Deep-Set Velocity String for Liner Deliquification

Abstract

The installation of a smaller size tubing or velocity string inside an existing tubing completion is a well-known deliquification technique. The velocity string comes in various designs providing different functionalities for deliquification. Typically, velocity strings are installed to the top of the producing reservoir interval. In case multiple reservoirs produce across significant liner length (the liner here is the length/area between the two reservoirs), this "shallow" velocity string does not provide deliquification across the reservoir liner section. Depending on the size and length of the reservoir liner and the inflow performance of the producing reservoirs, the liquid loading across the liner can have significant adverse impact on production in which case deliquification by means of a "deep" velocity string installed across the reservoir liner becomes essential. This paper shares different designs, a modeling methodology and real-life assessment cases of such deep-set velocity strings, to achieve deliquification across the tubing completion above the reservoir and the liner completion straddling the reservoir. The proposed designs provide different flow options by changing the setting of sliding side doors (SSD's) embedded in the design or isolating the two zones by packers. The proposed modeling methodology helps to compare the performance of different flow options for shallow and deep velocity string designs. This paper continues by sharing three field cases of deep-set VS for the assessment of its real-life application.