| abstract |
A method of enhancing the productivity of hydrocarbons from hydrocarbon bearing siliceous formations, particularly those made up at least in part of zeolites, is achieved by contacting the formation with a treatment solution comprising citric acid, phosphonate compounds, and hydrofluoric acid. The treatment solution can be applied prior to gravel packing or fracturing. This solution may optionally contain ammonium salts. Similar solutions comprising citric acid and phosphonate compounds without hydrofluoric acid may also be used to contact the formation prior to contacting the formation with the citric acid and phosphonate solution containing hydrofluoric acid. Other preflushes known in the art, such as hydrochloric, acetic or formic acid solutions, may also be used. |