A method and apparatus for conducting earth borehole operations include a reel (28) of continuous coiled casing (30), and an injector (20) for moving the coiled casing. The bottomhole assembly including at least a motor (54) and a bit (56) is connected to the free end of the coiled casing, and injected into the earth while circulating fluid through the coiled casing to form a drilled earth borehole having a borehole wall. The coiled casing drill string may be retrieved from the borehole, the bottomhole assembly removed, and the coiled casing again injected into the borehole, then suspended from a wellhead assembly. After severing the coiled casing, a bonding agent such as a cementitious material may be injected into the suspended coiled casing and into the annulus between the coiled casing and the borehole.