relational location it is to be understood that the subject of the present disclosure is not limited to the exact details of construction operation exact materials or embodiments shown and described as modifications and equivalents will be apparent to one skilled in the art in the drawings and specification there have been disclosed illustrative embodiments of the subject disclosure and although specific terms are employed they are used in a generic and descriptive sense only and not for the purpose of limitation accordingly the subject disclosure is therefore to be limited only by the scope of the appended claims referring now to fig2 one example of a wellbore assembly 40 is shown in a side sectional view where the wellbore assembly 40 is shown mounted above a wellbore 42 that is formed within a subterranean formation 44 in the example embodiment of fig2 the wellhead assembly 40 includes a production tree 46 that mounts over a wellhead housing 48 in the example of fig2 the wellhead housing 48 includes an outer tubular 50 shown depending into the wellbore 42 the outer tubular 50 can be a string of casing such as conductor pipe or production casing also depending into the wellbore 42 is production tubing 52 illustrated as concentrically disposed within the casing 50 and registering with the wellbore 42 a main bore 54 is shown above an upper end of the production tubing 52 that extends upward within the production tree 46 and includes a swab valve 56 in its upper portion a production flow line 58.