Geothermal Reservoirs

Grant, Malcolm A.; Bixley, Paul F.

doi:10.1016/b978-0-12-383880-3.10001-0

Cited by 51 publications

(76 citation statements)

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“…However, the parameters prevalent in the diffusivity equation are not constant. Therefore, we employ a semisteady‐state solution similar to the one by Dake and by Grant and Bixley . We use the value of the coupled diffusivity to estimate the radius up to which the pressure is disturbed; within this radius, we calculate the pressure using fully developed flow equations.…”

Section: Modelling Approachmentioning

confidence: 99%

“…The approximation is related to the fact that for values of

\frac{c r^{2}}{4 t} < 0.01

, the exponential integral (Equation ) can be approximated with a natural logarithm. For large enough times, an equivalent solution can be formulated as a logarithmic decay up to an influence radius—the pressure drop within that radius can thus be calculated using Darcy's law under the assumption of negligible storage [, p.36]. An additional argument to use this approximation is that we are mainly interested in the changes of stress close to the injection well, where the pressure changes are most significant.…”

Section: Modelling Approachmentioning

confidence: 99%

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A semianalytic time‐resolved poro‐elasto‐plastic model for wellbore stability and stimulation

Fokker

Singh

Wassing

2020

Num Anal Meth Geomechanics

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Summary Wellbore stability problems and stimulation operations call for models helping in understanding the subsurface behaviour and optimizing engineering performance. We present a fast, iteratively coupled model for the flow and mechanical behaviour that employs a time‐sequential approach. Updates of pore pressure are calculated in a timestepping approach and propagated analytically to updates of the mechanical response. This way, the spatial and temporal evolution of pressure and mechanical response around a wellbore can be evaluated. The sequential approach facilitates the incorporation of pressure diffusion and of time‐dependent plasticity. Also, it facilitates the implementation of permeability evolving with time, due to plasticity or stimulation. The model has been validated by means of a coupled numerical simulator. Its capabilities are demonstrated with a selection of sensitivity runs for typical parameters. Ongoing investigations target geothermal energy operations through the incorporation of thermo‐elastic stresses and more advanced plasticity models.

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Section: Modelling Approachmentioning

confidence: 99%

“…The approximation is related to the fact that for values of

\frac{c r^{2}}{4 t} < 0.01

Section: Modelling Approachmentioning

confidence: 99%

A semianalytic time‐resolved poro‐elasto‐plastic model for wellbore stability and stimulation

Fokker

Singh

Wassing

2020

Num Anal Meth Geomechanics

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“…Geothermal systems, especially those hosting an active hydrothermal system, provide a substantial resource to supply large populations with reliable, environmentally friendly, sustainable energy. The driving geological components of a hydrothermal system (i.e., heat source, convecting fluid, and permeable conductive zone; Grant & Bixley, ; Corrado et al, ) are complexly interrelated. Therefore, the interplay between these three variables is of utmost interest.…”

Section: Introductionmentioning

confidence: 99%

Increasing the Permeability of Hydrothermally Altered Andesite by Transitory Heating

Mordensky

Kennedy

Villeneuve

et al. 2019

Geochem Geophys Geosyst

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Changes in permeability can impact geological processes, geohazards, and geothermal energy production. In hydrothermal systems, high‐temperature heat sources drive fluid convection through the pore network of reservoir rocks. Additionally, thermal fluctuations may induce microfracturing and affect the mineralogical stability of the reservoir rock, thus modifying the fluid pathways and affecting permeability and strength. This study describes the results of thermal heating events lasting several hours on a “moderately altered” plagioclase‐clinochlore‐calcite‐quartz andesite and a “highly altered” plagioclase‐clinozoisite‐quartz‐clinochlore andesite from the Rotokawa Geothermal Field, New Zealand. We use a low thermal gradient (~1.2 °C/min) in an H2O‐saturated, 20‐MPa pressure environment to constrain changes in petrophysical properties associated with transitory thermal phenomena between 350 and 739 °C. As the treatment temperature increases, the mass reduces, while porosity and permeability increase. These effects were greater in the “moderately altered” andesite than in the “highly altered” andesite. Microfracturing is responsible for these changes at lower temperatures (e.g., ≤400 °C). At higher temperatures (e.g., >400 °C), microfracturing remains partially responsible for these rock property changes (e.g., higher permeability); however, these changes are also a product of clinochlore, quartz, and (when present) calcite reacting out of the altered andesite, and increasing porosity. We propose that at temperatures >400 °C, volumetric phase changes associated with heat‐driven reactions in a wet environment can contribute to microcracking and porosity/permeability changes. Our data support observations where high‐temperature conditions at the margins of magma bodies can be associated with substantial increased permeability and decreased strength.

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“…33 With the progress of HDR development and utilization technologies, especially the advancement of fracturing technology and the reduction of costs, the temperature limit of HDR resources is gradually blurred. It is referred to as hot dry rock (HDR) and is a very lucrative geothermal resource.…”

Section: Hot Dry Rock (Hdr) Resourcesmentioning

confidence: 99%

Geothermal power generation in China: Status and prospects

Zhang

Chen

Zhang

2019

Energy Science & Engineering

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Geothermal resources provide green, low‐carbon, and renewable clean energy, with abundant reserves and massive potential for application. The in‐depth analysis of geothermal resources in China, including their distribution and breakdown by shallow, hydrothermal, and hot dry rock (HDR) resources, is made in this study. Using the recent economic reports and state‐of‐the‐art technological solutions, this survey outlines the latest trends in the geothermal power generation in China. The application of geothermal power generation in China is still at an early stage, with the total installed capacity of 27.78 MW. The geothermal power generation technologies, such as dry steam technology, flash technology, binary cycle technology, and enhanced geothermal system (EGS), are briefly discussed and linked to their lucrative implementation sites. In particular, Tibet's Yangbajing is considered to be the most lucrative site for the EGS pilot project. The comparative analysis of low‐cost/large‐scale geothermal power generation technologies, such as low‐ to medium‐temperature one, solar‐geothermal hybrid one, and geothermal power generation in mines, was made, whose results strongly indicated the EGS technical and economical advantages. The concentration of 96% of China's population in the area to the east of Hu line affects the perspectives of high‐cost geothermal projects and has to be accounted in the comprehensive analysis of available data. Based on the revealed trends of geothermal resources’ development in China, the following guidelines are strongly recommended: comprehensive incorporation of geothermal energy generation into China's national energy and climate improvement plans, the rapid implementation of HDR technology, as well as comprehensive adaptation of the geothermal‐related projects to the local conditions/biased distribution of power consumers and state‐of‐the‐art challenges of power consumption.

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Geothermal Reservoirs

Cited by 51 publications

References 0 publications

A semianalytic time‐resolved poro‐elasto‐plastic model for wellbore stability and stimulation

A semianalytic time‐resolved poro‐elasto‐plastic model for wellbore stability and stimulation

Increasing the Permeability of Hydrothermally Altered Andesite by Transitory Heating

Geothermal power generation in China: Status and prospects

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