Flashcards in Chapter 7: Properties Of Wet Gases Deck (23):

0

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How many states does a wet gas usually go through when separated?

What are the 3 fluids produced after separation at the surface.

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A wet gas typically goes through 2 stages of separation

Fluids produced after separation:

1. Stock-tank liquid (condensate)

2. Separator gas (SP g)

3. Stock-tank gas (ST g)

1

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What are the conversion factors for:

a) lb-mol -> scf

b) bbl -> cu ft

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a) 1 lb-mol / 380.7 scf

b) bbl / 5.615 cu ft

2

## What is the first step in the conversion of GOR?

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Calculate the density and apparent molecular weight of the stock-tank LIQUID

Ma = sum(y * M) API = (141.5 / STO specific gravity) - 131.5

STO specific gravity = STO density / 62.37

3

## How can you estimate the molecular weight of the stock-tank liquid if it is not known?

###
M(STO) = 5954

_________

(API - 8.8)

Or

M(STO) = (42.43 * STO specific gravity)

___________________________

(1.008 - STO specific gravity)

4

## What is gaseous equivalent and how is it represented in the specific gravity of a reservoir gas equation?

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Gaseous equivalent is the volume in scf of a gas that the stock-tank liquid would occupy if it were vaporized

(133,300 * STO specific gravity) / M(STO)

5

## How do you find the specific gravity of the reservoir gas, if the SP gas & the ST gas properties are known?

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Specific gravity (res g)

= [R(SP) * SP gas specific gravity + R(ST) * ST gas specific gravity]

__________________________________

R(SP) + R(ST)

R = R(SP) + R(ST)

6

## How do you find the MW of the reservoir gas, if SP & ST gas properties are known?

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M(res g) = m(res) / n(res)

= [0.0762*R*(gas specific gravity) + 350.2*(STO specific gravity)] ___________________________________________

0.00263*R + [(350.2*STO specific gravity) / M(STO)]

Units = lb of gas / lb-mol of gas

7

## How do you estimate the PRODUCING GOR, if the properties & quantities of all surface gas streams are known?

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2-stage: R = R(SP) + R(ST)

3-stage: R = R(SP1) + R(SP2) + R(ST)

8

## What are the 4 steps to calculate the composition of a gas with known surface composition of a wet gas?

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1. calculate M(STO) & density of stock-tank LIQUID

2. convert GORs from

(scf SP gas/STB) => (lb mol SP gas/lb mol STO)

(scf ST gas/STB) => (lb mol ST gas/lb mol STO)

3. create a table

4. calculate mol fraction of the recombined reservoir gas

9

## If given the SP GOR and/or ST GOR, what additional steps do you have to take to find the composition of the recombined res gas?

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Convert (scf gas/STB) => (scf gas/STO)

(scf gas/STB) * (1/380.7) * (1/5.615) * [M(STO)/density(STO)]

10

## How do you estimate the specific gravity of the res gas from production data, if the properties & quantities of all surface streams are known?

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Find the weighted avg of the specific gravities of the SP gas & ST gas

=[R(SP) * SP spec gravity] +

[R(ST) * ST spec gravity] / [R(SP) + R(ST)]

11

## How do you find the specific gravity of a ST gas that has gone through a 3-stage SP system, if the quantity of the second SP gas is unknown?

### = [R(SP1)*specific gravity(SP1) + 4600* specific gravity oil + AGP] / R(SP1) + VEQ

12

##
What is equivalent volume (VEQ)?

How do you calculate it if GORs, specific gravity(STO), & M(STO) are known?

Where else can you get the VEQ?

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The vol of second SP gas & ST gas in scf/STB + the vol (in scf) that would be occupied by a bbl of ST liquid if it were a gas

VEQ = R(SP1) + R(ST) + 133,300*(STO specific gravity) / M(STO)

Can get VEQ value from VEQ Correlation charts

13

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What does addition gas produced (AGP) relate to?

How do you determine the AGP value?

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The mass of gas produced from the second SP & ST in a 3-stage separator system

AGP = R(SP2)*(SP2 specific gravity) + R(ST)*(ST specific gravity)

Can get AGP value from AGP Correlation charts

14

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How do you define the formation volume factor of a wet gas in:

a) words

b) an equation, with units

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a) the volume if res gas required to produce 1 STB of liquid at the surface

b) Bwg = V res gas @ res P and T

________________________ ,

V ST liquid @ Std P and T

Scf at res conditions / STB

15

## What are the 4 steps required to calculate Bwg, if surface composition & res conditions are known?

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1. calculate pseudo critical properties of res gas

2. determine z factor & calculate Vm of res gas

3. calculate vol of ST liquid condensate from 1 lb mol of res gas

4. calculate Bwg

16

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How can you determine the vol of res wet gas required to produce 1 STB of liquid?

What are the units?

### vol of res wet gas = R(SP1) + VEQ, (scf/STB)

17

## How do you calculate the molar vol (Vm) of ST liquid?

### Vm of ST liquid = M(STO) / STO density

18

## How do you calculate the vol of wet gas in scf?

###
Bwg = z * [R(SP1) + VEQ] * R T

______________________

380.7 * P

Ideal gas equation of state

19

##
What are the 2 simplified equations used to find Bwg in:

a) res cft gas/STB

b) res bbl gas/ STB

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a) 0.0282 * z * [R(SP1) + VEQ] * T res scf gas

____________________________ , ___________

P STB

b) a) 0.00502 * z * [R(SP1) + VEQ] * T res bbl gas

_____________________________ , ____________

P STB

20

## What are plant products?

### Liquified intermediate hydrocarbons removed from surface gas

21

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How do you find the quantities of liquid product that can be removed from a surface gas (GPM)?

What do you need to know in order to determine these quantities .

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Calculations are for individual components

GPM = 19.65 * [ (y * M) / density] , (gal/Mscf)

Or

GPM = 0.3151* [ (y * M) / specific gravity as a liquid], (gal/Mscf)

Must know the composition of the gas

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