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Model to predict the flow of tracers in naturally fractured geothermal reservoirs; Modelo para predecir el flujo de trazadores en yacimientos geotermicos naturalmente fracturados

Abstract

The proposed model has been developed to study the flow of tracers through naturally fractured geothermal reservoirs. The idealized system of the reservoir is made up of two regions: A movable region, where diffusion and convection mechanisms are present and a stagnant or immovable region where the diffusion and adsorption mechanisms are considered: in both regions the loss of mass by radioactive decay is considered. The solutions of the basic flow equations are in the Laplace space and for its numerical inversion the Stehfest algorithm was used. In spite of the numerical dispersion that these solutions involve, a well defined tendency to infer the system behavior under different flow conditions was found. It was found that, for practical purposes, the size of the matrix blocks does not have an influence on the concentration response, and the solution is reduced to the one presented by Tang and associates. Under these conditions, the system behavior can be described by two non-dimensional parameters: The Peclet number in fractures, P{sub e1}, and a parameter. The tracer response for the peak solution was also derived. An analytical solution limit was found for the case in which {alpha} tends to zero, which corresponds to the case  More>>
Publication Date:
Feb 01, 1988
Product Type:
Thesis/Dissertation
Reference Number:
EDB-00:012291
Resource Relation:
Other Information: TH: Thesis (M. Ing.); PBD: Feb 1988
Subject:
15 GEOTHERMAL ENERGY; FRACTURED RESERVOIRS; GEOTHERMAL EXPLORATION; ALGORITHMS; SOLUTIONS; GEOTHERMAL FIELDS; NUMERICAL DATA
Sponsoring Organizations:
Consejo Nacional de Ciencia y Tecnologia (CONACYT), Mexico, D. F (Mexico); Instituto de Investigaciones Electricas (IIE), Cuernavaca (Mexico)
OSTI ID:
20007737
Research Organizations:
Universidad Nacional Autonoma de Mexico (UNAM), Mexixo, D.F. (Mexico)
Country of Origin:
Mexico
Language:
Spanish
Other Identifying Numbers:
TRN: MX9900186
Availability:
Available from Unidad de Informacion Tecnologica, Instituto de Investigaciones Electricas, Av. Reforma 113, Col. Palmira, 62490 Temixco, Mor., Mexico, Tel: (7) 318 3811 ext. 7138, Fax: (7) 318 2461.
Submitting Site:
MX
Size:
[170] pages
Announcement Date:
Nov 08, 2000

Citation Formats

Ramirez Sabag, Jetzabeth. Model to predict the flow of tracers in naturally fractured geothermal reservoirs; Modelo para predecir el flujo de trazadores en yacimientos geotermicos naturalmente fracturados. Mexico: N. p., 1988. Web.
Ramirez Sabag, Jetzabeth. Model to predict the flow of tracers in naturally fractured geothermal reservoirs; Modelo para predecir el flujo de trazadores en yacimientos geotermicos naturalmente fracturados. Mexico.
Ramirez Sabag, Jetzabeth. 1988. "Model to predict the flow of tracers in naturally fractured geothermal reservoirs; Modelo para predecir el flujo de trazadores en yacimientos geotermicos naturalmente fracturados." Mexico.
@misc{etde_20007737,
title = {Model to predict the flow of tracers in naturally fractured geothermal reservoirs; Modelo para predecir el flujo de trazadores en yacimientos geotermicos naturalmente fracturados}
author = {Ramirez Sabag, Jetzabeth}
abstractNote = {The proposed model has been developed to study the flow of tracers through naturally fractured geothermal reservoirs. The idealized system of the reservoir is made up of two regions: A movable region, where diffusion and convection mechanisms are present and a stagnant or immovable region where the diffusion and adsorption mechanisms are considered: in both regions the loss of mass by radioactive decay is considered. The solutions of the basic flow equations are in the Laplace space and for its numerical inversion the Stehfest algorithm was used. In spite of the numerical dispersion that these solutions involve, a well defined tendency to infer the system behavior under different flow conditions was found. It was found that, for practical purposes, the size of the matrix blocks does not have an influence on the concentration response, and the solution is reduced to the one presented by Tang and associates. Under these conditions, the system behavior can be described by two non-dimensional parameters: The Peclet number in fractures, P{sub e1}, and a parameter. The tracer response for the peak solution was also derived. An analytical solution limit was found for the case in which {alpha} tends to zero, which corresponds to the case of a homogenous system. It was verified that this limit solution is valid, for {alpha}<0.01. For the case of continuous injection, this solution is reduced to the one presented by Coasts and Smith. For the peak solution, it was found that the irruption time corresponding to the maximum concentration is directly related to the non-dimensional group. Therefore, it is possible to obtain the value of P{sub e1} for a given X{sub D}, or vice versa. A group of graphs of non-dimensional concentration in the fracture versus non-dimensional time, was developed. It was found that if P{sub e1} remains constant whereas {alpha} changes, the limit solution is the envelope of a family of curves in a graph of C{sub D} versus t{sub D}. In this figure P{sub e1} fixes the characteristic of the family of curves. Also it was found that the irruption time for a given concentration depends strongly on {alpha}. [Spanish] El modelo propuesto ha sido desarrollado para estudiar el flujo de trazadores a traves de yacimientos geotermicos naturalmente fracturados. El sistema idealizado del yacimiento esta compuesto por dos regiones: Una region movil donde mecanismos de difusion y conveccion estan presentes y una region estancada o inmovil donde se consideran los mecanismos de difusion y adsorcion: en ambas regiones se considera la perdida de masa por decaimiento radioactivo. Las soluciones de las ecuaciones basicas de flujo estan en el espacio de Laplace y se utilizo el algoritmo de Stehfest para su inversion numerica. A pesar de la dispersion numerica que presentan estas soluciones, se encontro una tendencia bien definida para inferir el comportamiento del sistema bajo diferentes condiciones de flujo. Se encontro que, para propositos practicos el tamano de los bloques de matriz no tiene influencia sobre la respuesta de la concentracion, y la solucion se reduce a la presentada por Tang y asociados. Bajo estas condiciones, el comportamiento del sistema puede ser descrito por dos parametros adimensionales: El numero de Peclet en las fracturas y un parametro. Se derivo tambien la respuesta del trazador para la solucion pico. Se encontro una solucion analitica limite para el caso en que {alpha} tienda a cero, el cual corresponde al caso de un sistema homogeneo. Se comprobo que esta solucion limite es valida, para {alpha}<0.01. Para el caso de inyeccion continua esta solucion se reduce a la presentada por Coasts y Smith. Para la solucion pico, se encontro que el tiempo de irrupcion correspondiente a la maxima concentracion esta relacionada directamente con el grupo adimensional. Por lo tanto, es posible obtener el valor de P{sub e1} para una X{sub D} dada, o viceversa. Un grupo de graficas de concentracion adimensional en la fractura vs. tiempo adimensional, fueron desarrollados. Se encontro que si P{sub e1} permanece constante en tanto que {alpha} cambia, la solucion limite es la envolvente de una familia de curvas en una grafica de C{sub D} vs t{sub D}. En esta figura P{sub e1} fija la caracteristica de la familia de curvas. Tambien se encontro que el tiempo de irrupcion para una concentracion dada depende fuertemente de {alpha}.}
place = {Mexico}
year = {1988}
month = {Feb}
}