Coupon holder for corrosion test downhole in a borehole

In a borehole having a rod actuated downhole pump located at the lower end of a production tubing and a rod in said production tubing for actuating said pump, the combination with said rod of a coupon holder for measuring the rate of corrosion downhole in the borehole;

• said coupon holder comprising a main body having opposed ends by which said main body is series connected within the rod which is attached to the downhole pump which is suspended downhole in the borehole, and further comprising;
• said main body being an elongated cylinder;
• an axial chamber formed by an interior wall surface within said main body;
• spaced radial ports extending through a sidewall of said main body and communicating said axial chamber with ambient;
• said spaced radial ports being circumferentially disposed about the axial chamber and oblated to present a lower curved end opposed to an upper curved end;
• an insulator, means for mounting said insulator at one end of said chamber;
• a corrodible test coupon mounted within said chamber, means by which said coupon is supported by said insulator wherein said coupon is insulated from said interior wall surface;
• wherein the insulator has a boss formed thereon, said main body is made of upper and lower members affixed to one another;
• said upper member receives said insulator axially, and said coupon is supported by said insulator and extends along the central longitudinal axis of the chamber;
• said upper and lower members having spaced confronting shoulders that abuttingly engage opposed faces of said boss;
• said lower curved end of each port being sloped downwardly and outwardly with respect to said longitudinal axis whereby reciprocation of the coupon holder forces well fluid to flow through said chamber;
• whereby, well fluid makes contact with said coupon and the coupon reacts with the well fluid, and the rate of reaction between the coupon and the well fluid provides an indication of the corrosion rate.

In a pumping unit having a pump located in a borehole and a sucker rod string extending downhole through a tubing string to actuate the pump, the combination with said rod string of a coupon holder apparatus for measuring the corrosive properties of the fluid contained downhole in the borehole wherein;

• said coupon holder apparatus for measuring the rate of corrosion downhole in a borehole includes a main body;
• said main body has opposed ends by which said main body is connected within and forms part of said rod string and is thereby suspended down hole in the borehole in series relationship respective to the rod-string and supports part of the downhole pump, and comprising;
• an axial chamber in said main body formed by an interior wall surface;
• radical ports extending through a sidewall of said main body and communicating said axial chamber with the exterior of said main body;
• a corrodible test coupon, means by which said coupon is mounted within said chamber;
• means for insulating said coupon from the interior wall surface that forms said chamber;
• said main body being comprised of an upper member and a lower member;
• means threadedly attaching said upper and lower members together in a removable manner;
• wherein, said means for insulating is an insulator and said coupon is supported therefrom;
• said insulator has a boss formed thereon and is mounted to an end wall of the upper member and extends into the chamber, said chamber being located in the lower member, wherein an outer face of the boss is placed closely adjacent to an upper annular face of the lower member;
• whereby;
• well fluid makes contact with said coupon, and the coupon reacts with the well fluid, so that the rate of reaction between the coupon and the well fluid is an indication of the rate of corrosion.