المعهد الجزاي ري للبترول INSTITUT ALGERIEN DU PETROLE JOURNEES D ETUDES TIGHT & SHALE RESERVOIRS 17-18 Septembre 2013 Sheraton, Alger Tight Gas Reservoir Characterization PRÉSENTATEUR : M. Farid CHEGROUCHE ORGANISME : ENAGEO
Outline Objectives workflow o o o o analysis AVO/AVA analysis Conventional Pre-stack inversion analysis interpretation Conclusion
Objectives Available data 1. Seismic data: pre-stacked data 2. Well data Well 1 Cali GR Th, K, U PEF DT NA RHOB NPHI Resistivity Cali GR Th, K, U PEF DT SDT RHOB NPHI Resistivity 3. Engineering data 4. Geology data Problematic: - well 1 : gas traces - : DST test ( gas traces) -Core data : grain size (very fine, fine to medium ) Are wells well positioned? o o o At pay sandstone At hydrocarbon anomaly At good quality reservoir
Objectives Objectives 1. Reservoir mapping 2. Fluid nature & distribution identification 3. Reservoir quality study Solid Fraction Fluid Fraction Mineral Clay Shale water Water Hydrocarbon Sandstone volume Shale volume Effective Porosity
Workflow
Interprétation Sismique Isochone Dip variance
Interprétation Sismique Model
Workflow Wavelet Extraction Input CDP gather, well log Well Tie Target zone analysis well location at Build initial model 3D Volume inversion Output attributs Ip, Is, ρ,λρ,μρ Result
attributs
attributs
AVO/AVA Workflow Well Ties Modeling (Zoeppritz) QC AVO classes Partial stacks Intercept/Gradient Output: AVO Attributes Result interprétation Horizon Slice
AVO/AVA attributs Scaled Poisson Fluid Factor
Porosity (φ) Volume (patent) Matrix Volume Connectivity φ e volume τ tortuosité volume (patent) Water Saturation S w Permeability (K) volume Zone 3 Grain size volume
High rigidity Matrix volume Rigidity volume
Poor quality Low rigidity High rigidity Initial location Proposed location Matrix volume Rigidity volume High quality
Low porosity Matrix volume Porosity volume
Total porosity P impedance Low porosity with low density Shear impedance Bulk Density Porosity
Total porosity P impedance Shear impedance P Impedance S Impedance
low I s & low I p Initial location Proposed location P Impedance P Impedance S Impedance S Impedance high I s & low I p
Water saturation Water saturation Poisson Ratio Bulk density V p /V s
Water saturation Initial location 1 st Lame Modulus Proposed location Poisson Ratio V p /V s Ratio
Analyse AVO / AVA Paleozoique TMTN-O TMTNO TIL-1 Classe 1 Zone 2 TIL 1 Reservoir Top Scaled Poisson < 0 Fluid Factor < 0 Zone 1 Reservoir Base Scaled Poisson > 0 Fluid Factor > 0 Zone 3
Scaled Poisson Fluid Factor Top Scaled Poisson < 0 Fluid Factor < 0 Scaled Poisson Fluid Factor Base Scaled Poisson > 0 Fluid Factor > 0
Top Scaled Poisson < 0 Fluid Factor < 0 Base Scaled Poisson > 0 Fluid Factor > 0 Initial location Scalled Poisson Proposed location Initial location Fluid Factor Proposed location
Permeability Scaled Poisson connectivity Fluid Factor Fluid Factor Permeability connectivity
Permeability Scaled Poisson connectivity Fluid Factor Permeability Grain size
Obstacle effect (Tortuosity) Tortuosity Grain size
Obstacle effect (Tortuosity) Grain size connectivity Grain size connectivity
Conclusion In this work a detailed tight gas reservoir characterization study was presented. Two innovative approaches have been introduced: Porosity and Tortuosity. Unlike conventional methods, water saturation was calculated from Durbin model using tortuosity. As a result, an interpretation of gas indications observed at production well has been proposed