Drill collar measurement

The section modulus. Z, of the box should be 2 / times greater than the section modulus, z, of the pin in a drill collar connection. On the right side of the connection are the spots at which the critical area of both the pin (Ap) and box (A ) should be measured for calculating torsional strength. 

Mud Resistivity. The mud resistivity can be measured only with the water-base muds. It is measured easily with a small microlog-type sensor embedded in the outer wall of the drill collar. Assuming the free gas is dispersed in small bubbles in the mud, the resistivity of the gas cut mud is... 

The gamma rays are detected today with sodium iodide crystals scintillation counters. The counters, 6 to 12 in. long (15 to 30 cm) are shock mounted and housed in the drill collars. Several types of measurements can be made total gamma rays, direction-focused gamma rays, spectral gamma rays. 

The drill collar acts as a series of elongated electrodes in a way similar to the laterolog 3 wireline sonde. The lower electrode, which is the drill bit, is used to get the forward resistivity curve. A lateral resistivity measurement is made between the two toroid receivers. An example of toroid logs is shown in Figure 4-279. 

The recommended full load AP is 490 psi. When the pressure is measured inside the drill collars and below the motor, AP can be determined. The flowrate is also known and the hydraulic power can be calculated in real time ... 

Mark a center line on the top rear of the 8 tube. Measure 5/8 down each side from the center line and mark the tube. Measure 1 from the rear of the tube and mark again,intersecting the first 2 lines. These two points are the location for the tube support screws They can be drilled and tapped for machine screws or simply drilled for self tapping screws or pop rivets. Be sure that whatever fasteners used do not extend through the collar into the barrel itself. This allows the collar/ tube assembly to be removed from the barrel by loosening the bottom screw only. 

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