A non-commercial approach to measure fracture conductivity in the laboratory has been developed to assist operators in selection of proppants for high temperature and high stress hydraulic fracturing applications. Simple laboratory tests that would dictate proppant choice are no longer considered sufficient since test parameter choices affect the outcome so drastically. For example, extending the stress period from 1 hour to 18 hours can decrease the measured conductivity value by a factor of three. The added effects of brine flow at elevated temperature for extended time periods have been seen to result in even greater conductivity decreases.
Much conflicting conductivity data has been presented in our industry. Often, the choice of test parameters or the test cell design have been responsible for these discrepancies. Sometimes such data are used to select a certain product and may significantly disagree with other published test results which indicate the superiority of a different proppant.
In this work, several variables that can affect measured proppant conductivity were evaluated using five proppants of different composition.
The variables studied were: (1) Effects of extended time at different test conditions; (2) Variation between ambient and elevated temperature testing; and (3) Effects of brine flow at high, temperature and closure stress.