THC rich strains have been shown to act on the lower esophageal sphincter to decrease reflux of stomach acids back up into the esophagus.
GERD symptoms are caused by a malfunction of the lower esophageal sphincter which causes stomach acids to reflux back up causing the heartburn symptoms.
I would look for a THC dominant strain. It may be best to use vape, sublingual tincture form for rapid onset of action.
I am quoting from the "Asian Pacific Journal of Tropical Medicine":
"There is evidence that CB1 receptor stimulation with synthetic cannabinoids or Cannabis sativa extracts rich in Δ9-tetrahydrocannabinol inhibit gastric acid secretion in humans and experimental animals."