Novel Nano-Capsules for Oil Field Chemicals Delivery and Slow Release

Abstract

Chemicals in oil fields have shown a great potential for enhancing/improving oil recovery (EOR/IOR) beyond waterflood baseline. The objectives of this work are: (1) to develop a cost-effective method to deliver chemicals to deeper layers in reservoirs compared to conventional chemical operations, (2) to synthesize nano-capsules with improved stability under typical reservoir temperatures (80-110 °C), and (3) to demonstrate the gradual release of EOR/IOR chemicals over time at a given temperature within the above range. Multiple slow-release technologies were developed; (1) Nano-salt (2) liposomes and (3) nano-capsules. In the first method, nano-size surfactant salt particle that has a limited solubility can traverse the reservoir and deliver, over a long period of time, a constant concentration of surfactant was synthesized. In addition to surfactant salts, surfactant-loaded nano-capsules were synthesized by dissolving a known lipid formula in 20.0 mL chloroform, then, evaporating the solvent to form a dried lipid film. Acid nano-capsules for improving oil recovery operations were synthesized using In situ and interfacial polymerization. Scanning electron microscopy, an optical microscopy, dynamic light scattering, Inductive coupled plasma (ICP-AES), pH and surfactant electrodes were used to characterize the nano-capsules and dispersion. To assist the nano-platforms slow-release profile and the particles stability under reservoir conditions, the samples were incubated in oven at 95 °C. The nano-capsules’ slow-release and stability were monitored for several days. The liposomes contain 11 wt. % of PETRONATE® EOR2095 with particles’ average size of ~80 nm, the surfactant released was gradually increased over sixty hours. The acid nano-capsules contain 15 wt. % acid precursor with particles’ average size of 200 nm. The capsules release versus time curve showed that the release occurred when the temperature reached 95 °C, indicating that nano-capsules’ release is triggered by the temperature increment. The pH versus time release curve exhibits a gradual decreasing in the pH over six day indicating the acid precursor hydrolysis at 95 °C. Our results demonstrate the possibility of improving current chemicals flood via nano-encapsulation. The slow release technology may bring new potentials to the current hydrocarbon production operations.