particle. One method to locate the proppant utilizes the comparison of before-frac vs.after-frac compensated neutron (CNT) log or pulsed neutron capture (PNC) logcount rates or capture cross-sections. A second method to locate the tagged proppant utilizes only after-frac CNTlogs. This method compares observed after-frac count rates with after-fraccount rates computed from the N/F ratio. 18. Conclusions / Summary The second method can be utilized in wells where gas saturationcan change between before-frac and after-frac logs These new methods have been validated via both computersimulations and field log examples. These new methods eliminate the storage, handling, uniformmixing and radiation-related issues associated with priorradioactive tracer-based technologies to locate propped fractures 19. Field Application of a New Proppant Detection TechnologyThank YouQuestions?