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Survey calculation procedures on aegean part of turkey geothermal wells

Büyükkağnıcı, Burak
Productive sections of geothermal wells generally exceed hundreds of meters which is substantially longer than that of the oil and gas reservoirs. This brings a flexibility and cost-effective solutions in the application of directional drilling activities during geothermal drilling. Well trajectory, especially the bottom hole position, is critical for geothermal operators and three parameters (measured depth, inclination, and azimuth) obtained from MWD surveys are used to carry out survey calculations. The minimum curvature method (MCM) is considered the most accurate and the industry standard, although there exist several other calculations. The novelty of this thesis is to find out the geothermal well directional needs, on Aegean part of Turkey, in terms of survey calculation methods; later on, recommend which method(s) should be utilized at what conditions. In order to address this gap, 5 methods were chosen taking into account popularities and complexities; tangential, balanced tangential, average angle, radius of curvature, and minimum curvature methods. Afterwards, these 5 procedures were applied on 9 drilled pre-selected geothermal wells by using Python programming language. As a result, most divergence from MCM was observed with tangential method, having the easiest calculation formulas, on J type wells vi with increasing dogleg, inclination, and depth; which is around 5-6 m. Under the usual conditions the geothermal wells drilled in Turkey, it will be maximum of 10 m; even though it is quite satisfactory for most of the operators, average angle method, which is the easiest one after tangential, would also be utilized to have better results. This means that the operators, willing to establish their own directional drilling departments to decrease the costs of directional operations, may utilize a basic software or a spreadsheet, for their each well, depending on average angle, or even tangential method, to eliminate complicated formulas, while calculating the positions of each survey or interpolation depths. An only advanced software may be preferred for operator office.