The Use of Passive Seismic Monitoring for the Exploration and Production of Hydrocarbon Reservoirs

Peter M. Duncan, James Lakings, and Christopher Neale. MicroSeismic, Inc, 800 Tully Rd, Suite 175, Houston, TX 77079, phone: 7137254806, [email protected]

The use of passive seismic energy to help understand the static and dynamic nature of the subsurface is rapidly gaining industry interest. These naturally occurring sources can provide a wealth of information regarding larger scale structural features, as well as reservoir scale production or injection induced changes in fluid and rock properties.

Two applications are being progressed that exploit passive seismic on differing scales. Transmission Tomography utilizes local micro-earthquakes as seismic source to create three-dimensional P and S wave velocity volumes, from which structure, faulting and lithology can be inferred. The environmentally benign acquisition methods make Transmission Tomography ideally suited for many exploration applications in the Rocky Mountains due to the negligible permitting requirements and low overall cost.

Monitoring the release of micro-seismic energy associated with reservoir level production activities is becoming a well established technique for understanding several dynamic reservoir processes. Two different methods are being commercially progressed, downhole and surface monitoring. Downhole observation utilizes a linear array of geophones placed in a wellbore to detect and locate the hypo-centers of discrete micro-seismic events. Surface monitoring ‘beam-steers' the output from a relatively dense surface array to identify the location of both continuous and transient acoustic sources without requiring the detection of discrete events. Both methods allow the operator to relate micro-seismic events to the progression of dynamic reservoir processes such as hydraulically stimulated fracture growth, injected fluid movement, reservoir compaction, reactivated fault movement and compartmentalization.