Abstract: The invention provides a method of enhancing the recovery of shale-containing cuttings during the drilling of a borehole in a shale-containing subterranean formation which comprises adding to the drilling fluid circulating in the borehole a finely ground, very sparingly soluble, anhydrous, alkali metal silicate glassy material to provide the drilling fluid with a concentration of soluble silica in the range from about 0.1% to about 1.0% by weight of the aqueous phase of the drilling fluid. Preferably the drilling fluid has a pH in the range from about 8.0 to about 11.0, most preferably about 8.5 to less than 11.0. The preferred alkali metal is potassium.

Abstract: The invention discloses methods of formulating an alkali metal silicate-containing drilling fluid and drilling a well therewith. Thus an alkali metal silicate is added to an aqueous base drilling fluid, when the drilling fluid is being circulated while drilling, at a rate sufficient to react with the drilled cuttings and freshly exposed surface of the borehole while leaving very little excess soluble silicate in the drilling fluid circulated to the surface. The rate of addition of the silicate is based on the circulation rate of the drilling fluid in the wellbore and the volume of the hole being drilled.

Abstract: Method and apparatus for the nondestructive testing of rock samples as a function of time are disclosed. A rock sample is placed in a sample vessel which simulates in-situ wellbore conditions of pressure, temperature and fluid effects. Ultrasonic signals are transmitted through the sample and the transit time is measured. The measurements are repetitively performed and the time history of the development of strength is recorded in order to determine when the rock sample begins to weaken.