OPEC production cuts and economic woes are complicating Schlumberger NV’s (SLB.N) efforts to collect $1.1 billion from Ecuador’s state-owned Petroamazonas, casting a cloud over the oil services company’s first-quarter results.  “Continuing payment issues” in Ecuador are hurting earnings, Chief Executive Officer Paal Kibsgaard said in a text of a speech delivered at the Scotia Howard Weil energy conference in New Orleans on Monday.  Earlier this month, Kibsgaard wrote to Ecuadorean President Rafael Correa seeking to resolve an impasse over unpaid bills that he said was causing Schlumberger “considerable financial stress.”  Kibsgaard wrote that talks between top Schlumberger executives and Ecuadorean ministry officials since October “have made no real progress,” according to a copy of the letter seen by Reuters.  “The situation is obviously not sustainable in the long run,” he wrote, adding that Schlumberger was forced to expand debt to finance operations in the country.  Schlumberger did not respond to requests for comment.  Ecuador’s Ministry of Hydrocarbons declined to confirm the talks. The government has acknowledged some problems with payments to oil companies, without specifying which ones.