The
above figure depicts the relationships among LMS applications.
The heart of LMS
is the Metering application where it gets meter data either from the flow
computer or from a tank controlled by the tank management application.
Working together with Ticketing application, the Metering application defines the size of the batch in a ticket and the flow rate that will move this batch in the pipeline model of the batch tracking application. The batch tracking updates the position of the batch along the pipeline model and its linepack is calculated periodically.
As the
batch tracking application reposition the batches in the pipeline model, the
hydraulic profile is updated to reflect the effect of product in the batch on
the pressure profile.
Finally,
the metering data and linepack data along with the volume of product in the
tanks are taken as input to do volume balancing in the PLM application.
Liquids Management Suite (LMS) will be deployed
at the MCC SCADA as a centralized application.
LMS is a suite of applications that work together to provide the following liquid management functions :
·
Monitoring, correcting and
recording of metering data.
·
Managing ticket operations.
·
Tracking of batches in the
pipeline.
·
Tracking of anomalies (e.g.,
pig) in the pipeline.
·
Estimating the arrival (ETAs) of
batches and anomalies at checkpoints/nodes of the pipeline.
·
Calculating and recording
linepack information.
·
Detecting the potential leaks
in the pipeline.
·
Monitoring pressures along the
pipeline.
·
Monitoring tank information
The
applications/modules of LMS to be used to provide the above functions are as
follows :
·
Metering application will provide
the monitoring and the correcting of metering data.
·
Ticketing application will provide
the ticket operations management.
·
Batch tracking application will
provide the tracking of batches and anomalies in the pipeline, and calculating
the ETAs of the batches and anomalies at checkpoints.
·
Linepack application will calculate
and record the linepack information of the pipeline.
·
Pipeline Leak Monitoring
application (PLM) will provide the monitoring and detection of potential leaks
in the pipeline.
·
Hydraulic Profile application will
provide a visual representation of the pressure profile along the pipeline.
·
Tank Management application will
provide tank monitoring and tank volume calculation.
Metering
Metering
application allows LMS to read metering data directly from the Flow Computer
and perform corrections if required (usually the Flow Computer has already done
corrections on the raw meter data). The changes in meter data collected over
time are used to calculate the flow rate of the meter. Several metering
operating schemes can be accommodated, for example, metering can accommodate a
rolling (meter count that never resets) or a batching (meter count that resets
on a new ticket) metering count schemes.
Ticketing
Metering data collected and corrected by
the metering application are stored in tickets. A ticket represents a batch of
crude that passes through a meter. A ticket contains information about the
batch such as its shipper and destination, the start and end times of the
ticket, the projected and real sizes of the batch, and the product inside the
batch. Moreover, tickets can be subjected to operations essential to ticket
management such as ticket start, ticket stop and ticket cut. And most
importantly, completed tickets will be stored in historical database for
reporting purposes.
Batch
Tracking
After a ticket defines a batch as the product passes through a meter,
the location/position of the batch along the pipeline can be tracked using the
batch tracking application. Using a model of the pipeline, a batch shall move
along the pipeline proportional to the flow rate of the pipe segment it is in. This
pipeline modeling provides an approximation of the batch position in the
pipeline. To detect the actual batch position in the pipeline, interface
detection instruments such as densitometers are needed to detect the actual
start and end of a batch based on the density of the product in the batch. When
there is a discrepancy between the modeling approximation and the interface
detection data, an operator can do batch editing to fix the position and/or the
size of the batch.
Other than approximating the position of
the batch in the pipeline, the batch tracking application can also be used to
approximate the position of anomalies such as a pig as it travels along the
pipeline.
Using the position of the batch or anomaly
in the pipeline, the batch tracking application can also calculate their
estimated time of arrivals (ETAs) to checkpoints or nodes along the pipeline.
Checkpoints are usually configured at the pig traps, the booster and delivery
meter stations.
Linepack
Based on
the pressure and temperature telemetry data and the product that is occupying
the pipe segment, the linepack of the pipe segment can be calculated. And since
the pipeline is just a concatenation of pipe segments, the linepack of the
pipeline can also be calculated. The linepack of the pipeline represents the
inventory of the pipeline which can be calculated and recorded periodically for
reporting purposes.
Pipeline
Leak Monitoring (PLM)
PLM attempts
to monitor the pipeline for potential leaks. It uses a volume balancing
methodology where it tries to monitor the line balance (meter in and meter out)
and changes in linepack. PLM can be set to monitor this volume balancing over
short and long term periods. Short period monitoring is usually used for
detecting major leakages while the long period monitoring is better for
detecting minor ones.
Hydraulic
Profile
Other
than PLM, pressure profile can also be used to detect potential leakage and
sometimes its location. Using the telemetry pressure data from SCADA, a
pressure profile of the pipeline can be monitored in real-time. An unusual drop
of pressure can be visually reflected in the pressure profile which may
indicate a potential leak. Moreover, the pressure profile can also be used to
monitor for proper operating pressure of the pipeline. Along with the telemetry
pressure data and pressure interpolation between the telemetry data, the
maximum allowable operating pressure (MAOP) and elevation pressure are also
represented in the profile.
Because
the hydraulic profile depends on telemetry pressure data, the more transmitters
installed along the pipeline, the better the resolution of the pressure
profile. Telvent has recommended and made our assumption that there will be pressure
and temperature transmitters installed at every station, pig trap and block
valve locations.
Tank Management
Tank Management application allows monitoring of the level and product inventory inside a tank. Using data from tank level, pressure and temperature transmitters, the type of product inside the tank and the strap table of the tank, the volume of product inside the tank can be calculated and corrected.
