Step 1: These bits have three rotating cones that grind the rock by rolling and crushing. They require continuous rotary motion.
Step 2: Percussive tools like DTH hammers and jack hammers use impact, not rotation, so they cannot use tricone bits. Rotary-percussive drills also rely partly on percussive energy.
Step 3: Only a pure rotary drill provides the required motion for efficient tricone bit operation.
Thus, tricone roller bits are used with a rotary drill.
A vertical well is drilled up to a depth of 4000 ft. Further drilling starts with 10 ppg of fresh mud and \(50000 \, lbf\) weight on bit (WOB). An equivalent circulation density (ECD) of \(10.75 \, ppg\) was recorded. The total circulation pressure loss is estimated to be 110 psi. The still density is \(65.5 \, ppg\). The decrease in hook load is ________ lbf (rounded off to one decimal place). (Note: 1 ppg mud is equivalent to \(0.052 \, psi/ft\)).
A horizontal well is planned with two radial sections to land the target at an angle of \(90^\circ\). The total vertical depth (TVD) between the surface and the target is \(8000 \, ft\). The buildup rate is \(6^\circ\) per 100 ft in the first section and \(9^\circ\) per 100 ft in the second section. The total angle built by the second section is \(30^\circ\). The distance of the first kickoff point from the surface is _______ ft (rounded off to one decimal place).
An electricity utility company charges ₹7 per kWh. If a 40-watt desk light is left on for 10 hours each night for 180 days, what would be the cost of energy consumption? If the desk light is on for 2 more hours each night for the 180 days, what would be the percentage-increase in the cost of energy consumption?