Independent Design Review of Fiscal Metering Station

Client name: Confidential

Industry: Chemical & Process

Profile: TÜV SÜD National Engineering Laboratory was commissioned to undertake an independent design review of a new flow metering station. The review confirmed to the client that the proposed metering design did not satisfy the regulatory requirement of ±0.25% for fiscal taxation purposes. TÜV SÜD National Engineering Laboratory’s flow measurement experts were able to recommend solutions to overcome the issue. 

Business challenge: The development comprises a number of oil and gas fields. Oil is sent to an 870,000 bbl capacity Offshore Storage Installation (OSI), ready to be loaded into tankers for export worldwide.

The only provision made for quantifying production levels was the use of tank dips located on the OSI or receiving vessels. This led to the UK regulator, OGA (previously DECC), requesting that a flow metering station be installed on the OSI to satisfy fiscal taxation reporting..

Our approach: TÜV SÜD National Engineering Laboratory carried out an independent review to establish if the proposed metering station satisfied the regulatory requirements. In particular, the regulator’s guidelines specified a measurement uncertainty of ±0.25%. The metering station encompassed two full-bore ultrasonic meters arranged in a duty and master configuration. NEL reviewed the design, regulatory requirements and field conditions to ascertain the suitability of the proposed method.

Our solution: It was established that the proposed duty meter did not meet ±0.25% uncertainty. This was mainly due to the method of validating it against the master meter. The master meter had an increased uncertainty due to being installed in the field. Subsequently, this impacted the overall uncertainty of the duty meter.

Having reviewed the regulations, TÜV SÜD National Engineering Laboratory proposed steps to be taken by the operator to satisfy OGA requirements. OGA could award the operator dispensation if it could be demonstrated that achieving ±0.25% was not commercially viable or practical. To this end, TÜV SÜD National Engineering Laboratory proposed that a structural and cost/benefit analysis be done, together with a comprehensive uncertainty analysis.

Business benefits: TÜV SÜD National Engineering Laboratory developed a number of different options to help satisfy OGA. Although the proposed design was unable to achieve the ±0.25% guideline, it did provide a significant improvement on the tank dip method which had up to twice the uncertainty. The OSI was handling around 100,000 m3 offload every fortnight equating 630,000 barrels. Based on $50/bbl, this amounts to $31.5 million in monetary terms. This equates to a financial exposure of $2 million per year.

DOWNLOAD CASE STUDY

Related services: Design and Commissioning | Metering Advice & Management