| Puguang Gas field is the largest Marine integrated high sulfur gas field discovered in China.According to China oil and gas industry gas reservoir classification standard,Puguang Gas field belongs to very large gas reservoir.But as the development and production continue to deepen,and the formation temperature and pressure decrease,serious sulfur deposition occurred in some well areas,it brings great obstacles to gas reservoir development.The main purpose of this paper is to study the chemical dissolving sulfur deposition plugging technology as the core,optimize a complete set of new chemical dissolving sulfur system,and this system performance for a comprehensive evaluation.Firstly,through investigation and research,the status quo of sulfur blockage in Puguang gas field is sorted out.It is found that sulfur blockage is obvious and difficult to control.Secondly,in order to better determine the specific location of sulfur blockage in the wellbore of the gas well,on the premise of verifying that the original prediction method has a great error,the Chrastil formula is re-fitted with k,M and N parameters based on the test results of sulfur solubility under different pressures and temperatures obtained by the experiment of well P104-1 in Puguang Gas Field,and the average error of the prediction model is 2.47%.Meet engineering calculation requirements,on this basis,through the modification of gas reservoir PVT parameter calculation model,the new wellbore temperature pressure coupling model and multi-field coupling solution,the wellbore sulfur precipitation location under different temperature and pressure was defined.With the formation pressure decrease,the sulfur precipitation point in the wellbore gradually moved to the bottom hole,the pressure decreased by 3MPa,and the precipitation location deepened by about 230 m.After the location of sulfur deposition was determined,the optimization experiment of sulfur solubilizing agent was carried out.Firstly,sulfur powder in the laboratory was used as the dissolution object for optimization experiment,and the formula of indoor sulfur solubilizing agent was obtained.Field sulfur blocks were used to verify the indoor formula.Finally,the final sulfur-dissolving agent formula was optimized.The sulfur dissolving amount of the formula reached 21.7815g/100 ml,and the effect was remarkable.A series of comprehensive performance evaluations were carried out on the optimized formulation of sulfur dissolving agent,including its sulfur dissolving effect affected by temperature and time respectively,its own corrosion effects on rubber and metal used in wellbore,and its effects on other reagents on site.The experimental results show that the sulfur dissolving system performs well and meets the requirements of site construction.Finally,in order to achieve the best sulfur dissolving effect when the sulfur dissolving agent is applied in the field,the optimal injection method and injection device are designed and optimized,so that a complete sulfur dissolving system is formed,and the field test shows that the sulfur dissolving system is effective and can achieve the purpose of low toxicity and high efficiency chemical sulfur dissolving.The research results of this paper provide technical guarantee for the high and stable production of Puguang gas field,and have a strong guiding significance for leading the prevention and control of sulfur deposition in Puguang gas field. |
