and cavity each tube is lowered into the well at the end of a surface operated arm which is raised to the horizontal once inside the lined cavity 29 the tubing is then oriented and lowered so as to position the base of the tube over a connecting piece 37 at the end of each of the extended distributor arms when the connecting piece is mated with the base or the tube a pressure tight connection is achieved by means of suitable metal metal seals after all catalyst filled tubes have been installed at the periphery of the lined cavity an extension of the water tubing 3 consisting of a set of articulated radially extending spray ramps 38 is lowered into the well in the folded position and opened when inside the upper part of the lined cavity the extension of the syngas tubing 2 is then installed to connect with the center base plate 36 and radial distributor tubes 35 after installation of the valve section 9 and connection with the horizontal drainholes water is displaced from the syngas tubing and from the upper part of the lined cavity the downhole methanator is then ready for start up by injection of high pressure syngas which opens the check valves protecting the catalyst from water entry the start up sequence is the same as previously described under normal operations the lined cavity partly filled with boiling water serves as water steam separator the.