A New Insight into Comprehensive Treatment of Particle Migration Damage in Offshore Loose Sandstone Oilfield

Particle migration damage is widely common in offshore loose sandstone oilfield. And, the conventional acidification is used to remove the particle migration damage. However, it can decrease the cementation strength of reservoir rock and aggravate the particle migration damage. In this work, a two-step method of chelating weak acid combined chemical sand-consolidating fluid is proposed to treatment particle migrating damage. Luckily, this method not only protects the integrity and strength of the reservoir skeleton structure, but also avoids the re-migration damage. Moreover, the chemical liquid strengthen the cementation strength of the rock near the well zone, and inhibit the migration of movable particles with the formation fluid. The corrosion test, particle size test after corrosion and critical velocity test are employed to evaluate the comprehensive performance. The result shows that the corrosion ratio of chelating weak acid to clay minerals after 48 h can still be ~ 20% or above. It is found that migration particles larger than 800 μm can basically corroded or reduced. Especially, the corroded debris particle size located ~ 180 μm account the majority. It can stabilize the formation viscosity minerals, making the critical velocity of velocity sensitivity increase by 4 times. Besides, the experimental evaluation of compressive strength, erosion resistance and compatibility of chemical sand-consolidating fluid show that it can consolidate debris particles into cores with compressive strength up to 3.90 MPa, and its sand output rate is not higher than 0.011% under 9.15 MPa pressure difference. The field application case shows it has a significant stimulation and a long period of validity after the treatment of migration damage. The findings in this work might provide a insight into comprehensive treatment technology of particle migration damage in loose sandstone reservoirs.