A Multi-Continuum Multi-Component Model for Simultaneous Enhanced Gas Recovery and CO 2 Storage in Stimulated Fractured Shale Gas Reservoirs Jiamin

Transcription

1 A Multi-Continuum Multi-Component Model for Simultaneous Enhanced Gas Recovery and CO 2 Storage in Stimulated Fractured Shale Gas Reservoirs Jiamin Jiang M.S. Candidate Joined Fall

2 Main Points Advanced Process: numerical model for CO 2 - EGR in gas shale & simulation validation Hybrid Fractures Model: balance among Accuracy, Efficiency, Field-application Generic Simulator Prototype: flexible & rapidly implement new physics 2

3 Outline 1 Flow and Transport Mechanisms 2 Multi-Continuum Hybrid Model 3 Simulation Studies 4 Current and Future Work 3

4 Flow and Transport Mechanisms Production process in stimulated shales with several stages Desorption Advection & Diffusion 4

5 Flow and Transport Mechanisms Brief Summary for the Developed Model Model Single-Phase Multi-Component 3-D Knudsen diffusion Transport & gas slippage Matrix Extended Langmuir Sorption Isotherm Pressure-dependent Nfs Geo-mechanics permeability Flow Mechanisms Multi-Continuum model Large-scale fractures Matrix & natural fractures Matrix nested-mesh EDFM Dual-Continuum MINC 5

6 Knudsen diffusion & Gas slippage Nanopores: 1) non-continuum effects 2) dominant surface interactive forces F = 1 + 8πRT M 0.5 μ pr 2 α 1 D = 2r 3 8RT πm 0.5 k app = c g Dμ + Fk m Apparent Permeability: k app = φ m τ 2rμ 3RTρ g 8RT πm i r μ pr 2 α 1 8πRT M i 0.5 (F. Javadpour, 2009) 6

7 Adsorption/desorption Large-amount of methane molecules could adsorb to the organic matter in shales; CO 2 -injection for EGR is feasible: organic matter has greater sorption affinity for CO 2 than methane. Extended Langmuir isotherm: V i = V L,i px i P L,i 1 + px i P L,i Adsorption term: m i = ρ R ρ gs V i 7

8 Physical modeling and numerical approach Pressure-dependent permeability Stimulated natural fractures: (Unpropped or weakly propped) Governing Equations Control-Volume FD Formulation V i Δt t φρ gx i + 1 φ m i = ρ g x i υ + q i w + q i conn Gas-density: PR-EOS: Dempsey method: ρ g = p RTZ Z 3 + sz 2 + qz + r = 0 μ = μ g1 exp ln μ g μ g1 T pr φρ g x c n+1 + mc n+1 φρ g x c n mc n = d f k f = k fi exp d f p fi p f is the pressure-dependent coefficient ns s=1 T pr Flux n+1 n+1 ij Q i,c 8

9 Outline 1 Flow and Transport Mechanisms 2 Multi-Continuum Hybrid Model 3 Simulation Studies 4 Current and Future Work 9

10 Fractures in Unconventional Reservoirs Stimulated shale gas reservoirs comprise complex fractures networks: 1. Natural fractures network densely distributed hard to characterize geometrically 2. Large-scale fractures dominant role as fluid conduit identify from micro-seismic 10

11 Approach 1: Dual-Continuum Models Classical dual-porosity (Warren and Root, 1963) Extension: MINC (K. Pruess, 1985) Suitable for highly connected, small-scale fractures; Not applicable to disconnected fractured media or small number of large-scale fractures Classical dual-porosity 11

12 Approach 2: Discrete Fractures Model (DFM) Unstructured grid approach (C.L. Cipolla et al., 2011) (H. Hoteit et al., 2008) Capture realistic fracture geometry Explicitly consider the effect of individual fracture Disadvantage: high computational cost 12

13 Approach 3: Embedded DFM Embedded DFM (L. Li, 2008) : alternative to DFM 1) Flexible & Accurately handle Pfs 2) Computational efficient Apply WI concept: Pressure linearly distributed Trans: d = T ij = A ij d n xds S Could be used for dynamic fractures propagation 13

14 Challenge for Modeling Natural Fractures DFM Limitation Reservoir characterization Simulation Model matching Production Data pre-existing natural fractures Detailed characterization is often unavailable Dense fractures network modeling by DFM not suitable for history-matching: a. Large parameters set b. location, orientation, length and aperture 14

15 Hybrid model: EDFM + Dual-Continuum + MINC Extension: Interaction between Pfs and Nfs primary gridblocks groups of elementary units nested sub-cells 15

16 Hybrid model: EDFM + Dual-Continuum + MINC Coupled MINC model: Advection-Diffusion-Sorption Truly quad-porosity model: Organic-Inorganic-Fracture 16

17 Integrated Workflow Based on Hybrid Model Coupled Extract Large-scale fractures pattern Upscale (C.L. Cipolla et al., 2009) Micro-seismic: realistic geometry of fractures network EDFM + Dual-Continuum: Accuracy, Computational efficiency, Field practice 17

18 Outline 1 Flow and Transport Mechanisms 2 Multi-Continuum Hybrid Model 3 Simulation Studies 4 Current and Future Work SPE , Development of a Multi-Continuum Multi-Component Model for Enhanced Gas Recovery and CO2 storage in Fractured Shale Gas Reservoirs 18

19 Simulation studies Single-Well model SPE , Development of a Multi-Continuum Multi-Component Model for Enhanced Gas Recovery and CO2 storage in Fractured Shale Gas Reservoirs Pressure profile of Nfs at 2100 days Matrix factors Natural fractures factors d f Pressure-dependent coefficient 19

20 Single-Well model Complex Primary Fractures Pattern SPE , Development of a Multi-Continuum Multi-Component Model for Enhanced Gas Recovery and CO2 storage in Fractured Shale Gas Reservoirs pressure profile of fracture continuum primary fractures pattern d d d 5 3D View 20

21 Gas Injection Model for EGR CO 2 preferentially adsorbed over methane Competitive adsorption mechanism Schematic for CO 2 -EGR scenario Cumulative methane production Pressure distribution of fracture CO 2 mole fraction of the outer nested-cell continuum after 3500d of matrix continuum after 3500d 21 0

22 Outline 1 Flow and Transport Mechanisms 2 Multi-Continuum Hybrid Model 3 Simulation Studies 4 Current and Future Work 22

23 Current Work: Compositional Model A Fully-Coupled Multi-Continuum Compositional Model for CO 2 -EGR Process in Stimulated Fractured Shale Gas Reservoirs, Accepted for Oral Presentation at 14 th ECMOR Shale gas reservoirs: multi-phase flow are generally present; Shift towards liquid-rich regions for gas condensate: fluids properties and phase behavior in nano-pores systems 1. Spatial Confinement (pore proximity) Cause critical properties to change, phase behavior exhibit large deviations (L.C. Jin, 2013) 23

24 Current Work: Compositional Model 2. Capillary Pressure Interfacial tension: σ = N c χ i (x i ρ L y i ρ V ) i 4 P V P L = p c = 2σ r f i L T, P L, x 1 x Nc = f i V T, P V, y 1 y Nc 3. Aqueous Phase Solubility of hydrocarbon and CO 2 in brine: need modifications to EOS Advanced EOS: PC-SAFT, etc. Multi-Phase: oil, gas, aqueous, liquid CO 2 A Fully-Coupled Multi-Continuum Compositional Model for CO 2 -EGR Process in Stimulated Fractured Shale Gas Reservoirs, Accepted for Oral Presentation at 14 th ECMOR 24

25 Future Work: Hydraulic Fracturing Process Lots of works were done from simulation aspect to optimize the fractures stages and patterns Longer fractures and more complex patterns will lead to more production increase How to fulfill this stimulation goal? Fractures propagations process; optimizing the stimulation parameters during this process (G. Qin, 2012) 25

26 Future Work: Hydraulic Fracturing Process Physics involved is very complicated Wave equations for solving stress-field Multi-phase, non-isothermal, non-newtonian flow of fracturing fluids; proppant transport Fluid-solid coupling mechanics, fractures propagations Fractures interaction criteria: among adjacent fractures (stress-shadow effect); crossing, arresting, branching, etc. (analytical or experimental models) Rock deformations: stress-dependent porosity, permeability, and capillary pressure of rock (G. Qin, 2012) 26

27 A Multi-Continuum Multi-Component Model for Simultaneous Enhanced Gas Recovery and CO 2 Storage in Stimulated Fractured Shale Gas Reservoirs Jiamin Jiang M.S. Candidate Joined Fall