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Albe Gente - One of the best experts on this subject based on the ideXlab platform.

  • overview of naturally permeable fractured reservoirs in the central and southern upper rhine graben insights from Geothermal Wells
    Geothermics, 2018
    Co-Authors: Jeanne Vidal, Albe Gente
    Abstract:

    Abstract Since the 1980′s, more than 15 Geothermal Wells have been drilled in the Upper Rhine Graben (URG), representing more than 60 km of drill length. Although some early concepts were related to purely matrix-porosity reservoirs or Hot Dry Rock systems, most projects in the URG are currently exploiting the Geothermal resources that are trapped in fracture networks at the base of the sedimentary cover and in the granitic basement. Lessons-learnt from the European EGS reference site at Soultz-sous-Forets reveal highest natural permeability in the uppermost altered crystalline basement. Here, we present a compilation of related information to examine a more general validity of this hypothesis for the central URG. In this respect, 15 Geothermal Wells were analyzed concerning their lithologies, temperature distribution with depth, and their hydraulic yields. Among others, permeable fractures in Triassic sediments were observed among others during drilling operations at Soultz-sous-Forets, Rittershoffen, Cronenbourg (France), Landau, Insheim, Bruchsal and Bruhl (Germany). The Geothermal Wells at Soultz-sous-Forets, Rittershoffen (France), Landau and Insheim (Germany) also intersect well-connected fracture networks in the uppermost altered granitic basement. Permeable fractures are intersected to a depth of 5 km at Soultz-sous-Forets (France) and Basel (Switzerland). The compilation of geologic, hydraulic and thermal data of 15 Geothermal Wells shows permeability variation among the lithologies with the maximum observed at the top of the hydrothermally altered granite. This higher permeability is likely due to the intense fracture density in the fault core of the fracture zone and the large porous and altered damage zone which allow connection with the reservoir.

  • new stratigraphic interpretation of the soultz sous forets 30 year old Geothermal Wells calibrated on the recent one from rittershoffen upper rhine graben france
    Geothermal Energy, 2016
    Co-Authors: C Aichholze, Ph Duringe, S Orciani, Albe Gente
    Abstract:

    The Soultz-sous-Forets site (Alsace, France) is the first pilot Geothermal project in the world that furnished the proof of concept of enhanced Geothermal systems by producing energy from a deep-seated granite. The Alsace region, with its hundreds of previous drillings and seismic history related to both oil and potash exploitation, has been shown to have high subterranean temperatures. In the Soultz-sous-Forets Geothermal project, most attention has focused on the basement and the sedimentary cover/basement interface. Thus, the sedimentary portion of the well (approximately 1.4 km thick) has never been fully investigated. The only available data on the Soultz-sous-Forets sedimentary cover are from an old masterlog (GPK-1) with interpretations of the tops and bases of the main geological formations, and from some other less well-documented well logs (EPS-1 and GPK-2). The main challenge of this work is therefore to re-interpret the old well data to provide precise and detailed chrono-lithostratigraphic logs for GPK-1 and GPK-2, especially in their sedimentary portions. These new investigations of the GPK Wells have been possible due to the new data collected in the recent Geothermal Wells at Rittershoffen (GRT-1 and GRT-2, located 6.5 km from Soultz-sous-Forets), which are characterized by a quite complete stratigraphic succession. Both sites have been explored by deep drilling operations aiming to exploit the heat extracted from a deep granitic basement (Palaeozoic) covered by a stack of 1.4- and 2.2-km-thick sedimentary rocks (Mesozoic to Cenozoic) at Soultz-sous-Forets and Rittershoffen, respectively. Thus, the Rittershoffen chrono-lithostratigraphic logs have been used as a baseline to interpret the sedimentary succession in GPK-1 and GPK-2. In conclusion, all the well logs are compared for stratigraphic comparisons. With approximately 1400 m of sedimentary cover at Soultz-sous-Forets instead of 2200 m at Rittershoffen, the correlation between the two sites showed many differences exist in the sedimentary columns: layers missing due to erosion, lateral thickness variations in formations, and—above all—the occurrence of at least four major fracture zones affecting the units. In addition, a structural analysis was made to more precisely define the limits of the geological formations observed and to present more arguments for the presence of fracture zones or faults.

E Santoyo - One of the best experts on this subject based on the ideXlab platform.

  • determination of pressure drops in flowing Geothermal Wells by using artificial neural networks and wellbore simulation tools
    Applied Thermal Engineering, 2015
    Co-Authors: A Assam, Alvarez A Del Castillo, O Garciavalladares, E Santoyo
    Abstract:

    Abstract A new predictive approach based on artificial neural networks (ANN) and wellbore numerical simulation for the determination of pressure drops in flowing Geothermal Wells was successfully carried out. Several ANN computational models based on the Levenberg–Marquardt optimization algorithm, and the hyperbolic tangent sigmoid and linear transfer functions were evaluated. Two ANN models (ANN 1 and ANN 2 , characterized by using five and six input variables, respectively; and a common structure of 9 neurons in the hidden layer) were found to be the most suitable architectures for a reliable determination of Geothermal pressure gradients. These ANN models used a limited number of input variables which are commonly available in field measurements (e.g., wellbore production data: pressure, temperature and mass flow rate; and wellbore geometry data). Such ANN models were effectively trained by using a wellbore production database which was compiled from several world Geothermal fields. Additional wellbore simulation works were also carried out by using the same production data and a numerical simulator (GEOWELLLS). The pressure gradients predicted by using all these computing tools (ANNs and GEOWells) were statistically compared with measured field data. From this matching analysis, it was demonstrated that the ANN 2 model provided the most acceptable results (with average prediction errors less than 2.3%) in comparison with those results inferred from ANN 1 and GEOWELL tools. Details of the computational methodology developed in this study, as well as the numerical validation, and the comparative statistical analysis are comprehensively described.

  • solute and gas geothermometry of Geothermal Wells a geochemometrics study for evaluating the effectiveness of geothermometers to predict deep reservoir temperatures
    International Geology Review, 2014
    Co-Authors: Christian Guadalupe Garcialopez, Kailasa Pandarinath, E Santoyo
    Abstract:

    Deep reservoir temperatures of 10 important Geothermal systems of the world were estimated by applying 13 solute (Na/K) and 21 gas geothermometers. The predicted temperatures were comprehensively evaluated and compared with measured bottom-hole temperatures using geochemometric techniques. The present study reveals (1) high prediction performances in most of the Na/K geothermometers for the majority of the Geothermal fields with liquid-dominated reservoirs, whereas low prediction performances were indicated for the Geothermal fields with vapour-dominated and high-temperature reservoirs; (2) the gas geothermometers, in comparison to Na/K, are more successful in predicting the subsurface temperatures in high-temperature Geothermal systems; (3) the Geothermal systems for which Na/K geothermometers have indicated a high prediction performance, the gas geothermometers have specified a low prediction performances, and vice versa; (4) both Na/K and gas geothermometers, generally, overestimated the reservoir temp...

  • a new void fraction correlation inferred from artificial neural networks for modeling two phase flows in Geothermal Wells
    Computers & Geosciences, 2012
    Co-Authors: Alvarez A Del Castillo, E Santoyo, Garci O Avalladares
    Abstract:

    A new empirical void fraction correlation was developed using artificial neural network (ANN) techniques. The artificial networks were trained using the backpropagation algorithm and production data obtained from a worldwide database of Geothermal Wells. Wellhead pressure, steam quality, wellbore diameter, the fluid density and viscosity, and the dimensionless numbers Reynolds, Weber, and Froude were used as main input parameters. The target ANN output was defined by the optimized void fraction values (@a"o"p"t), which were calculated from the numerical modeling of two-phase flow using GEOWells (a wellbore simulator). The Levenberg-Marquardt algorithm, the hyperbolic tangent sigmoid, and the linear activation functions were used for the development of the ANN model. The best ANN learning was achieved with an architecture of six neurons in the hidden layer, which made it possible to obtain a set of void fractions (@a"A"N"N) with a good accuracy (R^2=0.9722). These void fraction estimates were used to obtain the new correlation, which was later coupled into the simulator GEOWells for the prediction of pressure gradients in two-phase Geothermal Wells. The accuracy of the new correlation (@a"A"N"N) was evaluated by a statistical comparison between simulated pressure gradients and measured field data. These simulation results were also compared with those data calculated by using Duns-Ros and Dix correlations, which were also programmed into GEOWells. Pressure gradients predicted with the new @a"A"N"N correlation showed a better agreement with measured field data, which was also confirmed by the lower values of some statistical parameters (MPE, RMSE, and Theil's U). The statistical evaluation demonstrated the efficiency of the new correlation to predict void fractions and pressure gradients with a better accuracy, in comparison to the other existing correlations. These successful results suggest the use of the new correlation (@a"A"N"N) for the analysis of two-phase flow mechanisms of Geothermal Wells.

  • estimation of static formation temperatures in Geothermal Wells by using an artificial neural network approach
    Computers & Geosciences, 2010
    Co-Authors: A Assam, E Santoyo, Jorge Andaverde, J A Hernandez, O M Espinozaojeda
    Abstract:

    An artificial neural network (ANN) approach was used to develop a new predictive model for the calculation of static formation temperature (SFT) in Geothermal Wells. A three-layer ANN architecture was successfully trained using a Geothermal borehole database, which contains ''statistically normalised'' SFT estimates. These estimates were inferred from seven analytical methods commonly used in Geothermal industry. Bottom-hole temperature (BHT) measurements and shut-in times were used as main input variables for the ANN training. Transient temperature gradients were used as secondary variables. The Levenberg-Marquardt (LM) learning algorithm, the hyperbolic tangent sigmoid transfer function and the linear transfer function were used for the ANN optimisation. The best training data set was obtained with an ANN architecture composed by five neurons in the hidden layer, which made possible to predict the SFT with a satisfactory efficiency (R^2>0.95). A suitable accuracy of the ANN model was achieved with a percentage error less than +/-5%. The SFTs predicted by the ANN model were statistically analyzed and compared with ''true'' SFTs measured in synthetic experiments and actual BHT logs collected in Geothermal boreholes during long shut-in times. These data sets were processed both to validate the new ANN model and to avoid bias. The SFT estimates inferred from the ANN validation process were in good agreement (R^2>0.95) with the ''true'' SFT data reported for synthetic and field experiments. The results suggest that the new ANN model could be used as a practical tool for the reliable prediction of SFT in Geothermal Wells using BHT and shut-in time as input data only.

  • numerical modeling of flow processes inside Geothermal Wells an approach for predicting production characteristics with uncertainties
    Energy Conversion and Management, 2006
    Co-Authors: O Garciavalladares, P Sanchezupto, E Santoyo
    Abstract:

    Abstract One dimensional steady and transient numerical modeling for describing the heat and fluid dynamic transport inside Geothermal Wells has been conducted. The mass, momentum and energy governing equations were solved using a segregated numerical scheme. Discretized governing equations for the fluid flow were coupled and solved with a fully implicit step by step method. The mathematical formulation used suitable empirical correlations for estimating the convective heat transfer coefficients as well as the shear stress and the void fraction parameters. Heat conduction across the wellbore materials was solved by an implicit central difference numerical scheme using the tri-diagonal matrix algorithm (TDMA). The flow characteristics of producer Geothermal Wells (pressure, temperature, enthalpy, heat fluxes, etc.) at each depth node were computed. Analytical data reported in the literature were used to validate the numerical capability of the wellbore simulator developed for this study (GEOWells). This simulator, together with another computer code (ORKISZEWSKI), was applied for modeling the heat and fluid flow processes inside some Wells drilled in Mexican Geothermal fields. The simulated pressure and temperature profiles were statistically compared against stable measured field data (through the computation of the residual sum of squares and Chi-square). A good agreement between the simulated and measured profiles of pressure and temperature was consistently obtained, having the best matching results for the GEOWells predictions. An analysis of the sensitivity and uncertainty was finally conducted to estimate the confidence to be accorded the simulation results predicted by GEOWells. Matching the sensitivity to variations in some input parameters (e.g., pressure, temperature, enthalpy and void fraction) was examined. The void fraction was identified as one of the most important parameters that affect the GEOWells simulations for matching measured field data correctly.

Andre Gerard - One of the best experts on this subject based on the ideXlab platform.

C Aichholze - One of the best experts on this subject based on the ideXlab platform.

  • new stratigraphic interpretation of the soultz sous forets 30 year old Geothermal Wells calibrated on the recent one from rittershoffen upper rhine graben france
    Geothermal Energy, 2016
    Co-Authors: C Aichholze, Ph Duringe, S Orciani, Albe Gente
    Abstract:

    The Soultz-sous-Forets site (Alsace, France) is the first pilot Geothermal project in the world that furnished the proof of concept of enhanced Geothermal systems by producing energy from a deep-seated granite. The Alsace region, with its hundreds of previous drillings and seismic history related to both oil and potash exploitation, has been shown to have high subterranean temperatures. In the Soultz-sous-Forets Geothermal project, most attention has focused on the basement and the sedimentary cover/basement interface. Thus, the sedimentary portion of the well (approximately 1.4 km thick) has never been fully investigated. The only available data on the Soultz-sous-Forets sedimentary cover are from an old masterlog (GPK-1) with interpretations of the tops and bases of the main geological formations, and from some other less well-documented well logs (EPS-1 and GPK-2). The main challenge of this work is therefore to re-interpret the old well data to provide precise and detailed chrono-lithostratigraphic logs for GPK-1 and GPK-2, especially in their sedimentary portions. These new investigations of the GPK Wells have been possible due to the new data collected in the recent Geothermal Wells at Rittershoffen (GRT-1 and GRT-2, located 6.5 km from Soultz-sous-Forets), which are characterized by a quite complete stratigraphic succession. Both sites have been explored by deep drilling operations aiming to exploit the heat extracted from a deep granitic basement (Palaeozoic) covered by a stack of 1.4- and 2.2-km-thick sedimentary rocks (Mesozoic to Cenozoic) at Soultz-sous-Forets and Rittershoffen, respectively. Thus, the Rittershoffen chrono-lithostratigraphic logs have been used as a baseline to interpret the sedimentary succession in GPK-1 and GPK-2. In conclusion, all the well logs are compared for stratigraphic comparisons. With approximately 1400 m of sedimentary cover at Soultz-sous-Forets instead of 2200 m at Rittershoffen, the correlation between the two sites showed many differences exist in the sedimentary columns: layers missing due to erosion, lateral thickness variations in formations, and—above all—the occurrence of at least four major fracture zones affecting the units. In addition, a structural analysis was made to more precisely define the limits of the geological formations observed and to present more arguments for the presence of fracture zones or faults.

Gilberto Espinosaparedes - One of the best experts on this subject based on the ideXlab platform.

  • thermal behaviour of Geothermal Wells using mud and air water mixtures as drilling fluids
    Energy Conversion and Management, 2004
    Co-Authors: Gilberto Espinosaparedes, Alfonso Garciagutierrez
    Abstract:

    Abstract This paper describes a comparative study of the thermal behaviour of drilling fluids and the surrounding rock when air–water mixtures and conventional muds are used as drilling fluids in Geothermal Wells. The computations were performed with two numerical simulators: TEMLOPI/V.2, which is used to compute the transient temperature disturbance when mud is employed, and GEOMIST, which is used when air–water mixtures are employed as drilling fluid. Data from a well from the Las Tres Virgenes Mexican Geothermal field are used in this analysis. The results of simulation include temperatures computed during circulation and shut-in, and the latter results are compared with temperatures logged during drilling stoppages. It was found that the thermal disturbance caused by circulation of an air–water mixture has a smaller thermal effect than the thermal disturbance caused by drilling muds.

  • estimation of static formation temperatures in Geothermal Wells
    Energy Conversion and Management, 2003
    Co-Authors: Gilberto Espinosaparedes, A Garciagutierrez
    Abstract:

    Stabilized formation temperatures were estimated at different depths in 40 Wells from the Los Humeros Geothermal field, Mexico, using the Horner and the spherical radial flow (SRF) methods. The results showed that the Horner method underestimates formation temperatures, while the SRF method gives temperatures that are closer to the true formation temperatures. This was supported by numerical simulation of a combined circulation and shut-in period in several Wells, and results for well H-26 are presented. Numerical reproduction of logged temperature is more feasible if an initial temperature profile based on the SRF method is employed instead of using an initial temperature profile based on the Horner method.

  • study on the flow production characteristics of deep Geothermal Wells
    Geothermics, 2002
    Co-Authors: Alfonso Garciagutierrez, Gilberto Espinosaparedes, Isaias Hernandezramirez
    Abstract:

    This paper describes a study on the potential flow production characteristics of three non-producing, deep (average depth 4000 m) Geothermal Wells in the Cerro Prieto Geothermal field. The expected production characteristics of these Wells were computed in order to determine whether their inability to sustain flow was due to: (1) heat loss effects in the well; (2) the influence of casing diameters; (3) transient temperature effects during the first days of well discharge, and/or (4) the effects of secondary low-enthalpy inflows. For the study, the conservation equations of mass, momentum and energy for two-phase homogeneous flow were solved for the wellbore, since homogeneous flow provides the simplest technique for analyzing two-phase flows when the flow patterns are not well established. The formation temperature distribution was computed assuming radial transient heat conduction. The numerical model was validated by comparison with analytical solutions and with measured pressure and temperature profiles of well H-17 from the Los Humeros Geothermal field, Mexico. It was found that the Wells should have sustained production. The early heat losses were so large that the flow needed to be induced, and flow will be sustained only after a few days of induced discharge. For well M-202, the analysis suggests that the inflow of secondary colder fluids was responsible for stopping the flow in this well.

  • templop v 2 a computer program for estimation of fully transient temperatures in Geothermal Wells during circulation and shut in
    Computers & Geosciences, 2001
    Co-Authors: Gilberto Espinosaparedes, E Santoyo, A. Garcia, I. Hernandez
    Abstract:

    This paper describes the development, validation and application of the TEMLOPI/V.2 computer program. This program is a useful tool for estimating in-situ the transient temperature distribution of the fluids employed for drilling Geothermal Wells. TEMLOPI/V.2 is based on a mathematical model which is developed to consider two-dimensional transient heat transfer during drilling and shut-in conditions in and around a Geothermal well. The solution of the partial dierential equations is based on the finite-dierence technique with an implicit scheme. This scheme serves to demonstrate the numerical solution procedure. Each radial grid node is placed in a dierent thermal region: flow inside the pipe, metal pipe wall, flow inside annulus, and the surrounding formation. The program was written in FORTRAN 77 using modular programming and runs on most IBM compatible personal computers. The software code, its architecture, input and output files, the solution algorithm, flow diagrams and source programs are described in detail. From validation tests, computed temperatures dier by less than 58C from analytically obtained temperatures. Comparison of results from the fully transient TEMLOPI/V.2 simulator and the pseudo-transient version, TEMLOPI/ V.1, with measured data shows that the fully transient model provides better results. Application of TEMLOPI/V.2 is demonstrated in a practical application study of well EAZ-2 from Los Azufres Mexican Geothermal field. # 2001 Elsevier Science Ltd. All rights reserved.