In addition to the sharp growth of unconventional natural gas wells in the past decade, there are few hundred thousands of abandoned and orphaned wells across the world, potentially contributing to gas emissions. Failure in the barrier and sealing capabilities of the cement and casing are of factors playing role in these leakages. Squeeze job as a remedial treatment is performed to place cement slurry from the surface to the target points to seal narrow spaces behind the casing and/or perforations placed in the casing. In this study, a novel additive for the squeeze-cement is proposed by introducing surface-modified graphite nanoplatelets (GNPs) to carefully adjust rheology and mechanical properties of the prepared cement slurry to remediate some flaws in pre-existing cement sheaths. We seek for better penetration into narrow spaces behind the casing with appropriate thickening time, low fluid-loss, and high final strengths. The process of surface modification is very important to generate a homogeneous cement composite with superior mechanical properties. We develop a chemical method for the surface treatment of GNPs to alter their intrinsically hydrophobic properties to hydrophilic, making them compatible with the aqueous medium of cement. Details of surface modification approach and the concentration of surface-modified nanoparticles are tailored to achieve a desirable slurry for squeeze treatments following API RP 10B-2 (2013) procedures. We believe that these nanoparticles due to their 2D nanostructure not only improve cement movability, but also provide appropriate sealing in the target zones. To assess the performance of the prepared cement slurry to effectively seal narrow targets, narrow-slot tests with 120 microns thickness are conducted to show the supremacy of the proposed solution in sealing narrow spots. We also investigate the effect of adding a commercial superplasticizer on the properties of nanoengineered cement slurry to better resemble field practices. Results show that the presence of surface-modified GNPs provide cement slurry with low rheological properties, zero free fluid, low fluid-loss, and deep penetration which are promising for future field trials.

在过去的十年中，除了非常规天然气井的急剧增长外，全球还有数十万个废弃和孤立的井，有可能导致天然气排放。水泥和套管的阻隔性和密封能力的失败是导致这些泄漏的因素。进行挤压处理作为补救处理，以将水泥浆从表面放置到目标点，以密封套管后面的狭窄空间和/或套管中放置的穿孔。在这项研究中，通过引入表面改性的石墨纳米片（GNP）来小心地调节所制备水泥浆的流变学和力学性能，以补救现有水泥护套中的一些缺陷，从而提出了一种用于挤压水泥的新型添加剂。我们力求通过适当的增稠时间，低漏液率和高最终强度，更好地渗透到套管后的狭窄空间中。表面改性的过程对于产生具有优异机械性能的均质水泥复合材料非常重要。我们开发了一种化学方法来对GNP进行表面处理，以将其固有的疏水性更改为亲水性，从而使其与水泥的水性介质相容。根据API RP 10B-2（2013）程序调整表面改性方法和表面改性纳米颗粒浓度的细节，以实现用于挤压处理的理想浆料。我们认为，这些纳米颗粒由于具有二维纳米结构，因此不仅可以改善水泥的可移动性，而且可以在目标区域提供适当的密封。为了评估所制备的水泥浆有效密封狭窄目标的性能，进行了120微米厚的窄缝测试，以显示所提出的解决方案在密封窄点方面的优越性。我们还研究了添加商业高效减水剂对纳米工程水泥浆性能的影响，以更好地类似于现场实践。结果表明，表面改性的GNP的存在为水泥浆提供了低流变性，零自由流体，低流体损失和深渗透性，这对于将来的现场试验是有希望的。我们还研究了添加商业高效减水剂对纳米工程水泥浆性能的影响，以更好地类似于现场实践。结果表明，表面改性的GNP的存在为水泥浆提供了低流变性，零自由流体，低流体损失和深渗透性，这对于将来的现场试验是有希望的。我们还研究了添加商业高效减水剂对纳米工程水泥浆性能的影响，以更好地类似于现场实践。结果表明，表面改性的GNP的存在为水泥浆提供了低流变性，零自由流体，低流体损失和深渗透性，这对于将来的现场试验是有希望的。