SHEAR THINNING FLUID FOR SHALLOW FRACTURE FORMATION

Drilling fluids (water based or oil based) are used to drill wells. Water based drilling fluid utilize fresh water, seawater, or brines. Selection of optimum chemicals are critical to maximize well’s productivity and reduces drilling cost without damaging equipment or the surrounding environment. Drilling fluids need to be evaluated prior to drilling to ensure technical and environmental requirements. There is always a strong relation between the performance of wells to the chemicals used in drilling and completion. Different polymers are used to control filtration loss, viscosity and shale stabilization. The objective of this study is to formulate low temperature water-based fluid that develop thixotropic properties at static conditions. The thixotropic conditions at static conditions is achieved at low temperature, which help in mitigating losses when drilling operations is suspended. Inorganic cross linkers trigger the thixotropic performance at static conditions. Inorganic trivalent metals cross linkers have been used since 1970. Cross linkers such as Cr (III) and Al (III) are used in operations such as fracturing. However, the issue with the inorganic cross linkers is the stability under high temperature (more than 90 °C). Such temperature limitation makes such thixotropic fluids ideal to drill through fractured shallow formation. A different study will address required modification to extend the temperature stability to be used in higher temperature formations. Standard performance for drilling fluids include: fluids preparation, density and rheological properties, HT/HP filtration, pH measurement, thermal stability and contamination testing. Different types of salts were tested for additional compatibility testing. The resulted formulations have shown outstanding rheology and fluid loss control at low temperature at low-density ranges.