Currently

the well control in the drilling engineering design of onshore oil and gas wells mainly includes wellhead device

pressure test and well control requirements in conventional operation

and does not involve the calculation of the overflow quantity of shut-in. In this paper

kick tolerance is considered to be added to the design above

and a calculation method of kick tolerance is given. Combined with the drilling condition of ? 311.1 mm hole of well LJ-20 in gas field A in the Sichuan-Chongqing area

examples were applied to analyze how to add kick tolerance and assist the well control of overflow in drilling site. The calculation results showed that

with the giv

en

KI

value

the deeper the hole was

the smaller the kick tolerance would be; while at the same depth

the kick tolerance also decreased with the increase of the

KI

value. Therefore

it is necessary to add the kick tolerance to the design. Thus

whether the shut-in operation with overflow is safe or not can be effectively judged. At the same time

further considering should be given to how to obtain the dynamic kick tolerance of shut-in which is more applicable in the field

so as to assist in safe drilling in the deep formations where pressure is difficult to be predicted accurately.