<> "The repository administrator has not yet configured an RDF license."^^ . <> . . . "Cotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations."^^ . "Hydraulic fracturing is widely used to stimulate production in oil and gas fields\r\nthroughout the U.S.. However, currently no method exists that can provide well operators with\r\ninformation on fracture dimensions in real time. The Cotton Valley Hydraulic Fracture Imaging\r\nProject, as initiated by a consortium of companies (UPR, Texaco, Amoco, Arco, Chevron), was\r\nestablished to determine if the monitoring of microseismicity was feasible, if microseismicity\r\ncan remotely provide accurate measurements of fracture geometry (azimuth, height, length,\r\nwidth, asymmetry) and growth, and if recording / analysis procedures can eventually be\r\nimplemented to allow for real time monitoring (Walker, 1997). The presence of microseismicity\r\nwas confirmed during the Phase I treatment of well CGU 22-10 in May, 1997 (see Figure 1 for\r\nlayout). The analysis for fracture dimensions involved the testing of various location techniques\r\n(forward modeling and inversion schemes) by ARCO, ESG, Los Alamos, and Sandia National\r\nLabs. To locate events, ARCO employed a series of model curves derived from pre-fracture\r\nshots in the treatment well and visual curve matching for data recorded in both monitoring wells.\r\nESG examined inversion approaches that could potentially result in the real-time determination\r\nof event locations and source parameters (characteristics of source size, strength, energy and\r\nstress release). The ESG analyses concluded that it is possible to use automatically determined Pand S-wave arrivals for a subset of signals recorded in the two monitoring wells, direction\r\nvectors (hodograms), and the inclusion of velocity variations to effectively locate events to an\r\naccuracy on average better than 50 ft. (Urbancic, 1998). Both Los Alamos and Sandia considered\r\nthe effect of array decimation on location which resulted in varying degrees of success.\r\nA Phase II was implemented in July, 1997, with the fracturing of well CGU21-9. The\r\ntreatment took place over three days (July 14, 16, and 18) and was supplemented with\r\nperforation shots on July 17. Although signals were recorded from sensors located in three wells\r\n(triaxial geophones in wells CGU21-9 and CGU22-9, 48 hydrophones in CGU22-7), only the\r\narray in well CGU22-9 provided interpretable data. In their analysis of the Phase II data,\r\nWithers and Dart (1997) were able to locate 164 events of 1,826 detected events by incorporating\r\ndirectionality into their forward modelling approach. The small number of located events was\r\nprimarily a result of generally weaker signals as compared to those recorded during Phase I, and\r\nthe large percentage of events that were deficient in P-wave energy, making analysis by their\r\ntechnique difficult. As shown in Figure 2, the derived locations were scattered and markedly\r\ndifferent from the expected trend of N70E, raising questions as to whether the technique\r\nemployed was appropriate or whether the geometrical constraints imposed by single-well\r\nmonitoring limits does not allow for events to be located to any degree of accuracy."^^ . "1998-06" . . . "Gas Research Institute"^^ . . . . . . "Ted"^^ . "Urbancic"^^ . "Ted Urbancic"^^ . . "Engineering Seismology Group Canada"^^ . . . . . . . "Cotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations. (Text)"^^ . . . . . "6.pdf"^^ . . . "Cotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations. (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Cotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations. (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Cotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations. (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Cotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations. (Other)"^^ . . . . . . "small.jpg"^^ . . . "Cotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations. (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #2163 \n\nCotton Valley Hydraulic Fracture Imaging Project: Phase II (CGU 21-9) Fracture Imaging Using Microseismic Event Locations.\n\n" . "text/html" . . . "Collective properties of seismicity" . . . "Cotton Valley" . . . "Unconventional hydrocarbon extraction" . .