State oil and gas regulators have acknowledged "routinely" allowing oil and gas producers to inject steam underground at pressure so high that it cracks open underground rock formations, in violation of state and federal regulation, according to a state Senate report prepared for Tuesday's joint hearing by the Senate's environmental quality and natural resources and water committees. The way that oil companies in California use steam injection to extract oil from aging oil fields came under scrutiny in June 2011, when a Chevron worker, Robert David Taylor, fell into a sinkhole of boiling fluid that opened suddenly in a Kern County oil field.