scholarly journals Potential influence of overpressurized gas on the induced seismicity in the St. Gallen deep geothermal project (Switzerland)

Solid Earth ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 909-933 ◽  
Author(s):  
Dominik Zbinden ◽  
Antonio Pio Rinaldi ◽  
Tobias Diehl ◽  
Stefan Wiemer
Keyword(s):  
Induced Seismicity ◽  
District Heating ◽  
Interesting Case ◽  
Drilling Mud ◽  
Hydraulic Connection ◽  
Well Control ◽  
Injection Test ◽  
Gas Kick ◽  
Seismological Data ◽  
Geological Conditions

Abstract. In July 2013, the city of St. Gallen conducted a deep geothermal project that aimed to exploit energy for district heating and generating power. A few days after an injection test and two acid stimulations that caused only minor seismicity, a gas kick forced the operators to inject drilling mud to combat the kick. Subsequently, multiple earthquakes were induced on a fault several hundred meters away from the well, including a ML 3.5 event that was felt throughout the nearby population centers. Given the occurrence of a gas kick and a felt seismic sequence with low total injected fluid volumes (∼1200 m3), the St. Gallen deep geothermal project represents a particularly interesting case study of induced seismicity. Here, we first present a conceptual model based on seismic, borehole, and seismological data suggesting a hydraulic connection between the well and the fault. The overpressurized gas, which is assumed to be initially sealed by the fault, may have been released due to the stimulations before entering the well via the hydraulic connection. We test this hypothesis with a numerical model calibrated against the borehole pressure of the injection test. We successfully reproduce the gas kick and spatiotemporal characteristics of the main seismicity sequence following the well control operation. The results indicate that the gas may have destabilized the fault during and after the injection operations and could have enhanced the resulting seismicity. This study may have implications for future deep hydrothermal projects conducted in similar geological conditions with potentially overpressurized in-place gas.

scholarly journals Potential influence of overpressurized gas on the induced seismicity in the St. Gallen deep geothermal project (Switzerland)

2019 ◽  
Author(s):  
Dominik Zbinden ◽  
Antonio Pio Rinaldi ◽  
Tobias Diehl ◽  
Stefan Wiemer
Keyword(s):  
Induced Seismicity ◽  
District Heating ◽  
Interesting Case ◽  
Drilling Mud ◽  
Hydraulic Connection ◽  
Injection Test ◽  
Gas Kick ◽  
Seismological Data ◽  
Geological Conditions ◽  
Temporal And Spatial Characteristics

Abstract. In July 2013, the city of St. Gallen conducted a deep geothermal project that aimed to exploit energy for district heating and generating power. A few days after an injection test and two acid stimulations that caused only minor seismicity, a gas kick forced the operators to inject drilling mud to combat the kick. Subsequently, multiple earthquakes were induced on a fault several hundred meters away from the well, including a ML 3.5 event that was felt throughout the nearby population centers. Given the occurrence of a gas kick and a felt seismic sequence with low total injected fluid volumes (~ 1200 m3), the St. Gallen deep geothermal project represents a particularly interesting case study of induced seismicity. Here, we first present a conceptual model based on seismic, borehole and seismological data suggesting a hydraulic connection between the well and the fault. The overpressurized gas, which is assumed to be initially sealed by the fault, may have been released due to the stimulations before entering the well via the hydraulic connection. We test this hypothesis with a numerical model calibrated against the borehole pressure of the injection test. We successfully reproduce the gas kick and the temporal and spatial characteristics of the main seismicity sequence that followed the well control operation. The results indicate that the gas may have destabilized the fault during and after the injection operations and could have enhanced the resulting seismicity. This study may have important implications for future deep hydrothermal projects conducted in similar geological conditions.

Smearing of a Kick While Being Displaced From a Well

1991 ◽  
Vol 113 (3) ◽  
pp. 154-156
Author(s):  
M. Haciislamoglu ◽  
J. Langlinais
Keyword(s):  
Computer Model ◽  
Velocity Profiles ◽  
Newtonian Fluids ◽  
Well Control ◽  
Gas Kick

Well control operations while drilling with an oil-base mud can suffer several unexpected phenomena. One of these is the dispersion (smearing) of the gas in solution whenever a gas kick is being circulated from the well. If the gas influx has gone into solution, it is very important to predict the movement of this gas-contaminated mud as it is circulated from the well. A computer model of non-Newtonian fluids flowing in an annulus of any eccentricity has been developed with which to accurately model this dispersion. The movement of the gas-contaminated mud is predicted as a consequence of the velocity profiles established as the displacement of the annulus progresses.

Well Control Technology of High Temperature and High Pressure with Different Well Shapes

2013 ◽  
Vol 316-317 ◽  
pp. 860-866
Author(s):  
Yan Jun Li ◽  
Xiang Nan He ◽  
Xiao Wei Feng ◽  
Ya Qi Zhang ◽  
Ling Wu ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Drilling Fluid ◽  
Control Process ◽  
Formation Pressure ◽  
Well Drilling ◽  
Well Control ◽  
Direct Invasion ◽  
Bottom Hole ◽  
Gas Kick

Well control safe is the prerequisite of safety drilling, especially for high temperature and high pressure horizontal wells. However, there are few papers about well control of horizontal well drilling, which mostly learn from vertical well control process. By means of analysis of the theory of gas kick, we conclude that underbalance, the bottom hole pressure is less than the formation pressure is the main means of gas invasion. During balance period, the gas also intrudes into wellbore through the way of direct invasion, diffusion invasion and replacement invasion, but the amount of gas kick is less, so the risk of well control is small. This paper also anlyses the kick tolerance, the kick tolerance decreases with the increasing of drilling fluid density when the formation pressure and drilling equipment is constant.

Evaluation of Ultrasonic Methods for In-Situ Real-Time Characterization of Drilling Mud

2005 ◽  
Author(s):  
Judith Ann Bamberger ◽  
Margaret S. Greenwood
Keyword(s):  
Physical Properties ◽  
Real Time ◽  
Speed Of Sound ◽  
Direct Contact ◽  
Drilling Fluid ◽  
Drilling Process ◽  
Drilling Mud ◽  
Well Control

A real time multi-functional ultrasonic sensor system is proposed to provide automated drilling fluid monitoring that can improve the capability and development of slimhole and microhole drilling. This type of reliable, accurate, and affordable drilling fluid monitoring will reduce the overall costs in exploration and production. It will also allow more effective drilling process automation while providing rig personnel a safer and more efficient work environment. Accurate and timely measurements of drilling fluid properties such as flow rate, density, viscosity, and solid loading are key components for characterizing rate of drill penetration, providing early warning of lost circulation, and for use in real-time well control. Continuous drilling fluid monitoring enhances drilling economics by reducing the risk of costly drilling downtime, increasing production performance, and improving well control. Investigations conducted to characterize physical properties of drilling mud indicate that ultrasound can be used to provide real-time, in-situ process monitoring and control. Three types of ultrasonic measurements were evaluated which include analysis of in wall, through wall and direct contact signals. In wall measurements provide acoustic impedance (the slurry density and speed of sound product). Through wall and direct contact measurements provide speed of sound and attenuation. This information is combined to determine physical properties such as slurry density, solids concentration and can be used to detect particle size changes and the presence of low levels of gas. The measurements showed that for the frequency range investigated in-wall measurements were obtained over the slurry density range from 1500 to 2200 kg/m3 (10 to 17 pounds solids per gallon of drilling fluid). Other measurements were obtained at densities in the 1500 to 1800 kg/m3 range. These promising measurement results show that ultrasound can be used for real-time in-situ characterization of the drilling process by monitoring drilling mud characteristics.

Fighting Invisible Kicks: Study of Time Dependent Vaporization of Methane Gas Dissolved in Base Oil

2020 ◽  
Author(s):  
Marius Staahl Nilsen ◽  
Sigve Hovda
Keyword(s):  
Analytical Model ◽  
Transition Rate ◽  
Drilling Fluid ◽  
Dissolved Gas ◽  
Base Oil ◽  
Well Control ◽  
Analytical Expression ◽  
Free Gas ◽  
Methane Gas ◽  
Gas Kick

Abstract Understanding the interaction between the drilling fluid and the natural gas from a gas kick may be of great importance when predicting how a well control incident evolves during drilling operations. This is especially true for oil based mud, which has the ability to dissolve large quantities of gas under high pressure, thus potentially hide any volumetric impact of a gas kick. When the pressure of the dissolved gas decreases below the bubble pressure, free gas will start to emerge. Dangerous situations can occur if the bubble point pressure is low and located close to the surface. This may result in a rapid volumetric expansion of the free gas, as it emerges from solution, thus little to no time to react and initiate proper well control procedures. Most conventional well control simulators that takes gas solubility into consideration assumes an instantaneous vaporization of gas as the vapour-liquid phase equilibria changes. However, this assumption might not always be realistic. It may take some time before a new equilibrium is reached when the conditions are changed. This will thus affecting the rate of gas liberation from the liquid. To better understand this complex issue, an analytical expression for the transition rate of dissolved gas to free gas in a supersaturated liquid has been derived for low pressure systems. The analytical model is strongly dependent on the solubility coefficient, Kh, and the transition rate factor, γ, and follows an exponential curve. In this expression, Kh is a measure of how much the liquid is supersaturated at any given time and controls how much gas that will be liberated. γ determines how fast the system will reach a new equilibrium, i.e. how fast the gas will be liberated based on the size of the supersaturation. Both Kh and γ are thought to be values given for a specific gas-liquid combination. In order to verify the analytical expression, experimental testing has been conducted. The experiment is carried out by pressurizing a tank partly filled with the base oil Exxsol D60 by feeding it with methane gas. Some of the gas will dissolve into the liquid. The rest will flow to the top as free gas and pressurize the tank. By quickly removing some of the free gas, thus depressurize the tank, the liquid will instantaneously become supersaturated, hence triggering liberation of free gas from the solution until a new equilibrium is established. By measuring the tank pressure throughout the degassing phase, values for Kh and γ can be estimated and compared to the analytical model.

scholarly journals Effects of Different Penetration Patterns on a Fault during Underground Fluid Injection

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Xiaochen Wei ◽  
Qi Li ◽  
Xiaying Li ◽  
Zhiyong Niu ◽  
Xiangjun Liu ◽  
...  
Keyword(s):  
Finite Element ◽  
Site Selection ◽  
Induced Seismicity ◽  
Anthropogenic Activities ◽  
Fault Reactivation ◽  
Fluid Injection ◽  
Barrier Effect ◽  
Hydraulic Connection ◽  
Shengli Oilfield ◽  
Fault Structures

At underground fluid injection sites with natural faults, understanding how to avoid the subsequent fault reactivation and induced seismicity plays a crucial role in the success of subsurface anthropogenic activities. In this work, with the objective of avoiding risky faults in site selection in the Shengli Oilfield, we investigated the faults that are usually encountered in the target demonstration zone; based on the geophysical observations of fault structures, we designed different fault tectonic scenarios to investigate the different penetration patterns of faults. We used the finite element-based numerical method to assess the influence of the effective lateral and vertical reservoir transmissivity in each fault penetration pattern. Our results indicate that when a permeable fault intersects into the target reservoir, it presents both barrier effect to reservoir transmissivity within the target reservoir and hydraulic connection between reservoirs. The effective lateral reservoir transmissivity is dominated by the barrier effect of the fault, and the effective vertical reservoir transmissivity is dominated by the hydraulic connection between reservoirs. Relatively impermeable faults with less contact with the target aquifer make higher effective lateral reservoir transmissivity and lower effective vertical reservoir transmissivity, which would mitigate the risk of caprock failure and the magnitude of the induced seismicity.

Distribution Law Detection of Aquifer in the First District of Lu Xin Mine Using TEM

2013 ◽  
Vol 303-306 ◽  
pp. 357-362
Author(s):  
Ming Zhang ◽  
Jian Guo Ning ◽  
Cheng Lin Tian ◽  
Xue Sheng Liu
Keyword(s):  
Coal Seam ◽  
Distribution Law ◽  
Hydraulic Connection ◽  
Transient Electromagnetic ◽  
Geological Conditions

As the background of hydrological and geological conditions in Lu Xin Mine of Xinwen Mining Group, the transient electromagnetic instrument was used to detect the distribution law of aquifer around the first district. The detection results show that the roof and floor of 13# coal seam and the top of Jurassic are relatively rich in water, but the hydraulic connection between the upper and lower is relatively weak. The roof and floor of 6# and 9# coal seam and the bottom of Neogene are rich in water and the hydraulic connection is strength, and this place is located in the edge of basin which is easy for groundwater to supply.

scholarly journals A WebGIS portal for exploration of deep geothermal energy based on geological and geophysical data

2016 ◽  
Vol 35 ◽  
pp. 23-26 ◽  
Author(s):  
Henrik Vosgerau ◽  
Anders Mathiesen ◽  
Morten Sparre Andersen ◽  
Lars Ole Boldreel ◽  
Morten Leth Hjuler ◽  
...  
Keyword(s):  
Geothermal Energy ◽  
District Heating ◽  
Geophysical Data ◽  
Heat Extraction ◽  
Depth Interval ◽  
Field Energy ◽  
Geothermal Resources ◽  
Geothermal Reservoirs ◽  
Geological Conditions ◽  
Deep Geothermal Energy

The Danish subsurface contains deep geothermal resources which may contribute for hundreds of years to the mixed Danish energy supply (Mathiesen et al. 2009). At present only a limited fraction of these resources are utilised in three existing geothermal power plants in Thisted, Margretheholm and Sønderborg (Fig. 1) where warm formation water is pumped to the surface from a production well and, after heat extraction, returned to the subsurface in injection wells (Fig. 2). Deep geothermal energy has the advantage of being a sustainable and environmentally friendly energy source which is furthermore independent of climate and seasonal variations, in contrast to wind and solar energy. The implementation of deep geothermal energy for district heating replacing conventional energy sources, especially coal and oil, may thus lead to a considerable reduction in the emission of greenhouse gases. There are therefore good reasons to include geothermal energy as a central component in Denmark’s future supply of energy for district heating. Furthermore, heat-demanding industries may consider the possibility to integrate geothermal energy and energy storage in their production process. In order to facilitate the use of geothermal energy, a broad majority in the Danish parliament has granted financial support for initiatives within the geothermal field (Energy policy agreement of March 22, 2012). The present paper deals with one of the outcomes of this agreement, namely a WebGIS portal with an overview of existing and interpreted geological and geophysical data. This will be relevant for all stakeholders in the exploration of deep geothermal resources in the Danish subsurface. The portal focuses on geothermal reservoirs within the 800–3000 m depth interval and provides an overview of the amount and quality of existing geodata, the geological composition of the subsurface, and interpreted thematic products such as geological maps of potential geothermal reservoirs. A comprehensive map from the portal showing onshore and nearoffshore locations where the geological conditions are potentially suitable for extraction of deep geothermal energy in Denmark is shown in Fig. 1. Many of the thematic maps are outcomes of the project The geothermal energy potential in Denmark – reservoir properties, temperature distribution and models for utilization under the programme Sustainable Energy and Environment funded by the Danish Agency for Science, Technology and Innovation.

A Numerical and Experimental Study of Kick Dynamics at Downhole

2018 ◽  
Vol 4 (2) ◽  
Author(s):  
Rakibul Islam ◽  
Faisal Khan ◽  
Ramchandran Venkatesan
Keyword(s):  
Two Phase Flow ◽  
Drill Pipe ◽  
Management Strategies ◽  
Phase Flow ◽  
Sudden Increase ◽  
Prevention Strategies ◽  
Two Phase ◽  
Well Control ◽  
Gas Kick ◽  
Dynamic Numerical Simulation

The early detection of a kick and mitigation with appropriate well control actions can minimize the risk of a blowout. This paper proposes a downhole monitoring system, and presents a dynamic numerical simulation of a compressible two-phase flow to study the kick dynamics at downhole during drilling operation. This approach enables early kick detection and could lead to the development of potential blowout prevention strategies. A pressure cell that mimics a scaled-down version of a downhole is used to study the dynamics of a compressible two-phase flow. The setup is simulated under boundary conditions that resemble realistic scenarios; special attention is given to the transient period after injecting the influx. The main parameters studied include pressure gradient, raising speed of a gas kick, and volumetric behavior of the gas kick with respect to time. Simulation results exhibit a sudden increase of pressure while the kick enters and volumetric expansion of gas as it flows upward. This improved understanding helps to develop effective well control and blowout prevention strategies. This study confirms the feasibility and usability of an intelligent drill pipe as a tool to monitor well conditions and develop blowout risk management strategies.

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