Abstract: Methods for drilling a wellbore into a subterranean formation include preparing a drilling fluid and circulating the drilling fluid in the wellbore while drilling in the subterranean formation, forming a filtercake from the drilling fluid, creating or encountering one or more fractures in the subterranean formation while drilling, and allowing a portion of the filtercake formed to at least partially seal the one or more fractures while continuing the drilling.

Abstract: Methods for drilling a wellbore into a subterranean formation include preparing a drilling fluid and circulating the drilling fluid in the wellbore while drilling in the subterranean formation, forming a filtercake from the drilling fluid, creating or encountering one or more fractures in the subterranean formation while drilling, and allowing a portion of the filtercake formed to at least partially seal the one or more fractures while continuing the drilling.

Abstract: Application of a photocurable lining to a downhole fixed surface surrounding the axis of a wellbore is carried out by skimming an applicator over the downhole surface while delivering a porous tape impregnated with a photocurable liquid composition between the applicator and the downhole surface so that the tape lies on the downhole surface and directing light of wavelength in a range from 100 nm to 1500 nm onto the curable composition impregnating the tape so as to initiate curing of the composition and thereby attach the tape to the downhole surface.

Abstract: A method and materials for stabilizing a wellbore against excess fluid pressure is described. It comprises forming or placing a flexible and essentially impermeable lining on or in the wellbore wall. The flexibility of the lining ensures that it remains in compression as the pressure in the wellbore is increased above the fluid pressure in the surrounding rock and it therefore does not need high tensile strength. The lining may be a preformed elastomer sleeve or formed in situ by the use of a reactive drilling fluid. Appropriate reactive formulations are described for the situation where the rock contains significant quantities of clay.

Abstract: A method and materials for stabilizing a wellbore against excess fluid pressure is described. It comprises forming or placing a flexible and essentially impermeable lining on or in the wellbore wall. The flexibility of the lining ensures that it remains in compression as the pressure in the wellbore is increased above the fluid pressure in the surrounding rock and it therefore does not need high tensile strength. The lining may be a preformed elastomer sleeve or formed in situ by the use of a reactive drilling fluid. Appropriate reactive formulations are described for the situation where the rock contains significant quantities of clay.

Abstract: An additive for a water-based fluid which is to be used when the likelihood of differential sticking is high and which reduces the sticking tendency of the fluid and mud cake. An additive according to the invention comprises a well dispersed-particulate phase such as an emulsion, a fine emulsion, a microemulsion, a micellar phase or a polymeric phase having a particle size comparable with the pore throat size of a mud cake and comprising a material which forms easily deformable particles and which reduces the sticking propensity of the mud. One embodiment of the invention comprises a microemulsion of an oil which is well dispersed, substantially stable and has a substantial portion of the particle size distribution in the range 5-500 nm. An alternative embodiment comprises a micellar phase comprising one or more surfactants. The additive is typically used at a level of about 5% by volume in the drilling fluid.