TY - THES

T1 - A Study of a concept geothermal ERD well for the South German Molasse Basin

AU - Minihold, Maximilian

N1 - no embargo

PY - 2024

Y1 - 2024

N2 - To ensure energy supply for Munich in the future, Stadtwerke München Services GmbH (SWM) is planning to utilize extended reach drilling (ERD) wells for resource development. With ERD wells it is possible to increase the potential from one well site, by producing heat in locations with a high demand. Complicated and cost-intensive connections to the heating network can thus be avoided. Several wells have already been drilled in the South German Molasse Basin and drilling processes have been timely improved. Wells in this area have been realized at around 3.000 m horizontal departure (HD) for shallow depths and 2.500 m for deeper depths, but potential for more horizontal reach is available. In geothermal projects within the Molasse Basin in southern Germany, several wells are usually drilled from one well site. To ensure sufficient spacing between boreholes in the reservoir, boreholes are drilled horizontally away from each other. Firstly, with increasing horizontal distance of the target point to the drilling site, the technical effort, costs and risks increase. Secondly, increasing the horizontal distance allows a significantly larger reservoir area to be developed from one drilling site. The ultimate goal of this thesis is to design a new well concept that focuses on a horizontal departure of at least 3.500 m up to 6.000 m in shallow depths of less than 2.500 m true vertical depth (TVD), taking into consideration solutions to overcome the current limitations, such as Torque/Drag, Hydraulics and Drag during Casing/Liner running. The final well design concepts established in this thesis should act as a foundation for future geothermal ERD wells in South German Molasse Basin. The basis for this thesis is a conceptual project selected in the northern region of Munich. Based on the most demanding well path of this project, various well path variations are developed using constant parameters to ensure comparability. This approach also allows the simulation of various difficulty levels, inclusive potential limitations. A full well design is established for all wells, taking into account existing SWM guidelines, literature, and expert insights from various industry disciplines. The developed well design is explained using one exemplary well. From the simulations can be concluded that, due to the implemented technology and expertise, all wells can be technically feasible simulated regardless of the length of the well, with only small operational changes (e.g., no rotation necessary during drill string tripping in) needed. A singular exception occurs during drilling simulations in Section 4 for well Var 3, which necessitates a top drive with higher torque capability. The well design established in this thesis encompasses selection and optimization of challenging well paths, collaboration with industry experts for the development of drilling fluids formulations, a casing design aligned with SWM guidelines that incorporates insights from manufacturers for the selection of proven ERD casing connections, and the incorporation of floating equipment for a 9.5/8¿ liner as well as a drill string configuration based on companies¿ recommendations. Furthermore, comprehensive simulations, including torque, drag, hydraulics during drilling and running liner as well as cementation modeling are conducted.

AB - To ensure energy supply for Munich in the future, Stadtwerke München Services GmbH (SWM) is planning to utilize extended reach drilling (ERD) wells for resource development. With ERD wells it is possible to increase the potential from one well site, by producing heat in locations with a high demand. Complicated and cost-intensive connections to the heating network can thus be avoided. Several wells have already been drilled in the South German Molasse Basin and drilling processes have been timely improved. Wells in this area have been realized at around 3.000 m horizontal departure (HD) for shallow depths and 2.500 m for deeper depths, but potential for more horizontal reach is available. In geothermal projects within the Molasse Basin in southern Germany, several wells are usually drilled from one well site. To ensure sufficient spacing between boreholes in the reservoir, boreholes are drilled horizontally away from each other. Firstly, with increasing horizontal distance of the target point to the drilling site, the technical effort, costs and risks increase. Secondly, increasing the horizontal distance allows a significantly larger reservoir area to be developed from one drilling site. The ultimate goal of this thesis is to design a new well concept that focuses on a horizontal departure of at least 3.500 m up to 6.000 m in shallow depths of less than 2.500 m true vertical depth (TVD), taking into consideration solutions to overcome the current limitations, such as Torque/Drag, Hydraulics and Drag during Casing/Liner running. The final well design concepts established in this thesis should act as a foundation for future geothermal ERD wells in South German Molasse Basin. The basis for this thesis is a conceptual project selected in the northern region of Munich. Based on the most demanding well path of this project, various well path variations are developed using constant parameters to ensure comparability. This approach also allows the simulation of various difficulty levels, inclusive potential limitations. A full well design is established for all wells, taking into account existing SWM guidelines, literature, and expert insights from various industry disciplines. The developed well design is explained using one exemplary well. From the simulations can be concluded that, due to the implemented technology and expertise, all wells can be technically feasible simulated regardless of the length of the well, with only small operational changes (e.g., no rotation necessary during drill string tripping in) needed. A singular exception occurs during drilling simulations in Section 4 for well Var 3, which necessitates a top drive with higher torque capability. The well design established in this thesis encompasses selection and optimization of challenging well paths, collaboration with industry experts for the development of drilling fluids formulations, a casing design aligned with SWM guidelines that incorporates insights from manufacturers for the selection of proven ERD casing connections, and the incorporation of floating equipment for a 9.5/8¿ liner as well as a drill string configuration based on companies¿ recommendations. Furthermore, comprehensive simulations, including torque, drag, hydraulics during drilling and running liner as well as cementation modeling are conducted.

KW - geothermal well

KW - extended reach drilling

KW - horizontal departure

KW - well trajectory design

KW - casing design

KW - drilling fluid design

KW - drill string design

KW - running loads simulation

KW - Geothermiebohrung

KW - Bohrungen mit großer Reichweite

KW - horizontale Distanz

KW - Bohrpfad-Design

KW - Rohrtouren-Design

KW - Bohrspülungs-Design

KW - Bohrstrang-Design

KW - Schleiflasten Simulation

M3 - Master's Thesis

ER -