The in-situ stress state of the Rhine-Ruhr region and its implications for the geothermal energy utilization

2020 ◽  
Author(s):  
Michal Kruszewski ◽  
Giordano Montegrossi ◽  
Tobias Backers ◽  
Erik Saenger
Keyword(s):  
Stress State ◽  
Geothermal Energy ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Energy Utilization ◽  
Natural Fracture ◽  
Electricity Production ◽  
The Future ◽  
Ruhr Region

<p>The Rhine-Ruhr region is one of the largest metropolitan areas in Europe, with more than 10 million inhabitants, located in western Germany. The region is defined by the rich coal-bearing layers from the upper Carboniferous period, extracted as early as the 13<sup>th</sup> century and belonging to the sub-Variscan Trough. In 2018, after more than 700 years of exploration, the last black coal mine was closed in the area. One of the most promising re-uses of the abandoned coal mines is the exploitation of geothermal energy sources. Additionally, to the geothermal energy extracted from existing mines, potential deep geothermal reservoirs within the Rhine-Ruhr, may exist at depths between 4.5 and 6 km, where Devonian limestones were found. Based on the available temperature profiles from deep exploration wells in the area, geothermal gradient amounts to 36.8<sup>o</sup>C/km and results in reservoir temperatures between 170<sup>o</sup>C and 220<sup>o</sup>C, which will enable not only heat but even electricity production. This study provides a comprehensive investigation of the full in-situ stress state tensor with its anisotropy and presents crucial physical formation and natural fracture properties. The data for this investigation was acquired from the extensive borehole logging and geomechanical campaigns carried out in deep coal exploration wells throughout the 1980s as well as from the recent shallow geothermal research wells. Acquired data allowed assessing critically-stressed, i.e. hydraulically active, fractures undergoing shear displacement, being primarily responsible for the future geothermal reservoir permeability. Extensive sets of microseismic, subsidence and drilling data were used to confirm the results of the analysis. Additionally, wellbore stability analysis and potential drill paths for the future medium-to-deep geothermal wells in the region were assessed. This study is a part of the 3D-RuhrMarie project, which aims to assess the intrinsic seismic risk within the Rhine-Ruhr region to promote safer and economically more efficient exploration and exploitation of the future geothermal resources.</p>

Numerical Modeling of Sand Production Potential Estimation and Passive Control Optimization: A Case Study

2018 ◽  
Author(s):  
Eva Lopez-Puiggene ◽  
Nubia Aurora Gonzalez-Molano ◽  
Jose Alvarellos-Iglesias ◽  
Jose M. Segura ◽  
M. R. Lakshmikantha
Keyword(s):  
Stress State ◽  
High Resolution ◽  
Plastic Strain ◽  
Pore Pressure ◽  
In Situ Stress ◽  
Point Of View ◽  
Wellbore Stability ◽  
Sand Production ◽  
Production Stress

Solids/sand production is an unintended byproduct of the hydrocarbon production that, from an operational point of view, might potentially lead to undesirable consequences. This paper focuses on a study centered in the geomechanical perspective for solids production. An integrated workflow is presented to analyze the combined effect of reservoir pore-pressure, drawdown, in-situ stress, rock properties and well/perforations orientation on the onset of solid production. This workflow incorporates analyses at multiple scales: rock constitutive modeling at lab scale, 1D geomechanical models at wellbore scale along well trajectories, a 3D geomechanical model at the reservoir scale and 3D/4D high resolution reservoir - geomechanical coupled models at the well and perforation scale. 1D geomechanical models were built using log and field data, drilling experience and laboratory tests in order to characterize in situ stresses, pore pressure and rock mechanics properties (stiffness and strength) profiles for several wells. Rock shear failure mechanism was also analyzed in order to build a pre-drill model and evaluate the wellbore stability from a geomechanical point of view. Pre-production stress modeling was simulated to obtain a representative initial stress state integrating 1D geomechanics well results, 3D dynamic model and seismic interpretations. Mechanical properties were distributed considering properties calculated in the 1D geomechanical models as input. 3D stress field was validated with in-situ stress profiles from 1D modeling results. This simulated pre-production stress state was then used as an initial condition for the reservoir - geomechanical coupled simulations. Effective stress changes and deformations associated to pore pressure changes were calculated including the coupling between reservoir and geomechanical modeling. Finally, a 3D/4D high resolution well scale reservoir - geomechanical coupled numerical model was built in order to determine the threshold of sand production. A limit of plastic strain was obtained based on numerical simulations of available production data, DST and ATWC tests. This critical plastic strain limit was used as a criterion (strain-based) for rock failure to define the onset of sand production as a function of pore pressure, perforation orientation and rock strength. Conclusions regarding the perforation orientations related to the possibility of producing solids can support operational decisions in order to avoid undesirable solid production and therefore optimize the production facilities capacity and design to handle large amounts of solids and/or the clogging of the well.

scholarly journals In Situ Stress State of the Ruhr Region (Germany) and Its Implications for Permeability Anisotropy

2021 ◽  
Author(s):  
Michal Kruszewski ◽  
Giordano Montegrossi ◽  
Tobias Backers ◽  
Erik H. Saenger
Keyword(s):  
Stress State ◽  
In Situ Stress ◽  
Field Configuration ◽  
Upper Carboniferous ◽  
Planar Structures ◽  
Deep Geothermal Energy ◽  
Ruhr Region ◽  
Rock Strata ◽  
Carboniferous Rock

AbstractIn this study, we carried out reactivation potential analysis of discontinuities revealed from four exploration boreholes penetrating heavily faulted and folded Upper Carboniferous rock strata of the Ruhr region. We performed this study based on the notion that slip is controlled by the ratio of shear to effective normal stresses acting on a pre-existing plane of weakness in the prevailing stress field configuration. The results of this analysis were supported by indicators of localized fluid flow, both on micro- and macro-scales, which confirm relationship between secondary permeability and in situ stress state in the Ruhr region. Findings from this study, in conjunction with results of destructive laboratory testing, indicate that the steep NW–SE- and NNE–SSW-striking planar discontinuities are likely to be either close to the critical state or critically stressed in the in situ stress configuration in the Ruhr region. These planar structures, as evidenced by indicators of localized permeability, are the main fluid pathways in the studied region. The NE–SW-striking discontinuities, on the other hand, are most likely to be closed and hydraulically inactive in the prevailing stress state. Based on results gained from this study, implications for utilization of deep geothermal energy in the region were discussed.

scholarly journals In situ stress state from walkaround VSP anisotropy in the Kumano basin southeast of the Kii Peninsula, Japan

2011 ◽  
Vol 12 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
Takeshi Tsuji ◽  
Ryota Hino ◽  
Yoshinori Sanada ◽  
Kiyohiko Yamamoto ◽  
Jin-Oh Park ◽  
...  
Keyword(s):  
Stress State ◽  
In Situ Stress ◽  
Kii Peninsula ◽  
Kumano Basin

A Novel Method to Determine the Drilling Fluid Density for Gypsum-Salt Layer

2021 ◽  
Author(s):  
Jitong Liu ◽  
Wanjun Li ◽  
Haiqiu Zhou ◽  
Yixin Gu ◽  
Fuhua Jiang ◽  
...  
Keyword(s):  
Drilling Fluid ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Shrinkage Rate ◽  
Fluid Density ◽  
Salt Layer ◽  
Rock Creep ◽  
Key Factor ◽  
Well Abandonment

Abstract The reservoir underneath the salt bed usually has high formation pressure and large production rate. However, downhole complexities such as wellbore shrinkage, stuck pipe, casing deformation and brine crystallization prone to occur in the drilling and completion of the salt bed. The drilling safety is affected and may lead to the failure of drilling to the target reservoir. The drilling fluid density is the key factor to maintain the salt bed’s wellbore stability. The in-situ stress of the composite salt bed (gypsum-salt -gypsum-salt-gypsum) is usually uneven distributed. Creep deformation and wellbore shrinkage affect each other within layers. The wellbore stability is difficult to maintain. Limited theorical reference existed for drilling fluid density selection to mitigate the borehole shrinkage in the composite gypsum-salt layers. This paper established a composite gypsum-salt model based on the rock mechanism and experiments, and a safe-drilling density selection layout is formed to solve the borehole shrinkage problem. This study provides fundamental basis for drilling fluid density selection for gypsum-salt layers. The experiment results show that, with the same drilling fluid density, the borehole shrinkage rate of the minimum horizontal in-situ stress azimuth is higher than that of the maximum horizontal in-situ stress azimuth. However, the borehole shrinkage rate of the gypsum layer is higher than salt layer. The hydration expansion of the gypsum is the dominant reason for the shrinkage of the composite salt-gypsum layer. In order to mitigate the borehole diameter reduction, the drilling fluid density is determined that can lower the creep rate less than 0.001, as a result, the borehole shrinkage of salt-gypsum layer is slowed. At the same time, it is necessary to improve the salinity, filter loss and plugging ability of the drilling fluid to inhibit the creep of the soft shale formation. The research results provide technical support for the safe drilling of composite salt-gypsum layers. This achievement has been applied to 135 wells in the Amu Darya, which completely solved the of wellbore shrinkage problem caused by salt rock creep. Complexities such as stuck string and well abandonment due to high-pressure brine crystallization are eliminated. The drilling cycle is shortened by 21% and the drilling costs is reduced by 15%.

The in situ stress state of Kailuan mining area

2010 ◽  
pp. 375-380
Author(s):  
J Han ◽  
P Zhang ◽  
X Tian ◽  
S Sun ◽  
H Zhang ◽  
...  
Keyword(s):  
Stress State ◽  
Mining Area ◽  
In Situ Stress

The measurement of the in-situ stress state by acoustic emission method (AEM) in weak rocks

Rock Stress ◽  
2020 ◽  
pp. 389-394
Author(s):  
H. Watanabe ◽  
H. Tano ◽  
Ö. Aydan ◽  
R. Ulusay ◽  
E. Tuncay ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Stress State ◽  
In Situ Stress ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Weak Rocks

Estimation of in-situ stress state at the maximum depth of the Jinping tunnels, China

2010 ◽  
pp. 345-350
Author(s):  
C Zhang ◽  
X Feng ◽  
H Zhou ◽  
C Zhang ◽  
S Wu
Keyword(s):  
Stress State ◽  
In Situ Stress ◽  
Maximum Depth
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