ASSEMBLY OF DRILLING STRING BOTTOM Russian patent published in 2012 - IPC E21B7/10 

FIELD: oil and gas industry.

SUBSTANCE: assembly of drilling string bottom includes rock-destructing tool, section of steel pipes with intermediate supports the diameter of which is equal to diameter of rock-destructing tool, and drill pipes. Assembly length ℓ is determined as per the specified relationship. At that, the number of intermediate supports in compressed part of the assembly is determined as per the relation where Z - the number of intermediate supports in compressed part of assembly; P_q - load on rock-destructing tool; G₁ - weight of stiff above-bit part of assembly; q_yδT2 - weight of one metre of heavyweight drill pipe in compressed part of assembly; a₁, b₁ - trial coefficients determined by Blokh procedure (a₁=1.76·10², b₁=0.92); D - diameter of rock-destructing tool; n - heavyweight drill pipe rotation frequency. On each intermediate support there are longitudinal flushing channels the profile of cross section of which has the shape of chain line.

EFFECT: reducing the borehole deviation.

1 dwg