Analysis of injection-induced failure for DuPont test 1#, Dongying, Shandong Province

Abstract

From December 3, 2005 to May 18, 2006, a water injection-induced seismicity test was conducted on DuPont test well 1# for about six months by China Earthquake Administration. To the vertical injected well, 11 water injection processes were conducted on four depth intervals, including middle Shahejie3, the top of the upper Shahejie3, the bottom of the upper Shahejie3 and Shahejie2, with the vertical span from 1 464 m to 3 034 m. Monitoring stations has been run throughout the procedure. From the recorded data, there were 5 090 events being picked out manually, 274 events located. It indicates that the energy of seismic signal is very small, and the largest magnitude is no more than M L 0.5. And also, the major energy is centered on the vertical component, while amplitude of the other horizontal components is very small. From the start of water injection, the number of seismic events varied with time. And the event was most frequent in the period of upper Shahejie3 injection. The distribution of events extended from the injected well to the outside with time, and the direction of events distribution rotated in different injected interval. Of which, in the low permeability interval, events trend close to the direction of principal compressive stress direction; while in higher permeability interval, they trend close to the predominant seepage direction.

Characterization of brittleness index of gas shale and its influence on favorable block exploitation in southwest China

“…They have brittle mechanical characteristics and are usually classified as brittle minerals (Nelson, 2001;Jarvie et al, 2007;Matthews et al, 2007;Rickman et al, 2008;Wang and Gale, 2009;Diao, 2013;Li, 2013;Jin et al, 2014). For North American shale, quartz is typically used as a molecule to calculate the brittleness index.…”

An New Approach for Estimating Critical Injection Pressure and Fault Stability during Fluid Injection into Rock Reservoir

“…We suppose that fluid injection at the boundary 0 r r = lead to such an increase in the pore pressure at a certain point ( ) , 10 p = Pa and 5 max 6 10 p = × Pa. Thus, a variation in the pore pressure of the order of 10 3 Pa is sufficient to initiate microseismics, and the majority of events will occur when the pore pressure increases within 5 10…”

“…The overall shape of the cloud of earthquakes is similar to that observed for the injection at Fenton Hill. During the hydraulic fracture experiment at German Continental Deep Drilling Borehole (KTB) in 2003,approximately 2799 microseismic events were induced 9 .From December 3, 2005 to May 18, 2006, a water injection-induced seismicity test was conducted on DuPont test well 1# for about six months by China Earthquake Administration, there were 5090 events being picked out manually274 events located 10 . Most induced events cluster into well-defined geometrical patterns, which typically form an elongated cloud of event locations and are rarely diffused 7 .more recently, seismicity caused by CO 2 injection into geological formation may also be considered 11,12,13 .…”