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1
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- Lectures #23 & #24
- Chapter 11: Pages 317-19, 321-22, 326-333
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2
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- Methods Discussed
- Given composition of saturated liquid- iterative procedure (guess
contribution of C1 & C2) – Excel file & Ex. 11-4
- Given composition of saturated liquid- correlation - using W1 & W2 –
Excel file & Ex. 11-5
- Given solution gas-oil-ratio, gas composition and stock tank oil
gravity (or API) – Excel file & Ex. 11-6
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3
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- Methods Discussed (cont.)
- All these methods evaluate oil density in stages
- Pseudo-oil at Tsc, Psc
- Correct oil density in (a) 1st for reservoir pressure
- Correct density in (b) for reservoir temperature
- JCPT paper method & Example 11-7 of text book
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4
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- JCPT paper method & Example 11-7 of text book
- Both require solution gas-oil-ratio, separator gas gravity, API gravity
of stok tank, pressure, and temperature
- JCPT includes a more current correlation
- Both calculate pseudoliquid density at standard conditions and adjust
for reservoir pressure and temperature using same equations as in the
other methods.
- Compare densities from both methods
- Oil density is at or below pb
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5
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- Example 11-7 highlights…
- Given data: API, Rs, T, p, ggs
- Find molecular weight of gas as
- Find mass of gas dissolved in one STB of oil as
- Find mass of oil in 1 STB as… (your turn!)
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6
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- Example 11-7 highlights… (more)
- Pretend that the oil components are two: stock tank oil & surface
gas
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7
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8
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- Compare the densities obtained by JCPT procedure with that from Example
11-7
- Discuss results
- Different evaluation methods will result in different values of Bo
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9
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- The oil formation volume factor is evaluated at or below pb
- How do we evaluate Bo above the bubble point?
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10
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11
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12
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13
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- Above bubblepoint pressure (undersaturated)
- Below bubblepoint pressure (saturated)
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14
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15
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16
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- Oil volume will change because of
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17
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- You can evaluate Co using the methods of JCPT paper…
- Need to have Bg
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18
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19
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20
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21
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22
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- Establish ranges of applicability (API, Rs, p…)
- Determine trends for the physical properties as a function of p, T, API,
etc.
- Does Bo increase with Rs?
- Does Bo increase with API?
- Provide quick estimates (sometimes)
- Exercise our visual skills
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23
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24
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- Viscosity is a measure of the resistance to flow exerted by a fluid
- This is called dynamic viscosity and has units of
- centipoise = g mass / 100 sec cm
- Kinematic viscosity is viscosity / density, units are in
- centistokes = centipoise /g/cc
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25
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- Calculation of two-phase flow
- Gas-lift and pipeline design
- Calculate oil recovery either from natural depletion or from recovery
techniques such as waterflooding and gas-injection processes
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26
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27
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28
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- Evaluate dead oil viscosity (no gas in solution) given oil API and
reservoir temperature (Figure 11-13)
- Correct for pressure by “adding gas in solution” (Fig 11-14)
- Most of the oil viscosity correlations are oil dependent (large errors)
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29
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30
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31
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32
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33
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34
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- No correction for p =pb
- Larger corrections for higher pressures
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35
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36
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37
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38
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39
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40
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41
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42
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43
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Notes
