Mirror zone flac3d verification#
Mirror zone flac3d series#

Anionic tracers travel with the water but cationic tracer undergo chemical exchange with cations on the surface of the rock. The time history of concentration, or breakthrough curve, will show a separation of the tracers. In multi-ionic tests several ionic tracers are injected simultaneously and the detected in a nearby pumping well. The focus of the tracer investigation was multi-ionic tests. As a result, we were able to predict which well pairs would demonstrate channelized flow. We found that these tests were much more effective than constant pumping tests in identifying a poorly connected well. This pressure signal is sensed in other wells and the attenuation and phase lag between the source and receptor is an indication of hydraulic connection. In such tests, rather than pumping or injection in a well at a constant rate, flow is varied to produce an oscillating pressure signal. The focus of the hydraulic investigation was periodic hydraulic testing. Nine small diameter boreholes were drilled from the surface to just above the fracture to allow the measurement of heat transfer between the fracture and the rock matrix. This simple system allowed a complete characterization of the fracture. Five boreholes were drilled in a вЂњfive spotвЂќ pattern covering 100 m2 and hydraulically isolated in a single bedding plane fracture. Because soil overburden is thin, it provided unique access to saturated bedrock fractures and the ability image using GPR which does not effectively penetrate most soils. Altona Flat Rock is an experimental site considered a geologic analog for some geothermal reservoirs given its low matrix porosity. The field site for these studies was the Altona Flat Fractured Rock Research Site located in northeastern New York State.

Mirror zone flac3d verification#

These methods were tested at a field site using two verification methods: ground penetrating moreВ В» radar (GPR) images of saline tracer and heat transfer measurements using distributed temperature sensing (DTS). We explored two methods of assessing channelization: hydraulic connectivity tests and tracer tests. The purpose of this project was to understand how channelized flow develops in fracture geothermal reservoirs and how it can be measured in the field. If water flow develops channels or вЂњshort circuitingвЂќ between injection and extraction wells thermal sweep is poor and much of the reservoir is left untapped. The prediction of the geothermal system efficiency is strong linked to the character of the flow system that connects injector and producer wells. The methodology described here is under development and currently being applied to several field sites.

Mirror zone flac3d series#

Through understanding of this behavior, it may be possible to use inverse techniques to refine the a priori assignment of fractures and their conductances such that we obtain the best fit to a series of well test results simultaneously. We are studying the behavior of well tests under such geometry. Because the fracture network is only partially connected, the resulting geometry of the flow paths may have fractal properties. Well tests can then be used to further refine the model. This structural information can be used as the basis for simulating the degree of fracturing within the zones. Therefore, tomograms can be used moreВ В» to identify fracture zones and provide information about the structure within the fracture zones.

These anomalies are often due to fracture zones. Cross-hole geophysics, either seismic or radar, can provide tomograms which are pixel maps of the velocity or attenuation anomalies in the rock. Combining a statistical approach with geophysical data may be extremely helpful in defining the fracture geometry. However, the interpretation of such tests, or ''inversion'' of the data, requires at least that we know the geometric pattern formed by the fractures. The analysis of fluid flow through fractured rocks is difficult because the only way to assign hydraulic parameters to fractures is to perform hydraulic tests.

Another is that hydraulic permeability in fractured media may be controlled by small-aperture , One reason why the velocity tomograms do not always provide unambiguous indications of flow paths is that the tomograms reflect rock electrical properties which vary because of lithologic heterogeneity at the site. We find a generally good, but not one-to-one, correlation between electromagnetic velocity tomograms and fracture projections from individual wells. We first show an example of 3-dimensional tomogram visualization with superimposed projections of hydraulically significant fractures. In this paper we examine radar tomograms produced from data acquired in the FSE well field at the fractured rock hydrology site at Mirror Lake, Grafton County, New Hampshire.