Study on Sulfate Removal Method in Drilling Filtrate
High sulfate concentration in drilling filtrate and poor performance of compound drilling fluid was one of the main challenges facing the recycling of offshore drilling filtrate.In this study,the effects of calcium salt precipitation and ettringite precipitation on sulfate removal in drilling filtrate were investigated respectively,and the method of calcium salt-ettringite precipitation for sulfate removal was proposed.The results showed that the SO42-and Ca2+concentrations in drilling filtrate could not meet the requirements for reuse of drilling filtrate(SO42-≤4 000 mg/L,Ca2+≤500 mg/L)by the treatment of calcium salt precipitation or ettringite precipitation;The SO42-and Ca2+concentrations in filtrate were reduced to 2 218 mg/L and 465 mg/L by the calcium salt-ettringite precipitation method,respectively,which could meet the requirements for reuse of drilling filtrate.The reaction conditions were as follows:12 000 mg/L CaCl2 solution was added in calcium salt precipitation method,and the Al/S(IAS)molar ratio and Ca/S(ICS)molar ratio were 1.25 and 2.5 in ettringite precipitation method,respectively.The research results could provide a reference for the design and operation of sulfate treatment process units in drilling filtrate.
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维普
