[PDF] Thermal Hydraulic Modeling Of Discretely Fractured Geothermal Reservoirs eBook

Author : Don Bruce Fox
Publisher :
Page : 324 pages
File Size : 13,56 MB
Release : 2016
Category :
ISBN :

GET BOOK

Enhanced/Engineered Geothermal Systems (EGS) have the potential to provide a significant amount of base load electricity and heat and to displace fossil fuel consumption globally. To determine the potential for the expansion of direct use geothermal energy, a detailed analysis of U.S. energy consumption was performed to estimate the amount of primary energy consumed as a function of its utilization temperature from 0 to 260? C. The analysis revealed that about 34 EJ annually, more than 30% of the U.S. annual energy demand is used for direct thermal use applications in the temperature range of 0 to 260? C. Both analytical and numerical models of discretely fractured reservoirs were developed to probe the thermal hydraulic behavior of model EGS reservoirs and quantify factors controlling performance. An analytical model for discrete, fixed aperture, rectangular fractures with specified uniform flow was used to illustrate the renew ability of EGS reservoirs with a ratio of production to renewal times of about 0.2 to 0.33. Fracture structure and connectivity were also shown to affect reservoir performance in modeling studies. In general, fracture connectivity is more important than aperture variations within the fractures. Flow channeling in fractures with spatially varying aperture fields were simulated using a developed numerical model. An ensemble of fracture realizations were used to illustrate how the magnitude of aperture variations lead to flow structures that often inhibit rather than enhance subsurface heat exchange. Finally, both conservative and reactive tracers were used to determine the spatially varying thermal field during heat extraction in a discrete fracture with variable aperture. Reduced order modeling of the fracture was used to create a tractable framework for inferring reservoir structure. Tracers revealed the capability to predict a reservoir's production temperature versus time, with reactive tracers providing better results. However, difficulties in accurately predicting the aperture field led to a non-unique outcome where more than one reservoir realization matched both the tracer curve and production temperature.

Author : Mark W. McClure
Publisher : Springer Science & Business Media
Page : 96 pages
File Size : 48,16 MB
Release : 2013-06-15
Category : Technology & Engineering
ISBN : 3319003836

GET BOOK

Discrete Fracture Network Modeling of Hydraulic Stimulation describes the development and testing of a model that couples fluid-flow, deformation, friction weakening, and permeability evolution in large, complex two-dimensional discrete fracture networks. The model can be used to explore the behavior of hydraulic stimulation in settings where matrix permeability is low and preexisting fractures play an important role, such as Enhanced Geothermal Systems and gas shale. Used also to describe pure shear stimulation, mixed-mechanism stimulation, or pure opening-mode stimulation. A variety of novel techniques to ensure efficiency and realistic model behavior are implemented, and tested. The simulation methodology can also be used as an efficient method for directly solving quasistatic fracture contact problems. Results show how stresses induced by fracture deformation during stimulation directly impact the mechanism of propagation and the resulting fracture network.

Author : Mehrdad Massoudi
Publisher : MDPI
Page : 470 pages
File Size : 44,48 MB
Release : 2020-04-16
Category : Technology & Engineering
ISBN : 3039287206

GET BOOK

Geothermal energy is the thermal energy generated and stored in the Earth's core, mantle, and crust. Geothermal technologies are used to generate electricity and to heat and cool buildings. To develop accurate models for heat and mass transfer applications involving fluid flow in geothermal applications or reservoir engineering and petroleum industries, a basic knowledge of the rheological and transport properties of the materials involved (drilling fluid, rock properties, etc.)—especially in high-temperature and high-pressure environments—are needed. This Special Issue considers all aspects of fluid flow and heat transfer in geothermal applications, including the ground heat exchanger, conduction and convection in porous media. The emphasis here is on mathematical and computational aspects of fluid flow in conventional and unconventional reservoirs, geothermal engineering, fluid flow, and heat transfer in drilling engineering and enhanced oil recovery (hydraulic fracturing, CO2 injection, etc.) applications.

Author : Norihiro Watanabe
Publisher : Springer
Page : 109 pages
File Size : 47,25 MB
Release : 2016-11-10
Category : Technology & Engineering
ISBN : 3319465813

GET BOOK

This book focuses on numerical modeling of deep hydrothermal and petrothermal systems in fractured georeservoirs for utilization in Geothermal Energy applications. The authors explain the particular challenges and approaches to modeling heat transport and high-throughput flow in multiply fractured porous rock formations. In order to help readers gain a system-level understanding of the necessary analysis, the authors include detailed examples of growing complexity as the techniques explained in the text are introduced. The coverage culminates with the fully-coupled analysis of real deep geothermal test-sites located in Germany and France.

Author : Lilja Magnúsdóttir
Publisher :
Page : pages
File Size : 33,97 MB
Release : 2013
Category :
ISBN :

GET BOOK

The configuration of fractures in a geothermal reservoir is central to the performance of the system. The interconnected fractures control the heat and mass transport in the reservoir and if the fluid reaches production wells before it is fully heated, unfavorable effects on energy production may result due to decreasing fluid enthalpies. Consequently, inappropriate placing of injection or production wells can lead to premature thermal breakthrough. Thus, fracture characterization in geothermal reservoirs is an important task in order to design the recovery strategy appropriately and increase the overall efficiency of the power production. This is true both in naturally fractured geothermal systems as well as in Enhanced Geothermal Systems (EGS) with man-made fractures produced by hydraulic stimulation. In this study, the aim was to estimate fracture connectivity in geothermal reservoirs using a conductive fluid injection and an inversion of time-lapse electric potential data. Discrete fracture networks were modeled and a flow simulator was used first to simulate the flow of a conductive tracer through the reservoirs. Then, the simulator was applied to solve the electric fields at each time step by utilizing the analogy between Ohm's law and Darcy's law. The electric potential difference between well-pairs drops as a conductive fluid fills fracture paths from the injector towards the producer. Therefore, the time-lapse electric potential data can be representative of the connectivity of the fracture network. Flow and electric simulations were performed on models of various fracture networks and inverse modeling was used to match reservoir models to other fracture networks in a library of networks by comparing the time-histories of the electric potential. Two fracture characterization indices were investigated for describing the character of the fractured reservoirs; the fractional connected area and the spatial fractal dimension. In most cases, the electrical potential approach was used successfully to estimate both the fractional connected area of the reservoirs and the spatial fractal dimension. The locations of the linked fracture sets were also predicted correctly. Next, the electric method was compared to using only the simple tracer return curves at the producers in the inverse analysis. The study showed that the fracture characterization indices were estimated somewhat better using the electric approach. The locations of connected areas in the predicted network were also in many cases incorrect when only the tracer return curves were used. The use of the electric approach to predict thermal return was investigated and compared to using just the simple tracer return curves. The electric approach predicted the thermal return curves relatively accurately. However, in some cases the tracer return gave a better estimation of the thermal behavior. The electric measurements are affected by both the time it takes for the conductive tracer to reach the production well, as well as the overall location of the connected areas. When only the tracer return curves are used in the inverse analysis, only the concentration of tracer at the producer is measured but there is a good correlation between the tracer breakthrough time and the thermal breakthrough times. Thus, the tracer return curves can predict the thermal return accurately but the overall location of fractures might not be predicted correctly. The electric data and the tracer return data were also used together in an inverse analysis to predict the thermal returns. The results were in some cases somewhat better than using only the tracer return curves or only the electric data. A different injection scheme was also tested for both approaches. The electric data characterized the overall fracture network better than the tracer return curves so when the well pattern was changed from what was used during the tracer and electric measurements, the electric approach predicted the new thermal return better. In addition, the thermal return was predicted considerably better using the electric approach when measurements over a shorter period of time were used in the inverse analysis. In addition to characterizing the fracture distribution better, the electric approach can give information about the conductive fluid flowing through the fracture network even before it has reached the production wells.

Author : Yu-Shu Wu
Publisher : Gulf Professional Publishing
Page : 568 pages
File Size : 32,80 MB
Release : 2017-11-30
Category : Technology & Engineering
ISBN : 0128129999

GET BOOK

Hydraulic Fracture Modeling delivers all the pertinent technology and solutions in one product to become the go-to source for petroleum and reservoir engineers. Providing tools and approaches, this multi-contributed reference presents current and upcoming developments for modeling rock fracturing including their limitations and problem-solving applications. Fractures are common in oil and gas reservoir formations, and with the ongoing increase in development of unconventional reservoirs, more petroleum engineers today need to know the latest technology surrounding hydraulic fracturing technology such as fracture rock modeling. There is tremendous research in the area but not all located in one place. Covering two types of modeling technologies, various effective fracturing approaches and model applications for fracturing, the book equips today’s petroleum engineer with an all-inclusive product to characterize and optimize today’s more complex reservoirs. Offers understanding of the details surrounding fracturing and fracture modeling technology, including theories and quantitative methods Provides academic and practical perspective from multiple contributors at the forefront of hydraulic fracturing and rock mechanics Provides today’s petroleum engineer with model validation tools backed by real-world case studies

Author : Wentao Feng
Publisher : Cuvillier Verlag
Page : 204 pages
File Size : 46,57 MB
Release : 2020-03-05
Category : Technology & Engineering
ISBN : 3736961707

GET BOOK

Hydraulic fracturing in combination with horizontal well is playing a key role in the efficient development of unconventional gas/oil reservoirs and deep geothermal resources. However, the integral operation, especially from the perspective of THM (Thermal-Hydraulic-Mechanic) interactions have not been studied systematically. In this thesis, targeted improvements were achieved through developing a series of mathematical/physical models, and their implementation into the existing numerical tools (FLAC3Dplus and TOUGH2MP-FLAC3D), including: (a) a new thermal module for FLAC3Dplus based entirely on the finite volume method (FVM), which is especially developed for the fracturing process and can also achieve the modeling of gel breaking; (b) a rock damage module of TOUGH2MP-FLAC3D, which also considers the impacts of rock damaging process on evolution of permeability; (c) an in-depth improved FLAC3Dplus simulator that obtains the ability to simulate a 3D fracture propagation with arbitrary orientation. After the corresponding verifications, the improved tools were applied in different case studies to reveal: a) influences of the fluid’s viscosity on the fracturing results in tight sandstone reservoirs; b) the induced seismicity during the fracturing operation and the reactivation of the natural faults; and c) the fracture propagation with arbitrary orientation.

Author :
Publisher :
Page : pages
File Size : 18,27 MB
Release : 1988
Category :
ISBN :

GET BOOK

In most geothermal reservoirs large-scale permeability is dominated by fractures, while most of the heat and fluid reserves are stored in the rock matrix. Early-time fluid production comes mostly from the readily accessible fracture volume, while reservoir behavior at later time depends upon the ease with which fluid and heat can be transferred from the rock matrix to the fractures. Methods for modeling flow in fractured porous media must be able to deal with this matrix-fracture exchange, the so-called interporosity flow. This paper reviews recent work at Lawrence Berkeley Laboratory on numerical modeling of nonisothermal multiphase flow in fractured porous media. We also give a brief summary of simulation applications to problems in geothermal production and reinjection. 29 refs., 1 fig.

Author : Wei Li (S.M.)
Publisher :
Page : 125 pages
File Size : 15,79 MB
Release : 2014
Category :
ISBN :

GET BOOK

Modeling of heat transfer between fluid and fractured rocks is of particular importance for energy extraction analysis in EGS, and therefore represents a critical component of EGS design and performance evaluation. In conventional fracture dominated geothermal systems with reinjection, this modeling process is also helpful for understanding how the thermal front migrates and for optimizing of reservoir management strategies. Both numerical and analytical approaches are used to help us get a better understanding of the heat transfer process between the fluid and the fractured rocks in a geothermal reservoir. In the numerical approach, a stochastic discrete fracture network model, GEOFRAC, is used to generate a fracture network. GEOFRAC-FLOW, is used to calculate the flow path in the fracture network and flow rate in each fracture. On the basis of the two, a heat transfer model, GEOFRAC-THERMAL, is developed. Parametric studies with the three models are conducted to analyze the sensitivity of the parameters. A case study with the three models on the Fenton Hill project is conducted to demonstrate the capability of the three models in modeling the heat and mass transfer in the geothermal reservoir. In the analytical approach, a conceptual geothermal reservoir model is introduced. The heat transfer process in the fluid and the fractured rock is formulated based on energy conservation. With the assumption of uniform rock temperature, the 0-D solution is obtained. Parametric studies and case study on the Fenton Hill project are conducted with the 0-D solution. With the assumption of heat conduction happening only in the transverse direction of the rock, the 1-D solution is obtained. Parametric studies are conducted with the 1 -D solution and useful conclusions are obtained. A simply configured heat transfer problem is used to compare the results of the finite element analysis and the 1-D solution. The effect of the simplification in the 1 -D solution is analyzed based on the comparison.