| 摘要 |
<p>The pulse-tool is used when injecting liquid into a borehole in the ground. When a pulse-valve of the tool opens, liquid passes through from an accumulator to the ground formation, whereby the accumulator pressure falls and the formation pressure rises. When the pulse-valve closes, the accumulator pressure rises and the formation pressure falls. The pulse-valve is driven to open when the pressure differential (PDAF) reaches a high-threshold, at which the PDAF overcomes a biasing force acting to hold the pulse-valve closed. The biasing force is provided by a pair of magnets, in attraction mode. When the PDAF reaches its high-threshold, and the magnets separate, the magnetic attraction force decreases rapidly. This characteristic helps the pulse-valve to open very rapidly, e.g explosively, creating an energetic penetrative shock-wave out into the formation.</p> |
