Application of molecular film/mixed organic acids combined blockage removal technology in under-injection wells of Jiyuan Oilfield

In Jiyuan Oilfield, the problem of under-injection well is increasingly serious, and there are a variety of blockages. Conventional acidizing cannot remove various blockages simultaneously. To solve this problem, this paper researched and developed a molecular film/mixed organic acids combined blockage removal technology of wider applicability by analyzing blockages and blockage removal mechanisms firstly. This new technology includes mainly mixed organic acids, novel molecular film, depolymerizing agent and additive. Experimental result shows that this combined blockage removal system has strong blockage removal capacity. Its dissolution ratio of field fouling samples is generally over 80% and its viscosity reduction ratio of polymers is over 90%. It is applicable to in-depth blockage removal and can effectively avoid secondary precipitation. Field application effect shows that the molecular film/mixed organic acids combined blockage removal technology can effectively reduce water injection pressure and improve daily water injection and is applicable to the reservoir stimulation of most under-injection wells.