Propulsion apparatus for positioning selected tools in tubular members

A method of propelling and positioning a selected tool in a tubular member in response to fluid pressure exerted within the tubular member, comprising the steps of:

• attaching propulsion apparatus to the lower mating end of the downhole tool, said propulsion apparatus comprising:
• a top sub portion adapted for connection to the mating end of the selected tool,
• an elongated tubular mandrel depending from said top sub portion and terminating in a lower free end,
• a tubular sleeve concentrically disposed around said elongated tubular mandrel and adapted for coaxial sliding movement with respect thereto,
• cup apparatus mounted on said sleeve and having at least one fin element projecting radially and circumferentially therefrom for substantially reducing all of the annular space between said sleeve and the inner surface of the tubular member and cooperating with said sleeve and the tubular member and fluid pressure exerted therein for translating fluid pressure developed in the tubular member into forces cooperating with said cup apparatus and acting as a propelling force applied to said sleeve, and
• sleeve retaining means cooperating with said sleeve and mandrel for positioning and retaining said sleeve in a first position with respect to said mandrel and cooperating with said fluid pressure for transmitting said fluid pressure forces cooperating with said cup apparatus and sleeve to said mandrel and the attached tool,
• increasing the pressure of the fluid in the tubular member above said cup apparatus for creating a fluid differential pressure thereacross that translates into coaxial propelling forces acting thereon,
• positioning the propulsion apparatus and attached tool to a desired position in the tubular member in response to said coaxial propelling forces acting on said cup apparatus, and
• creating a selected change in the fluid pressure differential across said cup apparatus for cooperating therewith and with said retaining means for releasing said sleeve from said mandrel and permitting predetermined coaxial sliding movement therebetween from said first position with respect to said mandrel, said predetermined movement of said sleeve with respect to said mandrel allowing substantial equalization of the differential pressure across said cup apparatus.