The main factors affecting the drilling speed of PDC bits
There are many factors that affect the drilling speed, and they are intertwined and become very complex. It is difficult to reflect all the influencing factors in a unified drilling speed model. However, the factors that have a relatively large impact and obvious changes include drilling pressure, rotation speed, tooth wear, hydraulic parameters, pressure differential, drilling fluid performance, etc., and among them, those directly related to the bottom flow include rotation speed, hydraulic parameters, pressure differential, drilling fluid performance, etc.
1. The influence of rotation speed on the drilling speed of PDC bits
From the principle of mechanical rock breaking, as the rotation speed n increases, the drilling speed Vm also increases correspondingly. Typical experiments conducted in the field and in the laboratory have shown that the drilling speed is exponentially related to the rotation speed, with an exponent less than 1. This reflects the time-effect problem of rock fragmentation by the bit. Their relationship can be expressed mathematically as shown in the formula. And if you may have interest, we can offer a reasonable pdc bit price.
2. The influence of hydraulic parameters on the drilling speed of PDC bits
The degree of bottom hole cleaning caused by hydraulic parameters has a significant impact on the drilling speed. Bottom hole cleaning is accomplished by jet hydraulic power. If the hydraulic power is not enough, the cleaning is incomplete, and the cuttings will stay at the bottom, causing repeated cutting and a decrease in the actual drilling speed. At the same time, the jet hydraulic power also has a certain degree of rock-breaking effect.
In 1975, the American Amoco Research Center gave a relationship curve that matched hydraulic parameters with mechanical rotation speed based on a large number of experiments. This curve divides the diagram into two areas: one with perfect hydraulic cleaning and the other with incomplete hydraulic cleaning. A certain drilling speed of PDC bits including pdc drag bit means the total amount of cuttings drilled out per unit time, and clearing these cuttings requires corresponding hydraulic power. If the actual hydraulic power is less than the hydraulic power required to clean the cuttings, the cuttings will accumulate at the bottom, affecting the increase of drilling speed.
As a pdc bit company, we notice that since the rock-breaking effect of hydraulic breaking is already limited by drilling pressure, the cleaning degree only affects the rotation speed from the perspective of ensuring the mechanical rock-breaking effect. That is to say, if the rock-breaking efficiency is constant and the bottom cleaning reaches saturation, it is impossible to increase the rotation speed no matter how to increase the hydraulic power under the condition of excluding the hydraulic breaking effect.
3. The influence of pressure differential on the drilling speed of PDC bits
Pressure differential refers to the difference between the bottom hole pressure and the formation pressure. The bottom hole pressure differential will increase the rock strength and produce a pressure-holding effect on the cuttings, thereby affecting the rock-breaking efficiency of the bit and reducing the mechanical drilling speed.
4.The influence of drilling fluid performance on the drilling speed of PDC bits
The influence of drilling fluid performance on drilling is complex because the various properties of drilling fluid are closely related to each other. Changing one property of the drilling fluid often causes corresponding changes in other properties, so it is quite difficult to evaluate the impact of a certain drilling fluid property on the drilling speed.
A large number of experimental studies have shown that the density, viscosity, water loss, solid content, and dispersion properties of drilling fluid all have different effects on the drilling speed of PDC bits.
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