Objetivo TO STUDY THE REACTION BETWEEN WATER AND ROCK IN ORDER TO OBTAIN A BETTER UNDERSTANDING OF REACTIONS THAT HAPPEN IN A HOT DRY ROCK SYSTEM. Geochemical studies of fluids and rocks in the Carnmenellis granite provides the basis for understanding the nature of the Rosemanowes Hot Dry Rock System. Fluid inclusion studies help to determine the role played by saline fluids during previous hydrothermal (80 to 170 C) circulation. Strontium isotope ratios have been determined for a range of rocks, single minerals and fluids which help to constrain the origins of solutes and the nature of mineral reactions. Comprehensive radiochemical studies on the granite (uranium, radium, radon and inert gases) provide the framework for developing the use of radon and helium to model properties (surface area, reservoir fluid volume and fracture width) of the hot dry rock (HDR) reservoir. Experimental studies have been carried out to investigate the reaction kinetics of principal rock forming minerals as a basis for determining chemically reactive surface areas. Possible heat exchange fluids for a 200 C HDR system have also been evaluated using water rock experiments. Fresh water flush experiments in the HDR reservoir have provided a means of testing the overall reactivity of the reservoir and together with the experimental studies provide the basis for geochemical modelling using the EQ3NR/EQ6 Code.THE PROGRAMME CAN BE CONSIDERED IN TWO PARTS: A. EVALUATION OF THE WATER CIRCULATION EXPERIMENTS AT THE CSM TEST SITE IN CORNWALL THE CONTEXT OF THE CARNMENELLIS GRANITE AND ADJACENT AREAS. B. ASSESSMENT OF THE LONG-TERM POTENTIAL OF DEVELOPING HDR SYSTEMS AND IDENTIFYING ANY POSSIBLE LIMITATIONS. THE PRINCIPAL OBJECTIVES UNDER -A- ARE: - TO DETERMINE THE EXTENT TO WHICH INJECTION FLUIDS ARE MODIFIED BY WATER ROCK INTERACTIONS, TO IDENTIFY THE NATURE OF SECONDARY MINERALS AND TO CHARACTERISE THE STABLE ELEMENTS, RADIOELEMENTS AND ISOTOPIC CHEMISTRY OF THE RETURN FLUID. - TO INVESTIGATE THE REGIONAL GEOCHEMISTRY AND MINERALOGY OF THE CARNMENELLIS GRANITE. - TO IDENTIFY ANY CONSTITUENT OR PROCESS THAT MIGHT BE CONSIDERED RESERVOIR DIAGNOSTIC. THE PRINCIPAL OBJECTIVES UNDER -B- ARE: - TO UNDERSTAND THE STABILITY OF MINERALS FORMING THE ROCK - TO PREDICT CHEMICAL CONSTRAINTS UNDER OPERATING CONDITIONS. - TO ADVISE ON CORROSION AND SCALING. ADVANCEMENT: ROCK-WATER EXPERIMENTS HAVE BEEN CARRIED OUT IN BOTH 'BATCH' AND 'FLOWTHROUGH' MODES IN AUTOCLAVES IN THE TEMPERATURE RANGE 80 DEGREES - 250 DEGREES C. LAUMONTITE, A CA-ZEOLITE, HAS BEEN IDENTIFIED AS A COMMON PRODUCT OF THE REACTION IN THE CARNMENELLIS GRANITE. 222 RN CONCENTRATION HAS BEEN MEASURED IN CIRCULATION FLUID. THESE CONCENTRATIONS AND SOME SIMULTANEOUS TRACER TEST RESULTS SUGGEST A MEAN FRACTURE WIDTH OF ABOUT 430 M, A RESERVOIR VOLUME OF ABOUT 1015 CUBIC METERS AND A HEAT TRANSFER SURFACE OF 4.7 X 10 TO THE POWER 6 M2. Ámbito científico natural sciencesearth and related environmental sciencesgeochemistrynatural scienceschemical sciencesinorganic chemistrynoble gasesnatural scienceschemical sciencesinorganic chemistryalkaline earth metalsnatural sciencesearth and related environmental sciencesgeologymineralogy Programa(s) FP1-ENNONUC 3C - Research and development programme (EEC) in the field of Non-Nuclear Energy, 1985-1988 Tema(s) Data not available Convocatoria de propuestas Data not available Régimen de financiación CSC - Cost-sharing contracts Coordinador NERC British Geological Survey Aportación de la UE Sin datos Dirección Maclean Building Crowmarsh Gifford OX10 8BB Wallingford Reino Unido Ver en el mapa Coste total Sin datos
