​INTRODUCTION

Turner Critical Rate
Kickoff
Tubing  Performance Curve
MCS Pilot Well
MCS  Endpiece
MCS Detailed Presentation



Multi-Channel (MCS) Production Tubing was specifically designed for wells that have liquid loading problems.  As gas wells deplete, reservoir pressure declines, and gas velocity up the well decreases.  Even if the gas-liquid ratio entering the wellbore is unchanged, sooner or later, liquid eventually starts to collect in the wellbore because the gas velocity becomes insufficient to carry all of the liquid out of the well.   

In a sense, MCS production tubing is a re-invention of the velocity string. They are similar in theory (reducing tubing diameter to regain steady state flow)... but the effect of an MCS (very small diameter) is to reduce by more than 10 times the minimum velocity of flow needed to evacuate all liquid (i.e., to maintain steady state production).  This results in greatly extending 
the timespan of its benefits (maintaining steady state flow), and by having multiple passageways, fixes the main drawbacks of velocity strings
(restricts production rate and difficulty in kicking off).

An MCS is a new type of "production tubing" that  divides the flow up the well into multiple flows through small-diameter internal passageways.  
By reducing the diameter of each individual flow passageway so much, 
it reduces the "Turner Critical Rate" (i.e., minimum gas flowrate/ velocity) required to maintain steady state flow up the well (see "Turner Critical Rate" page)... and by utilizing multiple flow passageways, it compensates for the restrictive/ choking effects of using a single small-diameter passageway (i.e., velocity string).  

For example, for 2-inch ID tubing, the minimum gas velocity flowing up
a well to evacuate all liquid, the "Turner Critical Rate", is > 20 feet per
second.  The MCS production tubing pictured above has seven 5.5 mm-diameter passageways around the perimeter, and a center passageway
of 7.4 mm diameter.  The minimum flowrate to maintain steady state
flow in 7.4 mm-diameter tubing is about 2 feet per second, and
for the 5.5 mm-diameter passageways, it is literally zero (no slippage
back down well, see drawing at right, "capillary bubble flow" pattern).
  
The 7.4 mm-diameter passageway is required to kickoff a well (see
"Kickoff" page), it adds to production volume capacity in times when
the well can produce it, and it can be plugged later when depletion results in liquid loading.  And the 5.5 mm-diameter passageways can be plugged one by one to maintain steady state flow and optimize the flowrate down to as low as 1 Mcf per day.  In a sense, MCS production tubing "digitizes" the flow, improving flow management capability.  Ultimate recovery is greatly increased, and without the costs and complexities of artificial lift.  

MCS production tubing is produced for stock in 1,800- to 3,600-foot coils
in 200-foot increments. and is shipped from Canton, Ohio.  The list price is $1.35 per foot (50% in advance) plus shipping.  About seven feet of MCS production tubing weighs about 1 pound, so coils of 1,800 to 3,600 feet weigh about 260 and 520 pounds, respectively, and they are coiled as a bundle without a spool for shipping.  Respooling onto a spooler having a brake is required. 

MCS production tubing requires no maintenance, no consumables, and no outside energy input.  Kickoff is automatic (no swabbing) using the MCS Tailpiece (see "MCS Tailpiece" page).  Particulates are produced along with the liquid, and the extrusion polymer is resistant to the buildup of salt, scale and paraffin.  

A custom-machined injector is available for using one MCS passageway
for the capillary injection of chemicals to prevent plugging.  Utilizing the injector to supply gas, burst strength of the MCS production tubing exceeded the 550 psi limit of the testing equipment.  MCS production tubing has tensile strength sufficient to permit utilization in wells exceeding 6,000 feet. 

Patents in the United States and Canada.  The gas production chart for a MCS production tubing well has a unique signature, where the sporatic gas flowrate spikes are almost completely smoothed out.