油田化学(英文)-第9章 滤饼清除剂.pdf

C h a p t e r 9 F i l t e r - C a k e R e m o v a l The drill-in fluids are typically composed of either starch or cellulose polymers, xanthan polymer, and sized calcium carbonate or salt particulates . Insufficient degradation of the filter-cakes resulting from even these clean drill-in fluids can significantly impede the flow capacity at the wellbore wall . Partially dehy- drated, gelled drilling fluid and filter-cake must be displaced from the wellbore annulus to achieve a successful primary cement job . Organic Acids Citric Acid A composition for dissolving filter-cake deposits left by drilling mud in wellbores is composed of an aqueous solution of citric acid and potassium chloride, alkali metal formate, acid tetraphosphate, alkaline earth chloride, and alkali metal thiophosphate [1012] . The composition is useful as an additive for clearing stuck pipe in wellbores and as a fixer spacer for cementing pipe in wellbores . Another use of the composition is as a well stimulation fluid in oil and gas production wells, in which the composition is effective to dissolve filter-cake that blocks pores in the production formation . Horizontal Well Acid Breaker Horizontal completions in unconsolidated formations are being enhanced by a hydrochloric acid (HCl) breaker system for well clean up . Typically, the use of HCl in open-hole environments is avoided because of wellbore stability concerns. However, HCl successfully removes salt fluid loss control materials in wells without noticeable hole collapse [33] . Acetic Acid A case study was reported regarding the use of acetic acid [1323]. A large- scale acetic acid-based stimulation treatment was developed to remove drilling mud filter-cake