Gas Well Deliquification Workshop Sheraton Hotel Denver Colorado

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

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. 17 - 20, 2013 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. 17 - 20, 2013 Gas Well Deliquification Workshop Denver, Colorado 3

Why don’t separators dump? Flowing Bottom Hole Pressure vs. Gas Rate 500 Tu rn er an MCF 400 bl/M 1000 b 300 F 220 bbl/MMC 100 bbl/MMCF 10 bbl/MMCF 200 100 Gray Correlation 600 ol em 700 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) C Bottom Hole Pressure (psia) • • 800 Li Annular flow (2 -3/8 in 7 inch) 50 psig separator pressure 900 0 - Feb. 17 - 20, 2013 1 000 2 000 3 000 4 000 5 000 Gas Rate (MSCF/day) 2013 Gas Well Deliquification Workshop Denver, Colorado 6 000 7 000 8 000 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. 17 - 20, 2013 Gas Well Deliquification Workshop Denver, Colorado 5

Separation flow for one annulus size Maximum Flow Rate for Separating Liquid from Gas in the Annulus (1/2 Gray Critical rate, 2 -3/8 tubing in 7 -inch casing) 5 000 Flow rate (MSCF/day) 4 500 4 000 3 500 3 000 1 bbl/MMCF 2 500 10 bbl/MMCF 2 000 100 bbl/MMCF 220 bbl/MMCF 1 500 1000 bbl/MMCF 1 000 500 0 Feb. 17 - 20, 2013 50 100 150 200 250 Flowing Casing Pressure (psig) 2013 Gas Well Deliquification Workshop Denver, Colorado 300 6

Separation flow for 10 bbl/MMCF 6 000 Flow Rate (MSCF/day) 5 000 4 000 2 -3/8 in 7 -inch 2 -7/8 in 7 -inch 3 000 3 -1/2 in 7 -inch 2 -3/8 in 5 -1/2 -inch 2 -7/8 in 5 -1/2 -inch 2 000 3 -1/2 in 5 -1/2 -inch 1 000 0 Feb. 17 - 20, 2013 100 200 300 Flowing Casing Pressure (psig) 400 2013 Gas Well Deliquification Workshop Denver, Colorado 500 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. 17 - 20, 2013 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 $90 k/yr at $3/MSCF) • Many pumps are passing 10 -15 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 $900 k/year) Feb. 17 - 20, 2013 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. 17 - 20, 2013 Gas Well Deliquification Workshop Denver, Colorado 10

Gas. Buster® • 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 Gas. Buster® 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 Feb. 17 - 20, 2013 Gas Well Deliquification Workshop Denver, Colorado CFD model, water superficial velocity red=fast blue=slow 11

Thank you for your attention Additional information can be found at www. muleshoe-eng. com David Simpson zdas 04@muleshoe-eng. com 505 -326 -2115 Feb. 17 - 20, 2013 Gas Well Deliquification Workshop Denver, Colorado 12

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