MSc defence by Nahashon Nzioka

Nahashon Karanja Nzioka from Kenya, MSc Fellow in Sustainable Energy Engineering at Reykjavík University will present his MSc project on Thursday 22 May at 10:00 at Reykjavík University in room M123.  

The title of the project is:
Cementing Techniques and Material Performance for Deep Geothermal Wells: A Case Study of the Olkaria Geothermal Field

Nash's supervisors are:
Kristinn Ingason, Head of Section, Geothermal Energy, COWI
Juliet Newson, Director of Iceland School of Energy, Reykjavík University

External examiner is Sverrir Thórhallsson, Geothermal Consultant  

Abstract
This thesis investigates cementing practices and material performance in deep geothermal wells, with a focus on the Olkaria Geothermal Field in Kenya. The study addresses challenges of poor zonal isolation, cement failures, and excessive cement use by evaluating both field practices and simulation modeling. A mixed-methods approach was adopted: historical cementing data from over 100 wells at Olkaria were analyzed and compared with practices in the Aluto (Ethiopia) and Icelandic geothermal fields. Simulation modeling using CemPRO+ was performed on well OW-923C to assess the effects of casing standoff, rotation, reciprocation, and flow rate on mud displacement efficiency. Results highlight that inadequate casing centralization (low standoff) is the primary cause of poor cement displacement, with significant mud channeling observed at <50% standoff. Incorporating casing rotation and reciprocation was found to improve displacement efficiency, particularly at intermediate centralization levels. Additionally, higher flow rates combined with sufficient standoff further enhanced cement coverage. Field benchmarking revealed that Olkaria’s high cement consumption is linked to severe lost circulation and lack of casing movement during cementing. In contrast, fields like Aluto utilized improved cement systems and placement techniques that minimized losses and reduced top-up jobs. The findings underscore the need for optimized centralizer placement, casing movement, and tailored slurry designs to improve cementing efficiency and reduce operational costs. The study contributes actionable insights to enhance geothermal well integrity in challenging high-temperature environments.