In oilfields, particularly during the exploration, development, and production of oil and gas fields, a wide variety of pressure gauges are used. Depending on different working conditions, measurement media, and accuracy requirements, various types of pressure gauges are selected.
1、 Classified by working principle and display mode
This is the most basic classification method.
1）Pointer type (mechanical) pressure gauge
Principle: Based on the deformation of elastic components (such as spring tubes, diaphragms, and corrugated tubes), the deformation is amplified through a gear transmission mechanism, which drives the pointer to indicate the pressure value on the dial.
Features: Simple structure, low price, durable, no need for power supply, it is the most widely used and basic pressure gauge in oil fields.
Common types:
Spring tube pressure gauge: The most common universal pressure gauge used to measure the pressure of non corrosive media to copper alloys.
Shock resistant pressure gauge: The case is filled with damping fluid (such as glycerin or silicone oil) and equipped with a damper or flow limiting device, which can effectively buffer medium pulsation and external vibration, preventing the pointer from shaking violently. This is a standard configuration for high-pressure and highly vibrating situations such as drilling and fracturing.
Diaphragm pressure gauge: The pressure medium is separated from the movement of the pressure gauge by a diaphragm isolator. Mainly used for measuring media with high viscosity, easy crystallization, strong corrosiveness, and high temperature, such as drilling mud, fracturing fluid, and oil and gas containing hydrogen sulfide.
Differential pressure gauge: used to measure the pressure difference between two different points, such as monitoring pressure drop before and after a filter.
2）Digital pressure gauge
Principle: Pressure sensors (such as piezoresistive, capacitive, ceramic capacitive) are used to convert pressure signals into electrical signals, which are processed and displayed digitally on the LCD screen.
Features: Intuitive reading, high accuracy, capable of carrying multiple output signals (such as 4-20mA, HART protocol, RS485, etc.), convenient for remote transmission and automation control. Some high-end models can record peak and valley values.
Application: increasingly used in situations that require precise data reading, recording, or integration into automation systems, such as well testing, production separators, precision pressure monitoring, etc.
2、 Classified by application scenarios and special functions
At different stages of the oil field, pressure gauges have more specific names and uses.
1） Drilling pressure gauge
Mud pump pressure gauge: This is the “eye” of drilling, used to monitor the mud pressure output by the drilling pump. It must be a high range and shock resistant pressure gauge, as the mud pressure fluctuates greatly and the pressure value is directly related to downhole safety and drill bit conditions.
Riser pressure gauge/drilling floor pressure gauge: installed on the drilling floor, convenient for the driller to observe the pressure of the circulation system in real time.
Casing pressure gauge: installed on the wellhead blowout preventer group, used to monitor the annulus pressure between the casing and the drill pipe, and is a key parameter for well control.
2）Pressure gauges for cementing and fracturing
These tasks have extremely high pressure, usually reaching tens or even hundreds of megapascals (MPa).
Using an ultra-high pressure gauge with a large dial range and a very sturdy housing, it must also have excellent shock resistance.
3） Pressure gauges for oil production
Wellhead pressure gauge: installed on the Christmas Tree, it measures tubing pressure (oil pressure) and casing pressure (casing pressure), and is a basic parameter for determining the production status of oil wells.
4） Anti corrosion pressure gauge: If the oil and gas contain corrosive gases such as hydrogen sulfide (H ₂ S) or carbon dioxide (CO ₂), a sulfur resistant pressure gauge must be used. All components that come into contact with the medium, such as spring tubes and joints, must be made of sulfur resistant steel (such as 316L, Monel alloy, etc.) that complies with NACE MR0175/ISO 15156 standards to prevent sulfide stress cracking.
Electric contact pressure gauge: An electric contact device has been added to the ordinary pointer pressure gauge, which can set upper and lower limit alarm points. When the pressure reaches the set value, the contact action can control the start and stop of the pump or trigger an audible and visual alarm for automation control and safety protection.
Precision pressure gauge/standard pressure gauge
High precision level (such as 0.4 level, 0.25 level), used for calibrating ordinary working pressure gauges (such as pressure transmitters, ordinary pressure gauges), and used as a standard.
3、 Key selection considerations
When selecting pressure gauges in oil fields, the following points must be considered comprehensively:
1） Range: The normal operating pressure should be between 1/3 and 2/3 of the range, and the maximum pressure should not exceed 3/4 of the full range.
2）Accuracy: Choose according to the process requirements. Ordinary monitoring can choose level 1.6 or 2.5, while calibration and precision measurement require level 0.5 or above.
3） Medium compatibility: When measuring corrosive media (such as H ₂ S, CO ₂, brine, acid), diaphragm type or compatible material pressure gauges must be used.
4） Seismic resistance: Near vibration sources such as pumps and compressors, seismic pressure gauges must be selected.
5） Working temperature: Consider the ambient temperature and medium temperature, and choose a suitable temperature range.
6） Connection methods: Common types include radial, axial, with front and back edges, and interface thread types (such as NPT, G, M, etc.).
7） Safety regulations: Especially in sulfur-containing environments, relevant safety standards must be strictly followed.
Hope this detailed introduction can help you fully understand the pressure gauges used in oil fields. If you have specific application scenarios, you can further discuss with Derkia.