An Unconventional Directional Sidetrack of a Geothermal Well: Menengai Well MW15A

Directional drilling, a key technology for exploration and exploitation of deep geothermal resources offers a number of significant advantages: it maximises wellbore exposure through productive zones in the reservoir, enables drilling to inaccessible locations like built up areas or beneath mountainous area, sidetracking, minimises environmental damage and is economical to drill several wells from a single well pad. Directional drilling techniques enables the wellbore to be deflected from the vertical and directed towards a desired direction in order to hit a predetermined target below the surface of the earth. Sidetracking directional drilling technique is applied in a number of situations such as to bypass fish or junk in the hole, sidetracking through casing, and to bypass an unusable section of the original wellbore. This paper highlights an unconventional directional sidetrack performed during drilling of Menengai well MW15A at a depth of 1335 metres to bypass a fish in the hole. The fish was left in hole after the drill string was backed off at 1567m as a result of stuck pipe at a total drilled depth of 1688 metres. After unsuccessful fishing, it was decided that the wellbore be filled with sand to a depth of 1400 metres, set a cement plug to 1200 metres and side track. The procedure was successfully performed and the well was drilled to a final depth of 2340 metres achieving the desired horizontal displacement of 600 metres.

Keywords: Directional drilling, geothermal, sidetracking, unconventional