Understanding Working Pressures and Test Pressures in Wireline Operations

Posted on by Crissa Fel Tawadan

One of the first things I learned in wireline well logging was that not all pressure ratings mean the same thing. I’ve been on jobs where engineers assumed that because the wellhead pressure matched the equipment’s rated working pressure, they were good to go—only to find out the hard way that they were pushing safety limits. That’s why understanding working pressures, test pressures, and maximum allowable operating pressures (MAOP) is critical for safe and efficient wireline operations.

Why Pressure Ratings Matter in Wireline and Perforating

In cased hole logging, well perforation, and production logging services, pressure control equipment must always be rated for the expected well conditions. Misunderstanding these ratings can lead to equipment failure, uncontrolled pressure events, and downhole tool loss—all of which can cause costly delays and jeopardize well integrity.

There was a job where a crew attempted to use 5,000 psi-rated equipment on a wellhead pressure of 5,000 psi. Everything seemed fine until a pressure surge hit. The result? Equipment failure, and an expensive downhole pipe recovery operation that could have been avoided if the right test pressure limits had been followed.

Breaking Down Pressure Ratings in Wireline Services

To ensure safety, wireline service companies follow strict definitions when it comes to pressure equipment ratings:

  • Wellhead Pressure (WHP) – The pressure measured directly at the wellhead.
  • Working Pressure (WP) – The maximum pressure an equipment component is rated for under normal operations. This pressure should never be exceeded.
  • Test Pressure (TP) – The pressure at which the equipment is tested to qualify for operational use. This is typically 1.5 times the WP.
  • Maximum Anticipated Surface Pressure (MASP) – The predicted maximum pressure that could be exerted at the wellhead, either from reservoir conditions or artificial stimulation (pumps).
  • Well Site Test Pressure (WTP) – The pressure at which the well site equipment is tested before operations. This is typically 1.2 times the MASP but never exceeds WP.
  • Maximum Allowable Operating Pressure (MAOP) – The real working limit. This is 80% of the WP, leaving a margin for unexpected surges.

Applying These Pressures in the Field

If you’re working on a 10,000 psi-rated system, here’s how these numbers play out:

  • Working Pressure (WP) = 10,000 psi
  • Test Pressure (TP) = 15,000 psi (1.5 × WP)
  • Maximum Allowable Operating Pressure (MAOP) = 8,000 psi (0.8 × WP)

Why Testing and Safety Factors Matter

Operating directly at WP is risky—it leaves no room for pressure fluctuations, which are common in wireline logging, perforating gun operations, and cased hole well services. That’s why we always operate below MAOP to ensure a safety margin for pressure spikes.

Before every wireline job, equipment should undergo a well site test pressure (WTP) to confirm its integrity under anticipated conditions. This test ensures that wireline pressure control equipment, BOPs, grease heads, and lubricators will perform reliably without exceeding their design limits.

Conclusion

In wireline and perforating operations, pressure ratings exist for a reason. Using working pressures, test pressures, and maximum allowable operating pressures correctly prevents equipment failure, tool loss, and safety incidents.

Whether working in formation evaluation, pump down perforating, or production logging services, following pressure guidelines keeps both personnel and assets protected. Cutting corners with pressure ratings isn’t just risky—it’s a mistake that no wireline engineer can afford to make.