Factors influencing the well control of HTHP horizontal wells in the Yingehai Basin

Horizontal well is an important technology to improve the gas well deliverability in the area of Yinggehai Basin, but its well control safety is seriously restricted by the high temperature and high pressure in this area. In this paper, a well kill model on HTHP (high temperature and high pressure) horizontal wells was built up according to seepage and multiphase flow theories of horizontal wells. And then, a well in the Yinggehai Basin was taken as an example to analyze the well control characteristic of HTHP horizontal wells. It is shown that overflow rate increases with the increasing of horizontal section length and permeability. Horizontal wells are higher in kick tolerance and longer in shut in time. The density of drilling fluid decreases in HTHP environment of this area. When the overflow condition is the same, the bottom hole pressure of high-temperature wells drops significantly. If oil based drilling fluid is used, the overflowing gas will be dissolved in it. With the upward migration, the gas is evolved continuously and expanded, resulting in sharp increase of drilling fluid pit increment at the late stage of well kill. The analysis on well control of HTHP horizontal wells in this paper provides the technical support for the safe and efficient development of the Yinggehai Basin.