MRIL OVERVIEW Team One NUMAR / HALLIBURTON. Crucial Formation Evaluation Questions What is the storage capacity ( ï¦ e and ï¦ t ) in a Complex Lithology

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  • MRIL OVERVIEW Team One NUMAR / HALLIBURTON
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  • Crucial Formation Evaluation Questions What is the storage capacity ( e and t ) in a Complex Lithology Environment ? Are there hydrocarbons, what types of hydrocarbons and, how are they distributed? What is the permeability (deliverability)? Will the formation produce water free? (what is irreducible saturation (BVI)) MRIL answers them all
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  • Only Fluids are Visible Thin Slice Image H Medical MRI
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  • hydrocarbon hydrocarbon Oilfield MRI (Relaxation Time Spectrum) Fluids Solids.invisible to MRI time, sec. 0 1 2 3 4 5 6 8 9 10 11 12 13 14 . irreducible movable water movable water movable water irreducible clay bound T 1 Magnetization no measurement T 2 relaxation times the measurement rock matrix dry clay
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  • Magnetic Dipole Proton H Hydrogen N S NMR works with Protons - Hydrogen -> H 2 O and C x H y +++
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  • N S N S N S N S N S N S N S N S N S N S N S N S N S N S t = 0 Random Orientation in Natural State Bo
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  • N S N S N S N S N S N S N S N S N S N S N S N S N S N S t = 0.75 sec M Bo=External Field M=Bulk Net Magnetization Wait time (sec) Magnetization Buildup Bo
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  • N S N S N S N S N S N S N S N S N S N S N S N S N S N S t = 6.0 sec M Bo=External Field M=Bulk Net Magnetization Wait time (sec) Buildup at 95 % polarization Bo
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  • Polarization Time T2T2 Decay Time T1T1 Magnetization T 1 characterizes the rate at which longitudinal magnetization builds up T 2 characterizes the rate at which transverse magnetization decays B0B0 MLML MTMT T 1 build-up and T 2 decay
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  • NMR Experiment Timing MoMo 0 M to B o (longitudinal component) M to B o (transverse component) MoMo 0 RF field 0 B1B1 00.51.01.52.02.53.03.54.04.55.0 time, seconds TWTW TETE TXTX adapted from Murphy, D.P., World Oil, April 1995 T 1 = 400 msec T 2 = 250 msec
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  • 3 * T 1 = Tw 95% Polarization % Polarization * = Measured Porosity t (s) % Polarization Gas: T 1 = 3s Water: T 1 = 0.33s T 1 Magnetization build up 0 1 2 3 4 5 6 7 8 9 10 11 12 Light Oil: T 1 = 2s 100 80 60 40 20 0
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  • T 1 Build-up T 2 decay Low Porosity Clean Cgr Sandstone Low Porosity Shaly Fgr Sandstone Higher Porosity Shaly Cgr Sandstone Time, sec. Effects of Chemistry and Texture on T 1 and T 2 (water filled) 0 1 2 3 4 5 6 7 8 9 10
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  • MRIL ProbeBorehole Sensitive Volume Cylinders (each 1 mm thick at 1 mm spacing) 24 16 Permanent Magnet and Field Pulsing RF and receiving RF Antenna MRIL in Wellbore
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  • MRIL Diameter of Investigation Multi - Frequency Series C Tool Frequency 3 NUMAR Corp., 1995 Formation 16 Frequency 1 6 Borehole Wall Mud Sonde Sleeve Magnet RF Antenna N S Frequency 2 2 3 1
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  • time (ms) Amplitude (pu) Decay rate (1 / T 2 ) => rock & fluid information Measured signal decay TETE TETE Amplitude = Porosity
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  • 3 Relaxation Mechanisms Bulk Relaxation - T 2B Intrinsic Property of fluid Diffusion - T 2D Molecular Movement Surface Relaxation - T 2S Pore-walls cause rapid dephasing Effect of Each Mechanism is Additive Time, msec. Amplitude Echo Amplitude vs Time
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  • T2T2T2T2 T2T2T2T2 T2T2T2T2 T2T2T2T2 T2T2T2T2 time time time time time Pore Size and T 2 (Water) T 2 = relaxation time constant. S = surface area of the pore. V = volume of the pore. 2 = relaxation rate constant.
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  • Surface Relaxation Mechanism Water Filled Pores Time, msec. T 2 -1 S/V) Small Pore Sizes = Rapid Decay Rate Large Pore Sizes = Slow Decay Rate
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  • Data Processing - Inversion T 2i are pre-selected: T 2i = 4, 8, 16, 32, 64, 128, 256, 512, 1024... MAP Inversion Processing T 2 [ms] Incremental Porosity [pu] T 2 Spectrum Best Fit Water-saturated rock: 2 = V/S NUMAR Corp., 1995 BVI FFI
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  • phi- NMR (pu)
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  • Permeability Chart E-4 0 0.1 0.2 0.3 0.4 0.5 00.20.40.60.81 S wir Porosity E - 4 1000 100 10 1.0 ( x Swirr) increases k (md)
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  • MRIL Permeability MPERM = ((MPHI/10) 2 (MFFI/MBVI)) 2 MPHI - MRIL Porosity (porosity units) MBVI - MRIL Bulk Volume Irreducible MFFI - MRIL Free Fluid Index MPERM - Permeability (millidarcies)
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  • Differential Echo / Spectrum Method
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  • Effect of Diffusion on T 2
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  • Diffusion - Shifted Spectrum Method
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  • Pay Recognition from EDM The Effect of Long T E
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  • Density Porosity Neutron Porosity Effective Porosity 0 0 0 0 -100 8 0 Variable Density (milliseconds) T2 Distribution 20482
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  • Whats new ? Pick your choice Low resistivity pay Extra pay identified Shale, Huh ? Integrating core data and MRIL data