Monitoring Of Deep Well Injection Of Hazardous Material

In the fall of 1993 ARC0 performed a field demonstration of technology to<br>predict and monitor hydrofracture injection of industrial waste solids and liquids.<br>Results of this test show it is feasible to inject large quantities of simulated waste<br>at pressures above those required to fracture the formation, while<br>simultaneously verifying containment within sealing horizons. This application<br>of hydraulic fracturing may provide an alternative to existing methods of waste<br>disposal.<br>Three wells were drilled and instrumented with geophones along one wing of<br>the predicted fracture wing at an East Texas site. A total of 4 million lbs of solid<br>and 2.1 million gallons of inert nonhazardous material was injected over a 5 day<br>period. The fracture growth was monitored using a variety of diagnostic<br>techniques: passive borehole seismic monitoring, an active surface seismic<br>technique, surface tiltmeters, and routine logging techniques, The fracture<br>height, a critical parameter for disposal applications, was monitored by<br>triangulation, noise logs and minimum time analysis of the acoustic emissions in<br>near real-time at the well site. The results analyzed to date convincingly showed<br>containment within the bounding shale layers.<br>The purpose of the program was to verify that ARCO’s state-of-the-art fracture<br>models successfully predict the containment parameters of a proposed fracture.<br>This paper will present the results of the program to design the wells and to<br>monitor the fracture evolution with the various seismic techniques. Analysis of<br>the numerous phases observed in the fracture process will also be presented.<br>The process to obtain regulatory approval of fracturing for waste disposal<br>applications is ongoing, based in part on the success of this carefully documented<br>test.