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Line 25: + + + − The figure below depicts typical decline curves for a wellbore draining a reservoir system with a strong water drive (A) and a partial water drive (B).+ − − [[file:predicting-reservoir-system-quality-and-performance_fig9-6.png|thumb|{{figure number|9-6}}See text for explanation.]]
Reservoir drive mechanisms (view source)
Revision as of 19:54, 19 February 2014
, 19:54, 19 February 2014→Water drive
==Water drive==
==Water drive==
[[file:predicting-reservoir-system-quality-and-performance_fig9-6.png|thumb|{{figure number|1}}See text for explanation.]]
A strong water drive provides very good pressure support from the aquifer (100% voidage replacement) with minimal pressure drop at the wellbore. The aquifer water expands slightly, displacing the oil or gas from the reservoir toward the borehole as pressure drops around the borehole. This mechanism exists only where the aquifer is of equal or better quality than the reservoir and has a much larger volume than the reservoir (about 10 times) or is in communication with surface recharge. A strong water drive is more effective in oil reservoirs than in gas reservoirs. On a semi-log plot of production decline, the curve tends to be flat.
A strong water drive provides very good pressure support from the aquifer (100% voidage replacement) with minimal pressure drop at the wellbore. The aquifer water expands slightly, displacing the oil or gas from the reservoir toward the borehole as pressure drops around the borehole. This mechanism exists only where the aquifer is of equal or better quality than the reservoir and has a much larger volume than the reservoir (about 10 times) or is in communication with surface recharge. A strong water drive is more effective in oil reservoirs than in gas reservoirs. On a semi-log plot of production decline, the curve tends to be flat.
In fields where the aquifer is smaller and/or has lower quality, there is limited expansion of water into the reservoir as oil or gas is withdrawn. This is a partial water drive.
In fields where the aquifer is smaller and/or has lower quality, there is limited expansion of water into the reservoir as oil or gas is withdrawn. This is a partial water drive.
[[:file:predicting-reservoir-system-quality-and-performance_fig9-6.png|Figure 1]] depicts typical decline curves for a wellbore draining a reservoir system with a strong water drive (A) and a partial water drive (B).
==Partial water drive==
==Partial water drive==