Question

The equipment used to drill a well (see sketch below) consists of a steel drill pipe with a drill bit at one end to cut through rock and a derrick at the other end to support and drive the pipe and bit.

As a result of its self-weight, the drill pipe is in tension over most of its length. This tension is maximum at ground level and decreases with depth into the ground.

Because the drill bit does not always bore a perfectly straight hole, there will be bending of the pipe in the ground.

Consider a design point near the ground surface where the pipe carries a tension of 500 kNkN.

The equipment used to drill a well (see sketch below) consists of a steel drill pipe with a drill bit at one end to cut through rock and a derrick at the other end to support and drive the pipe and bit.

As a result of its self-weight, the drill pipe is in tension over most of its length. This tension is maximum at ground level and decreases with depth into the ground.

Because the drill bit does not always bore a perfectly straight hole, there will be bending of the pipe in the ground.

Consider a design point near the ground surface where the pipe carries a tension of 500 kNkN.

Answer 1

The stretch in a 6.00 m steel drill pipe supporting the weight of a 3.00 km length of pipe and a 100-kg drill bit is calculated using the stress-strain relationship in materials, accounting for the steel's elasticity.

Step-by-step explanation:

The question pertains to the calculation of the stretch in a 6.00 m length of steel drill pipe under the tension caused by the weight of a 3.00 km length of drill pipe with a mass of 20.0 kg/m and a 100-kg drill bit. The properties of the drill pipe are described as being equivalent to a solid cylinder with a diameter of 5.00 cm.

To calculate the stretch, one needs to use the formula δ = σL / E, where δ is the stretch (deformation), σ is the stress (force per unit area), L is the original length of the section of the pipe, and E is the modulus of elasticity of steel.

The force exerted by the weight of the drill pipe and drill bit, the cross-sectional area of the steel pipe, and the value of the modulus of elasticity for steel would be needed to find the numerical value for the stretch.