Effects of a crosslinking agent on a supramolecular gel to control lost circulation

Abstract

To mitigate lost circulation during drilling operations, a supramolecular gel plugging agent (GP-A) was prepared in our study. The rheological characteristics and microstructure changes of the GP-A gel under the action of a crosslinking agent were studied. The starting pressure, the indicator of the plugging property of the 1.2 wt% GP-A and 1.0 wt% organic chromium crosslinker gel system—can tolerate a pressure of 154.2 kPa, which was much higher than that of the HPAM and GP-A gels on the 1.2 mm crack model. The microstructure showed that the GP-A gel was mainly a spider web-type star connection, different from the linear counterpart of HPAM. The three-dimensional network structure of the gel was observed via atomic force microscopy (AFM), and chromium increased the bonding effects of the gel inter-connected micro-structure and showed a higher mechanical strength. On the surface of the GP-A gel, numerous branches similar to tentacles adhered to the shaft lining to increase the flow resistance and the starting pressure. The results from our laboratory studies indicated that the GP-A gel in the presence of a chromium crosslinker could be a promising plugging agent for lost circulation treatments of fractured matrices.