Deep wells usually are provided with a well head, and sometime there are so many appurtenances attached to the well head that it becomes a Christmas tree. From time to time it is necessary to enter the borehole with various different downhole tools or apparatus which are run downhole into the wellbore, as for example, perforating guns; fishing tools; logging tools; instrument packages; special tools to set packers, and many other devices.
A lubricator is a long pipe section having special valves arranged thereon in a manner to permit various apparatus to be attached to a slick line, or wire line, passed through the interior of the lubricator, and thus introduced into the well bore. The wellhead has facilities by which the lubricator can be removably affixed thereto. One end of the lubricator is provided with an adaptor by which the lubricator is attached to the wellhead, with the other end extending vertically above the wellhead, thereby making it possible to translocate various tools or devices from ambient into the borehole.
The borehole usually has an internal pressure that is far above ambient and therefore specially trained technicians are entrusted with the task of translocating devices into the lubricator and thence into the borehole. It is necessary for the technicians to be present at the uppermost end of the lubricator to attend to a number of different tasks while lowering the various devices down through the lubricator and down into the borehole. It is dangerous to employ ordinary ladders for scaling the lubricator because of the everlasting messy condition of most well sites caused by the presence of crude oil from the wellhead and grease from the lubricator, all of which makes the well site or surroundings dangerously slippery.
Therefore it is desirable to have available a safety ladder made special for removable attachment to a lubricator, or a vertically disposed pipe, which enables a person to safely scale the lubricator after it has been affixed to a well head. Such a safety ladder apparatus is the subject of this invention.