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Hydraulic Fracturing Techbook 2018

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90 | August 2018 | hartenergy.com HYDRAULIC FRACTURING: CASE STUDIES conventionally but not included in the study). All odd-numbered stages from stages 11 through 25 were approximately 175 ft in length (plug to plug) and were completed with six clusters per stage. All odd-numbered stages from stages 27 through 47 were approximately 225 ft in length (plug to plug) and were completed with seven clusters per stage. Completion diagnostics were not employed in even-numbered stages to evaluate stage containment. Figure 1 sum- marizes the individual completion parameters and results for the stages included in the study. Objectives To ensure that there was no loss of perforation- cluster-treatment efficiencies or overall lateral cov- erage, SPECTRASTIM proppant tracers were added to the proppant slurry for each targeted stage of the Wolfcamp lateral, and the lateral was logged with a SPECTRASCAN imaging tool. Each perforation cluster was examined on the spectral gamma-ray log to determine cluster treatment efficiencies, the extent of lateral coverage for each stage, cement integrity, stage containment and early versus late proppant placement. A blue antimony tracer was used in 0 ppg to 0.5 ppg 100 mesh proppant ramp, a red iridium tracer was used in 0.5 ppg to1.0 ppg 40/70 mesh proppant ramp, and a yellow scandium tracer was used in 1.0 ppg to 2.0 ppg 40/70 mesh proppant/resin-coated proppant ramp. To assess the extent of vertical height growth/ communication between the proppant-traced Wolf- camp lateral and the parallel 300-ft shallower Bone Springs lateral, a SPECTRASCAN imaging run was also performed on the previously hydraulically frac- tured but untraced Bone Springs lateral. The extent of fracture fluid cleanup by the Wolf- camp lateral and fracture fluid communication with the Bone Springs lateral were evaluated using SPECTRACHEM chemical tracers injected through- out each stage of the Wolfcamp completion. Well- head water samples collected during flowback of the Wolfcamp well were analyzed for each of the injected tracers recovered from the two wells. Wellhead water samples also were collected during production of the Bone Springs well, and they were similarly ana- lyzed for each of the communicated tracers from the Wolfcamp well. Informed decisions Figure 1 summarizes the completion parameters for the Wolfcamp lateral for the odd-numbered stages 11 through 47. Stages 11 through 25 were the shorter stages (approximately 175-ft stage lengths) and were perforated with six clusters per stage. Stages 25 through 47 were the longer stages (approximately 225-ft stage lengths) and were perforated with seven clusters per stage. Figure 2 adds some additional completion param- eters detailing the fluid and proppant volumes for each stage and incorporating the SPECTRASCAN log, which reveals the early, intermediate and late traced proppant gamma ray counts for each stage. FIGURE 2. The fluid volumes (blue bars), proppant volumes (brown bars) and proppant placement (blue/red/yellow tracks) are displayed for the Wolfcamp lateral. (Source: ProTechnics) 225-ft stage lengths / 7 clusters per stage 175-ft stage lengths / 6 clusters per stage

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