Complex sentence: From 1994 to 2006, approximately 177,000 marginal wells were plugged and abandoned, representing a number equal to 42 percent of all operating wells in 2006, costing the U.S. more than $3.8 billion in lost oil revenue at the EIA 2004 average world oil price.
Split into simpler sentences: From 1994 to 2006, approximately 177,000 marginal wells were plugged and abandoned, representing a number equal to 42 percent of all operating wells in 2006. Costing the U.S. more than $3.8 billion in lost oil revenue at the EIA 2004 average world oil price.