Question

The Hawkins formula may be used to calculate the skin due to formation damage. A well completed on a 500 mD formation with a well spacing of 40 acres (re = 745 ft). The wellbore diameter equals 7 7/8" (0.328 ft). It is planned to perforate the pay zone with a through tubing gun where the perforation charges have a depth of penetration of 14 in. IF it is decided to case the hole. The drilling mud used to drill the well controls the extent of permeability impairment and the depth of damaged region extends beyond the wellbore. The following mud types are available: Mud Permeability in A 100 B 20 C 300 D 200 damage zone (mD) Depth of invasion (ft) 1.6 0.8 2.0 2.3 Procedure for the calculations: 1$^{st}$ Calculate the skin for each mud system using Hawkins equation 2$^{nd}$ calculate the Productivity ratio $J_{original}/J_{impaired}$: $\frac{\ln \frac{r_c}{r_w}}{\ln \frac{r_c}{r_w} + S}$ 3$^{rd}$ Fill in the following table using the calculation results Mud type S $J_{original}/J_{impaired}$ 4$^{th}$ Which mud system do you recommend from a well productivity point of view for an open hole and a cased hole completion?

          The Hawkins formula may be used to calculate the skin due to formation damage. A well
completed on a 500 mD formation with a well spacing of 40 acres (re = 745 ft). The wellbore
diameter equals 7 7/8" (0.328 ft). It is planned to perforate the pay zone with a through tubing
gun where the perforation charges have a depth of penetration of 14 in. IF it is decided to case
the hole. The drilling mud used to drill the well controls the extent of permeability impairment
and the depth of damaged region extends beyond the wellbore. The following mud types are
available:
Mud
Permeability in
A
100
B
20
C
300
D
200
damage zone (mD)
Depth of invasion (ft)
1.6
0.8
2.0
2.3
Procedure for the calculations:
1$^{st}$ Calculate the skin for each mud system using Hawkins equation
2$^{nd}$ calculate the Productivity ratio $J_{original}/J_{impaired}$:
$\frac{\ln \frac{r_c}{r_w}}{\ln \frac{r_c}{r_w} + S}$
3$^{rd}$ Fill in the following table using the calculation results
Mud type
S
$J_{original}/J_{impaired}$
4$^{th}$ Which mud system do you recommend from a well productivity point of view for an open hole
and a cased hole completion?

The Hawkins formula may be used to calculate the skin due to formation damage. A well
completed on a 500 mD formation with a well spacing of 40 acres (re = 745 ft). The wellbore
diameter equals 7 7/8" (0.328 ft). It is planned to perforate the pay zone with a through tubing
gun where the perforation charges have a depth of penetration of 14 in. IF it is decided to case
the hole. The drilling mud used to drill the well controls the extent of permeability impairment
and the depth of damaged region extends beyond the wellbore. The following mud types are
available:
Mud
Permeability in
A
100
B
20
C
300
D
200
damage zone (mD)
Depth of invasion (ft)
1.6
0.8
2.0
2.3
Procedure for the calculations:
1^st Calculate the skin for each mud system using Hawkins equation
2^nd calculate the Productivity ratio Joriginal/Jimpaired:
(ln(rc)/(rw))/(ln(rc)/(rw) + S)
3^rd Fill in the following table using the calculation results
Mud type
S
Joriginal/Jimpaired
4^th Which mud system do you recommend from a well productivity point of view for an open hole
and a cased hole completion?

Added by Amber J.

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