MCS Production Tubing

"The Scavenger"












​​The "Scavenger" is a 1-inch diameter extruded conduit having multiple internal passageways that is designed for conventional gas wells producing under 20 Mcf per day and having liquid loading problems... wells that are approaching the end of their life.

For most liquid-loaded wells, it eliminates the need for a pump, even for flow volumes as low as 1 Mcf per day.  It should be considered as an alternative to plugging a well, likely providing another 5 to 10 years of steady-state production.  

The Scavenger MCS production tubing has one 7.4 mm diameter passageway and seven 5.5 mm passageways (1 inch = 25.4 mm).  
The 7.4 mm diameter passageway is intented to enable the well
to kickoff automatically (see "Kickoff" page), and the 5.5 mm diameter passageways are most efficient in the transfer of energy from the gas phase to the liquid phase (no gas slippage with capillary bubble flow).  

As explained on the "Turner Critical Rate" page, the maximum transfer of energy from the gas phase to the liquid phase occurs with tubing diameters under 6 mm (in air-water systems);
capillary bubble flow is formed, where the liquid fully bridges
the diameter of the passageway, and these liquid slugs are
lifted to the surface between expanding gas pockets (in effect, virtual plunger lift, with the gas pockets substituting for the plunger).  There is no "minimum velocity" of gas as described
by Turner, and no flow reversals or slippage of the liquid back down the tubing, so no recirculation losses.

Capillary bubble flow is critical for the successful kickoff of a well using MCS production tubing, enabled by the MCS Tailpiece that creates favorable entrance conditions of sufficient gas phase concentrations (see "MCS Tailpiece" page).

The pressure gradient with capillary bubble flow can be very low.  
As a baseline, for a column of water in a 2-inch tube, the pressure gradient is about 15 psi per 35 feet of water in the column.  The pressure   needed to support a column of capillary bubble flow is a function of the mass of the liquid in the column, not its height 
(does not follow Pascal's Law).  In other words, if 35 feet of water 
is distributed as discrete slugs in a small-diameter tube
(having capillary bubble flow) spread out over a height of 1,000 feet, the pressure gradient would be 15 psi (ignoring the mass
of the gas).  This gradient is just to support the liquid in the 1,000-foot column, with any increase in pressure gradient resulting in net upward flow.  And this is true for 3,000 feet... in fact, any height.

For example, in our 1,930 foot pilot gas well (having seven 7 mm diameter passageways), 1) it kicked off automatically, evacuating 360 feet of water before converting to steady state flow, and
2) when flowing at steady state, the water content in the flow was calculated to be  under 1 foot of water (when flow is condensed) disbursed within the fluid flowing up the well at any given time,  assuming an LGR of ~130 Bbl/ MMcf (see "Pilot Well" page).