MCS Production Tubing
 1 - Inch Diameter

"The Scavenger"

This is our most efficient design of MCS production tubing.  
As the name suggests, it is intended to scavenge the last bit
of pressure differential provided by the reservoir.

The Scavenger is designed for conventional gas wells producing under 15 Mcf per day... wells that are near the end of their life.
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 7mm passageway and seven 5.5mm passageways.  High-efficiency 5.5mm passageways are intended to carry most of the flow, with the
7mm passageway intended to enable kickoff.  After kickoff, the 7mm passageway can be left open to provide flow capacity, or
it can be plugged so that all flow is up through the 5.5mm passageways, providing ultimate efficiency.

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.

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 
were distributed as 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 purposes of comparison, in our 1,930 foot pilot gas well 
when flowing at steady state, there was under 1 foot  of water (fully concentrated and condensed) within the fluid flowing up the well at any given time, calculated assuming an LGR of ~130 Bbl/ MMcf (see "Pilot Well" page).