Razzakov Kyrgyz State Technical University, Bishkek, Kyrgyz Republic

B. M. Bektashov, Senior Lecturer, bektashov_72@mail.ru
G. Sh. Baykelova, Candidate of Engineering Sciences, Associate Professor

Academician Adyshev Osh Technological University, Osh, Kyrgyz Republic

N. A. Kaldybaev, Senior Researcher, Candidate of Engineering Sciences, Professor

The exploration target is Tekelik-1 field in the Osh region of the Kyrgyz Republic. Local climate allows seasonal exploration for 4 months from June through September. Drilling was executed by specialized geological exploration agency Geoburservis using drilling rig SKB-4100. Rocks had drillability category VI-X, and diamond bits had diameters of 96 and 75.7 mm. The aim of the research is to improve core drilling with regard to complicated conditions at greater depths and shortened going in/out of hole time of a drilling string. Experience of exploration drilling in unstable rock mass of Tekelik-1 coal field is described; the local lithological section features frequent alteration of different drillability rock beds. The coalbearing bed contacts loose and very unstable rocks, which disturbs core structure. With a view to avoiding consequences of possible caving, design of the rotatable drill pipe at the junction with the rock-breaking tool is improved. A special drill bit with the inner recess allows drilling in complicated drilling intervals without going out of hole. Expensive well casing process is excluded. Test drilling showed that the special-design rotatable drilling pipe reduced the time spent for going in and out of hole and optimized the commercial cost of drilling. Population of the progressive experience of drilling in complicated geological conditions can be beneficial for geological exploration agencies that apply rotary core drilling.

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