US EPA

8802898 

Journal Article 

Sand valves to protect downhole pumping equipment in the conditions of high sand production 

Myrzakhmetov, BA; Nurkas, ZB; Toktamissova, SM; Krupnik, LA 

2020 

2020 

12 

125-136 

Russian 

10.25018/0236-1493-2020-12-0-125-136 

Sand production is one of the prevailing implications in in-situ leaching and one of the main causes of borehole pump failures. The adverse effects of sand production in in-situ leaching of uranium can be abated using techniques and equipment connected with optimization and control of pumping equipment operation and drainage rate, or involving engineering devices such as sand filters and sand anchors. Yet these techniques and guidelines are only efficient in case of continuous well performance. Now that many deposits approach their final operating phase, the problem of sand production becomes increasingly more acute, for wells with low flow rates are switched to periodic duty, which leads to formation of sand plugs above pumps. In this case, after such wells are started again after the work stoppage, the pumps can suffer from chocking, or hoses can collapse. High sand production during pumping-out of uranium pregnant solutions is due to the shallow depth of pumping wells (400-600 m) since the well bottoms occur in weakly cemented sand beds in this case. These problems call for engineering of effective downhole facilities both to prevent sand entry in pump inlets and also to eliminate plug formation above the pumps. This subject is discussed in this article. New designs of sand valves are proposed for rodless and sucker-rod pumps with adjustable actuation depending on concentration and sedimentation time of mechanical impurities in pumped fluids. This engineering solution allows discharge of the standing column with the highest concentration of mechanical impurities from the stalk to annular space. Furthermore, the energy input and the load on the pump motor during the well re-start are decreased. Application of the new-design sand valves can reduce operating expenses connected with equipment failure and can expand the repair interval of production wells. © 2020 Publishing house Mining book. All rights reserved. 

Downhole pumping equipment; Implications; Mechanical impurities; Protection; Sand production; Sand valve; Sucker-rod screw pump