Multifunctional proppants for enhanced oil production from shales

Abstract

The purpose of the work, which has been done during this thesis, has been to give a better basis for future research on the subject. The subject is functionalizing proppants and testing of these functions. The experimental focus has been to functionalize proppants. The function that have been look at during this thesis is reduction of settling speed of the proppants and impregnation of proppants with scale inhibitor and test for release rate. This was done by first covering sand with an iron-based catalyst and then grown carbon nanotubes upon the catalyst covered sand. Then coat with a hydrogel. The hydrogel coatings purpose is to lower the settling speed of the proppant, so that it can reach the furthest fractures. This is possible since the hydrogel will swell when coming in contact with water, lowering the specific gravity of the proppant. The scale inhibitor impregnation was done on a porous spinel s structure (MgAl2O4), which was made from alumina spheres infused with magnesium nitrate using incipient wetness method. The impregnated proppants was tested for release by pumping water through them and collecting samples. The spinel s was also tested for crush resistance. The CNT covered samples have higher wt. % of hydrogel then what just sand have, when the weight ratio of sand/CNT to hydrogel is the same. The settling speed for CNT samples is slower for the test with longer hydration period. An increase in calcination temperature for the spinel will decrease the diameter, surface area and pore volume, and thus also the amount of scale inhibitor that can be impregnated will decrease. However, the increase in calcination temperature will increase the mechanical strength of the spinel. To measure the chemical release rate a low flow rate and high amount of sample should be used.