Abstract: A system for connecting an exploratory well into a producing well by retrieving a permanent guide base (P) and replacing the same with a completion guide base (C) containing the necessary equipment for producing from the well. To do this, the permanent guide base comprises two parts; a gimbal part (32) and a platform part (34)--the platform part (34) can be detached from the low pressure wellhead housing (W) and retrieved leaving the wellhead housing (W) and the permanent guide base gimbal part (32) subsea. The wellhead housing (W), provided with a latching profile (154), though not used during exploratory drilling, is now used to latch the completion guide base (C) thereto for production from the well. The two parts of the retrievable permanent guide base are latched together by a latching mechanism (74) which is easily releasable to unlatch one part from the other, and both guide bases (P & C) are provided with wire line guide posts (82) which are easily detachable for replacement if necessary.