Coupled Simulation With Integrated 2-D and 3-D Factor of Safety Analysis for SAGD Caprock Integrity

Abstract

In this paper the strategy for using reservoir-geomechanical simulation and a dynamic factor of safety (FOS) analysis is employed for caprock integrity assessments during SAGD recovery. The coupled simulation approach has been developed to use to use fully heterogeneous models for both flow and mechanical simulation. The previously developed FOS approach has been extended, where FOS planes in the caprock can be searched in three dimensions and has been integrated into the coupled simulation platform. This work demonstrates the FOS analysis technique through 3D heterogeneous models which includes all material types in the reservoir system (reservoir and surrounding formations). The sequential coupling modelling based on CMG-STARS and FLAC3D are then employed to dynamically analyze the changes in stress and strain in reservoir system (reservoir and caprock). Once the evolved effective stress tensors and material properties are extracted at each time step for all locations in the caprock, the FOS algorithm is applied to determine the FOS distribution along the base of the caprock. The simulation then continues to the next time step and process is repeated, thus providing a dynamic FOS during the simulation. From the results using the FOS analysis, it is demonstrated that caprock becomes less stable with the expansion of the steam chamber and that shale facies types have an impact on the caprock FOS. Through our new integrated analysis system, it is possible to provide the operator a temporal assessment of the index of caprock safety factor required for the development of SAGD.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016