analisis nodal chapter 07

7/27/2019 Analisis Nodal Chapter 07

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Section 7

Work Session


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Section 7 Work Session

Introduction to Well Testing 7-2


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(Note: Section 6 has self contained work sessions in developing the Nodal Analysis concept)

Work Session for Section 1

1. Define porosity and permeability, explain briefly how they can effect a reservoirs performance?

2. As an example of the effect of grain size on a wetted surface, compare the wetted surface area of

a 1 m3 rectangular conduit with a 1 m3 rectangular conduit filled with 0.1 mm diameter sandgrains. (Porosity of the sand grain filled conduit is 20%)

Hint: Wetted surface = particle surface x number of particles.Number of particles = volume of cube divided by volume of sand grain.

Figure 7-1

What conclusion do you draw from the result?


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3. Define irreducible water saturation, discuss the relationship between this and permeability?

4. Explain the difference between saturated and unsaturated hydrocarbon molecules?


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5. Using the chart provided, figure 7-2, find Rsb, the solution gas-oil ratio at bubble point

pressure, under the following conditions:

pb = 900 psia

Twf = 140 F

g = 0.7

o = 40 API


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Figure 7-2


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6. Given that the density of air at standard conditions is 0.001223 gm/cc or 0.0762 lb/cu ft, findthe weight of 500 scf of gas with g = 0.55.

7. Find the density of gas at standard conditions when g = 0.7.

8. Find owf, the density of oil at well flowing conditions when;

Bo = 1.21

Rs = 350 cf/B

g = 0.75

o = 30 API

(Note a conversion factor of 1/(5.615) must be applied to the top right hand term of theequation for to convert from metric to English units)


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9. Repeat the same example with the chart provided, figure 7-3.


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Figure 7-3


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1. Draw a typical completion diagram for a dual string oil producing well. Explain how the wellcould be selectively produced from the upper zone only?


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2. List the advantages disadvantages between a tubing retrievable and wireline retrievable surfacecontrolled sub-surface safety valve?


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1. List several key objectives of well testing.

2. List the advantages and disadvantages of through tubing perforating and high shot densityperforating.


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3. Draw a typical DST string diagram for cased hole applications. Include TCP guns and anappropriate firing system.


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List 5 key points which should be noted from an operational viewpoint and/or from a dataenhancement viewpoint.

4. The attached diagram, figure 7-4 shows a typical layout for a surface test onshore. Label the keyitems.

List 5 key points which should be noted from an operational viewpoint and/or from a dataenhancement viewpoint.


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Waterfrom ?

Optionaldiesel supplyfor ?

Optionalgas supplyfrom ?for a ?

Fluids from well

Tubing

flare

lines

Oil flare Gas flare

Safety valve Rig floor

Coflexip,Chiksansor fixed

pipingLaboratorycabin

Burning pit

Figure 7-4


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5. Discuss the merits between strain gauge and crystal gauge pressure sensors. List oneapplication where you would use each type of sensor.

6. Discuss the difference between the resolution of a pressure transducer and that of a pressuregauge.

7. Discuss the importance of calibration with respect to data quality.


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1. Early Time Responses

1.1 Which flow regime gives a unit slope in early time on the log-log and derivative plots?

1.2 What gives a 1/2-unit slope on log-log and derivative in early time?

1.3 Which rarely-seen flow regime should give a 1/4-unit slope on log-log and derivative inearly time?

1.4 What is the effect on the derivative of partial penetration / limited entry?

2. Boundary Responses

2.1 What effect does a sealing fault have on the late time of the derivative plot?

2.2 What would be the result of 2 faults intersecting at 60-degrees?


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2.3 If the 2 faults were parallel, what would the log-log and derivative plots do?

2.4 What is the effect of a constant pressure boundary?

2.5 A closed reservoir gives contrasting responses on the drawdown and the build-up. What arethey?

3. Dual-Porosity responses

3.1 What are the 3 flow regimes seen in a dual-porosity reservoir, after storage, if C issufficiently small?

1

2

3


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3.2 What are the 3 standard dual-porosity models?

1

2

3

3.3 Which model gives the deeper dip on the derivative?

3.4 Which parameter controls the depth of the dip?

3.5 Which parameter controls when we see the dip?

3.6 Why do we not normally see the fissure system radial flow?

4. Gas Well Testing

4.1 Why do we have to use pseudo-pressures in gas well test interpretation?


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4.2 Why can you not perform a full interpretation of a gas well test by analysing a single build-up?

4.3 Calculate the true skin :Q (MMscf/d) S'5 710 1120 19

S0 =

5. Non-Unique Data Sets

5.1 What can a dual-porosity slabs/spheres response be confused with?

5.2 If the derivative dives down at the end of a build-up, what are the 2 possible solutions?

1

2

5.3 How can we decide which one is correct?


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6. Horizontal Wells

6.1 What are the 3 flow regimes seen in a horizontal well test?

1

2

3

6.2 Why would we be unlikely to see all three?

6.3 Which flow regime gives us the true kh of the system?

7. Special Responses

7.1 In an injection well test, which is the first model that you should consider?

analisis nodal chapter 07

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