G.V.CHERNOZUBOV, T.A. MOTYLIEVA FSUE "Arktikmomeftegazrazvedka", Russia

Main problems under well drilling on the Arctic Seas shelf, are stability maintenance of well walls in terrigenous deposits, presence of zones with abnormal high formation pressures and large anhydrite thicknesses.

Application of inhibiting potassium-chloride sea water drilling mud under well drilling on the Pechora Sea fields made it possible to minimize these problems.

Distinctive feature of composition of inhibiting potassium-chloride sea water drilling mud developed by FSUE "Arktikmomeftegazrazvedka", is a complete exception of alkaline sodium containing components including bentonite powders modified with calcined soda and maintenance of the best concentration of potassium chloride on the level of 70 kg / cub. m, sufficient to inhibit clay slates which form a section being drilled out as witnessed by low values of borehole cavernosity ratios.

Application of inhibiting potassium-chloride sea water drilling mud made it possible to restrict dispersion of reactive clays (МВТ did not exceed 70 kg / cub. m) and to provide possibility of operative adjustment of parameters by inserting a minor quantity of chemical agents. Inhibiting potassium-chloride sea water drilling mud has a high resistance to action of polyvalent cations under drilling out anhydrite and dolomitic deposits and also to cement contamination.

Application of inhibiting potassium-chloride sea water drilling mud as a conservative liquid proved its stability after 9 months of well conservation. Application as sea water dispersing medium excepted necessity to replenish drilling mud volume by fresh water.

By materials consumption (consumption per 1 m of run), inhibiting potassium-chloride sea water drilling mud compares favorably with drilling muds used previously on the Arctic shelf

While drilling out producing deposits saturated with sour oil, it brings up the issue of timely suppression of bacteria active life which restore sulphate - ions to hydrogen sulfide through simultaneous treatment of drilling mud by appropriate bactericide, hydrogen sulphide corrosion inhibitor and oxygen absorber. Otherwise, in addition to the deterioration of drilling mud parameters, the metal corrosion processes intensify.

ARCTIC SHELF OIL AND GAS CONFERENCE 2004