The drilling efficiency of a rotary rig is the ratio of the total depth of the drilling hole to the total time spent during normal operation. The factors that affect the drilling efficiency of rotary drilling machine are: hole depth, diameter, formation condition and drilling tool selection
1. Influence of hole depth on drilling efficiency of rotary drilling rig
In the construction of a rotary drill, each time the drill bit is filled with soil, the drill bit must be lifted and removed, and the drill tool lowered to the bottom of the hole. Obviously, the smaller the hole depth, the higher the efficiency. Drilling efficiency V=H, 8t, +t2+2H/V,)
It can be seen from the above formula that the larger H is, the smaller V is when other parameters remain unchanged. When the hole depth exceeds 100m, the drilling efficiency drops sharply. When the hole depth exceeds 120m, the drilling efficiency will be lower than other construction methods. The accident rate has risen sharply. Therefore, when carrying out ultra-deep hole construction, it is recommended to use other construction methods, such as positive and negative circulation.
2. Influence of aperture on drilling efficiency of rotary drilling rig
At present, the most commonly used rotary drilling rig is the rotary drilling rig. The barrel is hollow with two inlet doors at the bottom. When drilling, the ballast is cut into the bucket through the bucket door by cutting the drill bit. Under the thrust of the lower ballast, the upper ballast gradually rises into the barrel until the barrel is filled. The size of the hole diameter affects the drilling efficiency in two aspects. One is the speed at which the ballast enters the bucket, and the other is the speed at which the ballast rises in the bucket. First of all, the speed at which the ballast enters the gate is related to the entry area of the gate. The larger the hole diameter, the larger the Doumen entry area and entry speed;
