TREATMENT METHOD FOR BOTTOMHOLE AREA OF TERRIGENOUS BED OF GAS WELL UNDER ABNORMAL LOW PRESSURE Russian patent published in 2005 - IPC

FIELD: gas extraction industry, particularly for stimulating gas production.

SUBSTANCE: method involves forming bath by injecting aqueous solution of hydrochloric acid into tubing string and forcing thereof into well bottom; standing the bath and removing thereof; serially injecting and forcing aqueous hydrochloric acid and mud acid solutions into the bed through tubing string; removing worked-out aqueous acid solution. Aqueous solution includes 2-4% of hydrochloride acid and volume thereof is selected from condition set by calculation formula. Aqueous solution containing 7-15% of hydrochloric acid and aqueous solution of mud acid in the form of mixture including 7-15% hyrdrochloride acid and hydrofluoric acid with 1-3% concentration are used for serially injection and forcing into the bed. Aqueous solution of hydrochloride acid is injected in two portions. Volume of each portion is equal to 0.03-0.1 m³ per 1 m of exposed effective bed thickness. Aqueous solution of mud acid is injected between above portions in amount of 0.08-0.18 m³ per 1 m of exposed effective bed thickness. Above solutions are delivered to well bottom through tubing string with the use of gaseous agent fed through tubing string interior. The gaseous agent is selected from nitrogen, natural gas, exhaust gas supplied from combustion engine. After well head pressure stabilization inside tubing string and in hole annuity above gaseous agent is supplied into tubing string and hole annuity along with delivery of above solutions through tubing string to provide constant flow rate of gaseous agent supplied into tubing string and hole annuity in total volume of 16-31 m³ per 1 m of exposed effective bed thickness. Before used aqueous solution removal solid foam generating agent is introduced in well without gas-generating agent. After well head pressure inside tubing string and hole annuity stabilization sample of used aqueous solution is taken from dib hole. The sample is analyzed to determine residual concentration of hydrochloric acid and presence of trivalent ferric ions. Then solid foam generating agent in the form of rods and gas generating agent are introduced into the well. Number of rods is determined from correlation.

EFFECT: increased efficiency due to increased well output and used aqueous solution removal, reduced time, decreased corrosion activity of used aqueous solution and reduced chemical reagent consumption.

3 cl, 1 ex, 1 tbl