Mahogany B: Blueprint for the Future

Mahogany Scores! Debottlenecking Project secures added production for country and company...

A few short years ago, the Mahogany Bravo (B) hub, one of BP Trinidad and Tobago’s (bpTT) flagship platforms, located in the Greater Mahogany and Amherstia (GMA) area in the Columbus Basin, was a mere shadow of its former self producing a mere 200 million standard cubic feet of gas (mmscfd) per day.

The Mahogany A platform that feeds into the Mahogany B hub (hub) was not producing any gas. In its heyday the hub processed on average 450mmscfd eventually reaching 605mmscfd, a mere 45mmscfd shy of its maximum capacity of 650mmscfd. With natural depletion of the wells in the GMA area since the establishment of the hub in 1998, few could envision how this facility could continue to play a vital role in the future.

BP Trinidad and Tobago has always expressed great confidence in the hydrocarbon potential of the Columbus Basin. Over the last six years (2008-2014) seven new wells were brought onto production from the Savonette field. All of the production from these wells, approximately 900mmscfd, needed to flow to the Mahogany B hub for processing before entering the 40”
export line and being taken to bpTT’s Beachfield facility for further handling. The production from the Savonette wells represents a major revenue stream for Trinidad and Tobago and bpTT. 

Due to the production from the Savonette wells, the Mahogany B hub is, once again, critical to the future of bpTT. This presented the GMA team with a very unique problem – the production from the Savonette wells would exceed the processing capacity of the hub! 

Debottlenecking is the process of increasing the production capacity of an existing facility through the modification of existing equipment to remove restrictions hindering the flow of oil and gas.

Vibration 

The gas moving through the pipelines travels at high velocities and pressures causing the piping system to vibrate. Excessive vibration could cause the pipes to fail. The first course of action was to clamp and secure all the pipelines to the hub. Then, given the massive increase of gas in the hub’s system, the team needed to find a simple, cost effective way to monitor piping
vibrations. This led to the search for an online vibration monitoring system. The team decided to adapt already existing online vibration monitoring technology used for rotating equipment for the pipelines on the hub (static equipment). The GMA team was the first at bpTT and in the country to use real time vibration monitoring on static equipment.

Erosion

The high velocities at which the gas and liquids flow through the pipelines combined with any particulates, for example: sand, can cause erosion and failure of pipelines within a matter of minutes. Increasing the throughput of gas in the hub would make the piping system more vulnerable to erosion. To increase the longevity of the pipelines a series of engineering studies were commissioned: erosion modelling, oil and gas simulator (OLGA) modelling and computational fluid dynamics, alongside process safety hazard analyses. These studies identified the points along the piping system that were most vulnerable to erosion. The team then installed erosion monitoring probes (a technology usually deployed in flow lines
and wellheads) and ultrasonic thickness measurement devices that allow them to conduct real-time monitoring of the pipes for any erosion issues.

Noise

The high velocity gas has a lot of stored energy. Once this gas enters the pipelines this energy is converted into noise. As you increase the flow rates of the gas, the noise emanating from the pipelines increases and could exceed industry standards for hearing protection and/or be harmful to one’s hearing if the proper protective equipment is not worn. Studies needed to be
conducted to ensure that the noise from the increased throughput on the hub would be within an acceptable range for human exposure (studies showed that it was). 

After all the modifications and installations were completed, the team felt confident that they could begin to incrementally increase the amount of gas flowing to the hub. After months of tireless work (the project was completed primarily over
the 2013 Christmas season) the team was able to safely increase the capacity of the hub from 650 mmscfd to 850mmscfd securing an additional 200mmscfd in production for both company and country.

How does the team feel given this accomplishment? “There is a sense of overwhelming pride that each member of the team worked to the best of their ability to get the job done,” Jaikissoon shared. He added, “We took on one of the biggest projects in the GMA area, executed it safely and created experts in engineering along the way. Our team had the courage to be open to new experiences and ways of working and we succeeded.”