Díez Rebeka, Medina Oscar E, Giraldo Lady J, Cortés Farid B, Franco And Camilo A
Research Group on Surface Phenomena-Michael Polanyi, Faculty of Mines, National University of Colombia, 050034 Medellín, Colombia.
Nanomaterials (Basel). 2020 May 11;10(5):928. doi: 10.3390/nano10050928.
Fines migration is a common problem in the oil and gas industry that causes a decrease in productivity. In this sense, the main objective of this study is to develop nanocomposites based on the interaction of quaternary amine (hexadecyltrimethylammonium bromide-CTAB) and MgO to enhance the capacity of retention of fine particles in the porous medium. MgO nanoparticles were synthesized by the sol-gel method using Mg(NO)·6HO as a precursor. Nanoparticles were characterized by dynamic light scattering (DLS), the point of zero charge (pH), thermogravimetric analysis, and Fourier transform infrared spectroscopy (FT-IR). Different nanoparticle sizes of 11.4, 42.8, and 86.2 nm were obtained, which were used for preparing two system nanofluids. These systems were evaluated in the inhibition of fines migration: in the system I MgO nanoparticles were dispersed in a CTAB-containing aqueous solution, and system II consists of a nanocomposite of CTAB adsorbed onto MgO nanoparticles. The fines retention tests were performed using Ottawa sand 20/40 packed beds and fine particles suspensions at concentrations of 0.2% in a mass fraction in deionized water. Individual and combined effects of nanoparticles and CTAB were evaluated in different treatment dosages. The analysis of the interactions between the CTAB and the MgO nanoparticles was carried out through batch-mode adsorption and desorption tests. The best treatment in the system I was selected according to the fines retention capacity and optimized through a simplex-centroid mixture design for mass fractions from 0.0% to 2.0% of both CTAB and MgO nanoparticles. This statistical analysis shows that the optimal concentration of these components is reached for a mass fraction of 0.73% of MgO nanoparticles and 0.74% in mass fraction of CTAB, where the retention capacity of the porous medium increases from 0.02 to 0.39 mg·L. Based on the experimental results, the nanofluids combining both components showed higher retention of fines than the systems treated only with CTAB or with MgO nanoparticles, with efficiencies up to 400% higher in the system I and higher up to 600% in the system II. To evaluate the best performance treatment under reservoir conditions, there were developed core flooding tests at fixed overburden pressure of 34.5 MPa, pore pressure at 6.9 MPa and system temperature at 93 °C. Obtaining critical rate increases in 142.8%, and 144.4% for water and oil flow in the presence of the nanofluid. In this sense, this work offers a new alternative for the injection of nanocomposites as a treatment for the problem of fines migration to optimize the productivity of oil and gas wells.
细颗粒运移是石油和天然气行业中一个常见的问题，它会导致产能下降。从这个意义上讲，本研究的主要目的是基于季铵盐（十六烷基三甲基溴化铵 - CTAB）与氧化镁的相互作用来开发纳米复合材料，以提高多孔介质中细颗粒的滞留能力。氧化镁纳米颗粒采用溶胶 - 凝胶法，以Mg(NO₃)₂·6H₂O作为前驱体制备而成。通过动态光散射（DLS）、零电荷点（pH）、热重分析和傅里叶变换红外光谱（FT - IR）对纳米颗粒进行了表征。获得了11.4、42.8和86.2纳米的不同纳米颗粒尺寸，并用于制备两种体系的纳米流体。对这些体系进行了细颗粒运移抑制评估：在体系I中，氧化镁纳米颗粒分散在含CTAB的水溶液中，体系II由吸附在氧化镁纳米颗粒上的CTAB纳米复合材料组成。使用渥太华20/40目砂填充床和去离子水中质量分数为0.2%的细颗粒悬浮液进行细颗粒滞留测试。在不同的处理剂量下评估了纳米颗粒和CTAB的单独及联合作用。通过间歇式吸附和解吸试验对CTAB与氧化镁纳米颗粒之间的相互作用进行了分析。根据细颗粒滞留能力在体系I中选择了最佳处理方法，并通过单纯形 - 质心混合物设计对CTAB和氧化镁纳米颗粒质量分数从0.0%到2.0%进行了优化。该统计分析表明，当氧化镁纳米颗粒质量分数为0.73%且CTAB质量分数为0.74%时达到了这些组分的最佳浓度，此时多孔介质的滞留能力从0.02增加到0.39 mg·L⁻¹。基于实验结果，两种组分组合的纳米流体显示出比仅用CTAB或氧化镁纳米颗粒处理的体系更高的细颗粒滞留率，体系I中的效率提高高达400%，体系II中高达600%。为了评估油藏条件下的最佳性能处理方法，在34.5 MPa的固定上覆压力、6.9 MPa的孔隙压力和93℃的体系温度下进行了岩心驱替试验。在纳米流体存在的情况下，水和油的流动临界速率分别提高了142.8%和144.4%。从这个意义上讲，这项工作为注入纳米复合材料作为解决细颗粒运移问题的处理方法提供了一种新的选择，以优化油气井的产能。
