Analysis of stuck pipe and fishing operations : Case study of Olkaria geothermal field in Kenya

Abstract

In geothermal development, drilling is one of the main activities carried out for exploration and appraisal and later for production in a fully developed field. Drilling constitutes of 35-50% of the total project cost. It is therefore vital to manage drilling costs and keep them low. Stuck pipe and fishing are considered non-productive and increase drilling costs by more than 15% on average, hence, should be avoided where possible. For every stuck pipe, there is a mechanism that leads to the incidence and a corresponding procedure to free the string. The success of stuck pipe management and fishing is evaluated by the time it takes to complete the whole process. Unsuccessful fishing operations end up in loss of equipment and resources including time and sometimes lead to well abandonment. This paper examines different stuck pipe mechanisms, which indications there are prior to the stuck pipe and how the operator should respond to each sticking incidence. Fishing methods and fishing tools are also presented in this paper. Finally, the paper explores stuck pipe incidences in Olkaria geothermal field, Kenya whereby 5 wells with stuck pipe incidences are analysed for possible causes of sticking and fishing operations that were carried out. The results are then discussed and recommendations are made to avert such situations in the future.