Pipeline Vs. Upstream Flow Computers

Understanding the Differences

Grant Van Hemert, P.E.

Flow Computation

• Very Important Process Criteria• Used In A Variety Of Industries• Flow Is Determined By Two Means– Flow Meter– Flow Computers

Flow Computers vs. Flow MetersFlow Computer Flow Meter

Flow Direction

Leak Detection

Flow Total

Flow Composition DeterminationRevenue Billing Oil & Gas Drinking Water, Steam, etc.

Revenue Billing Based on Flow CompositionNeeds Flow Meter to Function

Not Applicable

Flow Computer Uses

• Oil or Gas Well Measurement• Pipeline Applications• STAR (Ship, Truck, Airplane, Rail) loading• WAGES (Water, Air, Gas, Electric, Steam) billing• Others

We Will Focus On Well and Pipeline Applications

O&G Flow Computer Differences

• Gas– Measures 1 or more

types of gasses– Must preserve records– Interfaces with Gas

Chromatograph– Typically compliant with

API-21.1

• Liquid– Measures 1 or more

types of liquids– Must preserve records– Interface with Density

Meters– Typically compliant with

API-21.2

Gas Measurement

• Easily Separates From Oil And Water• Natural Gas Has Multiple Components– Natural Gas Found At Production Well

• Transmission Can Be Pure, Or Natural Gas

• Gas Chromatograph Can Determine Composition

• Governed By API-21.1

Transportation and Production Product Is Similar

Liquids Measurement

• Does Not Separates Easily From Water• Refined Liquids ≠ Unrefined Liquids• Volume Varies By Temp Not Pressure • Different Liquids Applications• Governed by API-21.2

Liquid Pipeline Application Transportation

Heating Oil

Gasoline

Diesel

Heating Oil

Gasoline

Diesel

Pipeline

Same Pipeline could be used to Transport Different Liquids

Liquid Pipeline ApplicationTransportation

Heating Oil

Gasoline

Diesel

Heating Oil

Gasoline

Diesel

Pipeline

Same Pipeline could be used to Transport Different Liquids

Liquid Pipeline ApplicationTransportation

Heating Oil

Gasoline

Diesel

Heating Oil

Gasoline

Diesel

Pipeline

Same Pipeline could be used to Transport Different Liquids

Production Pipeline Application

• Same Liquid• Multiple Destinations (Refinery)• Multiple Sources (Batteries & Fields)• Custody Transfer At Input and Output

Upstream Application

• Only Three Products– Liquid (Sellable)– Gas (Sellable– Water (Non-Sellable)

• No Change To– Source (Always the Same Wells)– Destination (Same Tank or Pipeline)– Pipeline Contents

Water Must Be Accounted For and Managed

Upstream Application

• Separation Measurement– Test Separators– Portable Separators– Continuous Net Oil Measurement

• Calculations– Allocation• Estimate of Actual Production

Assigned to Each Well

– Proration• Estimate of Forecast Production

From Each Well

Allocation and Proration

Balanced at end of Month

Sporadic Well Testing

Result is Rounding and

Estimating

Pipeline Versus Upstream

Pipeline

Upstream

• Permanent Provers• Pure Liquid• High Accuracy Measurement• Not Tolerant of Instrument

Errors

• Small Volume Temporary Provers

• Mix of Water and Oil• Harder To Measure

• Tolerant of Instrument Errors

About API-21.2

“…apply to new metering systems that performs continuous on-line gross standard volume (GSV) calculations.”

About API-21.2

“…apply to new metering systems that performs continuous on-line gross standard volume (GSV) calculations.”

Upstream Allocation ≠ Continuous Measurement• Test Separator•Portable Separators

About API-21.2“Single-phase liquid hydrocarbon streams may include permissible amounts of water or other nonsalable components. Measurement of gas/liquid two-phase mixtures is not covered

About API-21.2“Single-phase liquid hydrocarbon streams may include permissible amounts of water or other nonsalable components. Measurement of gas/liquid two-phase mixtures is not covered

Upstream:• Too Much Water For “Permissible” Clause•Water & Oil = Two Phase mixture

What about API21.2 in Upstream

• Theory:– Does Not Apply

• Reality:– Must Conform to Record

Keeping and QTR– Required by BLM, and

others.

Upstream = Accurate Low Cost Measurement of 3

Phase Liquids

Other Upstream Considerations?

• More tolerant– Meter failure– Impurities

• Simpler to use and configure

• Less Expensive Then Pipeline

Upstream = Accurate Low Cost Measurement of 3

Phase Liquids

Conclusion

• Flow Meters ≠ Flow Computers

• Many Flow Computers Designed for Pipelines

• Not Suited for Upstream Applications– Allocation Determination– Tolerant of Impurities– Ease of Use– Lower Cost