By Emily Chow SINGAPORE (Reuters) – Oil prices rose as much as 1% on Friday as tensions persisted in the Middle East following Houthi attacks on ships in the Red Sea, although Angola’s decision to leave OPEC raised questions over the group’s effectiveness in supporting prices. Brent crude futures were up 70 cents, or 0.9%, to $80.09 a barrel by 0700 GMT, while U.S. West Texas Intermediate crude futures were up 66 cents, or 0.9%, at $74.55 a barrel. Both of the contracts have risen for a second week, each up over 4%, as the shipping concerns buoyed prices. Rising geopolitical risks due to the R…