Induced seismicity is occurring at the 315‐m‐high Nurek dam in Tadjikistan, USSR. An intense burst of seismicity accompanied the second stage of filling of the reservoir from 120 to 200 m during August to December 1976. Hypocentral locations and fault plane solutions determined using data from a 10‐station telemetered network surrounding the reservoir show the activity to be concentrated on a series of narrow, planar fault zones near the central basin and on more diffuse zones along the upstream edges of the reservoir. The activity extends to depths of 8 km and appears to be confined within the upper plate of the Ionakhsh thrust, a listric fault which outcrops 1 km north of the dam. The dominant mode of deformation in the post‐Paleozoic sediments of the Tadjik Depression is thrusting. Fault plane solutions for the induced seismicity show short segments of strike slip and thrust faulting for the most intense activity near the central basin and normal and thrust faulting along the upstream edges of the reservoir. None of the fault zones delineated by the induced seismicity corresponds to faults mapped at the surface, while none of the surface faults mapped in the reservoir area has shown an increase in seismicity. The spatial distribution of seismicity within the active zones is in general agreement with that expected from models of the changes in strength associated with reservoir loading. The temporal distribution of seismicity shows a migration outward from the center of the reservoir, probably associated with diffusion of pore pressure.

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Cyclic Steam Stimulation (CSS) is a cost-effective means to produce heavy oil at the Cold Lake field in Alberta, Canada. The high viscosity of bitumen is the main obstacle to economic production, but the bitumen viscosity decreases significantly with temperature. Steam is injected at fracturing conditions, resulting in complex interactions of reservoir expansion (dilation) and contraction (recompaction) that propagate stress and strain fields in the overburden. The mechanical loads on wells resulting from this production process are an important design consideration. To enhance operational integrity, a dedicated passive seismic monitoring well is installed on new development pads to provide early detection of casing failures and possible fracturing of the formation overburden. There is now an installed base of almost 90 such acoustic monitoring wells in the operator's field. With data acquisition of 15 to 30 geophones per system, recording continuously at 2000 or 3000 samples per second, the data management issues for this monitoring network are challenging. Several classes of acoustic events have been identified, including those due to casing failure, formation heave, near-wellbore cement cracking, and production rod pump background noise, in addition to "Continuous Microseismic Radiation" (CMR) that resembles harmonic tremors. Most casing failures are detected by observation of singular events. The detection of fracturing of the overburden, which may include the presence of bitumen and/or produced water that has migrated out of zone, is a more complex process that requires distinguishing shear events and CMR events from normal formation heave and other environmental noise. The operator has stewarded the development of a cost-effective system that includes local pad data acquisition, uploading of selected data to a server with data archiving facilities, and downloading data to dedicated analysts. This paper will present a summary of the data management and processing technologies developed to address the challenge of managing this data-intensive problem.

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