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Results
Sand and Ceramic Proppant Performance in Thin Layer/Monolayer Conditions Subjected to Cyclic Stress
Herskovits, Raphael (Saint –Gobain Proppants) | Fuss-Dezelic, Tihana (Saint –Gobain Proppants) | Shi, Jingyu (Saint –Gobain Proppants) | Wilcox, Craig (Saint –Gobain Proppants) | Kaul, Todd (Saint –Gobain Proppants)
Abstract Over the last several decades, the industry has generated a large amount of proppant performance data using designated API methods. However, recent studies validate that correlations and conclusions generated from standard API testing do not accurately predict ceramic proppant performance in unconventional reservoirs. This overestimate of proppant performance can have negative effects on initial well production, in addition to steepening the production decline curve. The same study suggests the modified API RP 19-C procedure for testing of proppant performance under thin layer/monolayer conditions yields results which better correlate with well production data trends. Also demonstrated in the study, the proppant pack failure mode and mechanism can be vastly different in a monolayer pack versus a multilayer pack and suggests that in order to improve well performance, operators would benefit by choosing proppants based on their ability retain fracture width under low proppant concentrations; such as 0.5 and 0.25 lb/ft. The presented study expands previously mentioned work to evaluate the influence of stress cycling on the performance of various proppants in thin pack/monolayer conditions. A cycle test involves a 2,000 psi/min ramp-up to desired pressure, 2 minute hold at pressure and ramp down to 25 psi. The process then repeats to obtain the desired numbers of cycles on the proppant. The results compare the performance of proppants under a single stress cycle to samples subjected to 3 or 5 cycles. Testing is performed with sample concentrations of 4 lb/ft (API standard) and 0.5 lb/ft (thin layer pack) at 6,000psi. The results reveal a decrease in mechanical performance for all tested samples under 3 and 5 cycles as compared to standard 1 cycle test. Clay-based ceramic proppants and sand proppants show a significant increase in crush with an increase in number of cycles. Clay based samples appear to be especially sensitive to stress cycling under thin layer/monolayer conditions. For example, 3 cycles at 0.5 lb/ft loading, the crush resistance of clay based proppants increases by close to 8%, while sand crush increases by only 6%. This high sensitivity is not present when testing is performed at 4 lb/ft. Intermediate strength ceramic (ISC) proppants show the highest resistance to cyclic stress under both thick proppant pack (4 lb/ft) and thin proppant pack (0.5 lb/ft) conditions. Paper quantifies the effect of reduced fracture thickness and stress cycling on performance of different proppant types. This study further discusses advantages and limitations of designed of used method as compared to common API procedures.
Laboratory Quantification of Environmental and Quality Risks Associated with Pneumatic Transfer of Frac Sand
Kidd, Ian (Saint-Gobain Proppants) | Fuss-Dezelic, Tihana (Saint-Gobain Proppants) | Shi, Jingyu (Saint-Gobain Proppants) | Wilcox, Craig (Saint-Gobain Proppants) | Herskovits, Raphael (Saint-Gobain Proppants) | Kaul, Todd (Saint-Gobain Proppants)
Abstract During use on the hydraulic fracturing site, proppants experience repetitive mechanical handling starting at unloading from railcars and trucks to the point of final blending with the fracturing fluid. At each point of transfer, quantities of fine dust particles develop which can affect worker safety. Due to the increase of proppant consumption per site, the industry has a concern about a corresponding increase in the time-weighted average exposure of workers to high silica dust. Recently approved changes to OSHA's crystalline silica rule require the permissible exposure limit (PEL) for respirable crystalline silica to be lower than 50 micrograms per cubic meter of air, averaged over an 8-hour shift. This study first investigates dust generation associated with pneumatic transfer of northern white sand to sand storage units on location. A laboratory apparatus is designed to mimic location conditions and allow for continuous exposure of sand particles to 15 psi of air jet pressure. During this attrition process, generated dust is collected using a dust collection system. Weight percent and particle size of collected particles is measured. Average weight percent of collected sand is 1.6%, which, on a 10 000 000 lb job translates to a loss of 160,000 lbs of material. Particle size analysis of collected dust shows that 30% of it is below 10 microns and is by OSHA considered respirable. As attrition related changes in surface morphology affect strength performance, morphology of attrited sand grains is also evaluated via crush testing per ISO 13503-2. At 4000 psi, attrited samples measure 6 weight % higher crush than non-attrited samples. The study also measures the effect of attrition on dust generation and mechanical stability of intermediate strength ceramic proppants. Following attrition testing, intermediate strength proppants show a 0.15% mass loss. XRD analysis of collected dust shows that none of the particles contain crystalline silica and are therefore not subjected to OSHA regulation. Mechanical performance of intermediate strength proppants, at 8,000 psi, is 1% higher on samples that were subjected to attrition than on non-attrited samples This study further discusses advantages and limitations of designed attrition methods compared to field testing and evaluates sand dust mitigation costs.
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.94)