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The Important Role of Pressure Transmitters in the Oil & Gas Industry

In the dynamic and volatile environment of the oil and gas industry, the pressure’s on to use rugged, reliable measurement instrumentation to keep operations running smoothly and safely. As oil efforts push ever further into remote locations to find new oil sources, the equipment used in exploration, drilling and production has become increasingly complex, making the need for dependable and durable pressure sensors more critical than ever.

Applications that require hazardous location pressure transmitters include wellheads, hydraulic fracturing, service trucks, drilling tools, mud systems, intelligent pigs, core analysis, compression systems and vapor recovery units.

During hydraulic fracturing, or fracking, millions of gallons of water, sand and chemical additives are pumped into the well to break apart rock and release gas and oil. These materials are injected at high pressures up to 10,000 psi down and across into horizontally drilled wells as far as 10,000 feet below the surface. The pressurized mixture causes the rock layer to crack. These fissures are held open by the sand particles or other viscous materials so that gas and oil can flow up to the well.

Pressure transmitters play an important role in the hydraulic fracturing process to monitor pressure at different stages in remote data monitoring vehicles including fracturing pumps, blending units, and cementing, wireline and workover trucks. FM, CSA and ATEX approved explosion-proof and intrinsically safe transmitters must be used for safe, reliable, repeatable performance in these applications. Other well servicing applications include pump pressure measurement on mud logging units at drilling locations, switching control of the liquid passing from tanks to the discharge hose on liquid additive trailers, and pressure measurement on mobile and stationary equipment control panels. Pressure measurement plays a key role on the control systems of cementing trucks, valve test benches, valve actuator panels, and chemical injection skids as well.

In wellheads and Christmas trees, monitoring wellhead pressure requires the use of rugged and weather-resistant intrinsically safe or explosion-proof pressure transmitters.  If the pressure is not contained during drilling operations by the column of drilling fluid, casings, wellhead, and blowout preventer, a well blowout could occur.

Downhole drilling tools use pressure transmitters to monitor hydraulic and pipeline oil pressure. This extreme environment can often require transmitters with extreme high pressure and temperature ranges.

Pressure measurement is also important in mud flow lines. This is an especially viscous application, so a transmitter in this application should be coupled with a flush diaphragm to avoid clogging.

Intelligent or “smart” pigs are devices that are used to test and perform maintenance operations in oil and gas pipelines, as well as inspect for dangerous leaks which could be explosive and dangerous to the environment. Multiple pressure transmitters may be attached to the pig to monitor pipeline and hydraulic pressure, including differential pressure transmitters. In this application, a transmitter with low power consumption works best to ensure long life.

Core analysis is used to study samples of reservoir rocks which provide information on the condition of a well, including porosity, permeability, fluid saturation and grain density which can provide insight on the well’s potential productivity. During core analysis an oil sample may be forced at high pressure through a piece of rock core. It’s essential that a pressure transmitter used in this application provide high accuracy measurement up to 10,000 psi with Hastelloy or Monel construction to avoid corrosion of the diaphragm.

As EPA regulations to reduce the emissions produced by the disposal of saltwater and other caustic by-products of oil and gas production become more stringent, reliable low pressure measurement has become even more critical. Vapor recovery units are designed to comply with these EPA standards, provide the producer with additional profits that may be lost due to stock tank vapor emissions, and eliminate stock tank vapor emission into the atmosphere. Recovered vapors have a significantly higher BTU content than natural gas from the pipeline, therefore recovered vapors can be more valuable than methane alone.

Vapory recovery units, along with salt water disposal systems and storage tanks, require precise pressure measurement to ensure optimal control and monitoring, and maximize recovered emissions and profit to the producer. Pressure transmitters used in vapor recovery control, salt water disposal control systems, tank vent monitoring systems and liquid level monitoring in shallow tanks must offer low pressure ranges and be intrinsically safe.

Depending on the type of application, hazardous location pressure transmitters must be of Intrinsically Safe, Explosion-Proof or Non-Incendive design. A flush diaphragm connection can also be used to protect against plugging, which is ideal for applications involving measuring viscous fluids and for measuring pressure when fluid is pumped down the well.  

 

Intrinsically Safe Transmitters use less electricity than the level of power required to set off an explosion within the defined hazardous area. Intrinsically Safe Transmitters are also not capable of storing large amounts of energy which could spark an explosion. Many oil applications require Intrinsically Safe Sensors that can be submerged into storage tanks or boreholes to monitor the level of potentially flammable liquids or in zones with potentially explosive atmospheres.

Similar to Intrinsically Safe Transmitters, Non-Incendive Transmitters cannot generate enough thermal or electrical energy to ignite a volatile atmosphere under normal operating conditions – but unlike their Intrinsically Safe counterparts they can create sufficient energy for ignition could be generated under fault conditions.

Rather than preventing explosions, Explosion-Proof Transmitters are engineered to contain a blast. They are not necessarily designed to withstand an external explosion, but to contain an internal explosion without allowing flames or hot gases to escape from the transmitter housing which might trigger an explosion in the surrounding environment. Explosion-Proof Transmitters are ideal for monitoring tubing and casing pressures in a wellhead. These sensors provide consistently accurate and stable output, stand up to extremely harsh environments, and endure the test of time.

Hammer Union Transmitters are used in harsh, viscous applications where high shock and vibration is encountered, including acidizing, choke & kill manifold, fracturing & cementing, mud logging & mud pumps, oil field & offshore and well head measurement.

In hazardous oil and gas environments, operators can’t afford to take a chance on faulty or inaccurate pressure measurement sensors. Choosing the right high quality, durable pressure transmitters can keep these systems running safely and smoothly, and prevent costly accidents.