Crude Oil Pipeline System & Pipeline Configurations C

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Crude Oil Pipeline System & Pipeline Configurations

Hydraulic Design Procedure system design comprises of three stages

conceptual design

system planning

detailed engineering design

conceptual design:

product properties such as viscosity and gravity

flow profile over the life of the project

pipeline length and preliminary route with the points of injection and delivery

Macro-economic data

isothermal assumption is assumed when liquid is being transported near ambient temperature. this way hydraulics is minimal.

temperature dependent classification of hydrocarbons:

light hydrocarbon liquids --> non-isothermal flow

intermediate hydrocarbon liquids

heavy hydrocarbon liquids --> non-isothermal flow

Pipeline Configurations A pipeline network is composed of:

injection points: inlet stations where the products are lifted into the line, storage facilities such as tanks and booster pumps are located there.

Delivery points: terminal, product will be delivered to the final consumer or to the other pipeline

Intermediate station: can provide a side stream injection or delivery point

pump stations: located along the line to move the liquid through the pipeline

Block Valve Stations: 1st line of consequence mitigation for pipelines. any segment can be isolated. they're located every 20-30 km

Regulating station: valve station where either pressure or flow is controlled. pressure regulates are located on the downhill side of a peak and flow regulates are found at delivery.

Side Stream Delivery:

dependent on:

delivery flow requirements

availability

nomination status

pipeline operational status

design operations :

Strip delivery through the branch line or at delivery point

ful stream delivery through the branch line

ful stream delivery through the main line

design considerations:

satisfying the delivery pressure requirements at both delivery locations while maintaining sufficiently high pressure at the take off point

using a pipe with a smaller diameter downstream of the delivery point if side stream delivery volume is large

installing an extra facility such as a pressure regulator or pump at the take off point on the branch line to stratify delivery pressure requirement

selecting pumps to meet the maximum and minimum flow requirements: if inlet is shut down flow rate can be lower than side branch flow rate

Side Stream Injection side stream injection leads to adding flow rate to the mainline flow downstream of the injection point

frictional pressure drop near the upstream segment is low due to low flow rate.

block valve is installed upstream of the injection point on the mainline, its closed when a full stream injection takes place or a new batch is created.

modes of side stream injection

side stream injection through branch line or at original point of injection

shutting down of the main line upstream injection point

branch line shutting down if no volume is available to be injected into branch

if a different product is injected into the mainline operational issues arise:

two products are blended if a partial injection takes place, this changes the properties of the blended liquid from that of the original main line liquid. fluid at the mainline injection point will not progress down the mainline until the side branch injection is finished

if the two products are not allowed to be blended; the injection should be a full stream injection. the main line flow is stopped upstream of the injection point

design considerations:

injection pressure on the branch line should be higher than the mainline pressure

pipe with larger diameter can be used downstream of the injection point depending on injection volume

pumps upstream of the injection point should be able to accommodate the reduced flow if partial side stream injection is present. if the side injection rate is high the upstream flow rate can be lower than the mainline flow.

pumping units should accommodate viscosity difference in the downstream of the injection.

side stream injection flow rate can be lower than minimum main line flow rate, pump stations should be able to meet the flow rate of the mainline.

injection of the same product; no batch is created

partial injection of a different product: a new blended batch with a different density and viscosity is created

full stream injection of a different product: a new batch retains the product properties of the injection fluid

Pipeline in Series when different flow rates are transported due to intermediate take-off or injection or different pressures are required along certain pipe segments pipelines could be connected in a series.

Different types of series arrangement:

different pipe sizes

different pipe wall thickness

different pipe grade

this provides different flow velocities but the same flow rate

Pressure requirement for this section can be calculated by applying:

flow equations for each section

combining all the segment pressure drops

total pressure requirements can be determined by calculating the pressure across all pipes

Connection of different pipe sizes in series due to:

change in flow

change in elevation

Connection of different pipe wall thickness due to:

reduce pipe material and construction costs

discharge pressure of an upstream pump is higher than deliver or suction pressure of a downstream pump

pipe thicknesses are used to compensate for different pressure requirements, thinner for lower pressures (downstream) thicker for upstream.

Connection of different Pipe Grade:

may be used instead of using a pipe with different wall thickness to satisfy pressure requirement design.

high grade= high pressure

the use of different thicknesses or different grades is not a good option is more pump stations are added/ flow is reversed.

the availability of a new pump in a thin or lower grade of a pipe obliges the pump to discharge at a lower pressure than initially needed.

Pipeline in Parallel pipelines are arranged in parallel to reduce the excessive pressure drop in certain sections of the pipeline

two or more pipes are connected at the upstream and downstream points so that the flow splits among individual pipes and merges at the downstream point

the split creates a common pressure across each pipe

the sizes of pipes can be different along with the flow velocity