In a Wall Street Journal article from last October, a petroleum engineering professor from Texas A&M University stated that one-fourth of all cement jobs fail to some degree and "Very rarely are they perfect."
I've blogged before about cement problems in onshore oil and gas wells that have led to groundwater contamination around the country, and a study that concluded that "many of today's wells are at risk."
This WSJ article focuses on offshore concerns, but confirms that a large amount of oil and gas wells have cement problems. We need the highest standards in place, and strict enforcement, to improve the integrity of oil and gas well construction.