Study On Wellbore Plugging Removal Technology For Gas Wells In Ultra Deep Sea Facies Gas Field

Ultra-deep marine sulphur-bearing gas field has abundant natural gas reserves,which is an important field of natural gas industrial exploration and development.However,during the exploration and development of sulfur-bearing gas wells,plugs such as hydrates,sulfur deposits and compounds will be formed in the wellbore,which seriously hinder the commissioning process of marine sulfur-bearing gas fields.How to effectively eliminate the influence of hydrate,sulfur deposits and compounds on gas wells is an important problem in the study of wellbore plugging removal technology in ultra-deep marine gas fields.In this paper,through the analysis of plugging types,formation causes and mechanism analysis,the treatment technology of different types of plugging has been systematically studied.(1)Systematically analyze the effect of hydrate properties and plugging on production,hydrate formation process and f-ormation conditions,and clarify the hydrate formation mechanism;simulate the engineering conditions of sulfur-bearing gas wells to analyze temperature,pressure,formation water,natural gas components(methane,hydrogen sulfide,carbon dioxide,nitrogen and ethane)and their coupling The influence of these factors on hydrate formation is determined and the mechanism of hydrate formation is determined.(2)The adaptability analysis of hydrate prediction methods(graphical method,empirical formula method,phase equilibrium calculation method,statistical thermodynamics method and software simulation method)is carried out,which provides a basis for the formulation of plugging removal scheme,process optimization and production control.(3)The adaptability of various treatment methods(heating,chemical inhibition,heat insulation,production control and downhole throttling)for hydrate plugging in sulphur-bearing gas wells is analyzed,and annulus heating and continuous tubing injection are used to remove hydrate plugging.(4)Systematically analyzing the source of elemental sulfur in sulphur-bearing gas wells,by means of experimental and theoretical research,the influencing factors and mechanism of sulphur deposition in sulphur-bearing gas wells are studied.The physical,chemical dissolution and deposition mechanism of elemental sulfur,and the influencing mechanism of temperature,pressure,gas composition and production on sulphur deposition are clarified.(5)Laboratory sulfur release experiments were carried out under the conditions of natural gas composition,temperature and pressure in sulfur-bearing gas wells,providing a scientific means for sulfur deposition prediction.(6)Taking low toxicity or non-toxicity,sulfur dissolving rate and solubility as the main indexes,and considering compatibility and economic requirements,the environmental protection sulfur dissolving formula suitable for ultra-deep marine gas wells is optimized through experiments of sulfur dissolving rate,sulfur solubility and compounding.(7)By sampling and analyzing the chemical composition,particle size distribution,solubility and other parameters of sulfur-bearing gas wells,combining with gas well completion engineering conditions,optimizing and optimizing single agent,production tubing and coiled tubing corrosion experiments,optimizing the ultra-deep marine gas field compound acid plug removal formula.Field application shows that plug removal technology in ultra-deep sea facies gas field can effectively solve hydrate,sulfur and compound plugging and ensure normal production of sulfur gas wells with remarkable economic benefits.