.......

the oil-and-gas pool was tapped with wells

Oil pool:
an underground reservoir or trap containing oil. A pool is a single, separate reservoir with its own pressure system so that wells drilled in any part of the pool affect the reservoir pressure throughout the pool. An oil field may contain one or more pools.
http://www.enervant.ca/wellsite-glossary.html
An accumulation or body of oil in sedimentary rock that yields petroleum on drilling. The oil occurs in the pores of the rock and is not a pool or pond in the ordinary sense of these words.
http://www.nps.gov/history/history/online_books/geology/publ...

Tap:
pierce in order to draw a liquid from; exploit, draw from; make good use of;
Process of cutting into. Tapping may be performed by a drilling machine.

to penetrate a reservoir - устойчивое выражение, используемое во всех отчетах по грр (егологоразведочным работам). Вскрытие (penetration) может быть полным (complete) или частичным (partial).

--------------------------------------------------
Note added at 2 hrs (2013-09-22 14:43:11 GMT)
--------------------------------------------------

Если наберете в google "penetrating well" или "penetrated reservoir", вылезет куча ссылок на документы, в том числе и на документы аудиторов (Miller&Lenz, RyderScott и др.)