* Oil-capture systems collect 23,080 barrels on Wednesday
* Alex did not interrupt oil capture, relief well drilling
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By Kristen Hays
HOUSTON, July 1 BP Plc (BP.L) (BP.N) said on Thursday that its oil-capture systems at its leaking well in the Gulf of Mexico collected or burned off 23,080 barrels of oil on Wednesday.
BP spokesman Mark Proegler said rough seas from Hurricane Alex, which went ashore in northeastern Mexico late Wednesday, did not interrupt oil-capture or relief well drilling operations.
He said the relief well the company began drilling on May 2 had reached 12,035 feet, or 2.3 miles, (3.7 km) beneath the seabed.
According to BP's drilling plan, the well will eventually intercept the blown-out well at or near its bottom, or 13,000 feet down, so heavy drilling fluid and cement can be pumped in to plug the leak.
The relief well was within 16 feet of the side of the blown-out well, according to the U.S. Coast Guard, but had to be drilled down further to reach the optimal intercept point.
Proegler said the process was slow because drilling occasionally stopped to allow the use of sensors, which will ensure the relief well is on the right path.
A second backup relief well, begun May 16, has reached 7,048 feet beneath the seabed, Proegler said.
BP spokesman Robert Wine said early to mid-August remained the targeted finish date for the relief wells.
Proegler also said some oil skimming and booming operations had been restarted after seven-foot (2.1 meter) waves and wind gusts of up to 25 miles per hour (40 km per hour) suspended those efforts on Wednesday.
"There will be more booming and skimming today as well," he said.
BP's current oil-siphoning systems can capture up to 28,000 barrels a day, according to its figures.
One system channels oil from a containment cap atop failed blowout preventer equipment through a fixed pipe to a drillship, while the other siphons oil from the blowout preventer through a hose and pipe to a rig, BP said.
The drillship system collected 12.6 percent less oil on Wednesday compared to the previous 24-hour period as lightning storms prompted a slowdown for nearly three hours, BP said on Thursday.
An undetermined amount of oil continues to gush out from under the cap and through vents on top into the sea. A team of U.S. scientists estimate that the leak is spewing up to 60,000 barrels a day overall. (Reporting by Kristen Hays; editing by Paul Simao)