Sensitivity Analysis for Joint Inversion of Production and - PowerPoint PPT Presentation

Sensitivity Analysis for Joint Inversion of Production and Time-Lapse Seismic Data of Norne Field Amit Suman and Tapan Mukerji SCRF Annual Meeting May 4-5, 2011

Introduction Static data Well log data Core data Reservoir 3D Seismic management Reservoir Dynamic data forecasting Production data 4D Seismic data 4-5 May 2011 SCRF 2

Joint Inversion Loop Predicted Observed flow and flow and seismic seismic response response Generate . multiple models Reservoir Model Evaluate misfit 4-5 May 2011 SCRF 3

Norne Field Segment E • Southern part of Norwegian sea • Five prime zones – Garn Gas � � – Not � � � � – Ile Oil and – Tofte � � water – Tilje • 3 producer and 2 injector wells 4-5 May 2011 SCRF 4

Data Available • Well logs • Horizons • Well data - Oil , gas and water flow rate - BHP (Bottom hole pressure) 4-5 May 2011 SCRF 5

Time Lapse Seismic Data Near, Mid , Far and Full 3D seismic Q – Marine Seismic 2001 2003 2006 2004 4-5 May 2011 SCRF 6

Seismic Amplitude on Top 2001 2003 2006 2004 4-5 May 2011 SCRF 7

Motivation Production Production Production Production data at time t data at time t data at time t data at time t Dynamic Dynamic Dynamic Dynamic modeling modeling modeling modeling Δ Δ Pressure Δ Δ Pressure Pressure Pressure Δ Saturation Δ Δ Δ Saturation Saturation Saturation Optimize Optimize Optimize Optimize mismatch mismatch mismatch mismatch Velocity at Velocity at Velocity at Velocity at time t time t time t time t Rock physics Rock physics Rock physics Rock physics modeling modeling modeling modeling Seismic data Seismic data Seismic data Seismic data at time t at time t at time t at time t Update Update Update Update parameters parameters parameters parameters 4-5 May 2011 8

“what are the sensitive parameters in joint inversion loop?” 4-5 May 2011 SCRF 9

Sensitivity Parameters • Relative permeability • Pore compressibility • Rock physics models • Saturation scale • Porosity and permeability models 4-5 May 2011 SCRF 10

Porosity Model Generation � � � � Structural Structural Structural Structural � � modeling modeling modeling modeling � � Generate Generate Generate Generate variogram variogram variogram variogram 168168 cells SGSIM SGSIM SGSIM SGSIM 4-5 May 2011 SCRF 11

Selection of Porosity Models Multi-dimensional scaling (MDS) A set of N earth models can be uniquely mapped in any dimension less than or equal to N using a pair wise distance between them Euclidean distance (Caers et al 2009) 4-5 May 2011 SCRF 12

Selection of Porosity Models MDS and Clustering 3 Porosity models selected for Analysis 100 Porosity Models 4-5 May 2011 SCRF 13

Relative Permeability 1 2 1 1 2 2 Oil and water relative permeability 4-5 May 2011 SCRF 14

Pore Compressibility Spatial variability in pore compressibility can play an important role in time lapse seismic modeling (Suman et al,2009) GARN ILE TOFTE TILJE Mean 0.27 Mean 0.25 Mean 0.30 Mean 0.27 P5 0.15 P5 0.16 P5 0.17 P5 0.16 P95 0.52 P95 0.34 P95 0.34 P95 0.47 All compressibilities are in the order of 10 -9 (Pa -1 ) (6.89 X 10 -6 Psi -1 ) 4-5 May 2011 SCRF 15

Rock Physics Models Cementing vs. Sorting Trends 6 Mineral point • Cemented sand 5 model clean 4 cementing trend Vp 3 sorting • Uncemented sand trend 2 Suspension Line model New Deposition 1 (Reuss Bound) 0 0 0.1 0.2 0.3 0.4 0.5 Porosity (Avseth et al., 2005) Velocity – Porosity trends can be established using well data but there are uncertainties away from the wells 4-5 May 2011 SCRF 16

Saturation Scale • Seismic velocities depend on fluid saturation as well as saturation scale • Reservoirs with gas are very likely to show patchy behavior Sengupta ,2000 4-5 May 2011 SCRF 17

Experimental Design 1.5X10 -10 5X10 -10 Pore 3X10 -10 (Pa -1 ) (Pa -1 ) (Pa -1 ) Compressibility Relative Low High permeability Rock physics Cemented Uncemented models Saturation Uniform Patchy behavior Porosity Model 1 Model 2 Model 3 4-5 May 2011 SCRF 18

Methodology Cumulative oil Cumulative oil Cumulative oil Cumulative oil production in production in Compare Compare Compare Compare production in production in Dynamic Dynamic Dynamic Dynamic 2001 2001 2001 2001 modeling modeling modeling modeling (1997 (1997- -2001) 2001) (1997 (1997 - - 2001) 2001) Δ Δ Δ Δ Pressure Pressure Pressure Pressure Δ Saturation Δ Δ Δ Saturation Saturation Saturation Seismic Seismic Seismic Seismic velocity in 1997 velocity in 1997 velocity in 1997 velocity in 1997 Rock Rock Rock Rock and 2001 and 2001 and 2001 and 2001 physics physics physics physics modeling modeling modeling modeling Difference in Difference in Difference in Difference in Compare Compare Compare Compare seismic seismic seismic seismic velocity velocity velocity velocity 4-5 May 2011 SCRF 19

Sensitivity of 4D Seismic Sensitivity to rock physics model Sensitivity to relative permeability L1 Norm of change in seismic velocity after 4 years Sensitivity to porosity model Cemented Uncemented sand model sand model 4-5 May 2011 SCRF 20

Sensitivity of Production Sensitivity to relative permeability Sensitivity to porosity model 4-5 May 2011 SCRF 21

Conclusions and Future Work • Rock physics model is the most sensitive parameter (amongst those tested) for seismic modeling • Relative permeability and Porosity models are second and third most sensitive parameters for seismic modeling • Relative permeability is the most sensitive parameter for flow response • Sensitivity to pore compressibility and saturation scale are under investigation • Other parameters to be tested (variogram ranges, poro- perm relations) • The result of this study will be used in joint inversion of time-lapse and production data of Norne field 4-5 May 2011 SCRF 22