After a quarter-of-an-hour, Blues were in front. Hyland slid the ball out to the left-hand side where diminutive winger Okai raced past Mason Stewart before sending an unstoppable shot into the top right-hand corner past Shaun Phillips.
At the time, Colchester were down to ten men as Tosin Olufemi received treatment and his replacement, Ross Gilfedder, had a chance to equalise with his first touch as the U's broke away from the restart, the substitute seizing on an under-hit header from Kane Ferdinand but sending his finish wide of the left-hand upright.
The visitors began to grow in confidence having taken the lead, although they were continually unable to find the target as Ferdinand powerfully nodded an Abdellah centre wide, Ofori-Acheampong galloped into the penalty area but hoisted a shot past the right-hand post and Smith smashed a rising half-volley narrowly over from 15 yards.
In between, Okai was only stopped from capitalising on a wonderful sweeping Stevens pass by an inch-perfect Stewart challenge, but the half ended with Colchester on top. Chambers produced a fine fingertip save to push a curling Ladapo shot out and the Essex Senior Cup winner fired over late on when Arnott's driven free-kick was deflected into his path.
The second half began with Chambers making a sprawling save to deny Gilfedder, and Blues doubled their advantage as a result in the 50th minute. The goal was made by Abdellah, who sent a teasing cross into the six-yard box from the right-hand side and, with Hyland lurking behind him, centre-half Allen inadvertently diverted the ball into his own goal.
Head of Youth Ricky Duncan took the opportunity to field Under-16 talent Lyle Della Verde as well as trialists Reece Hall and Steven Camacho, the latter a second-year scholar from Charlton Athletic, in the final 40 minutes of the match and Della Verde was unfortunate to see a skimming shot take a minute touch to send it wide after an enterprising run in the 66th minute.
Southend did score midway through the second half when Ferdinand showed excellent alertness to intercept Phillips' rolled clearance. The centre-half advanced to the bye-line, from where he cut the ball back to Ofori-Acheampong, who glanced it into the bottom right-hand corner.
Camacho's fierce effort was well-held by Phillips as the Shrimpers piled on the pressure and, after Chambers again looked impressive in parrying out a swerving Arnott attempt, they added a fourth with ten minutes remaining.
Della Verde started the move by lofting the ball over the top for Okai, who was closed down by 'keeper Phillips 30 yards out. The loose ball fell to Nesbitt, who immediately went for goal but saw the effort charged down into the path of Ofori-Acheampong, with the front-man then setting up Okai to roll in his third goal of the season.
Three minutes later, the rout was complete. Ofori-Acheampong battled hard for the ball up against Allen and Alex Gilbey, and then slid it in for Okai. The winger was denied a hat-trick when Phillips palmed away his shot, but Ofori-Acheampong continued his run and slammed the rebound into the net to record his fifth goal of the season.
Next weekend sees Southend take on Oxford United at Boots & Laces in the Second Round of the Youth Alliance Cup (kick-off 11:00am), with a date soon to be arranged for the FA Youth Cup First Round tie at Roots Hall against Luton Town.
Southend United: Luke Chambers, Anthony Furlonge, Teddy Nesbitt, James Stevens, Kane Ferdinand, Louis Baucutt, Hicham Abdellah (Steven Camacho 57), Michael Hyland (Reece Hall 63), Duane Ofori-Acheampong, George Smith (Lyle Della Verde 54), Julian Okai.
Substitutes not used: Ryan Auger, Rhys Mackay.
Goals: Okai (15, 80), Allen o.g. (50), Ofori-Acheampong (67, 83).
League