Sept 12 (Reuters) - NuVista Energy Ltd NVA.TO
* NuVista Energy Ltd provides operational update and pipestone well test results
* NuVista Energy Ltd - reiterate production guidance ranges for Q3 at 26,000 to 29,000 boe/d and Q4 at 35,000 to 38,000 boe/d
* NuVista Energy Ltd - guidance for full year of 2017 is also unchanged at 28,000 to 31,000 boe/d