Pre-Test Inspections – Direct Measurement Testing

Are you up to date with the current EPA Quad O regulations? Have you tested your production tank batteries for flash gas to determine whether you are “in or out?” If not, allow OTA Compression to assist you with testing and site preparation. Pre-test inspections are very important, especially when the site is outdated and has not been kept up with. Pre-test inspections are vital, in many cases. Equipment setup issues can take days to correct and if not caught before testing day will cost the operator extra money for our emission testing technicians to be on standby.
One method (the most accurate) that we utilize is called, “Direct Measurement.” The tank battery and auxiliaries (i.e. thief hatches, vent valves, etc.) must be in good working order or the test may be flawed, which is why we offer a pre-test inspection and highly recommend it.
Questions to ask yourself when considering a pre-test inspection are (the following):
Are the vent lines of the produced water and crude oil tanks commingled? If yes, then only one meter is needed for most applications. If not, are the vent lines from each set of tanks commingled? If so, at least two-meter runs will be needed. If not, the operator should consider commingled vent lines to lower the testing cost (less labor) and the operator will want to commingle vent lines to channel all vapor to a control device or VRU, eventually.
Are vent valves accessible? If not, a man lift is required, in order to inspect for damaged and underweighted vents. A vent valve located above a fiberglass tank is NOT accessible without a man lift for safety reasons.
Are the thief hatches in good working order? If not, OTA can place gaskets and springs before testing. If a hatch (or hatches) is (are) beyond repair, this is something to be found during the pre-test inspection (it may give us false-negative flow rates because of a leak. Remember, the slightest leak may resemble an additional meter run, without recording the flow rate. Are there access ports (2”, 3”, 4” NPT connections) in the vent lines? This can be either on the tanks or further down the line toward the emission control device (ECD). Available 4” taps directly into a tank vessel are the most preferred means to attach meter runs.
Is a VRU or Control Device in use? If yes, the emission control unit will need to be isolated (perhaps, powered down) from tank emission flow. Otherwise, the flash will flow in two directions and only of those paths is measuring the flow.
Are there any P-Traps? If so, any and all liquid buildup will need to be drained or the meters will need to be positioned upstream of P-Trap.
Are any wells shut-in? If so, testing can still be conducted but the following information is required:

  1. Productions rates: 24 hour testing period production rates (BOPD and BWPD) and average/highest production rates of down wells.
  2. H2S sampling needs are:
    1. Available port (i.e. ball valve tap) into vent lines or directly into storage tanks (1/4” – 4” NPT connections). All wells must be producing at time of sample extraction.

Is there >10 PPM H2S in the flash gas stream or anywhere field technicians are potentially exposed? If so, the industry/OSHA requires two man crews for the job.
So if you need to conduct Direct Measurements testing and you are unsure of the above requirements, let OTA do the work for you and do the pre-test inspection to ensure you are getting the most accurate report back. As always, do not hesitate to contact an OTA Representative in your area to help you!