Stewart Surface Production Operations: Vol 2: Design of Gas-Handling Systems and Facilities

3. Auflage 2014
ISBN: 978-0-12-382208-6
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 672 Seiten

Updated and better than ever, Design of Gas-Handling Systems and Facilities, 3rd Edition includes greatly expanded chapters on gas-liquid separation, gas sweetening, gas liquefaction, and gas dehydration -information necessary and critical to production and process engineers and designers. Natural gas is at the forefront of today's energy needs, and this book walks you through the equipment and processes used in gas-handling operations, including conditioning and processing, to help you effectively design and manage your gas production facility. Taking a logical approach from theory into practical application, Design of Gas-Handling Systems and Facilities, 3rd Edition contains many supporting equations as well as detailed tables and charts to facilite process design. Based on real-world case studies and experience, this must-have training guide is a reference that no natural gas practitioner and engineer should be without. - Packed with charts, tables, and diagrams - Features the prerequisite ASME and API codes - Updated chapters on gas-liquid separation, gas sweetening, gas liquefaction and gas dehydration

Dr. Maurice Stewart, PE, a Registered Professional Engineer with over 40 years international consulting experience in project management; designing, selecting, specifying, installing, operating, optimizing, retrofitting and troubleshooting oil, water and gas handling, conditioning and processing facilities; designing plant piping and pipeline systems, heat exchangers, pressure vessels, process equipment, and pumping and compression systems; and leading hazards analysis reviews and risk assessments.

Autoren/Hrsg.

Stewart, Maurice

Leseproben

Chapter Two

Basic Principles

Abstract

This chapter reviews the principles and fluid properties related to the selection and design of gas-handling, conditioning, and processing equipment. It also discusses some of the common calculation procedures, conversions, and operations used to describe the fluids encountered in gas-production operations. The chapter then provides a fluid analysis of a typical gas well, and the sample analysis is used to calculate values related to the design of gas-handling facilities, such as apparent molecular weight, gas specific gravity, liquid density and specific gravity, viscosity, and gas/liquid compositions. The chapter ends by characterizing the flow stream and performing flash calculations.

Keywords

fluid analysis

physical properties

equations of state

molecular weight

apparent molecular weight

gas specific gravity

liquid specific gravity

nonideal gas equations of state

liquid density

liquid volume

viscosity

flash calculations

gas composition

liquid composition

“K” factors

flash calculations

approximate flash calculations

dew point

bubble point

net heating value

gross heating value

Reid vapor pressure

phase equilibrium

2.1 Introduction

Before discussing gas-handling, conditioning, and processing equipment and design techniques, it is necessary to review some basic principles and fluid properties. We will also discuss some of the common calculation procedures, conversions, and operations used to describe the fluids encountered in production operations.

2.2 Fluid Analysis

An example fluid analysis of a typical gas well is shown in Table 2.1. Note that only paraffin hydrocarbons are shown. This is not correct, even though only paraffin hydrocarbons may be the predominant series present. Also note that all molecules of heptane and larger ones are lumped together as heptanes plus fraction.

Table 2.1

Example Fluid Analysis of a Gas Well

Component

Mol%

Methane (C1)

35.78

Ethane (C2)

21.46

Propane (C3)

1.40

i-Butane (i-C4)

5.35

n-Butane (n-C4)

10.71

i-Pentane (i-C5)

3.81

n-Pentane (n-C5)

3.07

Hexanes (C6)

3.32

Heptanes plus (C7 +)

3.24

Nitrogen

0.20

Carbon dioxide

1.66

Total

100.00

Sometimes operators request more complete analysis with many more components listed. Process engineers often like to input all of this data into their simulation models, but from a practical standpoint the exact composition of these higher-end components makes little difference in sizing equipment. In addition, fluid samples often are not totally representative of what is eventually produced through the facility as new wells are drilled and reservoir conditions change. Optimizing a design to a precise set of “given” fluid properties may result in a facility that is not flexible enough to handle the inevitable changes that occur in oil and gas field developments.

2.3 Physical Properties

An accurate estimate of physical properties is essential if one is to obtain reliable calculations. Physical and chemical properties depend on:

• Pressure

• Temperature

• Composition

Most hydrocarbon streams are mixtures of hydrocarbons that may contain varying quantities of contaminants such as:

• Hydrogen sulfide

• Carbon dioxide

• Water

The more similar the character of the mixture molecules, the more orderly is their behavior. A single-component system composed entirely of a simple molecule, such as methane, behaves in a very predictable, correctable manner.

The accuracy of calculations decrease in the following order:

• Single-component system

• Mixture of molecules from the same homologous series

• Mixture of molecules from different homologous series

• Hydrocarbon mixtures containing sulfur compounds and/or carbon dioxide

Performance data for a single-component system can be accurately correlated in graphic or tabular form. For all others, one must use either pressure/volume/temperature (PVT) equations of state or the weighted average. The weighted average assumes that the contribution of an individual molecule is in proportion to its relative quantity in the mixture. The more dissimilar the molecules, the less accurate the prediction becomes. Table 2.2 lists some of the physical properties of some of the paraffin hydrocarbon series.

Table 2.2

Physical Properties of Paraffin Hydrocarbons

Molecular weight

16.043

30.070

44.097

58.124

58.124

72.151

72.151

86.178

100.205

114.232

128.259

142.286

Boiling point @ 14.696 psia, °F

- 258.73

- 127.49

- 43.75

10.78

31.08

82.12

96.92

155.72

209.16

258.21

303.47

345.48

Freezing point @ 14.696 psia, °F

- 296.44

- 297.49

- 305.73

- 255.28

- 217.05

- 255.82

- 201.51

- 139.58

- 131.05

- 70.18

- 64.28

- 21.36

Vapor pressure @100 °F, psia

(5000.0)

(800.0)

188.4

72.58

51.71

20.445

15.574

4.960

1.620

0.5369

0.1795

0.0609

Density of liquid @ 60°F and 14.696 psia

Relative density @ 60 °F/60 °F

(0.3)

0.3562

0.5070

0.5629

0.5840

0.6247

0.6311

0.6638

0.6882

0.7070

0.7219

0.7342

°API

(340.0)

265.6

147.3

119.8

110.7

95.1

92.7

81.60

74.08

68.64

64.51

61.23

Absolute density, lbm/gal (in vacuum)

(2.5)

2.970

4.227

4.693

4.870

5.208

5.262

5.534

5.738

5.894

6.018

6.121

Apparent density, lbm/gal (in air)

(2.5)

2.960

4.217

4.683

4.861

5.198

5.252

5.524

5.729

5.885

6.008

6.112

Density of gas @ 60 °F and 14.696 psia

Relative density (air = 1), ideal gas

0.5539

1.0382

1.5225

2.0068

2.0068

2.4911

2.4911

2.9755

3.4598

3.9441

4.4284

4.9127

lb/M ft3, ideal gas

42.28

79.24

116.20

153.16

153.16

190.13

190.13

227.09

264.06

301.02

337.98

374.95

Volume @ 60 °F and 14.696 psia

Liquid, gal/lb-mol

(6.4)

10.13

10.43

12.39

11.94

13.85

13.72

15.57

17.46

19.38

21.31

23.45

Ft3 has/gal liquid, ideal gas

(59.1)

37.48

36.375

30.64

31.79

27.39

27.67

24.37

21.73

19.58

17.81

16.33

Ratio, gas/liquid, in vacuum

(442.0)

280.4

272.1

229.2

237.8

204.9

207.0

182.3

162.6

146.5

133.2

122.2

Critical conditions

Temperature,...