Integrated Uncertainty Management Planning and Advanced Reservoir Modeling in Angola Block 14 Deepwater

Mabe, Kathleen Elizabeth¹, John Baillie¹, Mark Moon¹, Martha Gerdes², Sebastien Strebelle³, Marjorie Levy³, Joy M. Roth¹ (1) ChevronTexaco Overseas Petroleum, Bellaire, TX (2) ChevronTexaco Energy Technology Co, Bellaire, TX (3) ChevronTexaco Energy Technology Co, San Ramon, CA

The benefits of integrating uncertainty management with advanced modeling techniques allow for prioritization of subsurface uncertainties and development of mitigation plans to reduce associated risks with Angola Block 14 deepwater developments. Advanced reservoir modeling techniques capture the range of subsurface uncertainties and increase under­standing of development risks associated with channel deposition, velocity, faulting, fluid and rock properties. Improved modeling workflows integrate uncertainty management with advanced modeling techniques to define probabilistic ranges of hydrocarbon volumes, recoveries and forecasts.

Deepwater channel deposition is modeled by incorporating multiple-point statistics and facies distribution modeling. These tools enable the modeling of geologically-realistic facies and better control of geobody spatial distribution. Detailed stratigraphic grids capture cross­flow between channels using pinchout functionality. Multiple models are built to represent stratigraphic uncertainties.

Faults play a significant role in defining connected fluid volumes in many deepwater reservoirs. Faults act as flow barriers by offsetting permeable strata and creating low per­meability gouge. Conversely, faults act as flow conduits if continuous fracture and joint net­works develop. Our modeling workflow includes 3D characterization of faults with spatially­varying flow properties. Faults in the stratigraphic grid are modeled with split-nodes to cap­ture cross-fault juxtaposition relationships. 3D fault variability is captured using a Vshale property conditioned to seismic and wells using principle component analysis. The fault geometry and Vshale property are used to estimate the impact on fluid communication in the model.

This improved workflow builds upon ten years of work efforts by ChevronTexaco with the Block 14 Contractor Group (Sonangol-P&P, Total, ENI and GALP).