The invention discloses a continuous sand-washing process and a continuous sand-washing device formed by, firstly, mounting
control valves one by one on the upper port of a sand-washing
pipe column and on the upper port of a single sand-washing
pipe column. When the control valve is open, a regular sand-washing
pipe column reaches down. When the sand-washing pipe column approaches or reaches the sand
sediment or oil send at the bottom of a well, if extension is needed, single sand-washing pipe columns provided with
control valves are connected one by one to establish sand-washing circulation channel, start a
mud pump and carry out sand-washing operation; the control valve in open state allows double-way passage and offers such options as regular positive circulation operation and reverse circulation operation. Meanwhile, the control valve is started or closed manually to decouple from or couple with the single sand-washing pipe column. The invention is not subject to the restriction of sand medium and is particularly suitable for sand-washing operation by
nitrogen foam under low-pressure well. The process saves the pressure-releasing time for connecting single sand-washing pipe column every time, realizes continuous sand washing, improves efficiency, prolongs the time of
oil well production, and thus reduces cost and increases benefits.