Oil and gas borehole drilling implies using rotational method exclusively, carrying the rock particles to the surface through circulating fluid jet. Depending on the location of the engine the drilling techniques are divided into two major groups: rotor drilling, when the engine is installed on the surface, activating the drill bit at the bottom by rotating the entire drill string and downhole motor drilling that demands using a drill motor or turbine when the engine is located close to the borehole above the drill bit.
In classical geophysics the drilling process includes the following aspects: tripping operations (descending drill pipe with a chisel into the wellbore to the bottom and lifting it with the exhaust bit) and the actual drilling at the bottom of a bit (bit rock failure). These operations are interrupted periodically for installing the casing in the well, designed to protect the borehole from landslides and separation of oil horizons.
Simultaneously the process of drilling is accompanied by a number of auxiliary operations performed; coring, mud logging preparation, well curvature measuring, testing or exploring the site to forecast the thickness of oil levels and etc.
- The full well construction project is comprised of the following submissions:
- Mounting platforms, drilling and platform development (typically includes infrastructure development).
- The process of drilling
- Opening and zonal isolation (implementing casing barrages and cementing; the stage that is considered to be the one that indicates the drilling process).
- Testing the well for the flow of oil, gas or water.
- Dismantling the equipment once the platform is up and running.
Actually, mentioned above are the general stages to underline, as an installation and dismantling may also include minor mending, while the process of testing may be divided into a multitude of stages.