## Conductor Design To prevent formation breakdown while drilling

### We need to calculate the minimum conductor setting depth based on the following data:

1. Formation strength gradient p FSG
2. Sea water gradient p sw
4. Water depth Dw
5. Flow line height above seabed Fh

Let X = the casing setting depth below seabed, then, (X x pFSG) + (Dw x psw) - (Fh 4 X) pm Example given p FSG = 0.67 psi/ft Dw = 175 ft psw = 0.445 psi/ft Fh = 240 ft pm* = 0.48 psi/ft

Depth of conductor BDF = 10 4 65 + 175 4 200 - 450 ft

* Mud weight in annulus based on calculated maximum drilling rate to avoid overloading.

### The maximum drilling rate can be calculated based on the following data:

1. Pump rate Q ( ft^min or m^min)
2. Volume of cuttings V ( ft^mln or ms/min)
3. Maximum annulus mud weight Pa (density Da = lb/ft3or kg/m3)
4. Density of drilled formation Dfm (lb/ft3or kg/m3)
5. Density of drilling mud Dm ( lb/ft3or kg/m3 )

Then,

Example

Let V = Volume of formation drilled where: Q = 100ft3/min or 2.83 m3/min

In a 26" hole the volume of formation cut per foot (m)drilled = 3.687 ft30r 0.032 m3

The maximum drilling rate then becomes

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