2P.D.Baycroft ect.Frac Packing with low Environmental impact Hydraulic Fracturing Fluid Benefits the Operator SPE94236.
3USEPA Method 1664,Revision A:"n-Hexane Extractable Material(HEM:Oil and Grease)and Silica Gel Treated n-Hexane Extractable Material (SGT-HEM; Non-polar Material) by Extraction and Gravimetry," Code of Federal Regulations,Title 40,Section 136,Appendix A,EPA-821-R-98-002,February 1999.
