Sanctions that somehow prevent Venezuela from pumping their own oil?
Yes and no. Sanctions block them from getting outside assistance for maintenance, of both oil infrastructure, and electrical grid. (No power, no oil!) And, it's not just pumping your own oil, it's also a matter of refining it, which is an entirely different process, and requires quite a lot of other materials as well. I have no idea how much of that stuff Venezuela has on its own. Following is from 2016, and I'm sure the issues are only worse now, especially since their biggest? power plant lost some turbines or something recently.
https://www.reuters.com/article/us-refinery-operations-pdvsa-idUSKCN0XN2RS
Output has dropped at the crisis-hit OPEC countrys refineries in recent months, with critics blaming shortages of spare parts, lack of maintenance, and a shaky electrical grid.
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At the weekend we were producing at around 25 percent, nothing more, lamented a worker at Amuay.
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The malfunctioning of several loading arms at Jose port has led to a backlog of tankers for the last month, according to a union leader and Thomson Reuters data.
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In addition, Venezuelas steep economic recession has crimped PDVSAs ability to pay contractors and service companies.
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This month, U.S. oil services firm Halliburton Co and Schlumberger, the worlds No. 1 oil services company, said they were curtailing or reducing activity in Venezuela.