南海油田砂岩储层损害机制及长效完井液技术

Mechanism of Sandstone Reservoir Damage and Long-term Completion Fluid Technology in the South China Sea Oilfield

南海某油田由于存在完井后不投产的情况,大量外来流体长时间滞留对储层造成严重伤害。通过对该油田储层特征分析及感性实验评价,分析油田储层潜在损害因素及敏感性损害程度;提出长时间完井不投产过程对砂岩储层损害小的对策,筛选出完井液稳定剂LSCF-1,研制出储层保护长效完井液体系。结果表明:储层岩性主要为石英砂岩,黏土矿物以绿泥石和伊/蒙间层为主,储层物性以中孔中渗储层为主,属于正常压力系统,储层速敏、水敏、碱敏、应力敏感较弱,盐敏、酸敏为弱~中偏强损害。储层保护长效完井液体系存在长时间静置性能变化小、抑制性强、通透性好、腐蚀性低、防水锁能力强等优点,能有效保护储层,降低完井长时间不投产的储层伤害。

Due to special operational requirements,a certain oil field in the South China Sea can only be put into production for 8 to 20 months.There is a situation where a large amount of external fluids are detained for a long time after completion,causing serious damage to the reservoir.Analyze the potential damage factors and sensitivity damage degree of the oilfield reservoir through analysis of reservoir characteristics and sensory experimental evaluation;Propose countermeasures for minimizing damage to sandstone reservoirs during long-term completion without production,screen and select completion fluid stabilizer LSCF-1,and develop a long-term completion fluid system for reservoir protection.The results show that the lithology of the reservoir is mainly quartz sandstone,and the clay minerals are mainly chlorite and interbedded shale/montmorillonite.The physical properties of the reservoir are mainly mesoporous and medium permeable reservoirs,belonging to a normal pressure system.The reservoir has weak sensitivity to velocity,water,alkali,and stress,while salt and acid sensitivity are weak to slightly strong damage.The long-term completion fluid system for reservoir protection has the advantages of small changes in long-term static performance,strong inhibition,good permeability,low corrosion,and strong waterproof locking ability.It can effectively protect the reservoir and reduce reservoir damage caused by long-term non production after completion.