MCS production Tubing was installed in a 1,930-foot vertical tight
gas well with 2-inch ID production tubing having liquid loading problems. It was on a 2-week slugging cycle, averaging about 15 Mcf and 2 Bbl of water per day over the cycle, with unloading aided with soap sticks, producing off-the-chart (lost revenue) when it kicked off. The wellhead casing pressure was 280 psi, and surface line pressure was 55 psi. Water salinates were > 130,000 ppm NaCl equivalent. When new, the well produced at a maximum rate of 120 Mcf per day.
When the MCS production tubing was installed, there was 360 feet of water (8 Bbls) in the well. Installation required about 3 hours by two men with a spooler truck. The MCS was 1 1/4 inches in diameter, having
seven 7 mm-diameter passageways, and it weighed under 700 lbs. Wellhead completion materials cost about $500.
The MCS production tubing started to flow within 20 hours. It took
more than 2 days for the 360 feet of standing water in the wellbore
to be produced at the surface. During this unloading period, the gas flowrate was very low; it was constantly spitting water, as seen through
a temporary clear section ("sightglass") in the wellhead tubing. The water was filled with debris... one person commented, "It was like cleaning out
a rat hole."
After the water was cleared from the wellbore, the gas flowrate became steady state. Gas production was exceptionally smooth on the gas chart.
The production rate settled in at 20 Mcfd along with 2.7 Bbl of water, and after a few months plateaued at 21 Mcfd. The casing pressure was 250 psi, and at the top of the MCS it was 70 psi against line pressure of 55 psi.
Production has continued for more than 2 years with gas production above 19 Mcfd, and no maintenance was required. It appears that there was a fundamental improvement in the production decline curve...
it flattened out. It is anticipated that the well will be able to produce at steady state for 10 plus years, and if flow does become intermittent, then the individual MCS passageways can be closed one by one to maintain steady state flow, matching reservoir influx with the cross section available for flow.