Extensive investigations of drilling mud for Sovetskoye oil field AB1 formation exposing

Authors: A.G. Skripkin, S.V. Parnachev, S.M. Samokhvalova, Yu.N. Kashirin (TomskNIPIneft JSC, RF, Tomsk), D.N. Voitenko (Schlumberger, RF, Moscow), A.I. Tyunkin (Tomskneft VNK OJSC, RF, Tomsk)

Key words: “ryabchik” reservoir, Koshay suite, drilling mud, clay swelling, permeability restoration.

Because of attic oil on the low-permeable top of the continuous AВ₁ reservoir expanded program of horizontal drilling was initiated for of Sovetskoye field (Western Siberia, Russia). As shaly interval stability is a specific issue in horizontal wells special attention is always paid to the drilling mud and seal shaly material interaction (incl. clay swelling and disintegration). Again, any mud used should not damage greatly the formation. For the set of 7 drilling muds lab tests were conducted to recognize the optimal composition which is both does not collapse a shaly seal of Koshay suite and recognized the best permeability to oil restoration for the reservoir. As a result two mud composition (Megadril™ and 1,08 g/cm³ Flo-Thru™) were suggested to use.