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Rigoberto Tovar

Bio: Rigoberto Tovar is an academic researcher. The author has contributed to research in topics: Superheated steam & Wellhead. The author has an hindex of 4, co-authored 6 publications receiving 38 citations.

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TL;DR: The results of an interlaboratory calibration of silica performed using commercial standards as samples are presented in this paper, where the analytical values for silica concentration are consistent for lower concentration samples, but there are significant variations among the values for the higher concentration samples.

14 citations

01 Jan 2015
TL;DR: In this article, the response to exploitation of the Los Humeros geothermal reservoir was inferred through the study of the changes in production of wells, the thermodynamic conditions of reservoir fluids, and the chemical compositions of fluids over time.
Abstract: In this work, the response to exploitation of the Los Humeros geothermal reservoir was inferred through the study of the changes in production of wells, the thermodynamic conditions of reservoir fluids, and the chemical compositions of fluids over time. Up to 2012, almost 123 million tons of fluids had been extracted from the reservoir. Well bottom conditions (pressure and enthalpy) were calculated using heat and flow simulation. The changes in the composition of fluids seem to be related to boiling. In high-enthalpy wells, condensation in the well or in the reservoir was inferred to occur. Results also showed a decreasing trend in fluid salinity due to increasing boiling and condensation. The average reservoir liquid saturation for the field has a decreasing trend over time. Analysis of gas data suggested that the number of wells produce either a steam phase or condensed reinjection returns. According to the results, five main processes were identified: (a) pressure decrease and enthalpy increase that produces a moderate boiling process with steam gain; (b) iSignificant boiling and steam condensation; (c) production of returns from reinjection; (d) interaction with deep fluids, and (e) decrease in reservoir liquid saturation due to insufficient recharge.

11 citations

01 Jan 2000
TL;DR: In this paper, a new method based on equilibrium of the FischerTropsh reaction and on the combined pyrite-hematite and pyritic-magnetite reactions was used.
Abstract: Gas data of the Los Humeros geothermal field were analyzed. A new method which is based on equilibrium of the FischerTropsh reaction and on the combined pyrite-hematite and pyrite-magnetite reactions was used. Reservoir temperature and reservoir excess steam were estimated for the initial state of the field by using early data taken from producing wells at controlled conditions. The same parameters were also obtained for the present stage by using 1997 gas data. Reservoir temperatures ranged from 275 to 337°C and positive values for reservoir excess steam fractions were obtained for the starting stage. For well H-1 no excess steam was found since this well was fed by the shallower liquiddominated reservoir. Results for 1997 showed lower scattering compared to earlier data and the possible occurrence of a heating process in the shallower stratum which could be due to exploitation.

6 citations

Journal Article
TL;DR: In this paper, a modelo conceptual del yacimientode Los Azufres se baso en the distribucion espacial de especies quimicas e isotopicas.
Abstract: Se presentan los modelos geoquimicos para los yacimientos geotermicos de Los Azufres y Los Humeros. En ambos casos lafase gaseosa tuvo un papel importante ya que de acuerdo con los fluidos producidos, el yacimiento de Los Azufres se clasificocomo de tipo vapor-liquido (VAP-LIQ) y Los Humeros se considera de tipo vapor dominante. El modelo conceptual del yacimientode Los Azufres se baso en la distribucion espacial de especies quimicas e isotopicas. Se estimo el “exceso de vapor de yacimiento”por medio del equilibrio de la reaccion de Fischer-Tropsch (CO2+4H2=CH4+2H2O), el cual se utilizo para corregir la composicionde los fluidos de descarga total para obtener la composicion de los fluidos del yacimiento. Los resultados indicaron que laconcentracion de especies volatiles es mayor a niveles someros, mientras que la concentracion de especies no volatiles es mayora profundidad. Este patron se interpreto como resultado de un proceso convectivo de ascenso y condensacion parcial de vapor enel yacimiento.En el campo de Los Humeros donde la fase liquida es escasa, se identificaron dos yacimientos. El mas profundo de tipovapor dominante con temperaturas entre 330 y 400°C y el mas somero de tipo liquido dominante con temperaturas menores. Elequilibrio gaseoso basado en la reaccion de Fischer-Tropsch (FT) y en el de la combinacion de reacciones pirita-hematita y piritamagnetita(HSH2) proporciono tanto la estimacion de temperatura de yacimiento como la de “exceso de vapor de yacimiento”.Considerando estos valores en una etapa temprana de explotacion y los mas recientes, se propone que los fluidos del yacimientoprofundo ascienden a traves de las fracturas hacia el yacimiento somero como consecuencia de la explotacion.

5 citations

01 Jan 2015
TL;DR: In the case of well H-43, analysis of discharge chemistry showed a pH value of around 3 with gaseous hydrogen chloride (HCl) gas content as discussed by the authors, which is attributed to the presence of hydrogen chloride.
Abstract: Production well H-43 was drilled in the northeast area of the Los Humeros geothermal field from October 21, 2007 to January 18, 2008. There were at least seven production wells drilled in the area during the 1980’s, with similar conditions to well H-43. These wells were eventually abandoned, because of the highly corrosive nature of their fluids. The wells showed low pH values in the discharge fluid, which was attributed to the presence of gaseous hydrogen chloride (HCl). This ionizes in the presence of humidity to form hydrochloric acid. In the case of well H-43, analysis of discharge chemistry showed a pH value of around 3 with HCl gas content. The well provides approximately 35 tons per hour of superheated steam (30°C superheat) at wellhead pressure of 40 barg (580 psig) and wellhead temperature of 285°C. This thermodynamic condition of the well present an opportunity to operate and connect the well to the production system, because the superheat ensures that the HCl gas remains in a dry environment , thereby preventing corrosion of the well production casing and surface facilities. The well has been supplying steam to the power plant since May 2013 with an acid inhibition system installed in the pipe system, which is discussed in this paper. The successful utilization of H-43 opens the possibility of exploiting wells with similar acid characteristics, representing approximately 200 MWe of power generation potential in this part of the reservoir.

4 citations


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TL;DR: In this paper, an analysis of production and reservoir engineering data of 42 wells from the Los Humeros geothermal field (Mexico) allowed obtaining the pressure and temperature profiles for the unperturbed reservoir fluids and developing 1-D and 2-D models for the reservoir.

68 citations

Journal ArticleDOI
TL;DR: A statistical evaluation of the results of geochemical analyses of geothermal waters during interlaboratory comparison programs of the International Association of Geochemistry and Cosmochemistry (IAGC) and International Atomic Energy Agency (IAEA) was performed to estimate the uncertainty of measurement of pH, electrical conductivity, Na+, K+, Ca2+, Mg2+, Li+, Cl−, HCO3−, SO42−, SiO2 and B. as discussed by the authors.
Abstract: A statistical evaluation of the results of geochemical analyses of geothermal waters during interlaboratory comparison programmes of the International Association of Geochemistry and Cosmochemistry (IAGC) and International Atomic Energy Agency (IAEA) was performed to estimate the uncertainty of measurement of pH, electrical conductivity, Na+, K+, Ca2+, Mg2+, Li+, Cl−, HCO3−, SO42−, SiO2 and B. The uncertainty of measurement was found to increase exponentially with decrease in value (concentration) for all the parameters except for pH, electrical conductivity and SiO2 and was of the same order of magnitude as the concentrations for values of less than 1 μ ml−1. There was an overall uncertainty of ± 2.5% in the measurement of pH and ± 30% in SiO2. For all the other chemical species the uncertainty data were modelled by exponential curves. The sample IAEA14 was prepared by dissolving commercial reagents (i.e., represents a solution of known composition). Thus, the calculated values are considered to be the conventional true values for each chemical parameter. The difference between the measured mean of the data submitted by participating laboratories and the conventional true value for each parameter (i.e., bias of submitted measurements) for the species Na+, K+, Ca2+, Mg2+, Cl− and SO42− was -3.5, -1.1, -13.3, -53.6, -12.6 and -86.6%, respectively. The observed bias was of the same order of magnitude as statistical fluctuations (1s) for Na+ and K+, but significantly higher for Ca2+, Mg2+, Cl− and SO42−. Two methods, uncertainty interval and GUM (“guide to the expression of uncertainty of measurement”) were used to propagate uncertainty in the pH calculation of geothermal reservoir fluid. The application of the methods is illustrated by considering the IAEA10 and IAEA11 samples analysed in the interlaboratory comparisons as separated geothermal waters at atmospheric pressure. Une evaluation statistique des resultats d'analyses geochimiques d'eaux geothermales collectes durant un programme de comparaison inter laboratoires, a ete effectuee. Ce programme etait organise sous I'egide de l'Association Internationale de Geochimie et Cosmochimie (IAGC) et de I'Agence Internationale a I'Energie Atomique (IAEA), L'evaluation statistique a visea estimer les incertitudes des mesures de pH, de conductiviteelectrique, de Na+, K+, Ca2+, Mg2+, Li+, Cl−, HCO3−, SO42− SiO2 et B. On a trouve que I'incertitude des mesures augmentait exponentiellement quand les valeurs (concentrations) de tous les autres parametres decroissaient, a I'exception du pH, de la conductiviteelectrique et de la teneur en SiO2 et etaient toutes du meme ordre de grandeur comme les concentrations pour valeurs inferieures a 1 μg ml−1. L'incertitude moyenne sur la mesure pour pH etait de 2.5% et de ± 30% pour SiO2. Pour toutes les autres especes chimiques devolution des incertitudes a pu etre modelisee par des courbes exponentielles. L'echantillon IAEA14 a ete prepare par dissolution des reactifs commerciaux (c.a.d. il represente une solution de composition connue). Done, les valeurs calculees sont considerees etre les vrai valeurs conventionnelles pour chaque parametre chimique. La difference entre la moyenne des donnees mesurees soumise par les laboratoires participants et la vrai valeur conventionnelle pour chaque parametre (ca.d. le biais des mesures soumis) des especes Na+, K+, Ca2+, Mg2+, Cl−, SO42−, etait -3.5, -1.1, -13.3, -53.6, -12.6 et -86.6% respectivement. Le biais observeetait du meme ordre de grandeur que la variation statistique (1s) pour Na+ et K+, mais considerablement plus grande pour Ca2+, Mg2+, Cl− et SO42−. Deux methodes, celle des intervalles d'incertitude et celle dite “GUM” (Guide sur I'expression des incertitudes de mesure) ont ete utilisees pour effectuer la propagation d'erreur sur le calcul du pH d'un reservoir geothermal. Ces methodes sont appliquees aux echantillons IAEA 10 et IAEA 11 (eaux geothermales separees a pression atmospherique), analyses lors de comparaisons inter-laboratoires.

51 citations

Journal Article
TL;DR: In this paper, the authors present three nuevas ecuaciones mejoradas del geotermometro de Na/K obtenidas a partir del analisis of una base of datos geoquimicos worldial mas representativa (n=212) that las hasta ahora empleadas, mediante herramientas computacionales (redes neuronales arti fi ciales) and geoquimiometricas (basadas regresion lineal ordinaria).
Abstract: RESUMEN En este trabajo se presentan tres nuevas ecuaciones mejoradas del geotermometro de Na/K obtenidas a partir del analisis de una base de datos geoquimicos mundial mas representativa (n=212) que las hasta ahora empleadas, mediante herramientas computacionales (redes neuronales arti fi ciales) y geoquimiometricas (basadas regresion lineal ordinaria). Los nuevos geotermometros desarrollados estan dados por las ecuaciones:273. 15log 0.908883o −⎟+⎠⎞⎜⎝⎛= KNat Co 1273.2 tanh 0.4144 log 0.5642 +1156.9⎥⎥⎦⎤⎢⎢⎣⎡⎟⎟⎠⎞⎜⎜⎝⎛⎟−⎠⎞⎜⎛= − ⋅ KNat C273. 15log 0.894( 0.032)883( 15)o −⎟+ ±⎠⎞⎜⎝⎛±= KNat C Estas nuevas ecuaciones geotermometricas fueron exitosamente evaluadas y comparadas con datos medidos de temperatura de fondo de pozos usando una base de datos geoquimicos diferente (n=112) para eliminar el sesgo del entrenamiento y de la regresion. Los resultados obtenidos de este estudio comparativo mostraron claramente que estas nuevas ecuaciones proveen sistematicamente estimaciones de temperatura de fondo mas realistas y confi ables que los geotermometros de Na/K previamente desarrollados (para temperaturas mayores a 160 oC). Detalles de las bases teoricas del geotermometro, las metodologias computacionales y geoquimiometricas usadas, asi como los resultados de validacion y comparacion son reportados en este trabajo. Palabras clave: geotermometria, estadistica, exploracion, geoquimiometria, redes neuronales arti fi ciales, sistemas geotermicos.Revista Mexicana de Ciencias Geologicas, v. 25, num. 3, 2008, p. 465-482

44 citations

Journal ArticleDOI
TL;DR: In this article, an updated review of the worldwide reinjection experience in geothermal fields is presented, highlighting the importance of understanding the type of geothermal system before starting reinjection and main challenges to successful reinjection along with possible solutions with particular emphasis on pressure support, cooling mitigation, injectivity, scaling and solid deposition, microearthquake and tracer testing.

42 citations

Journal ArticleDOI
TL;DR: The Los Humeros Geothermal Field (LHGF) is one of four geothermal fields currently operating in Mexico, in exploitation since 1990 as discussed by the authors, and a noble gas survey was carried out in which twenty-two production wells were sampled for He, Ne, Ar, Kr, and Xe isotope analysis.

38 citations