Borrsträng

Borrsträng is a Swedish term that translates to "drill string" in English. It refers to the assembly of drill pipe, drill collars, and other components that are lowered into a borehole during drilling operations. The primary function of the drill string is to transmit rotational torque and axial force from the drilling rig's surface equipment to the drill bit located at the bottom of the hole. It also serves as a conduit for drilling fluid (mud) to be pumped down to the drill bit and for cuttings to be carried back to the surface.

The drill string is a critical part of the drilling process. It must be strong enough to withstand the immense pressures and stresses encountered during drilling. The components are typically made of high-strength steel. Drill pipe, the longest section, connects to the surface. Drill collars, which are heavier and thicker than drill pipe, are placed near the drill bit to provide weight and stabilize the lower part of the string, helping to control the drilling direction and reduce vibration. Other components can include stabilizers, reamers, and specialized tools. The length of a drill string can vary significantly, from a few hundred meters to several kilometers, depending on the depth of the well being drilled.