Time-lapse Seismic and AVO Modeling, White Rose, Newfoundland This presentation will probably involve audience discussion, which will create action items. Use PowerPoint to keep track of these action items during your presentation In Slide Show, click on the right mouse button Select “Meeting Minder” Select the “Action Items” tab Type in action items as they come up Click OK to dismiss this box This will automatically create an Action Item slide at the end of your presentation with your points entered. Time-lapse Seismic and AVO Modeling, White Rose, Newfoundland Ying Zou and Larry Bentley

Outline Introduction Theory and methodology Case study: White Rose Field Three production scenarios Zero offset synthetics PP and PS AVO modeling Conclusions Future work directions Acknowledgement

Introduction Production of gas or oil Changes: Saturation Pressure Temperature Changes: Bulk modulus Shear modulus Bulk density Changes: Seismic response (e.g. PP, PS, AVO)

Theory and Methodology (Bentley et al. CREWES Rpt., 1999) Fluid properties + PVT data + Batzle & Wang(1992) + Vasquez & Beggs(1980) rf and Kf Velocity + density logs Kuold, muold and ruold Core f and Ks Gassmann Eq.

Theory and Methodology New Saturation Pressure Temperature fnew, Kfnew Production Kunew , unew

Theory and methodology FluidSeis---A Matlab fluid substitution Program Individual fluid property, Saturation & PVT FluidSeis.m rf , Kf Fluid, rock property, Saturation & PVT, velocity & density logs FluidSeis.m rf, Kf, Kd , Ku , ru Above properties for both pre and post production FluidSeis.m Above values & their changes

Case study: White Rose field-- Well Location

White Rose field--Well logs

Case study: White Rose field-- Three drive mechanisms: Original reservoir From sea bottom Gas In oil leg: Sg=0% So=78% Swc=22% 2758 m Oil 2851 m Water P & T maintained

Case study: White Rose field-- Gas Drive From sea bottom Gas Oil Water Gas 2758 m In oil leg: Sg=48% Sor=30% Swc=22% Oil 2851 m Water P & T maintained

Case study: White Rose field-- Water Drive From sea bottom Gas Oil Water 2758 m In oil leg: Sg=0% Sor=30% Sw=70% 2851 m P & T maintained

Case study: White Rose field-- Gas and Water From sea bottom Gas Oil Water Gas 2758 m 2851 m Water P & T maintained

Case study: White Rose field--Results Oil Leg Reflection Coefficient

Synthetic Zero Offset Traces P-P Synthetic Zero Offset Traces Water Gas drive drive Original L-08 VSP Corridor Stack

Case study: White Rose field--- PP wave AVO modeling NMO Corrected trace gather Stacked trace Gas-Water Water Gas Original

Original Gas Gas-Original

Original Water Water-Original

Gas+ Water Gas+Water -Original Original

Case study: White Rose field--- PS wave AVO modeling: pre-production

Original Gas Gas-Original

Original Water Water-Original

Summary Velocity changes less than 1% Density changes 1-2% P-P Reflection coefficient changes 15-20% P-P and P-S offset dependent changes are sensitive to fluid substitution P-P and P-S AVO are more diagnostic of fluid changes than stacked traces

Conclusions White Rose is a good candidate for time-lapse reservoir monitoring Multi-component recording of P-S converted waves appears to be a useful reservoir monitoring tool

Future Work Add noise to synthetic traces AVO attribute analysis Exploring additional by-passed oil and pressure maintenance scenarios True amplitude of seismic processing

Acknowledgements CREWES sponsors Husky Oil Larry Mewhort Jill McLean Hampson-Russell Qing Li