Strata Exploration, Inc. Nuclear Magnetic Resonance Solutions of Low Resistivity Pay Charles H. Smith and Layne Hamilton, Halliburton; John R Kinney II, Strata Exploration; Jon Christensen and George A. Payne, Consultants Solids….invisible to MRI Fluids irreducible moveable water clay bound rock matrix dry clay oil clay bound T2 Relaxation T1 Magnetization 0 1 2 3 4 5 6 time, sec. 8 9 10 11 12 13 14 ……. T2 – Relaxation time 16 ms Incremental Porosity % 100 80 60 40 20 0 0 100 200 300 400 T (ms) Small pores and large pores all contribute to early time response 500 T2 – Relaxation time 128 ms Incremental Porosity % 100 80 60 40 20 0 0 100 200 300 T (ms) 400 500 T2 – Relaxation time 8000 ms Incremental Porosity % 100 80 60 40 20 0 0 100 200 300 400 500 T (ms) Conclusion: To get a description or T2, you must measure a total of 8 seconds - Distribution of the pores will affect ability of the reservoir to produce T2 Bray-Smith Permeability Equation T 2 Bphi 2048 ms p Bray Sm ith Perm MPHI * ( wf * T Bphi/ BVI) 2 T 2 Bphi 4 ms • Where : Bray-Smith Perm = Bin calculated Permeability, MPHI = NMR effective porosity, wf = Bin weighting factor, Bphi = Bin porosity BVI = Irreducible porosity fraction. Factors p and s are empirically derived constants s Solids….invisible to MRI irreducible moveable water clay bound rock matrix dry clay Very early time = clay bound Fluids OIL Early time = BVI Middle time = free water clay bound Later time = hydrocarbon T2 Relaxation times T1 Magnetization 0 1 2 3 4 5 6 time, sec. 8 9 10 11 12 13 14 ……. T1 is much less sensitive to fluid type – alignment time defines fluid type Oklahoma MRIL Log Presentation Big Bin Ratio Oil Line Big Bin Ratio Perm 2006 - 2008 Planning Framework 11 Gas Line T1 Hydrocarbon Curve Tool Comparison Data volume acquired Pad-Based NMR single sensitive volume ~ 43 cc Mandrel-based NMR single sensitive volume ~ 778 cc If all else is equal – a mandrel-based NMR acquires 18 times as much data as a pad-based design Tool Comparison Data volume acquired Pad-Based NMR single sensitive volume ~ 43 cc Mandrel-based NMR single sensitive volume ~ 778 cc If all else is equal – a mandrel-based NMR acquires 18 times as much data as a pad-based design When logging speed is increased, all else is not equal! The ratio gets larger NMR logs very slowly for T1- requires 12 seconds T2 requires 8 seconds of measurement Carbonate Section with Oil/Water Contact OIL WATER NO RESISTIVITY CHANGE Carbonate Section with Transition from Water to Hydrocarbon TRANSITION TO HYDROCARBON NO RESISTIVITY CHANGE Miss Completion DST 4718-4754. Rec 340 feet of gas in pipe w/oil flecks Kinderhook Completion DST . 4788-4802. Rec 95 feet gas in pipe, free oil on top of tool Completed here, IP = 170 MCFD, 2-3 BOPD and 150 BWPD Miss Completion DST . 4792-4812. Rec 2340 feet GIP, trace of oil Completed 4792-4812, IP 35 Bbl/day, produce 5 Bbl/day Miss Completion TCP Perforate 4804-4814. Test flowed 5 Bbl/hour. Production rate = 80 Bbl/day water free Miss Completion DST . 4786-4806. GTS in 4.5 min, oil to surface Completed 4796-4806, IP 200 Bbl/day oil Conclusions • NMR data can be utilized to provide accurate effective porosity and permeability – Application of Bray-Smith permeability • NMR T1 data can be used to indicate fluid type independent of resistivity