A modularized gas wellpad apparatus and an expansion module, that is repeatable on a per-well or multi-wells basis and can be pre-manufactured. Tie-in points may be limited to a junction box and group and test headers only. The apparatus comprises gas handling components located close to the wellhead, and a heated, standalone enclosure for housing environmentally sensitive components. Various embodiments provide for a compact wellpad apparatus having a particular layout. Various embodiments include a built-in capability to mate-up to wellhead as-built locations and dimension deviations without field rework, even for multiple-wells modules.