Pts. Oil Formation Volume Factor (Bo).

PROBLEM SET 1.

DUE: Fiday, 11^th SEPTEMBER 2015, IN CLASS.

Pts. Learn to convert SI units to Metric Units.

Show us the calculation.

How many psia in 300Bars? (4352 PSI) (300*10^5)/6894

How many deg C in 99 deg F? ((99-32)/1.8=37.2

How many M3 in 150 STB? (150*0.159)=23.85

Pts. API degree

· What is the API degree of oil with density of 800 kg/m3 and 1050 kg/m3?

· 1) Oil density = 800kg/m3, water density at standard conditions = 1000kg/m3.

· SG(oil) = 800 / 1000 = 0.8

· API Gravity = (141.5 / 0.8) - 131.5 = 45.375

· 2) Oil density = 1050kg/m3, water density at standard conditions = 1000kg/m3.

· SG(oil)=1050/1000 = 1.05

· API Gravity = 141.5/1.05 - 131.5 = 3.3

·

· What is the density(kg/m3) of oil with API of 13?

·

· 3) API gravity = 13

· SG = 141.5/ (API gravity + 131.5) = 141.5 / (13+131.5) = 0.979 Density= (0.979*1000)=979 kg/m3

·

Pts. Phase Diagram.

Work with the phase envelop diagram (Figure 1, Y axis - pressure, X axis - temperature).

· Is there a Gas Cap in the reservoir if Pres=3800, Tres=70?

· Are Psep and Tsep at Standard Conditions? What is a standard conidtion?

· Not, because as the standrat conditions of pressure and temperature we assume 1atm and 25 degreeC

· If Tres=100degC, what would be Bubble Point Pressure?

· If Tres=170degC, what would be Dew Point Pressure?

Figure 1. Phase envelop diagram

pts. Oil Formation Volume Factor (Bo).

Reservoir pressure is 2500 psia and Oil volume is 1500BBL at that conditions.

a) what would be the volume of that oil under standard conditions?

Oil formation volume factor at 2500psia is equal to ~ 1.333

Bo - Oil formation volume factor

Bo = BBL/ STB

BBL - Barrel of Oil under reservoir conditions

STB - Stock Tank Barret (barrel of oil under standard conditions)

STB = BBL / Bo =1 500 / 1.333= 1125.28 STB

b) what would be the volume of that oil under 1200psia conditions?

b) So, Vo = 1125.28 STB.

From the Figure 2, you can see that at 1200psia pressure Bo = 1.210

Vo(BBL-reservoir Conditions) = 1125.28 * 1.210 = 1361.59 BBL.

Figure 2. Formation Volume Factor

6) 15 pts. Solution Gas/Oil Ratio(Rs).

The oil that used to be under reservoir conditions (Pres=3000) was produced to the surface and gas got separated from that oil. The surface volume of oil is 3000STB. What is the amount of gas (SCF) was released?

At pressure of 3500 psia, Solution Gas Oil Ratio - 567 SCF/STB (look at figure 3)

GOR = 567 SCF/STB

SCF - Standard Cubic Feet of Gas

STB - Stock Tank Barrel of Oil

Vo = 3000 STB

Vg = 567(SCF/STB) * 3000(STB) = 1701000 SCF of Gas

Figure 3. Solution Gas

6) 20pts. Combination of Formation Volume Factor and Solution Gas/Oil Ratio

Use Figure 2 and Figure 3 to solve this problem.

Reservoir Pressure (Pres=1200psia), oil volume under reservoir conditions is equal to 2200BBL.

· What is the oil volume under standard conditions?

· STB= BBL/B0= 2200/1.2=1833 STB

· What is the gas volume under standard conditions?

· GOR=337 (SCF/STB)

· V(gas)= 337*STB=337*1833=617721 SCF of gas

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