(a) When a well penetrates one or more workable coal beds, the well operator shall run and cement a string of casing in the hole through the workable coal bed or beds in such a manner as will exclude all oil, gas or gas pressure from the coal bed or beds, except such oil, gas or gas pressure as may be found in such coal bed or beds. Such string of casing shall be run to a point at least thirty feet below the lowest workable coal bed which the well penetrates and shall be circulated and cemented from such point to the surface in such a manner as provided for in reasonable rules promulgated by the director in accordance with the provisions of chapter twenty-nine-a. After any such string of casing has been so run and cemented to the surface, drilling may proceed to the permitted depth.
(b) In the event that gas is found beneath a workable coal bed before the hole has been reduced from the size it had at the coal bed, a packer shall be placed below the coal bed, and above the gas horizon, and the gas by this means diverted to the inside of the adjacent string of casing through perforations made in such casing, and through it passed to the surface without contact with the coal bed. Should gas be found between two workable beds of coal, in a hole, of the same diameter from bed to bed, two packers shall be placed, with perforations in the casing between them, permitting the gas to pass to the surface inside the adjacent casing. In either of the cases here specified, the strings of casing shall extend from their seats to the top of the well.