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Permalink Reply by Brian Powers on January 23, 2013 at 4:08am

Todd -

Final Open Flow, or more poperly, Absolute Open Flow, or AOF, is a theoretical maximum production flow capability of a well to produce against no surface backpressure and no other system losses, such as pipe friction, restrictions in pipe, etc. In my experence, it is a relative flow indicator and in states that prorate or regulate production to ensure that one or a few good wells don't drain the entire pool at the expense of others, the AOF seldom comes even close to the sustainable flow potential of a well.

 

A production choke is a flow throttling device that regulates flow and subsequent pressure at the tree, the valves at surface that connect to the wellhead upstream of the flowline. A very strong well that has properly designed production tubing with minimal restrictions and does not produce much water, free liquid hydrocarbons or proppant can be operated with the choke cracked more open, but if the tubing is too small diameter, if the gas to liquids ratio is too low or if the well produces any solids, then the choke is often pinched to keep the well flowing without letting the well load up and die.

 

Chokes come in two types, fixed and variable. The fixed chokes are stainless steel plates with a machined orifice that is held in place between two flanges, whereas a variable choke can be adjusted to regulate flow and pressure. Choke openings are in 64ths of an inch increments. Depending upon the opening size, pressure upstream of the choke, the pressure differential across the choke and the gas properties, the daily flow rate of dry gas can be calculated or estimated. choke equations cannot be used accurately for wet gas, just single phase gas or liquids.

 

Brian  

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Permalink Reply by Todd on February 2, 2013 at 7:43pm

Brian,

Thank you for helping me to understand about how chokes work.

Followup question:

So, in other words, the AOF could be "low" and you could still have a highly productive condensate/liquids well?

Thanks again for your experienced input.

Todd

 

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Permalink Reply by Todd on February 2, 2013 at 8:16pm

Brian,

The well is in WV and this is what I found for WV's definition of Final Open Flow:

Attribute_Label:GFOF

Attribute_Definition:Gas Final Open Flow:  The gas volume measured after the completion of well stimulation; measured in thousands of cubic feet of gas per day (Mcf/d).  Data Source:  WVDEP-OOG WR-35 completion record, submitted by the operator to WVDEP-OOG.

Attribute_Definition_Source:West Virginia Geological and Economic Survey

 

 

The final open flow did say that it was calculated in this case. 

Do you still think that WV is referring to Absolute Open Flow?

Thanks, Todd

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