Apparatus to pump multiple wells

Claim 1

In well pumping apparatus adapted to pump two wells via two rod strings in the respective wells and pumping means operated in the wells by the strings, the combination comprising: (a) means at the well surface operatively interconnecting the two rod strings for balancing loading imposed by said strings, (b) said means operatively connected with said strings to lift one string while the other string is lowered, and to lift the other string while said one string is lowered, (c) said means including (x) first piston and cylinder elements associated with one rod string, one of said first elements being connectible with said first rod string, and (y) second piston and cylinder elements associated with the other rod string, one of said second elements being connectible with the second rod string, (d) said means including an hydraulic system interconnecting said first elements with said second elements so that hydraulic pressure acts alternately to lift one of the first elements and then one of the second elements, said means also including an hydraulic fluid pump connected with said hydraulic system via valving having one position in which pumped fluid pressure acts to elevate said one of the first elements, and another position in which pumped fluid pressure acts to elevate said one of the second elements, and said hydraulic system including (i) primary ducting connected with said cylinder elements for alternately supplying fluid pressure to lower chambers defined by said piston and cylinder elements, (ii) secondary ducting interconnecting upper chambers defined by said piston and cylinder elements, and (iii) tertiary ducting interconnecting intermediate chambers defined by said piston and cylinder elements.