Non-aqueous fracturing technologies for shale gas recovery.

Experience gained in the use of hydraulic fracturing in Poland is discussed. The shale contains a certain volume of low-density smectite clay which exhibits a tendency to absorb frac water and to expand. Frac fluid and proppant injection may also lead to a significant increase in and reorientation of the existing formation stress. Increased formation stress and shale expansion in contact with water may cause soft shale layers to move and to plug perforations and close some fracture. The benefits and disadvantages of technologies which employ non-wetting fluids are reviewed, including liquid CO2 fracturing, nitrogen fracturing, fracturing foams, LPG fracturing and explosive/propellant systems (EPS). EPS are the most cost-effective and environmentally-friendly and allow sustained gas production levels which may equal hydraulic fracturing production performance at lower cost.
Experience gained in the use of hydraulic fracturing in Poland is discussed. The shale contains a certain volume of low-density smectite clay which exhibits a tendency to absorb frac water and to expand. Frac fluid and proppant injection may also lead to a significant increase in and reorientation of the existing formation stress. Increased formation stress and shale expansion in contact with water may cause soft shale layers to move and to plug perforations and close some fracture. The benefits and disadvantages of technologies which employ non-wetting fluids are reviewed, including liquid CO2 fracturing, nitrogen fracturing, fracturing foams, LPG fracturing and explosive/propellant systems (EPS). EPS are the most cost-effective and environmentally-friendly and allow sustained gas production levels which may equal hydraulic fracturing production performance at lower cost.