A series of laboratory experiments have been conducted with specially designed equipment to aid in measuring leakoff and pressure drop of proppant-laden slurries while flowing between coal, and quantifying regained permeability and conductivity of various fluids and proppants once placed in a coal fracture.
The rheology and proppant transport of borate-crosslinked fluids with and without proppant have been evaluated in a slot with walls cast from the surfaces of fractured coal in an effort to quantify the impact of tortuous coal fractures on the pressure drop down the fracture.
The long-term conductivity and permeability of various sands have been measured between fractured Fruitland Coal. Predictive equations have been developed to predict permeability between coal vs sand sieve size, and predict loss of permeability due to embedment and gel damage. Non-Darcy flow factors and constants are presented for calculating non-Darcy flow vs sand type and size between coal.