The team has just scored another success with the first offline cementing of zonal isolation in Fortin de Piedra, a field chiefly featuring high-pressure wells, which will lead to significant net savings in time and cost.

The first offline cementing was carried out for a 5” casing in a well in Fortin de Piedra, as part of a major field operation. “This was a highly intense and complex process, involving over seventy people working in tandem, but thankfully everything went according to plan,” said Ezequiel Bulant, Drilling Expert, in charge of coordinating the process together with Andrés Valacco, Drilling Sr. Manager, in a conversation with Tecpetrol Today.

The procedure was applied to the first well on pad FP-1275(h) at the reservoir, as the team neared the last stage of drilling. The result of this operation represents net savings of 31 hours, and USD 150,000. “This process is intrinsic to our continuous efforts to optimize processes. From now on, each well will be subject to a technical feasibility evaluation, based on the operating window available, which will establish whether it can be carried out or not," explained Valacco, referring to these procedures, which are indirectly linked to production development and increase at the field.

Cementing for beginners

The process takes place during the last stages of drilling a well and begins when the well has been drilled and cased. Liquid cement is pumped down the casing to the annulus, which is the space between the casing string and the borehole itself. The idea is to isolate the productive zones for completion, restrict fluid movement between the formations, bond and protect the production pipeline, and give it structural support.

To ensure that the casing is properly isolated against downhole pressures, the cement is pumped directly into the annulus from the surface, known as bullheading. This is a flexible grout, which means that it can absorb the stresses created in the pipe during fracturing and production.

Trying out other sequences

To begin with, the team defined the strategy for flooding operations, using software to run hydraulic pumping simulations and other maneuvers to see if the extraction sequence of the drilling tool could be modified. The challenge centers on how to remove it while keeping the well stable, and if this is worth the costs involved. 

The simulation offered the alternative of flooding the well at another point. Usually, in unconventional wells, this is done at the landing point, but this time the team decided to carry this out in the horizontal branch. "Flooding with mud of a sufficient density was implemented to prevent the supply of gas to the well, to ensure that at the end of the casing maneuver, the well is hydraulically stable," explained Bulant.

Offline cementation process

Once drilling the lateral branch has concluded, the drill string is extracted. In this maneuver, the well is flooded with enough kill weight mud to remove the tool and insert the tubing to its final depth with the wellbore overbalanced at all times.

With the pipe at its final depth, the double barrier is verified in a direct and annular fashion to disconnect the well control equipment before proceeding to skid to the next well on the pad.

With the wellhead released, the lines are assembled with the offline cementing equipment, while the rig and related services are assembled at the next well. Carrying out operations simultaneously requires coordinating each task with great attention to detail, which is critical to avoid delays on either of the two work fronts, as the time window available is limited.

For this first offline operation, we worked for several months with the service companies involved (MPD, Cementation, Rig, Heads), performing simulations and adapting the necessary materials/resources. Work was also carried out with the drilling team (Company, Engineers, HSE) to develop these procedures step by step, evaluating the risks involved and analyzing the time and resources required to perform the tasks at the same time.

"The planning was very intense, as the service companies had to adapt their materials, especially for this operation and we needed time to simulate it, in addition to the fact that in the field, there were several operations going on simultaneously and in linked fashion," said Andrés Valacco. “Until recently, it seemed that it would be impossible to do this within Fortin's parameters, where pressure is higher than normal, but it all turned out very well.”

"We knew that offline cementing had already been done by other operators, but due to the challenges we have to deal with in Fortin de Piedra, things are more complex," explained Bulant, sharing the satisfaction of a successfully completed task. “All of us involved did our best and things went off without a hitch, with no safety incidents of any kind. We’re very proud of our achievement!”