Abstract: The well killing device comprises: a first path; a flow regulating device; a pressure detector and a controlling device. The controlling device may control the discharge amount of the killing fluid in different killing stages according to the gas-fluid two-phase flow theory, the pressure of the killing fluid at the wellhead, and the rising speed of the drilling column.

Abstract: The method for determining fracture toughness includes clamping a cutting element in a first orientation, exerting a confining pressure on the cutting element, applying a first load at a first distance from a perimeter of the diamond table of the cutting element, increasing the first load to a first level sufficient to fracture, and recording the first level sufficient to fracture. Then, another load is applied at another distance from a perimeter of the diamond table with another cutting element or the same cutting element in another orientation. The load is increased until fracture again. The steps are repeated at different distances and different orientations to create a profile of the fracture toughness of the cutting element. The method also includes wearing the cutting element and measuring fracture toughness at a worn distance. The profile is a more complete rating of the cutting element under drilling conditions.