Multipath, multistage, erosion-resistant flow control valves have been developed that can sustain the extremely high pressure of deep oil wells. Fitting in the restricted available space and operating using limited power with a long lifetime are challenges for choke valves in the downhole environment of oil wells. These valves must control the flow rate from high-pressure oil reservoirs in the presence of fluids that have non-zero sand concentrations. This design consists of a digitized flow control valve with multipath and multistage pressure reduction structures. Specifically, the valve is configured as a set of parallel flow paths from the inlet to the outlet.
The choke valve controls the total flow rate by digitally opening different paths or different combinations of paths. Each path is controlled by a poppet cap valve operated in on/off states. To avoid erosion from sand in the oil and high-speed flow, the seal area of the poppet cap valve is located at a distance from the flow inlet away from the high-speed flow. The path is a multistate structure composed of a jet orifice and settling chamber pairs. The pressure drop of each stage and, therefore, the flow speed at the orifices for a set flow rate, is controlled by the number of stages. The paths have relatively small diameters (in centimeters), or cross-sections, and can be relatively long (in meters) for large numbers of stages and still fit in the strict annular space limit in the typical downhole region of an oil well. The actual inlet of the valve for the flow from the formation is located between the inner pipe and the casing pipe, whereas the outlet is positioned towards the inner pipe. The available space for this downhole valve is an annular cylinder between the inner pipe and the casing pipe.
This work was done by Xiaoqi Bao, Mircea Badescu, Stewart Sherrit, Jeffery L. Hall, and Yoseph Bar-Cohen of Caltech for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Technology Transfer at JPL
Mail Stop 321-123
4800 Oak Grove Drive
Pasadena, CA 91109-8099
Refer to NPO-48980.