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Data Flow Analysis and Uncertainty

HomeSystem AssuranceData Flow Analysis and Uncertainty
HomeSystem AssuranceData Flow Analysis and Uncertainty

Introduction

UKCS Introduction

To comply with environmental legislation operators of offshore installations in the North Sea must regularly submit totals of flare gas, fuel gas and produced water to the Oil & Gas Authority (OGA). These totals are generated by the installed flow meters and the associated systems. The associated systems are often standard platform control systems, Data Historians, hydrocarbon accounting systems rather than dedicated flow computing systems. However the reported totals must still be demonstrated to have an uncertainty which is within the limits of the legislation.

KELTON provide a service that can:
▪ Verify Flow Data Integrity (from meter to reporting)
▪ Assess the uncertainty in the reported totals (not just the uncertainty in the instantaneous flowrate at the meter).

Combining this service with the KELTON UNCERTAINTYPLUS modules provides a powerful method to demonstrate environmental compliance.

Overseas Introduction

In order to comply with commercial agreements, government legislation and internal company procedures etc., oil and gas operators are required to generate and report a multitude of totals such as:
▪ Production Totals (Well, Field)
▪ Export Totals
▪ Reservoir Management Totals (Injected Water or Gas)
▪ Environmental Totals (Flare, Fuel and Water Overboard), etc.


These totals are generated by installed flow meters and their associated systems. The associated systems can include:
▪ Flow Computers
▪ Platform Control Systems
▪ Data Historians
▪ Hydrocarbon Accounting Systems
▪ Business Reporting Systems

It is important that data integrity and uncertainty levels are maintained within these systems, as commercial agreements and government legislation require that the totals are fully verified and their uncertainty is within stipulated limits. KELTON provide a service that can:
▪ Verify Flow Data Integrity (from meter to reporting)
▪ Assess the uncertainty in the reported totals (not just the uncertainty in the instantaneous flowrate at the meter).

Combining this service with the KELTON UNCERTAINTYPLUS modules provides a powerful method to demonstrate environmental compliance.

Objective

The objective is to demonstrate that the uncertainty in a customers reported environmental totals, complies with the uncertainty requirements of current legislation. To achieve this, the following are recommended:

  • Development of meter uncertainty model (UNCERTAINTYPLUS)
  • Data flow analysis
  • Development of a data flow uncertainty model
  • Review of the meter and data flow uncertainty models
  • Identify any meter or data flow modifications required to meet uncertainty limits.

Data Flow Analysis

This is a systematic process of route tracing and identification of data handling/manipulations (i.e. data flow elements) applied within a data flow structure. It can identify elements that may affect data integrity.  

Data Flow Uncertainty Model

The data flow uncertainty model determines the uncertainty in the reported totals. To do this it includes contributions from:

  • Meter flow rate readings
  • Data flow elements.

Meter Flow Rate Readings

The flow rate readings contribution to the reported total uncertainty is derived from the meters flow rate uncertainty characteristic (UNCERTAINTYPLUS).  The contribution depends on the flow rates that generate the reported total. If operational flow rates are below the linear region of the meter uncertainty characteristic then an analysis will be required to determine the contribution.  

Data Flow

Data flow elements (i.e. data handling and manipulation methods) can potentially result in additional uncertainty in the reported total. Each data flow element is reviewed and if required an estimate of the additional uncertainty is calculated. Examples of data flow elements which result in additional uncertainty include:

  • Low specification analogue to digital converters
  • Low update frequency totalisation
  • High data compression settings
  • Volume/mass conversions using high uncertainty density values
  • Inappropriate allocation methods (e.g. by difference on low flow stream).

 

Find out more

UNCERTAINTYPLUS:

UNCERTAINTYPLUS

System Compliance:

System Compliance

System Support:

System Support and Support Partnerships

System Uncertainty:

System Uncertainties

User List - Uncertainty:

User List Uncertainty

Data Flow & Uncertainty PDF:

Environmental Data Flow Analysis and Uncertainty

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