TY - THES

T1 - Real-Time Monitoring of Cement Hydration to Verify TOC and Well Integrity

AU - Csar, Elisabeth

N1 - no embargo

PY - 2019

Y1 - 2019

N2 - Primary cementing is critical to zonal isolation and well integrity. Besides, cement plugs are used for several operations in the oil and gas industry, such as lost circulation control, formation testing, directional/sidetrack drilling, zonal isolation, and well abandonment. Set cement may be too soft or not in the planned location and hence fail to provide hydraulic seal and lead to well integrity and safety issues. This could be due to a number of issues, including contamination with wellbore fluids, ineffective displacement, and casing eccentricity. This thesis focuses on continuous monitoring real-time data during the hydration process of cement to be able to determine the phase of hydration process, to define the exact location of the cement, to establish contaminated parts of cement and prove a competent/imperfect well barrier. Electrical conductivity measurements could be an indication of how the cement slurry is hydrating and the degree of contamination. Several tests with different levels of mud contamination were performed and analyzed. In addition, experiments with fiber-optic sensoring to measure strain and temperature changes during cement slurry hydration were conducted. Both the electrical conductivity and fiber-optic measurements are able to identify degree of hydration and also level of contamination. The lab setup, test procedure, data, analysis, and results are presented and discussed. These measurements, analysis, and application would significantly improve the accuracy of cement jobs, and operational performance in the oil and gas industry. Benefits to the industry from continuous monitoring and evaluation are discussed. In addition, recommendations for future work and conclusions can be found in the last chapter of the thesis.

AB - Primary cementing is critical to zonal isolation and well integrity. Besides, cement plugs are used for several operations in the oil and gas industry, such as lost circulation control, formation testing, directional/sidetrack drilling, zonal isolation, and well abandonment. Set cement may be too soft or not in the planned location and hence fail to provide hydraulic seal and lead to well integrity and safety issues. This could be due to a number of issues, including contamination with wellbore fluids, ineffective displacement, and casing eccentricity. This thesis focuses on continuous monitoring real-time data during the hydration process of cement to be able to determine the phase of hydration process, to define the exact location of the cement, to establish contaminated parts of cement and prove a competent/imperfect well barrier. Electrical conductivity measurements could be an indication of how the cement slurry is hydrating and the degree of contamination. Several tests with different levels of mud contamination were performed and analyzed. In addition, experiments with fiber-optic sensoring to measure strain and temperature changes during cement slurry hydration were conducted. Both the electrical conductivity and fiber-optic measurements are able to identify degree of hydration and also level of contamination. The lab setup, test procedure, data, analysis, and results are presented and discussed. These measurements, analysis, and application would significantly improve the accuracy of cement jobs, and operational performance in the oil and gas industry. Benefits to the industry from continuous monitoring and evaluation are discussed. In addition, recommendations for future work and conclusions can be found in the last chapter of the thesis.

KW - Kontaminierte Zementbrücken

KW - Bohrlochintegrität

KW - kontinuierliche Überwachung

KW - Glasfasertechnik

KW - Messung der elektrischen Leitfähigkeit

KW - Contaminated cement plug

KW - Well integrity

KW - Continuous monitoring

KW - Fiber-optic sensoring

KW - Conductivity measurment

M3 - Master's Thesis

ER -