Challenging HDD Project in Trinidad Completed
March 23, 2011Not all horizontal directional drilling (HDD) contractors are created equally. That much was clear last fall in the Republic of Trinidad and Tobago.
There, Michels Directional Crossings once again proved why it is regarded as one of the premier HDD
contractors in the world.
The National Gas Co. of Trinidad and Tobago Ltd. (NGC) contacted Michels this past fall when the original HDD contractor could not complete a 36-in. diameter steel pipe offshore landing on the island of Trinidad.
The landing was part of the North Eastern Offshore Project (NEO), a crucial update to Trinidad and Tobago’s infrastructure that was designed to open access to a new gas field and create an opportunity to develop other marginal fields by lowering infrastructure development cost.
Horizontal directional drilling was used on the landfall section in order to prevent cutting through the coastline and minimize the impact on the sensitive surrounding environment, as well as minimizing risk by avoiding other existing utilities.
Because of the previous contractor’s failed attempt, Michels faced an added challenge to re-drilling the landing — working around the abandoned bore-hole and product pipe left from the previous contractor’s unsuccessful attempt.
In stark contrast to the many months spent on the previous attempt, Michels ultimately achieved success by finishing the complicated drill and pullback in just 42 days from the time equipment landed on site.
“NGC called us up and asked if we wanted to take it on,” said Michels marine operations manager Ray Viator. “We’ve done drills in Trinidad before and they’ve all went really well, so we were excited to be involved.”
Michels first met with the NEO team and presented a comprehensive drilling plan to complete the installation. Due to the extensive delays during the previous contractor’s attempt, NGC imposed an accelerated schedule on the project. With the likelihood of weather-related interrupt-ions increasing as the winter months moved closer, NGC needed a contractor that could mobilize and get the job done quickly in the rapidly closing weather window of opportunity.
This left Michels with no room for error throughout the project. The company quickly set about the task of precisely loading equipment in its Brownsville, Wis., yard. All major equipment, along with a spare parts inventory, had to be accounted for and expedited to make the last possible ship to Trinidad.
Everything that could possibly be needed for Michels to complete the re-drill had to be mobilized with the original shipment — there simply was no time to wait for replacement equipment to be mobilized once the re-drill of the HDD landing was underway. In addition to quickly clearing Michels’ key HDD personnel to work in Trinidad on short notice, a significant local contingent had to be secured and mobilized quickly to support the HDD operations. Anything less than precise execution of the HDD landing by Michels would have pushed the HDD completion into much riskier working conditions, and an almost certain perilous state for the project itself.
NGC’s decision to source the re-drill of the HDD landing to Michels immediately paid dividends, as Michels’ unique experience and expertise shone through. In fact, after arriving onsite and constructing an exit trench, it took Michels less than 10 days to complete a pilot hole that was successfully drilled directly into the center of the offshore transition trench, roughly 40 ft under the ocean’s surface.
Reaming operations began immediately thereafter, and Michels used proprietary equipment and methods to achieve a reamed hole in less than 30 days — exponentially faster than the nearly six-month process of the previous contractor.
Finally, Michels used a custom-built swab tool to clean out the reamed hole. Michels met little resistance and saw very low torque levels, indicating that the reaming passes had been executed with great diligence and skill. After one more pass to further ensure hole integrity, Michels was ready to pull back the pipe nearly five days ahead of schedule.
The only thing that could stop Michels at that point — Mother Nature — reared its ugly head. Tropical Storm Tomas bore down on Trinidad, unleashing high winds and heavy downpours. Sea conditions became choppy and visibility underwater rapidly deteriorated, leaving divers unable to perform critical operations, including dewatering of the pipeline and the final subsea hookup to the pullback swivel and drill stem. As the storm worsened, all marine support ultimately had to be evacuated from the site to safe harbor on Oct. 30.
NGC and the offshore marine contractor had to carefully consider when to dewater the pipe in preparation for the HDD pullback installation, especially with pending repercussions from the tropical storm. The pipe was laid on the sea floor in deeper waters. Dewatering too soon could have resulted in strong subsea currents carrying it away on a one-way trip to Venezuela. Dewatering too late, on the other hand, could have resulted in the collapse of the finished HDD hole. This mistake could have required further HDD reworking of the hole and potentially even necessitated the pipeline to be refilled in order to re-secure it to the sea floor.
After carefully weighing the risks, NGC and Michels decided to retract the pulling assembly through the hole. Michels was careful to secure the pulling assembly in order to ensure that the storm didn’t stir up material and inadvertently bury it, possibly causing the loss of all progress up to that point.
Extensive contingency planning and prior preparedness based on Michels’ previous experience with shore landings meant that this challenge could be overcome with minimal additional delay or risk.
After waiting out the weather, marine support was able to return to the site three days after the initial evacuation. Michels then pushed out a specially designed hole-chaser to recondition the hole and further evaluate its “real-time” condition. When that process was complete, it took divers about 48 hours to connect to the pipeline. After the marine contractor completed dewatering and checked the buoyancy levels, Michels began pulling the pipe into the opened hole at 6 a.m. on Nov. 5.
From there, it was a true tropical breeze. By 2:30 a.m. on Nov. 6, less than 21 hours after the operation got under way, the pullback was completed. According to locals, Michels completed the job in less total time than it took the prior HDD contractor to even drill a pilot hole.
“We would have been five days ahead of schedule if not for the bad weather,” Viator said. “We went in there with our plan and they weren’t sure we would be able to complete it, but we got ahead of schedule and completed it on-time.”
With the pullback and hydro testing complete, NGC had one last request for Michels — to stabilize the other contractor’s abandoned borehole left over from the prior attempt. With its equipment still on the island, Michels grouted the previously abandoned hole in order to ensure the future structural integrity of the roads and surrounding land that ran over it.
By Nov. 17, everything was packed up and at the port awaiting a ship back to the United States.
It was the second successful Trinidad drill for Michels superintendent Craig Larson, who oversaw the entire project ranging from financial paperwork to procurement and local relations. Larson takes little credit, though.
“[Viator] is really the mastermind behind this whole thing,” Larson said. “He was responsible for the operations part of it and it was his mastermind design — I’m just extremely proud that I could help him implement it.”
Drilling for Michels was Jack Edmonds and his crew, who also were on their second Trinidad HDD landing. In keeping with the company’s strong safety record, Edmonds and his crew completed the job with no recordable incidents and didn’t even have to open a first aid kit. This was in large part due to safety coordinator Greg Warner, who was onsite for the entire project and held daily safety meetings each morning with local workers and subcontractors.
For all of the project’s troubles with the prior contractor, Michels transformed a potential doomsday scenario into a resounding success.
“[NGC was] kind of amazed with us throughout,” Viator said. “But we had a plan, we had the experience, and we executed it perfectly.”
Bob Wothe is marketing specialist for Michels Corp., based in Brownsville, Wis.