According to the depth of the oilfield and the quality of oil, the main oil recovery methods are:
Spontaneous injection-production method: when the reservoir pressure is higher than the liquid column pressure in the well, the oil in the reservoir is lifted out of the well by itself through tubing and Christmas tree.
Artificial lifting oil recovery method: a method of artificially adding energy to the bottom of an oil well to lift the oil in the reservoir to the wellhead. With the continuous increase of total oil production, the reservoir pressure is decreasing day by day; An oil field or well developed by water injection.
The percentage of water production gradually increases, which makes the proportion of fluid increase, and both of them make the self-injection ability of oil wells gradually weaken. In order to increase production, it is necessary to adopt artificial lifting oil production (also known as mechanical oil production), which is the main method of oilfield exploitation.
Type, especially in the late stage of oilfield development, there are two methods: pump oil recovery and gas lift oil recovery.
Gas-lift oil recovery method: inject natural gas into the well from casing annulus or tubing to reduce the specific gravity of fluid in the well, so that the pressure of liquid column in the well is lower than the reduced reservoir pressure, thus leading the fluid out of the well from tubing or casing annulus. There are two types of continuous gas lift and intermittent gas lift. In most cases, casing annular gas injection and tubing production are used.
Pumping oil production method Pumping oil production method is to drive the sucker rod and pump through the pumping unit, and convert the circular motion of the power machine (usually the motor) into reciprocating linear motion, and pump the reservoir underground. There are two kinds of pumping units: walking beam type and no walking beam type.