Constructing oil and gas wells: "many of today's wells are at risk"
Posted May 14, 2010
The tragic catastrophe in the Gulf of Mexico caused by the oil spilling from the Deepwater Horizon rig sounds more and more like the results of a perfect storm of poor drilling practices. We've read about potential contributors being the cementing process, faulty equipment, unorthodox process, drilling mud weight, what testing that was done, and whether or not anyone was paying attention to the results of tests along the way. What happened may have been a combination of one or more of these. NRDC colleagues are blogging with more information on the disaster in the Gulf. It is essential that there is as thorough an investigation as possible to ensure that nothing like this happens again.
Well construction accidents are not limited to offshore drilling. These types of failures occurr onshore, including faulty cementing and casing. A 2003 article in Oilfield Review details all of the things that can go wrong before, during and after cementing. It concludes that ".....many of today's wells are at risk." I have heard from people with industry experience about many things that can potentially go wrong during the well construction process. Here are just a few examples of onshore cementing and casing accidents.
In 2004, EnCana drilled a well in Garfield County, Colorado. The company ran tests which showed the cement was far below the level required on the well permit and that there could be some pressure issues in the well. Yet EnCana continued to complete and hydraulically fracture the well. Shortly after, a local citizen reported seeing gas bubbling in West Divide Creek--a creek that supports aquatic life, recreation, water supply needs, and agriculture. High levels of benzene were found in the creek as well as in springs fed by groundwater. It was estimated that 115 million cubic feet of natural gas blew out underground and some of it found its way to the groundwater. Despite remedial cementing, benzene and other hydrocarbons continue to be found in the groundwater six years later.
In Dimock, Pennslyvania, groundwater was contaminated in 2009 for nine square miles, leading to a loss of clean drinking water for 14 families. One family's water well exploded, and residents reported neurological and gastrointestinal illnesses. The Pennsylvania Department of Environmental Protection found "insufficient or improper cemented casings" in up to six natural gas wells.
In Bainbridge Township, Ohio, an investigation by the State of Ohio found that a natural gas well was completed and fractured in 2007 even though "the cement behind casing was insufficient by standard industry practice." One house exploded, and the accident contaminated the underground source of drinking water for more than 40 families and the Bainbridge police station.
In Bradford Township, Pennsylvania, the state's Department of Environmental Protection found contamination in the drinking water of at least seven families in 2009. It was caused by the drilling of 26 natural gas wells in one little community. The PADEP found a lack of a cement return in some natural gas wells, needed to protect aquifers from contamination, as well as excessive pressure in others.
In 2006, a drill rig in Clark, Wyoming, encountered an overpressured zone at a depth of over 8,000 feet and experienced a blow-out. Drilling mud, natural gas, and natural gas condensate erupted up through the ground up to 150 feet away from the well. Twenty-five nearby homes were evacuated for several days. Ultimately it was determined that eight million cubic feet of explosive methane and vaporized drilling fluids were released into the atmosphere. Drinking water sources and surface soils were contaminated with benzene, and local springs had high levels of petroleum hydrocarbons. The cause of the Clark blow-out was found to be "weaknesses in the surface casing."
These accidents all contaminated clean water. There are accidents like the one in Clark, where it's clear something happened (although the operator waited hours before reporting the accident to authorities). But in others, citizens are the ones reporting the problems. No one notifies them that there was an accident and their water may have been contaminated; it's not until they smell, taste, or see the contamination that they know there is something wrong. There are likely many accidents that the public doesn't even know occurred because the effects are as yet undetected.
As the Pennsylvania Secretary of Environmental Protection said yesterday: "There’s no such thing as zero-impact drilling.” We need to end our addiction to fossil fuels, but that won't happen overnight. What can happen overnight is a change in company practices with a new emphasis on quality control and safety, rather than speed and greed. In the immediate future, stronger environmental regulations are essential to minimize the chances of accidents like these happening again.