渤海注聚油田储层堵塞、产液下降机理分析及调整措施

Mechanism analysis and adjustment measures of reservoir blockage and production decline in Bohai field

渤海X油田位于渤海辽东湾北部海域,属于疏松砂岩油藏,且原油胶质、沥青质含量高。目前,该油田注聚区受效井日产油626m^3,日产液5707m^3,含水89%。在生产中发现,老受效井已经出现"产出端堵塞严重,产液下降严重"等问题,一直干扰油田产量指标的完成。针对该问题,本研究在整体分析X油田驱油剂、地质类型、地层压力的基础上,跟踪了每口产液下降井的生产动态资料并筛选出同时期产液下降较严重的井,利用显微镜观察、抽提物检测分析、固体组分检测分析等实验方法综合分析了堵塞物成分,总结出了堵塞及储层伤害机理,并提出了相应的解决思路。研究发现,原油胶质、沥青质、少量聚合物包裹在出砂微粒周围,乳化增粘又加重疏松砂岩出砂程度,形成大量粘塑性油砂颗粒堵塞地层;同时,残酸中的Al^3+或Fe^3+等高价离子,形成了铁盐、铝盐、氟化物等无机垢沉淀堵塞地层,即出砂和结垢是导致堵塞的根本原因。在明确临界流速、生产压差的同时,针对疏松砂岩做好深部稳砂,实施"有机无机交替解堵+化学固砂"的措施,防止砂粒解堵后再次运移、延长解堵有效期的解堵思路。

The Bohai X Oilfield is located in the northern waters of the Liaodong Bay in the Bohai Sea.It belongs to unconsolidated sandstone reservoirs and has high crude gum and asphaltene content.At present,the effective wells in the polymer injection area of this oilfield produce 626 m^3 of oil per day,5707 m^3 of fluid per day,and 89% water.It was found in production that problems such as"severe blockage at the output end and a serious drop in production fluid"have occurred in the old affected wells,which have always interfered with the completion of oilfield production targets.In response to this problem,based on the overall analysis of the oil displacement agents,geological types,and formation pressures in the Bohai X Oilfield,this study tracked the production dynamics of each fluid-falling well and screened out the wells with a severe decline in fluid-production during the same period.Experimental methods such as microscope observation,extraction detection analysis,and solid component detection analysis comprehensively analyze the components of the plug,summarize the mechanism of plug and reservoir damage,and propose corresponding solutions.The study found that crude oil colloid,asphaltene,and a small amount of polymer are wrapped around the sand-producing particles.Emulsification and viscosity increase the degree of loose sandstone sand formation,forming a large number of viscoplastic oil sand particles to block the formation.At the same time,Al^3+ or Fe^3+ in the residual acid have formed inorganic scales such as iron salts,aluminum salts,fluorides,etc.to block the formation.That is,sand production and scaling are the root causes of blockages.While clarifying the critical flow velocity and production pressure difference,do a good job of deep sand stabilization for unconsolidated sandstone,and implement the"organic-inorganic alternate deblocking+chemical sand fixation"measures to prevent sand particles from relocating and extending the effective period of deblocking.