Development of high-performance and environmentally friendly water-based fluid systems for the oilfield industry

The goal in this project is to develop drilling fluids based on bio-based fibres in nano-scale. The fibres are made from cellulose and the material is called microfibrillated cellulose (MFC). Drilling fluids must have high viscosity and good thermo-stability. The fluids must maintain their stability for several days, something which is very challenging. If the required stability at high temperatures is obtained, MFC based drilling fluids can be an environmentally friendly alternative to the oil-based drilling fluids that are used today. The project has started with production of several MFC qualities where key properties are varied systematically. The effects of these properties on rheology and temperature stability are being assessed. The MFC qualities have been compared to two of the most common viscosifiers used in water based drilling fluids today; carboxymethyl cellulose (CMC) and xanthan gum. Xanthan gum is regarded to have the best performance of commercial water based drilling fluids. MFC-samples produced in the WaterFlu project showed much better results compared to both CMC and xanthan gum. They had stable rheology after heat ageing for three days at 150 °C while xanthan and CMC had a large loss in viscosity at such high temperature. The stability has been tested in complete fluid compositions with very good results. The rheology profile can easily be controlled by adjusting the MFC concentrations. The results confirm the expected promising performance of MFC as viscosifier in drilling fluids.

The underlying idea of the innovation is to develop new, economically viable, high-performance and environmentally friendly water-based fluid systems for the oilfield industry, suitable for one or more of the application areas water-based drilling fluids, fracturing fluids, acidizing fluids, oil well cementing or water shut-off. The key element in the invention is the development of completely new and innovative microfibrillated cellulose (MFC) particles for use in fluid systems. Such particles have extr emely interesting properties for water-based fluid systems. Rheology properties are superior, forming strong gels at low shear rates and being highly shear-thinning. Rheology properties are likely to be maintained at elevated temperatures. MFC has good ab ility to form a filtering layer at the bore walls, likely to restrain fluid components from pentetrating into the formation. Further, MFC is likely to be robust in interaction with other fluid components. A successful project will open for substantial e conomical and environmental benefits for the consortium participants and society, and give the following effect goals: - Improved efficiency of injection fluids for enhanced oil recovery by minimizing fluid loss and plugging of reservoirs during drilling - Reduced costs during drilling and intervention, due to more efficient drilling operations - Substitute oil-based drilling fluids with water-based drilling fluids, e.g. at HTHP conditions, and thereby improve environmental impact during drilling and sta rt-up phase - Cost-effective solutions for well stimulation - Increased market share in fluid applications through development of a new series of water-based fluids based on nanofibrillated cellulose - Increased margins by developing, producing, marketing and selling a new series of nanofibrillated cellulose for use in the oilfield industry