MRIL Applications Mechanisms of Relaxation Interpreting NMR T2 Spectra Importance of Proper Acquisition Effects of Minerals, Fluids and Rock-Fluids Applications and Examples Basic, BVI, SBVI, FFI, K Hydrocarbon Typing - gas and lighter oils Diffusion - Sor, Sw quantification Enhanced Diffusion - intermediate crudes Heavy Oil MRIL - Applications 11/14/2018

Relaxation Mechanisms Echo Amplitude vs Time Effect of Each Mechanism is Additive T2A = T2B+T2D+T2S Bulk Relaxation - T2B Intrinsic Property of fluid Amplitude Diffusion - T2D Molecular Movement Surface Relaxation - T2S Pore-walls cause rapid dephasing Time, msec. MRIL - Applications 11/14/2018

Bulk T1 of water for Bulk Fluids T1T2 T1 of water MRIL - Applications 12 10 8 6 T1 (s) 4 2 from Simpson and Carr (1958) 50 100 150 200 250 Temperature (F) MRIL - Applications 11/14/2018

Spin Echo Attenuation by Diffusion in a Gradient Magnetic Field only stationary spins are completely rephased by p pulses in a CPMG expt spins diffusing in a gradient magnetic field undergo unrecoverable dephasing... Þ echo attenuation Þ transverse relaxation mechanism ..... two sources of magnetic field gradients ..... B0 B0+d B0+2d B0+3d cfluid B0 Grain Rock Grain Pore cgrain Rock Grain pair of cpmg trains at two different TE’s diffusion “propagator” (D/12)(g××G×TE) fixed vs. pulsed field gradient nmr measurement of D 2r Rock Grain Natural ... grain scale gradients arising due to magnetic susceptibility c contrast between minerals and pore fluids ... randomly varying at grain scale pore size and mineralogy dependent Applied ... MRIL uses strong gradient magnetic field to perform “slice selection” ... known, well-defined gradient gives predictable T2 shifts that depend only on diffusion MRIL - Applications 11/14/2018

Diffusion and T2D Only effective for T2 relaxation (not for T1) 12 T 2D D when T2D = D . ( G .  . Te )2 D : Diffusion Coefficient of Fluid (cm2/sec) depends on Temp. (K) & Viscosity G : Magnetic Field Gradient (Gauss/cm) depends on Tool Freq. & Temp.  : Gyromagnetic Ratio (Hz/Gauss) = 4258 for Hydrogen Te : Inter-Echo Spacing (sec.) T 2D e when T 2D G when MRIL - Applications 11/14/2018

Effect of Diffusion on T2 MRIL - Applications 11/14/2018

Surface Relaxation Mechanism Water Filled Pores Small Pore Sizes = Rapid Decay Rate Large Pore Sizes = Slow Decay Rate T2 -1 @ r (S/V) Time, msec. MRIL - Applications 11/14/2018

Importance of Acquisition Porosity & Porosity Distributions Parameters Mostly Impacts Wait time Tw Interecho time Te Number of echoes Signal to Noise (SNR) The correct porosity The correct porosity vs T2 Distribution MRIL - Applications 11/14/2018

Porosity & Porosity Distributions Acquisition Parameter: Wait Time Wait time OK 0.0 0.5 1.0 1.5 2.0 2.5 5 10 15 20 25 Wait Time Tw Experiment Incremental Porosity (pu) Cumulative Porosity, p.u. Amplitude Time, msec. 0.1 1 10 100 1000 10000 Relaxation time T2, (msec.) Wait time too short 0.0 0.5 1.0 1.5 2.0 2.5 Time, msec. Tw Experiment Amplitude Incremental Porosity (pu) 0.1 1 10 100 1000 10000 MRIL - Applications Relaxation time T2, (msec.) 11/14/2018

Porosity & Porosity Distributions Acquisition Parameter: Interecho Spacing Te OK 0.0 0.5 1.0 1.5 2.0 2.5 5 10 15 20 25 Ao Te OK incremental porosity cumulative porosity Te too long Te Amplitude (A) Incremental Porosity, p.u. Cumulative Porosity, p.u. Time, msec. Te too long Ao Te Amplitude (A) 0.1 1.0 10.0 100.0 1000.0 10000.0 Relaxation time T2, (msec.) Time, msec. MRIL - Applications 11/14/2018

Porosity & Porosity Distributions Acquisition Parameters: Number of Echoes Number of Echoes OK 0.0 0.5 1.0 1.5 2.0 2.5 5 10 15 20 25 Number of echoes OK incremental porosity cumulative porosity Not enough echoes Amplitude (A) Time, msec. Incremental Porosity, p.u. Cumulative Porosity, p.u. Not Enough Echoes Amplitude (A) 0.1 1.0 10.0 100.0 1000.0 10000.0 Time, msec. Relaxation time T2, (msec.) MRIL - Applications 11/14/2018

Porosity & Porosity Distributions Acquisition Parameters: Signal to Noise Ratio (SNR) High SNR High SNR incremental porosity cumulative porosity Lower SNR 0.0 0.5 1.0 1.5 2.0 2.5 5 10 15 20 25 Amplitude (A) Incremental Porosity, p.u. Time, msec. Cumulative Porosity, p.u. Lower SNR Amplitude (A) 0.1 1.0 10.0 100.0 1000.0 10000.0 Time, msec. Relaxation time T2, (msec.) MRIL - Applications 11/14/2018

media is controlled by: Porosity & Porosity Distributions Effects of different fluids: air/brine displacement H1 proton precession of water in porous media is controlled by: 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 After air/brine displacement Brine filled pore Incremental Porosity, p.u. 0.1 0.3 0.6 1.6 4.0 10.0 25.1 63.1 158.5 398.1 1000.0 2511.9 6309.6 After air/brine 100 psi 100% Brine saturated Relaxation Time (T2), msec. MRIL - Applications 11/14/2018

Porosity & Porosity Distributions Effects of different fluids: oil/brine displacement H1 proton precession of water in porous media is controlled by: After oil/brine displacement Brine filled pore of oil (non wetting) in porous media is controlled by the bulk relaxation mechanism 0.1 0.3 0.6 1.6 4.0 10.0 25.1 63.1 158.5 398.1 1000.0 2511.9 6309.6 0.2 0.4 0.8 1 1.2 1.4 1.8 2 Relaxation Time (T2), msec. Incremental Porosity, p.u. After air/brine 100% Brine saturated After oil/brine displacement MRIL - Applications 11/14/2018

Interpretations - Clay and/or Microporosity Brine Saturated Incremental Porosity, (p.u.) 0.5 TE, (msec.) 1.2 TE, (msec.) 0.1 1 10 100 1000 10000 Cumulative Porosity, (p.u.) _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ 0.1 1 10 100 1000 10000 Relaxation time T2, (msec.) MRIL - Applications 11/14/2018

Confirmation from Core Internal Gradients Confirmation from Core Authigenic Siderite 0.1 1.0 10 100 1000 Relaxation Time, T2, msec. 0.3 msec. TE  = 17.6 0.6 msec. TE  = 16.5 1.2 msec. TE  = 15.0 SEM - Pore Lining Siderite Lab T2 Spectrum, G = 0 MRIL - Applications 11/14/2018

Constant Bulk Oil T2 Altered Wettability Average T2 of SMF 0.1 1 10 100 1000 10000 Relaxation time (T2), msec. Average T2 of SMF sample 29 Ka (md) = 2180 Por. (%) = 19.7 sample 98 Ka (md) = 202 Por. (%) = 22.7 sample 143 Ka (md) = 18.1 Por. (%) = 18.2 After air/brine 100psi After SMF Flush After oil/brine 100/psi Altered Wettability MRIL - Applications 11/14/2018

Basic Applications BVI (CBVI and/or SBVI) FFI Permeability Movable fluids (hydrocarbon/water) MRIL - Applications 11/14/2018

Producible hydrocarbon will produce some water NMR - Porosity Model Neutron  Density  Resistivity Sw clay matrix capillary bound water BVI clay bound water movable water rock matrix hydrocarbons NMR BVI NMR FFI Integration of MR Log and Resistivity Log Interpretation MR porosity (effective) MR porosity (total short TE) nonmovable water Producible hydrocarbon will produce some water MRIL - Applications 11/14/2018

Bulk Volume Irreducible (BVI) Relaxation time distribution Standard Method to Determine BVI 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 0.1 1 10 100 1000 10000 T2 Relaxation time, ms Incremental Porosity, % Bulk Volume Irreducible (BVI) Free Fluid Index (FFI) Relaxation time distribution Standard Fixed T2 cutoff Relates to a capillary pressure or pore radius MRIL - Applications 11/14/2018

Variation in T2 Cutoff Values 1 10 100 5 10 Sample Number 15 20 25 MRIL - Applications 11/14/2018

T2, Cutoff T2 and Pore Size 1/T2 = 2 S/V Pc =cos 2/r 1/T2  2 2/r MRI Relaxation Time (T2) & Surface to Volume Ratio 1/T2 = 2 S/V Capillary Pressure (Pc) & Pore Throat Radius (r) Pc =cos 2/r Since S/V of a capillary tube = 2/r then; 1/T2  2 2/r Since T2 is related to Pore Size & S/V: then T2 is directly proportional to K, and T2 is inversely proportional to Swi MRIL - Applications 11/14/2018

T2 Cutoff Related to Pc Rock Type A Rock Type B B Shale A Bore hole Capillary Pressure , psi 50 100 150 200 250 300 350 400 2 4 6 8 10 12 Bulk Volume Water, % Height Above Free Water, ft. Rock Type A Rock Type B B Shale A Equivalent T2 cutoff @ 50 psi Free Water Level MRIL - Applications 11/14/2018

Spectral BVI Model BVI FFI standard cutoff model 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0.1 1.0 10 100 1000 10000 Normalized Incremental Porosity Relaxation Time (msec.) Spectral Fraction BVI FFI SBVI Model: a step function MRIL - Applications 11/14/2018

SBVI Model Linked to Permeability Equations Given: K1/2 = 100f 2 (FFI/BVI) K1/2 = 4f 2 T2GM Equating the two equations gives: = 0.04 T2GM , or 1-SWIRR SWIRR Substituting: f (1-SWIRR) for FFI f SWIRR for BVI 1 SWIRR = 0.04 T2GM + 1 Coates equation becomes: K1/2 = 100f 2 1-SWIRR SWIRR The empirical form is: 1 SWIRR = mT2GM + b MRIL - Applications 11/14/2018

Lab Method to Determine SBVI Core Swi vs T2 0.2 0.4 0.6 0.8 1 50 100 150 200 T2 Geometric, ms Swi (Core), frac. SBVI - Slope Determination 2 3 4 5 6 7 8 20 40 60 80 120 140 T2, Geometric, ms 1/Swi (Core) Correlate Core Swi and T2 Compute fraction for each T2 Bin SBVI = 1/((0.0243 T2) + 1) Bin # T2 time BVI Fraction 1 2 0.919 2 4 0.849 3 8 0.738 4 16 0.585 5 32 0.414 6 64 0.261 7 128 0.150 8 256 0.081 9 512 0.042 10 1024 0.022 y = 0.0243x + 1 R2 = 0.89 MRIL - Applications 11/14/2018

BVI Model Comparison Cutoff T2 SBVI Model Swi from cutoff T2 10 20 30 40 50 60 70 80 90 100 Core Swi Swi from cutoff T2 10 20 30 40 50 60 70 80 90 100 Core Swi Swi from SBVI SBVI Model Cutoff T2 MRIL - Applications 11/14/2018

Permeability Chart E-4 E - 4 Porosity Swir 0.5 0.4 0.3 0.2 0.1 0.2 0.4 1000 Porosity (f x Swirr) increases 0.2 100 10 1.0 0.1 k (md) 0.2 0.4 0.6 0.8 1 Swir MRIL - Applications 11/14/2018

Permeability from Porosity and Water Saturation 40 35 5000 30 k, Permeability (md) 2000 25 1000 Phi x Swirr 500 20 0.12 Porosity 100 0.10 50 0.08 15 20 0.06 10 5.0 0.04 10 0.02 1.0 0.01 0.10 5 0.005 0.01 10 20 30 40 50 60 70 80 90 100 Swir MRIL - Applications 11/14/2018

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) MRIL - Applications 11/14/2018

MRIL Field Standard Presentation Single Activation MRIL - Applications 11/14/2018

MRIL Field Standard Presentation CTP Activation MRIL - Applications 11/14/2018

MRIL Field Standard Presentation Dual (Te or Tw) Activation Dual Wait Time (Tw) 8 sec & 1 sec MRIL - Applications 11/14/2018

Conventional Logs Density, Neutron, Resistivity, GR and Cal. MRIL - Applications 11/14/2018

MRIL Final Result Water @ Bottom of Zone MRIL - Applications 11/14/2018

Conventional Logs Density, Neutron, Resistivity, GR and Cal. MRIL - Applications 11/14/2018

Zone Productive - little to no water cut MRIL Final Result Zone Productive - little to no water cut MRIL - Applications 11/14/2018

Hydrocarbon Typing Dual wait time TDA Best for: light oils excellent gas detection MRIL - Applications 11/14/2018

Direct Hydrocarbon Typing Differential Spectrum Method Brine Gas Oil Porosity Long Recovery Time (TR) Short Recovery Time (TR) Difference T2 Time (ms) 1 10 100 1,000 10,000 MRIL - Applications 11/14/2018 ã NUMAR Corp., 1995

1. Ability to hydrocarbon type in difficult environments, Time Domain Analysis 1. Ability to hydrocarbon type in difficult environments, 2. Direct Effective Porosity, 3. Resistivity independent Sxo. MRIL - Applications 11/14/2018

Line Broadening T2 TIME T2 TIME 30 200 1 10000 30 200 1 10000 200 1 10000 T2 TIME 30 200 1 10000 T2 TIME MRIL - Applications 11/14/2018

- = Time vs T2 Domain time time time T2 T2 T2 MRIL - Applications - = time time time T2 T2 T2 MRIL - Applications 11/14/2018

Gas / Oil contact confirmed MRIL TDA Final Result Gas / Oil contact confirmed MRIL - Applications 11/14/2018

Diffusion Dual Te Determine Sw, Sor Used to Determine Fw Best for: oil with low D and low viscosity MRIL - Applications 11/14/2018

MRI Log - Diffustion Processing & Interpretation Based on the Thermal Diffusion properties of Fluids in the pore space D DW RDDW = D : Diffusivity of Fm. Fluid DW : Diffusivity of Water at Fm. Temp. & Press. = 12.5 at surface Temp. & press. 0.0 RDDW 100% Water Saturation 50% Water Saturation 1.0 1 / T2int 1 / T2Hy 1 / T2irr T2irr : Lower T2 boundary of Free Fluid MRIL - Applications 11/14/2018

Challenge 2 - Rel. K and NMR Mounting - For Steady State Relative Permeability and NMR Measurements Teflon end plug Teflon tape wrapped sample glass tube .. Fluid in Fluid out Pressure porous media mixer head Pressure heat shrinkable Teflon MRIL - Applications 11/14/2018

Results Diffusion / Fractional Flow Concept T2 and D echo spacing gradient Gyromagnetic ratio Diffusion Constant observed T2 intrinsic T2 MRIL - Applications 11/14/2018

Results Diffusion / Fractional Flow Concept T2 and D Combining Two TE Measurements yields Determination of D and the short TE yields determination of T2 MRIL - Applications 11/14/2018

Results Diffusion / Fractional Flow Concept T2 and D T2 is a function of surface and bulk fluid relaxation Thus in a dual TE experiment the computed D = Doil + Dwater The Ratio D/Dw Given as RDDW provides a contrast to Determine Saturation surface relaxation bulk fluid relaxation In water wet Rocks: MRIL - Applications 11/14/2018

Results Diffusion / Fractional Flow Sample 11 100% Brine @ Swi = 29% @ 50/50 fraction Sw = 61% @ Sor, Sw = 77% MRIL - Applications 11/14/2018

Results Diffusion / Fractional Flow MRIL - Applications 11/14/2018

Enhanced Diffusion Introduction and theory Data processing and interpretation Recognizing pay T2 domain to determine residual oil Time domain to determine residual oil MRIL - Applications 11/14/2018

Introduction and Theory At Long TE’s Effects of Surface Relaxation are Minimized Effects of Diffusion are Maximized 1000 Water Oil T2A=T2S T2DW = 50 100 T2S , msec. 10 T2DW = 50 Upper limit of T2Water 1 1 10 100 1000 1 10 100 1000 T2A , msec. T2A , msec. MRIL - Applications 11/14/2018

Common EDM Log Response MRIL - Applications 11/14/2018

Pay Recognition from EDM The Effect of Long TE MRIL - Applications 11/14/2018

Effect of Internal Gradient 4.8 msec. TE Fully Polarized 4.8 msec. TE Differential Spectrum GR DEPTH feet 0 GAPI 200 4 msec. 2048 4 msec. 2048 Water peek X450 T2DW T2DW MRIL - Applications 11/14/2018

EDM - Single vs Dual Wait Time MRIL - Applications 11/14/2018

Residual Oil Saturation MRIL - Applications 11/14/2018