Carbon Nanotubes: A New Methodology for Enhanced Squeeze Lifetime CNTs

A new potential application of nanotechnology for mineral scale prevention in the oil and gas industry is presented. In current squeeze treatments, in which scale inhibitors are squeezed into wells to adsorb or precipitate onto rock surfaces for later release, a large proportion of the injected inhibitor does not adsorb and is therefore returned very quickly from the reservoir upon well re-start. Here it is demonstrated that nano-particles have the potential to enhance squeeze lifetime by greatly increasing the adsorption of inhibitors within the formation. An extensive literature review is presented, exploring the potential for using nano-scale materials in squeeze treatments. One of the observations from scale inhibitor squeezes into sandstone reservoirs is the apparent lack of suitable surfaces available for adsorption. The main constituent of sandstones, quartz, has a very low ability to adsorb inhibitor (1 mg/I). Given this, research using nanotechnology was targeted towards enhancing the available sites for scale inhibitor adsorption within the near wellbore. Specifically, research was undertaken to examine the potential benefits of using carbon nanotubes in a process called Nanotechnology Assisted Squeeze Treatment (NAST). The process involves carbon nanotubes adsorbing and permanently modifying the near wellbore with scale inhibitors subsequently adsorbing onto the nanotubes. This process was observed to be significantly higher than a non-modified near wellbore surface, with a maximum adsorption of more than 85 and 160mg/g onto the nanotubes in solution of distilled water (DW) and CaC12 in DW; respectively, compared to 1 mg/g directly onto the rock. Coreflood tests comparing the NAST procedure with a simplified standard coreflood show the potential for improvement of the squeeze lifetime.