Title: Proppant Transport Characterization of Hydraulic Fracturing Fluids Using a High Pressure Simulator Integrated with a Fiber Optic/LED Vision System
Author(s): S.N. Shah, The University of Oklahoma and M. Asadi, Stim-Lab
Publication: SPE Production & Facilities
Date: February, 2001
Abstract: Slurries of selected hydraulic fracturing fluids such as 40 lb/Mgal HPG gel and 35 lb/Mgal borate-crosslinked guar gel were evaluated to characterize their proppant transport properties using 6 ppg 20/40 mesh sand. In addition, hydraulic fracturing fluids such as water, clean 40 lb/Mgal HPG gel, clean and 35 lb/Mgal borate-crosslinked gel solution were used to evaluate their capabilities in eroding bed height and transporting proppant within fluidized bed located on top of a compacted sand bed. The experimental part of this study utilized a unique high pressure parallel plate flow cell, simulating downhole fracture, integrated with a vision system of fiber optic and Light Emitting Diodes (LED). The vision system was used to quantify proppant transport characteristics and to study various aspects of proppant transport including bank buildup. Selected hydraulic fracturing fluid slurries were pumped into the 0.375" fracture gap width high-pressure flow cell through a 3000 ft of 1.188 in. ID coiled tubing, a 500 ft of 2 in. ID heat exchanger, and a 2.75 in. inlet manifold that could be configured to represent a wellbore having various perforation configurations. The slurries were pumped at various shear rates of 60 to 120 sec-1 for a selected time. The slurries were followed by various clean and/or slurries of water, 40 lb/Mgal HPG gel, and 35 lb/Mgal borate- crosslinked gel to assess the degree of compaction within the deposited bed. Data analysis indicates that slurry sedimentation in polymer solutions follows a non-linear relationship with time at a fixed shear rate and that perforation configuration affects proppant transport, bed height growth, and proppant lift near the wellbore. It is also shown that bed height growth is a non-linear function of shear rate. In addition, the study indicates that although fluidized bed, the upper bed height, is easily removed by the clean crosslinked gel, erosion of the more compacted bed (below fluidized bed) depends on factors such as type of the fluid leaving the deposit, injection rate of clean fluid to remove bed height, pumping time, and type of the fluid used to erode the compacted bed.