If , only 18th (Lanzhou, J-7H), 97th (Urumqi, J-7E), and 99th Brigade (Urumqi, unspecified variant) fly J-7.
Considering J-7E is several years newer than J-7H, I am leaning on 18th Brigade.
I must admit, even if it sounds arrogant, I would thrust my own work () more than Wiki. None of these assignments seem to be correct: The 18th is subordinated to the Ürümqi Base, whereas both the 97th and 99th Brigades as subordinated to Lanzhou Base.
Concerning the 18th I agree with You and it would have been my favourite, but given a post in the PDF by "Icloo":
No detail info on location other than Western Theater, flat land and scattering mountains in far away background may indicate somewhere in North West China.
I'm no longer sure ... In the extreme far-North west there are no J-7 units, the westernmost ones are assigned to the 108th Brigade at Changji or the 112th Brigade at Malan all subordinated to Ürümqi Base.