Abstract: Wellbores are cemented with a cement composition formed from drilling fluid occupying the wellbore by circulating a quantity of drilling fluid mixed with a cement material and a dispersant such as a sulfonated styrene copolymer with or without an organic acid into the wellbore to displace the drilling fluid and to continuously convert the drilling fluid into the cement composition. The cement composition may be recirculated through the space in the wellbore to completely evacuate any drilling fluid not converted to cement so as to minimize any faults in the cement composition occupying the wellbore. A preflush composition containing the dispersant and being rheologoically compatible with both the drilling fluid and the drilling fluid converted to cement slurry may be used as a displacement fluid.

Abstract: A method for stimulating an unconsolidated formation in a well wherein the unconsolidated formation is fractured in the unconsolidated state, i.e., without having had any prior consolidation treatment practiced thereon, the fracturing step employing a propping agent, and consolidating essentially only a portion of said propping agent in the fractures created by the fracturing step. The unconsolidated formation remains essentially unconsolidated after the method of this invention has been completed.

Abstract: A method for displacing a freezable liquid from a permafrost zone in a wellbore and replacing the displaced freezable liquid with an essentially nonfreezable liquid, wherein the nonfreezable liquid is introduced into the wellbore and displaced freezable liquid returns are recovered at the earth's surface, the nonfreezable liquid being of known water and solids content. The liquid returns are monitored for changes in water and solids content until a cumulative volume of freezable liquid has been recovered at the earth's surface which indicates displacement of the freezable liquid originally in the permafrost zone of the wellbbore to the desired extent.

Abstract: A method for completing a well whose wellbore passes through a permafrost zone, the wellbore having at least one annulus in the permafrost zone, the annulus initially containing a freezable liquid. In the method openable and closable apertures are disposed near the bottom of the permafrost zone for achieving access between the interior of the wellbore and the annulus. Using these apertures, a hard collar, for example composed of cement, is emplaced in the annulus in the vicinity of said apertures. Thereafter the freezable liquid is displaced from the annulus above the collar using an essentially nonfreezable liquid which can be left in the annulus in the permafrost zone for the life of the well.