MICROSTRUCTURAL AND MECHANICAL CHARACTERIZATION OF ZEOLITE ENHANCED WELLBORE CEMENT FOR PLUGGING AND ABANDONMENT By SAI VAMSI KRISHNA VISSA Bachelor of Science in Biosciences (Honors) Sri Sathya Sai Institute of Higher Learning Bangalore, Karnataka, India 2014 Master of Science in Nanoscience and Nanotechnology Sri Sathya Sai Institute of Higher Learning Puttaparthi, Andhra Pradesh, India 2016 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE December, 2021