PEH Volume I Chapter 5: Gas Properties

The next chapter in Volume I of the Petroleum Engineering Handbook worth reviewing is Chapter 5: Gas Properties.

Most of what you will need regarding gas properties is in the Petroleum Engineering Guidebook on page 9 PVT 2. Review this page closely, especially the notes and equations. Know how to use the chart.

Below is some additional material. Again, if unfamiliar with anything (especially terminology) read those sections in detail until it makes sense. Otherwise, the outline should suffice.

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Gas Properties:
     CRITICAL: gas can't be liquid
     IDEAL: gas particle volume negligible compared to total gas volume
     PSEUDO: gas mixture
     PSEUDOPOTENTIAL: integral of pressure divided by z factor & viscosity (more accurate)
     REAL: gas particle volume considered; z = real/ideal volume; pV = znRT

Gas Viscosity:
     I-237-240    
     Estimate by chart, Carr et al

Vapor Pressure or Normal Boiling Point:
     I-241-252
     Pressure when vapor & liquid in equilibrium
     Use for pure substance only
     Estimate using: 
          Clausius-Clapevon equation (ideal gas only, accurate <~0.2 psi)
          Cox Chart 
          Calingeart & David or Antoine equation (generally <2% error) 
          Lee-Kesler equation (most accurate)

Petroleum Engineering Handbook: Volume I

The 18 chapters in the Petroleum Engineering Handbook (PEH) Volume I are as follows:

C1-3: Math
C4: Fluid Sampling
C5: Gas Properties
C6: Oil Correlations
C7: Thermo/Phase
C8: Phase Diagrams
C9: Asphaltene/Wax
C10: Produced Water
C11: Phase Behavior
C12: Emulsions
C13: Rock Properties
C14: Permeability
C15: Relative Permeability
C16: Economics
C17: International Law
C18: 21st Century Law

The first chapter in Volume I that is worth reviewing is C4: Fluid Sampling.
Below is an outline. If any of the material is unfamiliar (especially terminology) read those sections in detail until it makes sense. Otherwise, the outline should suffice.

I would especially note the section on "gas sampling for reservoir oil remix"; understand how to use the chart.

Note the list below seems pretty short and simple at first glance, but it's really not. It literally took hours to cull the wheat from the chaff to make this reference. Be aware: 90% of this chapter lacks utility for the average engineer but it's hard to sort it out at a glance.

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Fluid Sampling: RP44

BS&W: Basic Sediment & Water

DST: Drill Stem Test; note samples often unconditioned (early flow)

GOR: Gas Oil Ratio; often largest sample error

P&T: Pressure & Temperature

RFT: Repeat Formation Tester; several depths gradient; note filtrate contamination.

SI: Shut In

WELL CONDITIONING: Flow until stable (WHP/mud filtrate/workover fluids/reaction products).

WHP: Well Head Pressure

Samples:

·           Preserve P&T state during handling/storage.

·           Multiple before excessive drawdown.

·           Asphaltenes: single-phase (monophasic) sampler keeps at reservoir psi.

·           Water: aquifers vary laterally & by depth; RP 45: pH, T, alkalinity, O2, CO2, H2S, iron, turbidity.

·           Waxes: use heated chamber samplers.

·           Separator sample method: 1) drop flow rate by steps, 2) take sample when GOR/flow stabilizes.

·           Separator gas sample volume for reservoir oil remix; need separator GOR & PSI: FIG 4.4 (I-190).

·           Wellhead/Flowline: single phase only (e.g. dry gas, very-low GOR, or high-P high-T condition).

·           Split-stream sample (isokinetic): two-phase; side stream equal velocity (e.g. gas condensate).

·           Choke may change GOR: due to 1) two-phase flow effect, 2) phase changes, 3) gas condensate.

·           Downhole capture method: 1) SI for pressure, 2) flow low to clean near wellbore, 3) SI, 4) sample.

·           Downhole capture tools: by timer, mechanical clock, or electrical signal.

 

Petroleum Engineering Handbook: Overview

Petroleum engineers should be familiar with the Petroleum Engineering Handbook (PEH). See the Amazon link, lower left under "Useful Links" for further information. Many engineers have been slow to embrace the PEH for several understandable reasons:

First: seven volumes?! Clunky.
Second: each chapter is written by a different author so the quality is uneven. It lacks the unity of its single-volume predecessor by Bradley (see my Amazon review linked in the upper-right corner of this blog).

Regardless of one's opinion of the PEH, every PE should purchase and become familiar with it. Bradley is simply too dated, and there is some pretty good stuff in the PEH. After you get used to it, it's really not that bad. However, I do have suggestions to make it more manageable:

1) Tab each chapter in each volume, clearly labeled (see picture below).
2) Tape a chapter TOC (with page numbers) to both the cover and spine for quick reference.
3) Use pencil to mark passages. Forgo pens or highlighters. As you learn more and gain more experience a lot of the original marks will be obvious and make it hard to discern what's important. You really need to be able to erase and remark as you go.

I try to include relevant quotes from the PEH in the Guidebook. This process is ongoing.

Note the PEH is very long and detailed, so a good percentage of it is simply beyond the scope of the PE exam and most engineering work. Reading it cover-to-cover is not a wise investment of precious time for the typical engineer. So be selective when reading it. Make no mistake, it's a deep dive.

On this blog I'll include an ongoing outline of what I think are "relevant" PEH chapters (starting this week). These posts will be an excellent review for people taking the PE Exam. Everything I include I think is worth knowing and being prepared for.