Optimization Research And Application Of Wellbore Blockage Removal Technology For High Hydrogen Sulfide Gas Well In Puguang Gas Field

Puguang gas field is a high-acid gas field,the main reservoir is marine formation,the average H₂S content in fluid composition is 15.16%,the average daily gas output of single well is 50×10⁴ m³·d^-1.Since the gas field was put into production,with the deepening of development,the inner wall of high sulfur-bearing gas well bore caused different degree of throttling and blockage due to impurity sediment attachment,which directly affected the normal production of gas well.Among them,the wellbore blockage position caused by the composite sediment is close to the well head and the trap pressure below the blockage point,and there is a risk of pressure agitation in the process of plugging and cleaning,and the effect of the conventional plugging liquid system on the composite sediment is not ideal.It is necessary to develop an effective anti-blocking agent system process which can effectively solve the complex blockage in the shaft of high sulfur-containing gas well to realize the safe and efficient wellbore plugging removal and restore the production capacity of the gas well.In view of the blockage of high sulfur-containing wellbore in Puguang,the author first collected the analysis data of clogging composition,and found the change trend of wellbore clogging composition through comparative analysis.It is clear that the main component of wellbore composite clogging is carbon scale+organic scale.After that,according to the characteristics of the composition of the compound plugging material,the performance requirements of the wellbore plugging agent system are clarified,and the optimal evaluation experiment of the main agent and auxiliary agent of the compound plugging agent is carried out,The main agent system of compound plugging agent was determined by dissolution test with hydrochloric acid chelating agent and dispersant osmotic agent respectively;By screening high temperature corrosion inhibitor,iron ion stabilizer,resistance reducer,drainage aid,anti-expansion agent and other additives to improve the performance of the composite plugging system,the formula of the composite plugging system was finally determined:8%HCl+4%chelating agent+20%dispersant+1%osmotic agent+3%high temperature corrosion inhibitor+2%iron ion stabilizer+0.09%resistance reduction ant+0.6%surface active agent,the dissolved calcium carbonate capacity of the system is 194.9 g·L^-1,the dissolution rate of organic components is 95.1%and 130℃the corrosion rate is controlled within 9.78 g·m^-2·h^-1,and the iron stability ability is 1300 mg·L^-1.Lastly,according to the need of safety and high efficiency wellbore plugging compound clogging,the author adopts theΦ3 mm×4 hole jet nozzle and the side nozzle and the tool axis30°angle down nozzle to improve the washing efficiency by optimizing the flushing nozzle parameters,and introduces the back pressure control technology to improve the safety control level of well control in field construction.Safety and smooth implementation of 3 pilot test wells in high sulfur gas wells,with average daily output of 27.5×10⁴ m³·d^-1 per well,combined with back pressure control flushing and plugging removal technology of continuous oil pipes with high sulfur content and newly prepared composite plugging relief working fluid system The results show that the optimized wellbore plugging removal technology is suitable for the use of low pressure and difficult liquid return reservoir and gas wells with composite blockage in wellbore,and can be popularized and applied to similar high sulfur gas fields such as Yuanba and ordinary gas fields,which has a wide application prospect.