Novel Eco-friendly Additives for Aqueous and Non-aqueous Fluid Design

The global oil and gas industry has a long standing initiative to develop and use the most environment friendly solutions in the exploration and exploitation of oil and gas resources to prevent any damage or degradation of other marine and terrestrial resources. This is reflected by increasing research in academics, research institutes and organizations around the globe to develop better and more environment friendly base fluids, viscosifiers, fluid loss additives, emulsifiers, lubricants, etc. to protect the local, regional and global environments, eco-systems, habitats and also the OHS of workers and professionals working in the oil and gas industry. This paper describes the development, testing and evaluation of several novel additives to demonstrate their suitability for oil and gas field applications to avoid any negative impact to the surrounding environment. Experimental results indicate that the newly developed additives provide desirable, similar or better performance with respect to conventional additives used by the industry and thus demonstrate their suitability for application in aqueous and non-aqueous fluid design. The plant-based organic additive identified to use as an ecofriendly viscosifier for aqueous mud system can also control the fluid loss behavior of clay free system and thus can act as a bi-functional additive. Several waste vegetable oil-based eco-friendly additives have been developed for their application as spotting fluids, base oil and emulsifiers for invert emulsion oil based mud. These additives have similar or better technical performance than the equivalents and the eco-friendly nature of the mud additives demonstrates their ability to perform the functional tasks with better protection of the surrounding environments.

A salt-induced viscosifying smart polymer for fracturing inter-salt shale oil reservoirs

Inter-salt shale oil reservoirs located between two salt layers are always accompanied by high temperature and high salinity. However, the present commonly used water-soluble polymers in fracturing fluids su er from poor tolerance to high temperature and high salinity. Thermoviscosifying polymers(TVP) whose aqueous solution shows viscosity increase upon increasing temperature and salt concentration have received considerable attention recently, which is promising for utilization in fracturing fluids to overcome these problems. In this work, both the salt-induced viscosifying property and mechanism of a TVP solution were investigated and the performance of TVP used as fracturing fluid based on the conditions of the Jianghan inter-salt shale oil reservoir in China was evaluated. It is found that the salt-induced viscosifying property of the TVP solution decreases with temperature and shear rate, but increases with polymer concentration. The number of intermolecular hydrophobic domains increases with the salt concentration contributing to the strengthening of a 3D network structure, which results in an increase in viscosity. In addition, the TVP fracturing fluid formulated with saturated brine exhibits excellent temperature and shear resistance, sand-suspending performance, and gel-breaking performance. Its viscosity remains above50 m Pa s after being sheared for 1 h even at a high temperature of 140 °C and the sand-suspending stability can be maintained for more than 1 week at 100 °C. Furthermore, the fracturing fluid can be easily broken down within 12h using 0.2 wt%–0.3 wt% potassium persulfate without residue.