Oil and natural gas are buried in the rocks with pores, cracks or caves ranging from tens of meters to thousands of meters underground. In order to find and exploit oil and natural gas, the process of drilling a channel between the oil and gas layers facing the ground is called oil and gas drilling. So how does an oil and gas well get drilled?
Before drilling, it is necessary to first determine the drilling position on the ground (that is, the drilling well location), and then lay the foundation for the installation of the drilling rig at the well location and install the derrick and the drilling rig. During drilling operations, the power of the rig drives the drill pipe and the drill bit to rotate, and the drill bit breaks down the encountered rock layer successively, and forms a wellbore (also known as the hole). The size of the drilling hole is determined by the size of the drill bit. At the same time, drilling fluid (commonly known as drilling mud) is injected into the ground through the hollow drill pipe, and a large number of rock debris generated by the drill bit in the broken formation is brought to the surface by the circulating drilling fluid. After the solids control device on the surface removes the cuttings from the drilling fluid, the drilling fluid is driven into the well again through the drilling pump. The drilling fluid flows through the inner hole of the drill pipe to the water hole of the bit, and then returns to the surface from the annular space between the shaft wall and the drill string. The process of drilling is that the drill bit breaks up the rock, and the drilling fluid continues to carry the cuttings through the circulation and form the wellbore.
After drilling to the designed depth, special instruments should be lowered into the wellbore for logging operations, the purpose is to determine the lithology of the underground formation and the location of each oil, gas and water layer. Then the seamless steel pipe (also known as casing) that is smaller than the drilling hole is lowered; Cement slurry is injected into the annular space between casing and well wall to fix casing on the well wall; The final step is to perforate the casing where the reservoir is located, creating an artificial hole through which oil and gas flow into the casing. When the formation pressure of oil and gas is high, it can flow out of the surface by itself. This kind of well is called flowing oil and gas well. When the pressure of oil and gas is low, it needs to be pumped from the hole by external forces. This kind of well is called non-flowing well. When drilling, it is necessary to have a complete set of drilling RIGS with complete functions, drill pipe, casing and drill bit with excellent quality and not prone to accidents, and drilling fluid with excellent performance and drilling lithology matching. In short, the purpose of oil and gas drilling is to cut through the rock, find and protect the oil and gas reservoir, and create a channel to ensure that the oil and gas flow to the surface. Drilling is an important process in the petroleum industry, is an essential means of exploration and development of oil and natural gas, is a costly, complex technology, high risk system technology engineering.
