Abstract
Abstract
Excessive water production is one of the significant phenomena of reservoirs worldwide that influence oil production and costs. At the same time, a comprehensive collection of treatments is available to solve this issue, such as mechanical water shutoff, polymer-based gel, and crosslinkers-based gel. However, they all possess drawbacks, including but not necessarily limited to surface mixing and handling problems. Foamed gel systems can enhance oil production by plugging the high water permeability zones due to their physical plugging, adsorption, dynamic trapping, and in-depth injectivity. In this study, a novel foamed gel system containing a composite of nanosheet material (NS), and viscoelastic surfactant (VES-SURF) was developed for inhibiting undesirable water in different watercourses of high permeable zones (zones far away from well, transient zones, and near-wellbore zones). The NS/VES-SURF-based foamed gel is prepared at the surface facility and then injected to control gelation time and gelling certainty.
The foamed gel stability, foamability, and rheology were examined at 77-200 °F. Foam loop rheometer experiments were conducted at 1500 psi, and 70% N2 quality to assess foamed gel rheological properties and stability at dynamic conditions. High-resolution optical microscope was utilized to detect the foam morphology and stability altering with time stability. The gelation time of foamed gel was calculated at 77-200 °F. A viscometer was also used to measure the viscosity and thermal stability of VES-SURF and NS/VES-SURF-based foamed gel systems at 100-200 °F.
The experimental results demonstrate that the VES-based foamed gel system converted to gel within two days, while NS/VES-SURF foamed gel requires only ninety minutes. In this foamed gel system, the gelling time can be easily controlled by altering the concentrations of NS and VES-SURF. Moreover, the VES-SURF-based foamed gel system was stable for ten days at room temperate. In contrast, NS/VES-SURF foamed gel system was stable without any phase separation for 35 days. VES and NS/VES-SURF-based foamed gel systems’ viscosity was 1000 and 1500 cP at 100 °F. Increasing the temperature to 200 °F enhanced the viscosity of foamed gel systems to reach 3500 cP for NS/VES-SURF and 2000 cP for VES-based foamed gel systems.
The NS/VES-SURF-based foamed gel characterizes by high mechanical strength, low volume, less damage, and lower cost than the traditional gel systems. In addition, the NS/VES-SURF foamed gel system is stable in harsh environments, including high temperatures, salinity, and pH. Once gelation occurs, gels do not flow and distribute along the rocks due to the high viscosity of the invented system.