After news broke that 4,700 gallons of hydrochloric acid spilled at a Chief Oil and Gas drilling pad in Bradford County on Wednesday, several readers emailed StateImpact Pennsylvania to ask why the corrosive agent was being stored at the site.
The answer: hydrochloric acid plays a key role in the hydraulic fracturing process. After the natural gas well’s hole is bored, drillers will pump thousands of gallons of water mixed with acid down into the well. The point, as drilling website FracFocus explains, is to clear out cement debris left over from the drilling stage, and to help open up the underground shale fractures.
After the “acid stage” is complete, drillers inject slickening fluid and sand into the well, in order to flush the natural gas out.
Chief had completed fracking at its Leroy Township Yoder well when the spill took place. A company spokeswoman emails the acid was being stored on-site, waiting to be moved to another drilling location.