Research on Hydraulic Fracturing in Deep Ice Core Drilling Borehole Wall

Abstract:

In order to maintain the stability of deep ice core drilling borehole wall and avoid the occurrence of in-hole accidents, the hydraulic fracture become one of the important scientific problem which need to be solved urgently. On the basis of deep analysis of the ice drilling data, and combining the ice sheet dynamics related theory, we calculated the change rules of ice density, temperature and internal stress with depth. Then, combining the hydraulic fracturing technology in oil and gas resources exploration drilling and ice drilling fluid theory, we established a reasonable differential pressure calculation method of ice borehole wall and discusses the mechanism of hydraulic fracturing for deep ice drilling deeply. By developing a true-triaxial hydraulic fracturing equipment, we obtained the brittle deformation mechanism of ice borehole under different confining pressures. Combining the actual deep ice core drilling in Dome A, we obtained the depth interval and necessary initial fracture length of occurring potential hydraulic fracture in this borehole. This method provides an important theoretical basis for subsequent safe and efficient in future ice drilling engineering.

Key words:hydraulic fracturing; ice drilling; drilling fluid; hydraulic fracturing simulation experiment; brittle deformation