Changes

More complex tests, with abrupt changes in rate and BHP, are more readily analyzed with computer reservoir simulators. These simulators are used to history-match production data to obtain a reservoir description, which is then used to obtain a long-term production forecast and thus to estimate reserves. [[:file:pressure-transient-testing_fig8.png|Figure 8]] shows an example of a history match of production data and a forecast of future performance of the well using the reservoir description obtained from the history match.

More complex tests, with abrupt changes in rate and BHP, are more readily analyzed with computer reservoir simulators. These simulators are used to history-match production data to obtain a reservoir description, which is then used to obtain a long-term production forecast and thus to estimate reserves. [[:file:pressure-transient-testing_fig8.png|Figure 8]] shows an example of a history match of production data and a forecast of future performance of the well using the reservoir description obtained from the history match.

==Interference and pulse tests==

==Interference and pulse tests==

[[file:pressure-transient-testing_fig9.png|left|thumb|{{figure number|9}}Active and observation wells in an interference pulse test.<ref name=pt09r7>Earlougher, R. C., Jr., 1977, Advances in Well Test Analysis: Dallas, TX, American Institute of Mining, Metallurgical and Petroleum Engineers, Society of Petroleum Engineer's Monograph 5, 264 p.</ref>]]

[[file:pressure-transient-testing_fig10.png|thumb|{{figure number|10}}Schematic illustration of rate history and pressure response for an interference test. (After <ref name=pt09r7 />.)]]

Interference and pulse tests are run to obtain the following information:

Interference and pulse tests are run to obtain the following information:

* Average porosities in the areas influenced by the tests

* Average porosities in the areas influenced by the tests

[[file:pressure-transient-testing_fig10.png|thumb|{{figure number|10}}Schematic illustration of rate history and pressure response for an interference test. (After <ref name=pt09r7 />.)]]

[[file:pressure-transient-testing_fig11.png|left|thumb|{{figure number|11}}Schematic Illustration of rate (pulse) history and pressure response for a pulse test.<ref name=pt09r7 />]]

===How the tests are run===

===How the tests are run===

Interference tests are run by first shutting in the portion of the reservoir in the area affected by the test. Then one produces (or injects into) one well (called the active well) and measures the pressure response in the offset wells. [[:file:pressure-transient-testing_fig9.png|Figure 9]] shows a typical interference test pattern, and [[:file:pressure-transient-testing_fig10.png|Figure 10]] is a plot of a typical response in an observation well.

Interference tests are run by first shutting in the portion of the reservoir in the area affected by the test. Then one produces (or injects into) one well (called the active well) and measures the pressure response in the offset wells. [[:file:pressure-transient-testing_fig9.png|Figure 9]] shows a typical interference test pattern, and [[:file:pressure-transient-testing_fig10.png|Figure 10]] is a plot of a typical response in an observation well.

Pulse tests are performed by first producing (or injecting into) the active well for a few hours. The active well is then shut-in, then returned to production, shut-in again, and so on in a regular, repeating pattern. The response in the offset wells is then measured while continuing to produce all wells in the field except those directly involved in the test. This is possible because the “noise” caused by continued production of wells not directly involved in the test can be filtered out using the response caused by the repeated on-off pattern in the active well. [[:file:pressure-transient-testing_fig11.png|Figure 11]] shows a typical response in a pulse test observation well.

Pulse tests are performed by first producing (or injecting into) the active well for a few hours. The active well is then shut-in, then returned to production, shut-in again, and so on in a regular, repeating pattern. The response in the offset wells is then measured while continuing to produce all wells in the field except those directly involved in the test. This is possible because the “noise” caused by continued production of wells not directly involved in the test can be filtered out using the response caused by the repeated on-off pattern in the active well. [[:file:pressure-transient-testing_fig11.png|Figure 11]] shows a typical response in a pulse test observation well.