Laboratory study of the effect of proppant operating variables on fracture conductivity under minimum horizontal stress conditions in one of the Iranian reservoirs

Document Type : Original Article

Authors

Department of Petroleum Engineering, Amirkabir University of Technology, Tehran, Iran

Abstract

As the most significant factor determining the final success of a hydraulic fracturing operation, fracture conductivity is influenced by proppant operating variables including mesh size, proppant concentration, and crushing behavior under minimum horizontal stress. Outcrop samples of the Ilam Formation were cut and prepared in the desired dimensions to simulate fracture in one of the Iranian reservoirs. As natural proppants, two groups of silica sand were collected from Firozkoh and Hamadan mines. Three mesh sizes were used to screen the proppants: 16/30, 20/40, and 30/50. In conductivity tests, Firozkoh proppants were used at two concentrations of 2 and 0.5 pounds per square foot. Experiments were carried out with a conductivity measuring apparatus by injecting nitrogen gas into the conductivity cell at different flow rates. This was done to simulate gas flow through fracture media. As a final step, the crushed percentage of proppants was determined and Forchheimer's equation was used to calculate conductivity values. As determined by the study, a significant decrease in conductivity values was observed with increasing closure stress. Firouzkoh 20/40 displayed better conductivity than Hamedan 20/40 proppant and performed better under the same stress conditions. Higher values of sphericity and roundness explain this. A comparison of the conductivity of 16/30, 20/40, and 30/50 proppants from Firuzkoh sand revealed that the 30/50 proppant had the lowest conductivity reduction compared to the other two samples up to a stress of 7251 psi because there are more contact points between the particles, the stress distribution is better between the particles, and the proppants do not crush as easily. A comparison of two amounts of Firouzkoh 20/40 proppant showed that more particles formed in the fracture as the proppant concentration increased. Consequently, the crushed percentage was reduced and conductivity values were maintained at higher proppant concentrations.

Keywords


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