2012 SEG/SPE/AAPG Summer Research Workshop Pressure and saturation estimation from 4D seismic constrained by reservoir flow simulation 53 06 *Alessandra Davolio davolio@dep.fem.unicamp.br Célio Maschio celio@dep.fem.unicamp.br Denis Schiozer denis@dep.fem.unicamp.br

Objective Main research: development of methodology to integrate reservoir simulation and 4D seismic data in a quantitative way. This work: estimation of pressure and saturation variations from 4D seismic data constrained by flux conditions. Pequenas mudanças

Main idea of the methodology 4D seismic Reservoir simulation Constraints Smin < Sw < Smax Pmin < Pre < Pmax Uncertainty analysis Optimization Trocaria optimization  inversion Pre Sw Model 1 Model 2 … Model n Pre Sw Pre Sw Pre Sw

Premin < Pre < Premax Inversion procedure Usual constraints Swc< Sw < 1-Sor Preb < Pre < Preover Não entendi bem... Talvez seja melhor deixar claro no titulo o que quer com esse slide... É o que vc sugere ou o que é feito e o que vc vai sugerir mudanças? Constraints from multiple simulations Smin< Sw < Smax Premin < Pre < Premax

Methodology: multiple models LOCATION Importante que é preciso confiar na análise de incertezas - Acho que as figuras não estão claras – ou seja – não dá para entender que para cada bloco – há um minimo e um máximo que são obtidos por todos os cenários – acrescentei texto For each grid block: minimum (lower among all simulations) and maximum (higher among all simulations) values

Problem Statement (building a synthetic data set to test the methodology) Reference reservoir model “Reference” seismic attributes P,S maps PEM Multiple realizations P,S min & max values Inversion Algorithms Inverted P,S maps Inverted P,S maps (calibrated) Pequenas mudanças Base model “Base” seismic attributes P,S maps PEM Simplification: no scale differences between seismic and simulation data!

Assumptions Seismic is at simulation scale Water injection case  above bubble point pressure (no presence of gas) PEM – unconsolidated sand model + Gassman equations

Application: case studied Uncertainties Porosity and permeability fields Geostatistical realizations Faults transmissibility Relative permeability Kz/Kx 400 models Example: geostatistical realizations of porosity (left) and permeability (right) 8

Synthetic seismic 4D difference (without noise) P impedance S impedance 9

Synthetic seismic 4D difference (with random noise) P impedance S impedance 10

Application First case Inversion is run using usual constraints. Second case Inversion constrained by min and max extracted from 400 models simulations. Third case Inversion constrained by min and max extracted from some selected models simulations. Selection based on well pressure data.

Application: production data to select the best models 2nd case 3rd case 12

Expected Results 13

(estimated – true answer) Results – First case Inversion results LOWER LEFT CORNER Errors (estimated – true answer) Constraints Swc< Sw < 1-Sor Pb < Pre < Pover 14

(estimated – true answer) Results – Second case Inversion results Errors (estimated – true answer) 15

(estimated – true answer) Results – Third case Inversion results Errors (estimated – true answer) 16

Results Reduces number of blocks with high error Increases number of blocks with low error Colocar titulo no eixo y – não acho que é trivial para quem está assistindo

Conclusion It was presented a methodology that uses uncertainty analysis with reservoir simulation to constrain the estimation of dynamic properties from 4D seismic Necessary due to problems related do 4DS (noise, resolution, scale, …) More iterations may be necessary so each technique can constrain the other Well data (pressure) was used to improve the constraint applied to the inversion Promising results, specially in the estimation of water saturation variation Next step: to use seismic information in a probabilistic approach. Pequenas mudanças 1º item – importante falar que isso é devido a todos os problemas proveniente da S4D – ou seja – a inversão deve proporcionar algo fisicamente consistente com os cenários 2º item – can ? Ou foi usado? Troquei... 4º item – vai explicar? Continuidade? 18

Acknowledgments UNISIM-UNICAMP

Thank you! 2012 SEG/SPE/AAPG Summer Research Workshop *Alessandra Davolio davolio@dep.fem.unicamp.br Célio Maschio celio@dep.fem.unicamp.br Denis Schiozer denis@dep.fem.unicamp.br