I doubt US exports to china have much effect on domestic crude prices. Global economic slowdown plus trump cheerleading for ME increased prod to offset iran then at the last minute oh yeah and iran can continue to export to a few destinations for a while yet has more to do with crude prices. US is gradually backing away from global cop role. When the first tanker is hijacked and US shrugs shoulders look out. Or iran blocks shipments out of Persian gulf to put others on equal footing with its sanctions. But current US crude prod trajectory allows us not to care that much any longer. The times they are a changing.

https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=MTTEXCH1&f=M