Drilling time

Factors Affecting Drilling Rates 1090. Selection of Weight on Bit, Rotary Speed, and Drilling Time 1091. Selection of Optimal Nozzle Size and Mud Flowrate 1097. 

W. C. Chin. Formation invasion With applications to measurement-while-drilling, time lapse analysis, and formation damage. Gulf Publishing Co, Houston, 1995. 

Offshore drilling costs may exceed similar land operations by 30 to 40 times and hence it is important to be able to minimize the overall drilling time. This is accomplished through mathematical modeling of the drilling penetration rate and operation (Wee and Kalogerakis, 1989). 

Figure 6.4 The drilling time in SACE glass gravity-feed drilling for a 0.4 mm cylindrical stainless steel tool-cathode in 30 wt% NaOH. Reprinted from [84] with the permission of the Journal of Micromechanics and Microengineering.

The fluctuation in the drilling time increases with the machining voltage. Due to these large fluctuations, the drilling time cannot be used as a control parameter for the drilling depth. 

The tool-electrode feeding rate has to be selected properly. Feed rates faster than the mean material removal rate of the process will result in breaking either the workpiece or the tool-electrode. On the other hand, very slow feed rates will increase drilling times and may result in large heat affected zones around the microhole. So far only a few studies have been carried out on the optimal feeding rate. Typical values reported in the literature are, depending on the tool-electrode... 

The inverse volcano-like curve of the mean drilling time as a function of the oscillation amplitude is due to the competition between two effects. On one hand, increasing the vibration amplitude favours an increase in the drilling... 

As in the case of tool-electrode vibration, the electrolyte flow can be promoted by tool-electrode rotation. An example combining gravity-feed drilling with tool-electrode rotation is shown in Fig. 7.6. A tungsten carbide flat sidewall tool-electrode (Fig. 7.3b) with pulsed voltage supply was used [136]. The drilling time for the fixed depth of 450 p,m increases with the tool-electrode rotation rate due to the reduced heat power. The entrance diameter shows an inverse volcano dependence on the tool-electrode rotation rate. This effect was attributed by the authors to the competition between the promotion of the electrolyte flow and the increased drilling time [136]. 

In the process of the gas extraction drilling in coal mine, the collision between the drUl pipe and the coal hole wall can cause the instability phenomenon such as the coal hole wall collapse and the jam of the drilling tool which reduce the gas extraction effect and prolong the gas extraction drilling time. At the same time, the collision can also cause the damage of the drilling equipment (Xu et al 2009, Liu et al 2011, Fu et al 2011). 

By any standard of measure, corrosion is a severe and costly problem in the drilling industry. Corrosion costs the oilfield millions of dollars each year, and a large portion of this expense is due to the replacement of steel goods. Other expenses include lost drilling time due to equipment repairs, fishing operations, and extra trips caused by corrosion-related failures. 

Fourth, the total drill time per load required per drill size (j) is entered to calculate the... 

An option is to enter the total drill time per load instead of entering the time for each of the drill sizes and multiplying the total drill time per load by the number of machine loads to determine total machine time. 

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