The angiogeology and precision of its dynamic water model

Contrary to the traditional hydrogeology which is interested in the water reservoirs and their static characteristics, the angiogeological survey concentrates on the detection of ascending water circulation. This circulation, negligible within the water reservoirs, takes place - apart from those - via water vessels which connect these water reservoirs between them. These vessels form narrow slender structures (the measuring unit of the diameter of their section is the decimetre), but their 3 D structure - measured by angiogeoscopy - is very revealing interest of the aquifers of which they come or which they feed (see why angiogeology). The purely captive and preserved sheets of any exchange (called fossil aquifers) are completely exceptional; the majority undergo an efferent flow (outgoing) - and thus also a related flow (entering). These flows balance because of their steady state character (and all the more steady state as these flows occur with great depth). The representation of such a water system is illustrated in 3D. Its projection on the surface is also presented to illustrate the principal sight during an angiogeological survey.

The angiogeology concentrates on the key: underground water flows at their point of maximum concentration

Contrary to the waterways of surface for which exists very a large range of cross-sections of stream discharge, the hydrodynamics of underground circulation is such as the water vessels always have a diameter limited (of about size of ten centimetres) for reasons of stability of flow. The flows and gradients of pressure can vary in a very important way between water vessels, but the sections remain of comparable size. In the event of important flow of exit of a water reservoir, the water vessels gear down and form cone branches what is called (of Latin “cum natus”, born with). There thus do not exist water “rivers” (saturated), crossing a porous environment, whose diameter would be measured in meters or of tens of meters. The underground rivers (such as the speleologists know them) are not to regard as “large” water vessels, because their flow does not induce any filtration (they have a free surface and run out like any waterway on the surface). Water circulation within the water vessels rises from the differential of pressure between the aquifers which these vessels connect. The starter of this ascending water cycle is at the level of the leakages which occur in the geothermal reservoirs located at great depth. The geothermal reservoirs are also supplied by a related flow which is not detectable by angiogeoscopy. The “engine” of this ascending water circulation is the magmatic heat transmitted directly or indirectly to groundwater.

The knowledge which water is not uniformly distributed in the ground, but concentrated in pockets - groundwater sheets - is largely widespread, even near nonspecialists (independently of the representation which they can be made of these underground layers and who is seldom correct). On the other hand, the fact that these water pockets are connected between them by a network of fine water vessels (compared to the dimension of these pockets or their length) and stable is not integrated yet by the professionals and even less by the public.

The angiogeology does not seek “to drain” the geothermal reservoirs but to recover, via a well of drilling placed in an optimal way, the geological fluid which runs out naturally and continuously of this geothermal reservoir.

The angiogeoscopy makes it possible to map in space the complexing (morphology) of the water vessels and, more specifically, to locate their origin which corresponds to the leakage point of the water reservoir from which they result. Several water vessels generally occur on the level of the same leakage point. These leakage points correspond precisely to the optimal collecting location of the water reservoir because:

• they concentrate the totality of natural outgoing flow of the water reservoir,
• they are located towards reservoir nearest to terrestrial surface (typically of 1 with maximum 2 kilometers of depth),
• they minimize the risk of obstruction (for example by sands), because it is by them that circulates the dbit of exit naturalness of the reservoir since “geological times”,
• it is the place where the geological fluid is purest (C. - with-D. that it contains less suspended particles and gases nonsoluble),
• they are localizable with an exceptional precision (with the centimetre close compared to the plan of surface) by the proprietary technique used by Angioo: the angiogeoscopy,
• to carry out a water collecting well at this place deteriorates less the underground hydrodynamics and affects less the tensions lithospheric, reducing thus at least the risk of induced seismicity.

The angiogeological survey is precise, reliable and fast

As soon as it becomes possible to precisely map 3 D structure of a network of water vessels, it becomes also possible to determine the optimal collecting location of geothermal reservoirs or aquifers.

If, moreover, this space location of the water bearing sites can be done quickly and without expenses of investment, the main obstacles with the deployment of geothermal, hydrothermal or mineral-water exploitations are seen some swept.

ANGIOO approaches the hydrogeological survey under the new and fertile angle of the hydrodynamics of the water bearing sites and either starting from reservoir models. The angiogeoscopy can be seen like Holy Grail it hydrogeological survey: it is precise (it detects the collecting locations with their absolute optimum), reliable (the productive character of the layer is guaranteed for all the specified drilling locations and all the exploitable layers are detected) and rapid (it lasts only a few weeks at most).

Its limits are not handicapping

Intellectual honesty pushes us however to mention that, if the angiogeology represents rigorously and detects the ascending water cycle exactly (via the water vessels), it is disabled much vis-a-vis the water cycle going down. This One feeds the geothermal reservoirs - by a mechanism approached within the framework of our presentation on the cycle of water - like the aquifers - by infiltration of surface water.

What limits the disadvantages of our ignorance of the water cycle descendant is the fact that only the location of the vectors of the ascending cycle water - water vessels - is necessary for the geothermal exploitation, hydrothermal or mineral-water. To Understand the cycle going down is especially useful to analyze the effects of contamination or pollution of water reservoirs.

The synthesis of the differences between traditional hydrogeology and angiogeology is presented in a comparative table.