Study On The Well Control Safety In High Sulfur Area Of Tarim Oilfield

With the deepening of oil and gas exploration and development,deep and ultra-deep wells drilling have been more common.The characteristics of high sulfur gas reservoir in Tarim oilfield are as follow:high temperature,high pressure and high sulfur content.High sulfur areas are typically accompanied by high pressure,which easily lead to the gas kick.After the high-sulfur gas kick,the density,the viscosity and other physical properties of gas would be making a great change, especially near well head. The expansion of the high-sulfur gas volume take place in a very short time, which will lead to blowout and cause serious drilling accidents.So it is necessary to study the flow law of high sulfur gas kick. Based on the wellbore flow rule,the appropriate control measures.are given.Based on the analysis of PVT properties of sour gas, this paper provides the high precision method(Helmholtz free energy equation for CH4,H2 S,CO2) of physical properties including the density and the viscosity. The model for gas-liquid two-phase flow coupled with wellbore heat transfer was developed while high sulfur gas kick.The two-phase flow law for high sulfur gas under different conditions are analysed,the flow mechanism of hydrogen sulfide in drilling wellbore is revealed,the theoretical basis for the precautions and treatments of blowout and other drilling accidents are given.The study for this paper provides technical guidance for improving ROP and the safe in the drilling process of high sulfur content area of Tarim oilfield.