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Keeping your production data accurate

Thursday, December 11, 2014

Chittimalla Malliah explains the best techniques to getting accurate flowmetering. By Chittimalla Malliah, manager process engineering, Gujarat State Petroleum Corporation Limited

Accurate and timely production data is very important in E&P business for production loss management, reservoir analysis and regulatory reporting.

An efficient metering management system is required to maintain the accuracy of production data that flows from wells to plant to corporate offices. This will allow operational staff and business managers to be more efficient and control the value of production from upstream operations.

Production fluids are measured at different measurement points and at different time intervals. Some type of data is required in real time, others intermittently.

The key is to determine what needs to be measured, location of measurement points, frequency of measurement and the degree of accuracy.

In E&P industry there are many end users for production data.

Reservoir managers need production data for reservoir simulations, Commercial / Finance team need to for generating invoices, Production team, Operations team for various analysis like actual vs. target / forecast, loss management, locked in potential and for production planning.

Metering Management System
There are many types of meters in E&P industry - fiscal, custody transfer, operational and allocation meters.

These are used to measure the quantity and quality of the produced fluids such as gas, condensate, oil and produced water. Suitable management procedures required to ensure the maximum reliability and required data accuracy.

The meter management life cycle must start at the 'define/conceptual' stage and continues to 'execute' stage to 'operate' phase.

'Define/conceptual' stage
Various commercial agreements usually document the requirements for fiscal and custody transfer meters. These agreements must refer to latest applicable and updated standards (for example AGA standards)

An instrument specification document to be developed to mention the purpose (i.e. operational or fiscal), required accuracy, range

Project execution stage
This is the next phase of the project, the conceptual team hands over the requirements to project team. Project team shall review the requirements and ensures that the metering system is designed, fabricated and installed to meet appropriate standards, commercial requirements. The following provides key guidelines for the factory acceptance test (FAT).

A detailed acceptance criteria to be developed and all stake holders including government representatives must be invited for FAT; complete the integrations with 3rd party solutions; all meter calibration must be witnessed by concerned; all flow computer calculations must be verified;

All configurations with respect to flow computer, online analyzers, gas chromatographs, pressure and temperature transmitters must be verified against design; pressure and temperature transmitter's calibration validity & recalibration schedules; recalibration schedules for online GC, ultrasonic flow meters; verify the data sheets for all transmitters and RTDs

Project 'Operate' stage
Once the formal handover and take over format is signed by Projects and Operations, Operate phase of the metering system commences.

OMIR - operations, maintenance, inspection and repair of metering system is of utmost importance.

At this stage metering management must ensure the following:

All metering system calibration reports and other certificates are maintained in a proper document management system and accessible easily when required

Standard meter operating procedures and maintenance procedures are prepared and up to date

All operational spares and spare calibration gas cylinders are procured and maintained in warehouse

Regular audits of the metering system shall be undertaken to ensure that metering systems are compliant with the required regulations, standards and commercial agreements.

Production Monitoring
The production monitoring business function enables consistent monitoring and analysis of asset's production data and facilitate decision making. Define performance indicators for well, facility performance, losses emissions etc; collect the data and calculate the performance KPIs.

Typical data examples are down hole pressure, temperature, well head flow meters, facility custody meters, online gas analysis all provide necessary information for well performance KPI.

Once KPIs have been defined, determine the measurement and reporting frequency. Categorize KPIs into facility performance, plant performance and production critical. The date must be stored in a secured database for access from any location.

Presentation of production data is required for analysis; identify the daily, weekly and monthly reporting requirements. Typically, well and production facility performance data is required daily, loss data weekly and locked in potential monthly.

Visualization tools must be engaged to generate real-time and automated production reports and graphical representations of the production data.

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