there are existing oil riggs of the coast of California which were shut down with the ban

Which ban? And can you provide any documentation to verify this? I cannot find one single piece of legislation or bill passed that shuts down any existing platforms. Even the California State Lands Commission Offshore Gas and Oil lease summary shows that existing leases have continued to be developed since 1965, with undeveloped leases dropping to NONE in 2008).
Source: California State Lands Commission Oil and Gas Lease Summary - 2008

Even so, according to the California Division of Oil, Gas and Geothermal Resources (DOGGR) January 2008 preliminary report, offshore drilling (both State and Federal) in California produced a total of 38.2 million barrels of oil in 2007, and has been declining steadily. Given that, according to recent US Department of Energy estimates, the US consumes 20.68 million barrels of oil a day, that (1 years worth of pumping) would not even provide us with two days worth of oil. The addition of a few more wells would, as the proverbial saying goes, just be a drop in the bucket.

Source: US Department of Energy Petroleum Basic Statistics
Source: State of California DOGGR 2007 Preliminary Report of Oil and Gas production

See how the GOV defines "reserves"

Sure, here it is:

Proved reserves are estimated quantities that analysis of geologic and engineering data demonstrates with reasonable certainty are recoverable under existing economic and operating conditions.

And while "some people" believe there is more oil, does it really matter? Shouldn't we instead be focusing on the real goal of moving away from oil, and towards other renewable energy sources. I for one, would rather see the money that would be spent trying to find additional oil better spent on finding and developing cheaper and more environmentally friendly renewable alternative energy sources.

Cheers,
Brad

To be old and wise, you must first be young and stupid.