硅酸锂/乳液复合封堵剂的制备及性能

Preparation and properties of lithium silicate/emulsion composite plugging agent

摘要:

为保持钻井过程中页岩稳定，实现对地层微纳米级孔隙和裂缝达到耐高压封堵，以水溶性和油溶性非离子表面活性剂为原料，经乳化制备合成乳液（OSE），将其与硅酸锂（LS），制备硅酸锂/乳液复合封堵剂（LOSE），采用粒径及Zeta电位、生物显微镜和表面张力测试仪，对LOSE的粒径分布、微观形貌和表面张力进行测定。将LOSE添加至膨润土基浆中，通过流变滤失性、封堵性等性能测试实验，考察m(OSE)∶m(LS)对LOSE表观黏度、塑性黏度和屈服应力等流变性能的影响，探究LOSE添加量（以基浆质量为基准的质量百分数，下同）对钻井液老化前后流变性能和过滤性能的影响。通过粒径及Zeta电位和SEM表征，对LOSE的封堵性作用机理进行推测。结果表明，m(OSE)∶m(LS)＝2∶2为制备LOSE的最佳复配比例，制备的LOSE-22中值粒径为2.50 μm；LOSE-22表面张力降低至36.47 mN/m；LOSE-22添加量4%时，钻井液中的API滤失量从22 mL减少到15.6 mL，降低了29.1%；LOSE-22添加量1%可以将基浆侵入砂床的体积分数从100%降低至50%，并将老化前WBDFs的中值粒径降低了58.8%；LOSE-22添加量3%时，钻井液侵入砂床体积分数为71%，API滤失量为16.0 mL，表现出最好的降滤失性和封堵性的综合效果。LOSE-22通过非离子表面活性剂的尾部疏水作用与LS的成膜作用协同，实现封堵、保护储层的效果。

Abstract:

In order to keep the shale stable during drilling and to achieve high-pressure resistant plugging of micro- and nano-scale pores and fractures in the formation, a synthetic emulsion (OSE) was prepared by emulsifying water-soluble and oil-soluble nonionic surfactants as raw materials, which was then combined with lithium silicate (LS) to prepare lithium silicate/emulsion composite plugging agent (LOSE), and particle size and zeta potential, biomicroscope, and a surface tension tester were used to The particle size distribution, microscopic morphology and surface tension of LOSE were determined. LOSE was added to the bentonite base slurry, and the effects of m(OSE):m(LS) on the rheological properties of LOSE, such as apparent viscosity, plastic viscosity, and yield stress, were examined through the rheological filtration loss and blocking performance test experiments, and the effects of the LOSE additive amount (mass percentage based on the mass of the base slurry, hereinafter the same) on the rheological and filtration performance of drilling fluids before and after aging were explored. The blocking action mechanism of LOSE was speculated by particle size and zeta potential and SEM characterization. The results showed that m(OSE):m(LS) = 2:2 was the optimal compounding ratio for the preparation of LOSE, and the median particle size of the prepared LOSE-22 was 2.50 μm; the surface tension of LOSE-22 was reduced to 36.47 mN/m; the API filtration loss in the drilling fluid was reduced by 29.1% from 22 mL to 15.6 mL when LOSE-22 was added at a dosage of 4%; the API filtration loss in the drilling fluid was decreased by 29.1% from 22 mL to 15.6 mL at the dosage of 4%; the API filtration loss in the drilling fluid was decreased by 29.1% from 22 mL to 15.6 mL at the dosage of 4%. LOSE-22 at 1% can reduce the volume fraction of base slurry intruding into the sand bed from 100% to 50%, and reduce the median particle size of WBDFs before aging by 58.8%; at 3% LOSE-22, the volume fraction of drilling fluid intruding into the sand bed is 71%, and the API filtration loss is 16.0 mL, which shows the best combination of filtration loss reduction and blocking effect. LOSE-22 synergizes with the film-forming effect of LS through the tail hydrophobicity of nonionic surfactant to achieve the effect of sealing and protecting the reservoir.