Research On Drainage And Gas Recovery Technology For Offshore Low-Yielding Gas Wells

In the middle and later stage of production in the East China Sea FHT gas field,there are problems such as low natural gas productivity,high water production and wellbore effusion are prominent,and the production situation and benefits are getting worse and worse.Therefore,it is necessary to study the water production of wells and study the efficient drainage gas production technology,so as to provide support for improving the drainage gas production technology level of offshore low production gas wells.Based on the systematic analysis of the liquid production status of typical production wells in FHT gas field,this paper selects and compares the commonly used drainage gas production processes,and optimizes and designs the drainage and production process measures suitable for FHT gas field,such as bubble drainage,pipe string optimization and gas lift liquid drainage.For wells with high gas production and large amount of water,the parameters of oil gas separator and electric pump are screened,and a new technology of oil casing combined production is developed It can meet the demand of drainage and gas production.The results show that:（1）Considering the demand of gas reservoir production management,the principle of"three stabilities"should be adopted to maintain the normal and stable production of gas wells,and to avoid frequent changes of working system after water production;（2）The geological and development analysis of gas reservoirs shows that the main reason for the water production of FHT gas wells is the invasion of edge water in the same layer;（3）For the large water yield there is a tendency of liquid accumulation or liquid accumulation for wells with self injection or weak injection capacity,such as B1 and B7 wells,it is recommended to choose foam drainage and gas recovery process.The specific plan is:³/₈"capillary plus piston pump technology,the foaming agent is CT5-7 type,and the pump is20MPa/200L plunger metering pump.（4）The BA6 well is recommended to discharge the wellbore fluid through the well chosen string and recover the production according to the condition of the well;（5）For B5 well with large displacement,continuous gas lift drainage is recommended.The calculation shows that the optimal gas-liquid ratio is 800m³/m³ under 9Mpa wellhead pressure,and only when the gas injection pressure is not less than 14MPa can the gas lift discharge requirements be met;（6）For C4H wells with high gas production and large amount of water,it is recommended to run electric submersible pump and oil-gas separator,and reconstruct the surface facilities to take oil The new technology can meet the requirements of drainage and gas recovery.