Research On Combined Production Technology Of Bottom-hole Purification, Drainage And Gas Production In Mid-shallow Layers Of Western Sichuan

The western Sichuan gas field belongs to the dense clastic rock multi-layer gas reservoir.The reservoir is characterized by low porosity and low permeability.Most gas wells must undergo sand fracturing to obtain industrial production capacity.In the mining process,with the layer energy loss is fast,production declines rapidly,Wellbore blockage,bottom-hole pollution and bottom hole liquid loading,gas wells are difficult to stable production.In addition,due to the imperfect process of the well bottom purification method,such as imperfect well selection method and unsound pharmaceutical system,it is unable to effectively solve the problems occurred in the production and effectively improve the productivity of gas wells.Therefore,this paper focuses on the above issues and mainly carried out the following work:(1)The gas well pollution diagnosis and analysis research was carried out,combined the component analysis of the sampled pollutants and production history of gas well to judge the pollution type.Based on the experimental analysis,the pollution types of the gas wells were summarized and the evaluation indicators were formed to guide the subsequent diagnosis and analysis of bottom-hole pollution.(2)The experiment of compounding the bottom hole purification agent and the bubble discharge agent which is widely used at present is carried out,analysis its compatibility and judgement the deblocking and drainage performance of each agent.On this basis,a new experimental study of compounding agents was carried out to meet the requirements of bottom-hole purification and drainage.(3)Based on the bubble discharge,gas lift and bottom-hole purification process,combined with the wellbore flow state analysis,the combined process optimization research was carried out to determine the better combination process.The parameters such as filling amount and system,filling and returning process design and operation procedures in the joint construction process are optimized.(4)The optimized bottom-hole purification,drainage compound formulation and joint process application were applied on site.The results show that the composite agent has different degrees of enhancement on the gas well production after different wells are constructed,and the optimized combined process has obvious effect on the purification and drainage of the well.The research results in this paper have been validated on the spot,which is of great significance for the drainage and gas production in the western Sichuan gas field.