This project is a circumstantial study in laboratory concerning the relationship between the morphology, the flow and the chemical reactions water-rock. The objective is the achievement of an experiment designed for the validation of chemistry-hydromechanical transport of coupled models which integrate explicitly the morphology of the voids of the fracture and its variations.
This project is a circumstantial laboratory study concerning the relationship between the morphology, the flow and the chemical reactions of water and rock. The objective is to achieve an experiment validating the chemical and hydromechanical transport of coupled models which explicity integrate the morphology of the voids of the fracture and its variations. The conception of the prototype testing equipment was done in consultation with geochemists, to avoid problems of contamination of the fluid by elements existing in the various parts of the prototype. With regards to the chosen fracture, casting of the voids has been achieved and methods of examining the microroughness of the fracture are currently under examination.
In this study, the morphology of the fracture has been put in relation with hydromechanical behaviour of the fracture. This knowledge will be important in order to prepare the tests of percolation and to understand the interaction between the fluid and the rock. To prepare the study of the channels network in the fracture, the casting of the voids has been realized according to the protocol defined in previous works concerning the hydraulical behaviour of the fracture.
The morphology of a natural fracture in a granite will be studied from profiles recorded on each side of the fracture and from the casting of the voids. The flow channels will be determined from the morphology of the voids and from radial flow experiments. The petrology of each side of the fracture will be studied. All these data will permit the choice of a few little fields on the sides of the fracture about which the micro-roughness will be analyzed.
After this preliminary phase, radial flow tests will be performed on the fracture. The tests will be realized at various levels of normal stress and in temperature. During the tests, the chemistry of the water entering and exiting of the fracture will be determined. At the end of each experiment, the morphology of the fracture will be examined again.
The scheduled successive phases for the achievement of the works are:
- design, fitting of the prototype of testing equipment and qualification tests,
- choice of the sample and initial characterization of the fracture,
- tests of percolation (3 or 4 tests according to the necessary duration for each percolation),
- presentation and interpretation of the results.