Perfect symbiosis of time and N-SPEC® of Brenntag Oil & Gas

Brenntag Oil & Gas Europe, one of the world’s leading suppliers in pipeline cleaning services, recently managed to open an offshore 7.3 km, 6 5/8” crude trunk line with N-SPEC 50 dispersant/solvent. The line, which belongs to Petromar, Romania’s offshore petroleum exploration company, had been obstructed for six years and previous efforts to open it had failed. It took almost one and a half years before the N-SPEC crew managed to open the line. Peter Verkiel, European Product Manager N-SPEC products & services at Brenntag, elaborates on the project.

Mid July 2004, Brenntag Oil & Gas Europe started the job. It was essential to Petromar to have this line opened, as it connected P3 and P6, Petromar’s two fixed offshore platforms in the Romanian Black Sea. It was formerly used for crude production and salt water injection. Consequently, one line less meant that Petromar had to seriously decrease production. Several attempts were made to open the line – Petromar even brought the pipeline to the surface to cut

it – but without success.

First European offshore project for N-SPEC

N-SPEC products have been the key success factor in the removal of the paraffin, which were blocking the pipeline. As a leading provider of solutions for the pipeline and system cleaning industry, Brenntag Oil & Gas has developed an innovative package of environmentally friendly cleaning chemicals, together with supporting technology, under the N-SPEC brand-name. N-SPEC products are designed to remove the adhesive characteristic of deposits, such as paraffin, black powder, hydrates, scales etc., allowing them to be disconnected from the inner pipe wall and to be transported through the pipeline with a specially designed pig. N-SPEC 50, which is designed to penetrate and remove organic deposits, like paraffin and waxes, has been tested according HOCNF (Harmonised Offshore Chemical Notification Format) and approved by Scandinavian and UK authorities for offshore use. The Petromar task was the first practical test of its application in a European offshore project. Many projects have already proven its effect before in the U.S.A. and Canada.

Very small flow after a few days work

Initially, all fluids and solids in both open ends of the line at each platform were removed and replaced with N-SPEC; water was used as a diluent. In the next step of the process, the P3 end was pressurized while the pipeline end at the other platform was simultaneously monitored. Then the same procedure was repeated in the opposite direction, starting from the P6 end. While allowing the N-SPEC chemical to do its work, the Brenntag team optimized the entire set-up at both platforms and was able to pressurize. The N-SPEC crew decided to increase the pressure to create an ‘annulus’ between the inner wall of the line and the paraffin plug or plugs through the re-rounding effect of the material. After a few days they were finally able to achieve a very small flow in the line. However at that moment when the re-opening of this pipeline was registered, they didn’t know how long it would still take them to get the line back into service.

New method: hydraulic-shock therapy

To boost the, yet miniscule, breakthrough of the N-SPEC chemical through the paraffin, the Brenntag experts decided to increase the movement that was needed in the line by introducing pressure cycles and dual pressure cycles. To do so they pressurized and depressurized one side at a time, alternating between each side, and varying from fast to slow. Peter Verkiel labeled these new methods “hydraulic shock therapy” and “dual-cycle shock therapy”. These resulted in an increased flow, although it remained small. It took another 16 days for a more or less continuous but varying flow to be achieved.

Step by step improvement

Knowing that the N-SPEC chemicals needed some time to dissolve and disperse as they continued their migration through the line, the Brenntag team left the site and returned by the end of October 2004. After cleaning both ends, they then filled them with fresh N-SPEC chemicals and inserted a coiled tubing of approximately 1 kilometer in length into each end. This allowed them to ascertain that 2 kilometers were open and they continued pressurization. The fight against their tough paraffin opponent proved time-consuming, with very small steps leading to small improvements. The essential element was time, supported by pressure. That is what the chemical needed. Finally the line gave more flow, stopped, started again and then a lot of paraffin came out. In December 2005, almost a year and a half after having started the project, N-SPEC and the Brenntag experts’ know-how had proven successful – the line was open.

Conclusion

After the plugged pipeline had been out of action for more than seven years, Brenntag’s client Petromar was once again able to put it back into operation. The first European offshore project with N-SPEC 50, an environmentally friendly cleaning chemical, proved very successful for Brenntag Oil & Gas and there are high expectations for further unplugging of pipelines in offshore applications. The pipeline is open now but the cleaning is not yet finalized. Brenntag does hope to have the opportunity to also look after that last part of the job. N-SPEC cleaning chemicals have so far been successfully applied in the cleaning of crude oil and gas pipelines, flowlines and gas lift wells belonging to approximately 400 companies worldwide.

Product information

Facts and figures on the two N-SPEC products used for the project.

N-SPEC® 50 – Paraffin disperent/solvent

Description:

- Multi-use dispersant/solvent

- Dissolves and removes organic deposits in oil & gas applications

- Strong dispersing/solvating properties designed to penetrate oil, paraffin and grease deposits

- Biodegradable

- High flash point

- Thanks to its biodegradability and low toxicity the product has received the yellow label for offshore use.

Typical physical properties:
Appearance	Liquid, mild scent, clear amber
Specific Gravity @ 20°C	0.87
Flash Point °C	>300
Pour Point °C	-6
pH	Na
Solubility	Oil & water soluble
Sulfur (%)	>0.01

Application for oil pipeline:

- Can be applied into the pipeline by batch addition or by continuous injection

- Recommendation for equipment: use of initial cleaning pig with 2 lb. density and “flow through holes”

- Run through velocity: 1 to 1.5 m/s

- Key success factor time: Allowing maximum contact time over any interval is key to achieve a successful application of this product

N-SPEC® 120 – Natural gas pipeline cleaner

Description:

- Biodegradable co-solvent micro emulsion, wetting agent and dispersing surfactant

- Internal cleaning of gas pipelines and surface equipment

- Non-corrosive; will not attack metal surfaces

- Possesses strong solvating capabilities for organic material

Typical physical properties:
Appearance	Liquid, lemon scent, clear dark blue
Specific Gravity @ 20°C	0.95
Flash Point °C	>200
Pour Point °C	-9
pH	6-6.5
Solubility	Water soluble, oil dispersible

Application for oil pipeline:

- Should be applied into the pipeline by batch addition or by pre-dilution with water before injecting into the line

- Cleaning pig velocity be such as to prevent establishing a sub-laminar flow regime along the pipe wall during contact phase of application

- Key success factor time: Allowing maximum contact time over any interval is important to the successful application of this product

Reader enquiries

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3300 AB DORDRECHT
Netherlands

+31 (0)78 65 44 143

Info-oilgas-europe@​brenntagoilandgas.com

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