3Albahlani A M, Babadagli T. A critical review of the status of SAGD:where are we and what is next? [R]. SPE 11328a,2008.
4Grills T L. Magnetic ranging technologies for drilling steam as sisted gravity drainage well pairs and unique well geometries:a comparison of technologies[R]. SPE 79005,2002.
5Pratt C K, Hartmann R A. A magnetostatic well tracking technique for drilling of horizontal parallel wells[R]. SPE 28319, 1994.
6Kuckes A F, Hay R T,Nord A G,et al. New electromagnetic surveying/ranging method for drilling parallel horizontal twin welts[J]. SPE Drilling & Completion, 1996,11 (2):85-90.
