| 摘要 |
A dual well pumping unit (12) has two hydraulic ram units (26), one for each well, which are connected together for regenerative assist. Synchronized variable stroke and variable speed pump down control is provided, such that should pump down be encountered in one of the wells, programmable controllers (46) reduce the speed and the stroke of a ram unit (26) for a pumped-down well by the same percentage, to maintain a constant cycle time between upstrokes and down strokes such that the ram unit (26) of the pumped down well will remain synchronized with a ram unit (26) of the other well. Preferably the speed and the stroke of the ram unit (26) of the pumped down well will be decreased by 1.5 % per stroke when pump down is detected, and will be increased by 3% per stroke until a constant fluid level is reached. |
