Drilling
Drilling is the classical technology of drilling vertical, inclined and horizontal wells for extraction of oil and gas with a depth of up to 5,000 meters.

An oil or gas well is created by drilling a hole into the earth with a drilling rig which contains all necessary equipment and generates the required onsite power for all operations. The drilling rig rotates a drill string with a drill bit attached. The drill bit, aided by the weight of thick walled pipes („drill string“), cuts into the formation. Drilling fluid (“mud”) - a complex, carefully tailored mixture of fluids, solids and chemicals - is pumped down the inside of the drill pipe and exits at the drill bit in order to cool and clean it. As the drilling fluid circulates back to surface outside the drill pipe, it sweeps up the generated rock “cuttings” and helps preventing destabilization of the rock in the wellbore walls.

The drill string is gradually lengthened as the well gets deeper by screwing additional sections of pipe at the surface. After the hole is drilled, sections of steel tubing (“casing”) slightly smaller in diameter than the borehole, are placed in the hole and secured with cement between the outside of the casing and the borehole. The casing provides stability to the newly drilled wellbore and isolates potentially dangerous high pressure zones from each other and from the surface. Thus, the well can be drilled deeper with a smaller bit, and also cased with a smaller size casing.

In addition, the drilling rig is equipped with a device to control the downhole pressures and devices for hoisting and turning the pipes as well as for circulation of the drilling fluid and for removing cuttings from it.

Nine new rigs were ordered and delivered to Russia in 2011. During 2012 the new rigs were successively adapted and put into operation.