Hydraulic fracturing uses pressure to force ______ into existing fractures to open and separate different _____.

• A. Air, mineral boundaries
• B. Water or fluid, strata
• C. Air, strata
• D. Water or fluid, mineral boundaries

Answer: (B)

In hydraulic fracturing, a fluid such as water is pumped at high pressure into a rock formation to push on existing cracks. This forces the fluid into those fractures, widening them and causing the surrounding rock layers to separate. The fluid helps create pathways through the rock, increasing permeability so oil or gas can flow toward the well. The reason water or fluid is used is that liquids transmit pressure effectively and can carry proppants to keep the fractures open after the pressure is released. Air wouldn’t sustain the necessary pressure, and “mineral boundaries” isn’t the usual way we describe the rock layers—those are called strata.