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NOPSEMA chides Esso for water-in-oil measurement errors

Australia’s National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) issued a direction to Esso Australia Resources on May 21…

Australia’s National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) issued a direction to Esso Australia Resources on May 21, saying the company’s measurement methods at offshore production facilities were “inaccurate and unreliable.” This led to the company underestimating oil levels in produced water discharge.

This is the first time the authority has issued such a notice to an operator, highlighting the difficulties upstream companies face when trying to adhere to the measurement and reporting requirements in their environment plans.

In February 2017, NOPSEMA made recommendations to Esso after completing a series of inspections ending with the company’s Tuna platform. The authority followed up in February and March 2019 to verify compliance; however, it found that oil-in-water levels were still above the regulatory limits. In late May, NOPSEMA told Esso to make “whole-of-company” changes or it could face prosecution and fines of up to AUS$2.1 million.

Esso was given six mandates to implement at production facilities in eight licenses in the Gippsland Basin offshore Victoria. One of NOPSEMA’s stipulations was that, within 60 days, Esso must fully follow the manual ASTM D7066-04 (2017) detection method and ensure that produced water discharge does not contain more than 30 mg/l of oil. Furthermore, Esso will need to perform tests of its online detection method and have those verified by an independent third party to demonstrate that correct measurements are being taken.

While Esso is the first to be issued a direction for noncompliance related to measurement and reporting of oil in water, it is not the only operator facing time-consuming or costly challenges in this area. One issue is that no remote, online monitor is reliable enough to continuously measure oil in water. This is a problem at unmanned platforms, Dr. Lisabeth Wagner, Drilling Operations Engineer for Inpex Australia, told Water in Oil.

“Also, the requirement to check the performance of the online method on a regular basis usually results in recalibration and additional work due to the requirement to take manual samples. This is an issue for most operators,” she said. “As soon as any of the production conditions change – for example, if a different well is brought online or the production flow rate changes – the online method has to be recalibrated.”

Esso’s communications and media adviser, Travis Parnaby, told Water in Oil that the company is now evaluating how it can efficiently and effectively address NOPSEMA’s direction. He also said that “while we accept that improvements can be made to our produced water measurement, our recent study at the Tuna platform, peer reviewed by CSIRO [Commonwealth Scientific and Industrial Research Organisation], showed that impacts to the marine environment from produced formation water are lower than predicted in our accepted environment plan.”

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