Q. Oil is produced at a constant rate from a well in a bounded reservoir. The variation of the bottom-hole pressure with time is shown in the given Table. The magnitude of the slope of the pressure vs time curve that you would use to find the drainage area is_____-psi/day (round off to 1 decimal place).
| Time (days) | Flowing bottom- hole pressure (psi) | Time (days) | Flowing bottom- hole pressure (psi) |
| 0 | 3500 | 6 | 2512 |
| 1 | 2864 | 7 | 2482 |
| 2 | 2725 | 8 | 2452 |
| 3 | 2644 | 9 | 2422 |
| 4 | 2587 | 10 | 2392 |
| 5 | 2542 | 11 | 2362 |
Ans: 29-31
Sol:
| Time (days) | FBHP (psi) | Slope (∆P/∆t), psi/day |
| 0 | 3500 | |
| 1 | 2864 | -636 |
| 2 | 2725 | -139 |
| 3 | 2644 | -81 |
| 4 | 2587 | -57 |
| 5 | 2542 | -45 |
| 6 | 2512 | -30 |
| 7 | 2482 | -30 |
| 8 | 2452 | -30 |
| 9 | 2422 | -30 |
| 10 | 2392 | -30 |
| 11 | 2362 | -30 |
For a bounded reservoir having constant rate, well must be under pseudo-steady state condition, therefore the slope is -30 psi/day
Magnitude of slope is 30 psi/day