What matters in transferring ownership: 5 ways to ensure accurate measurements
As part of the ownership transfer, technicians routinely calibrate all pressure and
temperature transmitters involved in oil and gas flow as well as pressure in pipelines and
related equipment.
Often, in the search for accuracy, attention is focused entirely on the performance of the
flow meter under ideal conditions. But there are many other controllable factors that affect
the accuracy of the system. Here are some measures to consider:
- Correctly align the pipes leading to and away from the flow meter.
-A typical proprietary transfer system has several flow meters mounted across a single
header. Resize these headers correctly to avoid inaccurate results.
-Place temperature sensors in locations that follow AGA guidelines.
-Select high quality flow system components suitable for the required accuracy.
-Maintain and calibrate flow system components on a regular and proper basis.
Regular calibration is a vital part of maintaining system accuracy. It can be performed on site
or in the laboratory. This application is typically calibrated using three calibration devices to
measure low pressure, high pressure and temperature. Alternatively, you can use a multifunction calibrator such as the Fluke 721 or 721EX Precision Pressure Calibrator, which have
two built-in pressure ranges and the ability to measure temperature.
Most pumps used to provide pressure for calibrations greater than 600 psi are hydraulic
pumps. But since hydraulic pumps use fluids to generate pressure, liquid contamination of
the system being calibrated is a risk. You can use gas instead, using a gas cylinder, but that is
a burden in the field and may also pose a safety risk. For field calibration, the best solution is
an air pump designed for pressures up to 3,000 psi. An example of this type of pump is the
Fluke Calibration 700 HPPK pneumatic pressure pump. It can deliver pressures up to 3,000
psi in the field without the risk of liquid contamination. It is also lightweight and easy to
carry.
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background
An oil and gas company specialized in the exploration, development and production of
hydrocarbons, managing various assets in the Middle East. Crude oil quantities are delivered
from oil fields to oil processing companies.
Measurement requirements
Settlement of crude oil cargoes is subject to custody transfer. Therefore Custody Transfer
Measurement System (CTMS) is one of the key components of the entire oil field as it is
mandatory for crude oil export and billing procedures.
The oil company has invited tenders to supply a full scale CTMS system including all
measuring instruments and peripheral equipment such as flow meters, control cabinets,
flow computing, automatic sampling system as well as supervision and validation software
systems. The CT measuring system meets the stringent requirements of API.
Because even relatively small errors can have significant financial implications, the operator
only considered CT-certified flow meters with a proven track record in high-precision oil and
gas transportation operations. To enable on-site verification of the embedded operating
meters, the oil production company also required the mobile installer to be part of the CTMS
package.
Measurement specifications:
Measured medium Crude oil
Volume flow rate 280…850 m³/h
Density 830…850 kg/m³
Pressure 35…77 bar / 507.6…1116.8 psi
Temperature +50…+70°C / +122…+158°F
Viscosity 3.1 cSt (at +80°C /+176°F)
7.63 cSt (at +20°C /+68°F)
Crohn's solution
As a well-known and long-standing supplier of metrology solutions and CT measurement
systems to the oil and gas industry in the Middle East and beyond, KROHNE prevailed and
was trusted in this project. A complete nursery relocation solution is designed,
manufactured and supplied by KROHNE to customer specifications.
The measurement solution includes:
- Custody transport flow measurement system for crude oil with ALTOSONIC 5 as its core
component. This inline ultrasonic flow meter is designed for CT measurement of
hydrocarbons and has proven itself in a wide range of upstream and downstream
applications. Due to its advanced multi-path configuration, it can handle all flow regimes
without Reynolds number limitations. It provides a large number of diagnostics, allowing the
complete flow profile to be recognized and visualized. The API 5.8 compliant and OIML R117
certified slip-on flow meter is used in main and duty meter configuration.
- Flow control slide featuring butterfly type valves with electric actuator and check valves at
the outlet.
- Automated liquid sampling system equipped with rapid loop pumps, densitometers,
viscometers, electrosamplers, static mixer, as well as an OPTIMASS 6400 Coriolis mass flow
meter. The KROHNE flow meter is one of the most accurate devices in its class, providing
reliable readings for crude oil quality analysis. Installed in the cabinet's DN15 mini sample
line.
- Compact stabilizer mounted on a mobile stabilizer for on-site verification of CT flow
meters.
- Water intake system to check small volume coolant.
- Metering control panel including SUMMIT 8800, SynEnergy and PLC. SUMMIT 8800 is a
high-performance digital CT flow cytometer. SynEnergy is KROHNE's web-based HMI/SCADA
solution that provides continuous process monitoring and visualization of the complete
CTMS system.
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Property transfer measurement systems for crude oil and refined products
Fluid measuring solution
- Straight Coriolis tube and ultrasonic flowmeters to reduce pressure drop
-Systems with mobile or integrated main meters, one- and two-way ball stabilizers, and
small-format stabilizers
-Includes