| CPC E21B 21/08 (2013.01) [E21B 21/106 (2013.01)] | 6 Claims |

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1. A well-killing system for ultra-deep well drilling with co-existence of overflow and lost circulation, comprising:
a wellhead blowout preventer;
a mud pit;
a freshwater tank;
a mud material tank;
a mud preparation tank;
a first pressure sensor;
a first three-way control valve;
a second three-way control valve;
a first mud pump;
a second mud pump;
a lost circulation material mud tank;
a third three-way control valve;
a third mud pump;
a first well-killing fluid tank;
a second well-killing fluid tank;
a second pressure sensor;
a first flowmeter;
a second flowmeter;
a fourth three-way control valve;
a gas-liquid separation tank; and
a computer terminal;
wherein the wellhead blowout preventer is provided on an upper side of a wellhead device; and the mud pit, the freshwater tank, the mud material tank and the mud preparation tank are provided outside a wellhead;
an upper part of the wellhead blowout preventer is connected to a first port of the first three-way control valve through a first pipeline; a second port of the first three-way control valve is connected to a first port of the second three-way control valve through a second pipeline; a second port of the second three-way control valve is connected to the first mud pump and the lost circulation material mud tank through a third pipeline; a third port of the second three-way control valve is connected to the second mud pump and the mud pit through a fourth pipeline; a third port of the first three-way control valve is connected to a first port of the third three-way control valve through a fifth pipeline and a first one-way valve; a second port of the third three-way control valve is connected to the first well-killing fluid tank and the second well-killing fluid tank through a sixth pipeline and the third mud pump; a first port of the fourth three-way control valve is connected to a side of the wellhead device through a seventh pipeline; a second port of the fourth three-way control valve is connected to a third port of the third three-way control valve through an eighth pipeline; a third port of the fourth three-way control valve is connected to the gas-liquid separation tank through a ninth pipeline; a lower end of the gas-liquid separation tank is connected to the mud preparation tank through a tenth pipeline; an upper end of the mud preparation tank is connected to the freshwater tank and the mud material tank through an eleventh pipeline; the first pressure sensor and the first flowmeter are provided at the first pipeline; the second pressure sensor and the second flowmeter are provided at the seventh pipeline; and the first pressure sensor, the first flowmeter, the second pressure sensor and the second flowmeter are connected to the computer terminal via a first data cable, respectively.
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