Abstract
A well control model for the numerical simulation is presented. The model bases on the Wait and Weight method, and simulates both of liquid and gas kicks. For a behavior of an influx in a well, it is assumed that the influx holds constant mass during a kill operation, and does not rise through the mud by the gravity effect. Other assumptions are as follows:
1) The bottom-hole pressure is maintained at a given value during the kill operation.
2) The influx stays at the bottom until resuming circulation.
3) The influx temperature does not change during the kill operation.
Simulated behaviors of well pressures of gas kick are compared with those of liquid kick. On the occasion of the gas kick, the casing pressure rises rapidly when the gas approaches the wellhead, and falls steeply with the gas discharges. Changes of the gas discharge rate and the pit volume increment are also simulated. On the occasion of the liquid kick, the casing pressure decreases monotonously as the liquid ascends, and falls stepwise at the liquid discharge.
The model is written in BASIC, and small units of programs are linked successively by “R” option to be adapted easily to a small memory capacity computer such as PC-8001.
