• Blow and cratering in the oil and gas industry refers to the uncontrolled release of oil, gas, water, or drilling fluid from a well that is being drilled (blow), or the collapse of a well that has already been drilled. Blowouts are usually caused by an intrusion into a reservoir containing gas or oil that is at a higher pressure than allowed; often oil or gas catches fire. When a funnel forms in a well, often the drilling rig itself goes under water along with the well. Coverage of the insured person’s liability for damage to property of others caused by a blowout or cratering is not mandatory under a commercial liability policy (CGL). A special cover, Well Control Insurance, provides coverage for the cost of eliminating a controlled release, cleaning up any resulting contamination, and damage to operator property.