--> Abstract: Monitoring Steam-Induced Geomechanical Deformation Using Microseismicity and Tiltmeters, by Shawn Maxwell and Jing Du; #90078 (2008)

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Monitoring Steam-Induced Geomechanical Deformation Using Microseismicity and Tiltmeters

Shawn Maxwell1 and Jing Du2
1Pinnacle Technologies, Calgary, AB, Canada
2Pinnacle Technologies, Houston, TX

Optimizing steam injections is an important factor in enhanced recovery in heavy oil reservoirs, as well as other EOR injections. Steam injection results in significant geomechanical changes, including pore pressures, thermal stresses and expansion, and significant constitutive property changes. These changes result in deformation that can be used to track the steam migration. Surface uplift associated with the steam movement can be used to image the underground strains associated with the injection. The presence of microearthquake or microseisms can also be used to infer that fracture movement and resulting permeability enhancements play a role in steam movement. Together the surface and seismic deformations can be used to assess the geomechanical state of the rockmass and potentially validate the results of a reservoir flow simulator linked with a geomechanical model.

Here a case study is presented demonstrating the use of microseismicity and surface movements recorded during the warm-up steam injection in a SAGD well pair. Microseismic sensors were placed in an abandoned vertical well slightly offset from the SAGD wells, and a surface tiltmeter array was also installed. Tiltmeter data was inverted for the reservoir strain associated with the steam injection and compared with the microseismic data. The relative timing of the surface and seismic deformations were also examined to assess the significance of induced fracturing as a mechanism for steam migration. The computed reservoir strain was also used to calculate induced stress changes and to predict the geomechanical shear failure state. The associated estimated regions of shear failure were compared with the microseismic event hypocenters.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas