بنك الاسئلة EPS 1ST 2010 441

Problem #1:  A well drilled to 3000 ft penetrates a formation containing 28 ºAPI oil.  If reservoir pressure is 1300 psia, what is the shut-in surface pressure?  If reservoir pressure is 1000 psia, how many ft of oil will be standing in the wellbore?

Problem #2:  The average reservoir properties of a 300 acre reservoir are: φ = 18% and S_w = 36%.  Estimated volume of oil originally in place = 410 MM STB.  Formation thickness = 2000 ft.  Determine the oil formation volume factor.

Problem #3:  The following data are given for the Hout Oil Field:

Area                                                     = 26,700 acres

Net productive thickness                       = 49 ft

Porosity                                                = 8%

Average S_w                                          = 45%

Initial reservoir pressure, p_i                   = 2980 psia

Abandonment pressure, p_a                    = 300 psia

B_o at p_i                                                 = 1.68 bbl/STB

B_o at p_a                                                 = 1.15 bbl/STB

S_g at p_a                                                 = 34%

S_or after water invasion              = 20%

Calculate the following:

1)  Initial oil in place

2)  Oil in place after volumetric depletion to abandonment pressure

3)  Oil in place after water invasion at initial pressure

4)  Oil reserve by volumetric depletion to abandonment pressure

Solution:

V_b = 7758 x A x h = 7758 x 26,700 x 49 = 10.15 MMM bbl

1)  The initial oil in place is given by:

This yield:

2)  Oil in place after volumetric depletion to abandonment pressure is given by:

This yield:

3)  Oil in place after water invasion at initial reservoir pressure is given by:

This yield:

4)  Oil reserve by volumetric depletion

i.e. RF = 118/266 = 44%

Problem #4:  The following data are given for the Bell Gas Field:

Area                                                     = 160 acres

Net productive thickness                       = 40 ft

Initial reservoir pressure                        = 3250 psia

Porosity                                                = 22%

Connate water                                      = 23%

Initial gas FVF                                      = 0.00533 ft³/SCF

Gas FVF at 2500 psia                          = 0.00667 ft³/SCF

Gas FVF at 500 psia                            = 0.03623 ft³/SCF

S_gr after water invasion              = 34%

Find the following:

1)         Initial gas in place

2)         Gas in place after volumetric depletion to 2500 psia

3)         Gas in place after volumetric depletion to 500 psia

4)         Gas in place after water invasion at 3250 psia

5)         Gas in place after water invasion at 2500 psia

6)         Gas in place after water invasion at 500 psia

Solution:

V_b = 43,560 x A x h = 43,560 x 160 x 40 = 278.784 MM ft³

1)  Initial gas in place is given by:

Which yields:

2)  Gas in place after volumetric depletion to 2500 psia:

3)  Gas in place after volumetric depletion to 500 psia:

4)  Gas in place after water invasion at 3250 psia:

5)  Gas in place after water invasion at 2500 psia:

6)  Gas in place after water invasion at 500 psia: