Differences between natural gas wellhead pressure, oil pressure, and casing pressure

Wellhead pressure is divided into tubing pressure and casing pressure

The main pressures that need to be measured in oil wells are: (1) Oil pressure: Oil pressure is the residual pressure of the oil flow as it moves from the bottom of the well to the wellhead. The pressure gauge for measuring oil pressure is installed at the location where the tubing is connected, in front of the tree nozzle. A high measured oil pressure indicates that the oil well has a strong capacity to supply oil ； Low oil pressure indicates that the oil well has a weak capacity to supply oil. (2) Casing pressure: The pressure gauge used to measure the casing pressure is installed at the casing gate of the production tree, and it is connected to the annular space between the tubing and the casing. Its size reflects the pressure in the annular space and the amount of natural gas that has separated from the oil. During normal operation of an oil well, the casing pressure remains relatively stable. (3) Back pressure: The pressure gauge used to measure back pressure is installed on the main oil transport line of the oil well. The connection location is near the tree nozzle. Back pressure reflects the flow resistance in the surface pipelines between the oil well and the metering station. If the measured back pressure is high, it indicates that the oil has a high viscosity or contains a large amount of wax; the wax precipitates and adheres to the pipe walls, hindering the flow of the oil. (4) Flow pressure: Flow pressure, also known as bottom hole pressure, is measured using a specialized bottom hole pressure gauge. When the production conditions remain unchanged, the flow pressure changes in accordance with the reservoir pressure; the difference between the reservoir pressure and the flow pressure is commonly referred to as the production pressure drop. It can be controlled using nozzles; the larger the diameter of the nozzle, the lower the flow pressure, the greater the production pressure difference, and the more oil will be produced from the oil layer. However, if the production pressure difference is too large, although the short-term oil production volume increases, it can sometimes lead to crude oil degassing, water invasion of the oil reservoir, and a rapid drop in reservoir pressure, severely affecting well production and greatly reducing the cumulative oil output. Therefore, the production pressure difference must be controlled properly. (5) Separator pressure: The pressure gauge for measuring the separator pressure is installed on the production separator at the metering station. It reflects the capacity of the metering station to collect crude oil from the wells it serves and transport it to the combined processing station. Reasonably adjusting and utilizing this pressure can not only achieve energy savings and reduced consumption but also increase the production of oil wells.

The main pressures that need to be measured in oil wells are: (1) Oil pressure: Oil pressure is the residual pressure of the oil flow as it moves from the bottom of the well to the wellhead. The pressure gauge for measuring oil pressure is installed at the location where the tubing is connected, in front of the tree nozzle. A high measured oil pressure indicates that the oil well has a strong capacity to supply oil ； Low oil pressure indicates that the oil well has a weak capacity to supply oil. (2) Casing pressure: The pressure gauge used to measure the casing pressure is installed at the casing gate of the production tree, and it is connected to the annular space between the tubing and the casing. Its size reflects the pressure in the annular space and the amount of natural gas that has separated from the oil. During normal operation of an oil well, the casing pressure remains relatively stable. (3) Back pressure: The pressure gauge used to measure back pressure is installed on the main oil transport line of the oil well. The connection location is near the tree nozzle. Back pressure reflects the flow resistance in the surface pipelines between the oil well and the metering station. If the measured back pressure is high, it indicates that the oil has a high viscosity or contains a large amount of wax; the wax precipitates and adheres to the pipe walls, hindering the flow of the oil. (4) Flow pressure: Flow pressure, also known as bottom hole pressure, is measured using a specialized bottom hole pressure gauge. When the production conditions remain unchanged, the flow pressure changes in accordance with the reservoir pressure; the difference between the reservoir pressure and the flow pressure is commonly referred to as the production pressure drop. It can be controlled using nozzles; the larger the diameter of the nozzle, the lower the flow pressure, the greater the production pressure difference, and the more oil will be produced from the oil layer. However, if the production pressure difference is too large, although the short-term oil production volume increases, it can sometimes lead to crude oil degassing, water invasion of the oil reservoir, and a rapid drop in reservoir pressure, severely affecting well production and greatly reducing the cumulative oil output. Therefore, the production pressure difference must be controlled properly. (5) Separator pressure: The pressure gauge for measuring the separator pressure is installed on the production separator at the metering station. It reflects the capacity of the metering station to collect crude oil from the wells it serves and transport it to the combined processing station. Reasonably adjusting and utilizing this pressure can not only achieve energy savings and reduced consumption but also increase the production of oil wells. The wellhead pressure you’re referring to is the oil pressure and the casing pressure; when the well is completed and handed over to the production team, the pressure at which the well is shut down is also called wellhead pressure!