Gas Well Deliquification Workshop Sheraton Hotel, Denver, Colorado February 17 – 20, 2013 Wellbore Gas/Liquid Separation David A Simpson, P.E., Principal Engineer MuleShoe Engineering Feb , Gas Well Deliquification Workshop Denver, Colorado 1

Wellsite Facilities Scope of Facilities Engineering in wellsite design: –Decide between horizontal and vertical separators –Decide between 2-phase vs. 3-phase separator –Select pipe size and pipe material –Determine whether a downhole pump would discharge into the separator or a tank/gathering system Eliminating the separator was not usually within Engineering scope even when separators on similar wells never dump Feb , Gas Well Deliquification Workshop Denver, Colorado 2

Why are separators “required”? In the early days of gas production the only reason to produce a gas field was to recover condensate and NGL—and you have to have a separator to get the liquids The rule stayed with us long after it stopped making universal sense –CBM and many Shale-gas fields produce zero condensable hydrocarbons –A significant number of unconventional wells require mechanical pumping for their entire life –Observations show that the separators on pumping wells rarely (if ever) dump when the pump doesn’t go to the separator Feb , Gas Well Deliquification Workshop Denver, Colorado 3

Why don’t separators dump? Gray Correlation Bulk of water is pumped Residual is near 10 bbl/MMCF line and needs 4.5 MMCF/day (Gray) or 1.8 MMCF/day at 150 psia BHP (Li) Coleman Turner Li 1000 bbl/MMCF 220 bbl/MMCF 100 bbl/MMCF 10 bbl/MMCF Feb , Gas Well Deliquification Workshop Denver, Colorado 4

How can this be? Because of the size of the annulus (2-3/8 tubing in 7 inch casing has an effective flow area of a 5-1/4 inch ID pipe), flow velocity is very slow and most of the water has fallen out by the time the fluid gets to the top Somewhere in the annulus, the fluid mixture changes from gassy water to watery gas At the bottom of the tubing, the fluid mixture is water with some gas (and any gas that is sucked into the pump stays in the tubing) Feb , Gas Well Deliquification Workshop Denver, Colorado 5

Separation flow for one annulus size Feb , Gas Well Deliquification Workshop Denver, Colorado 6

Separation flow for 10 bbl/MMCF Feb , Gas Well Deliquification Workshop Denver, Colorado 7

What about the tubing? While the annular space can easily be seen as a “separator” with fairly poor efficiency/unit length (but with a lot of length), what do we have in the tubing? –Conditions at the pump suction are quite chaotic and violent –Any gas that gets to the pump inlet will be pumped Careful measurements of “pumped gas” are rare, but every time it has been done some amount of gas was measured –The smallest volume has been around 6 MCF/day –The biggest volume measured to date was 244 MCF/day This gas represents a safety, environmental, and economic problem Feb , Gas Well Deliquification Workshop Denver, Colorado 8

Gas in water Gas in a water gathering system can: –Collect at high points and increase gathering system pressure –Represent quantities that violate the Clean Air Act (6 MSCF/d from 100 wells is 5000 tonne/year) –Become a fire or explosion hazard at SWD facilities –Represent an economic loss (the 100 wells above are venting $90k/yr at $3/MSCF) Many pumps are passing times the minimum gas so vented gas becomes a real problem for environmental compliance and revenue (10 times the above numbers are 50,000 tonnes/yr and $900k/year) Feb , Gas Well Deliquification Workshop Denver, Colorado 9

Wells with Downhole Pumps Where do you go with a pump discharge? –To Separator? Minimum Separator pressure limited to water line pressure unless you have a blowcase or a transfer pump –To water line? Every pump makes some gas (some pumps make a lot of gas), you don’t want it in your water system Getting gas out of the water system can be a chore There seems to be fewer problems when the pump goes to the water system, but even these can be solved with a gas knock out Feb , Gas Well Deliquification Workshop Denver, Colorado 10

GasBuster ® Goal is: –Remove gas from a “liquid” stream –Retain enough pressure to capture the gas for resale –Retain enough pressure to let the water enter the water system without a transfer pump (i.e., use downhole pumping power to transfer the water) Available products all treated gas as a waste product and vented it at atmospheric pressure Started development on GasBuster ® in 2009 –20 installed to date (13 installed without any gas/liquid separator) –Patent protection has been applied for and approval is pending –Performance envelope developed by Los Alamos Nat’l Lab CFD model, water superficial velocity red=fast blue=slow Feb , Gas Well Deliquification Workshop Denver, Colorado 11

Thank you for your attention Additional information can be found at David Simpson Feb , Gas Well Deliquification Workshop Denver, Colorado 12

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