Abstract
Drilling exploration, production and injection wells is one of the major capital investments required for geothermal energy production. Current practice of drilling geothermal wells in single well penetration increases cost, reduces production due low reservoir exposure and de-accelerates long-term production. Furthermore, there is less flexibity in well selection and monitoring especially when rating a wellhead generator through increase in service to surface equipments costs. This study investigates economic benefits of lateral drilling. This research compared the overall techno-economics for vertical and directional drilling operation from the year 2008 to 2012 at Olkaria Domes, Olkaria East and Olkaria North East. The data were collected through actual field experimental experience, observation and sampling. A total population of 56 wells and a sample size of nine wells were selected within three pads in different fields with each pad hosting three separate wells. Data were analyzed with Drilling Cost Formular (Rabia 2009) and Excel to provide Drilling Cost Predictions. Auto-Desk Inventor and Grapher softwares were used for Cost Sensitivity Analysis. Economic comparison of the two drilling methods shows that, the overall drilling cost of multilateral application at pad #915 saves cost by 26%, pad#44 and pad#733 reduces cost by 28% and 34% respectively in comparison to a single penetration in each pad. It was noted, the overall drilling time of multilateral application reduces by 37% in average for all scenarios. The results indicate, multilateral drilling application at Olkaria Geothermal Steamfield reduces cost by a third that of directional single penetration. Furthermore, the wellhead power output is higher giving less payback period of 2years from 3.5years. The study also shows that, the more the laterals the more cost reduction alongside more output. This study recommends adaption of multilateral practice to save drilling cost by 30%. Economically, increase in well diameter and depth symmetry is recommended in future for more power output and cost reduction.
