HOUSTON - A backlog of tankers waiting to unload around Venezuela has built up, even though a crude cargo from France’s Total and another six tankers carrying products were recently discharged at state-run PDVSA’s ports after weeks of delays, according to Reuters tracking data and shippers. Several oil providers and PDVSA have agreed to a type of prepayment mechanism that involves loading cargoes and paying for them just before delivery, but even so some unpaid cargoes have been swirling around Venezuelan ports since November, traders said. A dozen and a half tankers, mostly carrying refined products, were anchored around Venezuela and Curacao - where PDVSA operates a refinery and a storage facility - waiting to discharge as of Dec. 2, according to Reuters vessel tracking data. Another 45 vessels were heading towards the Caribbean or waiting to load crude or products at PDVSA’s terminals as well. “PDVSA has paid some providers, tanker owners and brokers, but the company still has many pending debts,” a shipper waiting for freight payments told Reuters. A dozen tankers waiting to unload and some 50 preparing to load were anchored around Venezuela last week, according to the same data. The firm responded to backlog reports, saying its exports, imports and port activity were “completely normal.” It added that it was importing under open credit agreements, letters of credit and prepayments. An oil tanker that was anchored off Nicaragua’s coast for four days waiting for a freight payment from PDVSA discharged last month and is now passing through the Panama Canal to load again in Curacao, according to the data. But a 935,000-barrel cargo of Angolan Girassol crude on tanker Maran Pythia sold by Statoil is still waiting to discharge after 27 days. Another one, on tanker Barcelona Spirit sold by trading firm Helsinge Inc, is expected to arrive in Curacao from Nigeria on Dec. 9 carrying 1 million barrels of Qua Iboe crude. A PDVSA’s internal report seen by Reuters on Wednesday said that last week it received three heavy naphtha cargoes, of 460,000-500,000 barrels each, from trading firms Citizen Resources LLC, Helsinge Inc and Vitol. Most of them were loaded at the U.S. Gulf Coast and have not discharged yet.