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|align = "center"|Schlumberger
|align = "center"|<font color="#0000FF"><u>[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7726404.PN.&OS=PN/7726404&RS=PN/7726404 US7726404B2]</u></font>
|Use of carbon-dioxide-based fracturing fluids