钻井液用自降解屏蔽暂堵剂的制备与性能评价OA

In drilling fractured low-permeability reservoirs,bridging temporary plugging agent particles,because of their large sizes,are difficult to achieve tight plugging,and these particles exhibit low self-degradability.To address these technical challenges,a self-degradable bridging temporary plugging agent SMNP-1 was prepared via inverse microemulsion polymerization and using liquid microfluidics technology.The plugging agent SMNP-1 was synthesized using acrylamide(AM)and sodium p-styrenesulfonate(SSS)as the monomers,and β-cyclodextrin diacrylate ester(β-CD-AA)as the crosslinking agent.The molecular structure of SMNP-1 was verified with infrared spectrometer,and the particle size distribution and micromorphology of SMNP-1 were characterized with laser particle size analyzer and scanning electron microscope(SEM).Laboratory experiments were conducted to investigate SMNP-1 for its water absorption and swelling performance,adsorption performance,temporary plugging and unplugging performance,self-degradability,pressure-bearing capacity,and compatibility.Experimental results demonstrate that at elevated temperatures,SMNP-1 exhibits a moderate volumetric expansion rate after absorbing water,and a strong adsorption capacity.The SMNP-1 particles,after high-temperature treatment,show a normal size distribution and are morphologically nano-micron sized microspheres.At test temperatures of 100℃,120℃,140℃and 160℃,the rates of SMNP-1 to plug natural cores are 96.88%,96.63%,96.57%and 95.27%,respectively.After 240 h of high temperature exposure,the unplugging rates of SMNP-1 are 87.22%,89.95%,93.27%and 96.13%,respectively,and the rates of self-degradation are 52.05%,56.40%,63.04%and 74.11%,respectively,demonstrating remarkable reservoir protection effect.At test temperature of 100℃,the maximum displacement pressure difference is 55 MPa,and a maximum displacement pressure difference of 25 MPa can still be achieved when the temperature is increased to 160℃,demonstrating an excellent plugging performance.SMNP-1 exhibits little effect on the rheology of drilling fluids,it can effectively enhance the wall-building capacity of a drilling fluid after fluid-loss and the reservoir protection effect.SMNP-1 has been successfully applied in the wild-cat well Xinsheng-1.