Exxon Production Research Company

George G Binder, Jr

Yuh-Hwang Tsao

L Donald Maus

A method for cementing a casing into a borehole. The borehole is drilled to the desired depth in the usual manner. Before removing the drill string and without substantially interrupting the flow of fluids in the borehole, the mud therein is displaced with a fluid substantially free of undissolved solids from the portion of the borehole into which it is desired to cement the casing. When the solids-free fluid is in place, the drill string is removed, the casing suspended in the borehole, and a cement slurry placed in the annulus where it is allowed to set. Preferably, the solids-free fluid is more viscous and dense than the mud, and less viscous and dense than the cement slurry. Optionally, mutually compatible spacer fluids or cementing plugs are used to separate the mud from the solids-free fluid and the solids-free fluid from the cement slurry.

Method of cementing a casing in a borehole

A method of drilling and cementing a well using a novel drilling fluid convertible in place by the extrinsic application of heat into a settable cement slurry and composition therefor. The novel drilling fluid comprises an aqueous drilling mud containing in intimate admixture therewith cement and a thermally deactivatable deflocculant which prevents the cement from setting while the fluid is being used as a drilling mud. The method comprises drilling a well with a rotary bit through which the novel drilling fluid is circulated; suspending a casing in the well; removing the fluid from inside the casing; and applying sufficient extrinsic heat to the fluid in place in the annulus of the well to deactivate the deflocculant, thereby converting the fluid in place into a settable cement slurry.

Method of drilling and cementing a well using a drilling fluid

A method and apparatus for determining the gel strength of drilling mud by the repetitive steps of: flowing mud through a conduit positioned in a nonhorizontal attitude at a flow rate where the shear rate of the mud is in the range of greater than zero to about 20 sec..sup.-1, interrupting the flow of mud to provide a static column of mud in the conduit, and measuring the differential pressure of the mud between vertically spaced points during both the flow and static intervals.

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Houston, TX, United States of America

George G Binder, Jr