Well fluids and methods are provided that can be used for stabilizing a shale formation, especially during drilling of a well into or through a shale formation. The well fluids include: (i) a continuous water phase; (ii) a viscosity-increasing agent, wherein the viscosity-increasing agent comprises water-soluble hydrophilic polymer; (iii) a fluid loss control agent; and (iv) a cyclodextrin-based compound. The methods of drilling include the steps of: (A) introducing the well fluid into a zone of a subterranean formation; and (b) drilling the zone.

Well fluids and methods are provided that can be used for stabilizing a shale formation, especially during drilling of a well into or through a shale formation. The well fluids include: (i) a continuous water phase; (ii) a viscosity-increasing agent, wherein the viscosity-increasing agent comprises water-soluble hydrophilic polymer; (iii) a fluid loss control agent; and (iv) a cyclodextrin-based compound. The methods of drilling include the steps of: (A) introducing the well fluid into a zone of a subterranean formation; and (b) drilling the zone.

Wellbore synthesis techniques are disclosed suitable for use in geothermal applications. Embodiments are provided where open hole drilled wellbores are sealed while drilling to form an impervious layer at the wellbore/formation interface. The techniques may be chemical, thermal, mechanical, biological and are fully intended to irreversibly damage the formation in terms of the permeability thereof. With the permeability negated, the wellbore may be used to create a closed loop surface to surface geothermal well operable in the absence of well casing for maximizing thermal transfer to a circulating working fluid. Formulations for the working and drilling fluids are disclosed.

Wellbore synthesis techniques are disclosed suitable for use in geothermal applications. Embodiments are provided where open hole drilled wellbores are sealed while drilling to form an impervious layer at the wellbore/formation interface. The techniques may be chemical, thermal, mechanical, biological and are fully intended to irreversibly damage the formation in terms of the permeability thereof. With the permeability negated, the wellbore may be used to create a closed loop surface to surface geothermal well operable in the absence of well casing for maximizing thermal transfer to a circulating working fluid. Formulations for the working and drilling fluids are disclosed.

Drill-in fluids disclosed herein comprise an aqueous base fluid, a viscosifier, a fluid loss control additive, and a degradable bridging agent comprising a degradable high strength polymetaphosphate material capable of undergoing an irreversible degradation downhole. The present disclosure further relates to a method for controlling fluid loss through a subterranean surface by using the drill-in fluid for form a filter cake on the subterranean surface. Also provided is a method of degrading a filter cake with an aqueous fluid or aqueous acidic fluid, wherein the filter cake is produced from the drill-in fluid. Further provided is a specific order of addition of constituents of the drill-in fluid, which results in improved filter cake performance and/or filter cake removal.

Drill-in fluids disclosed herein comprise an aqueous base fluid, a viscosifier, a fluid loss control additive, and a degradable bridging agent comprising a degradable high strength polymetaphosphate material capable of undergoing an irreversible degradation downhole. The present disclosure further relates to a method for controlling fluid loss through a subterranean surface by using the drill-in fluid for form a filter cake on the subterranean surface. Also provided is a method of degrading a filter cake with an aqueous fluid or aqueous acidic fluid, wherein the filter cake is produced from the drill-in fluid. Further provided is a specific order of addition of constituents of the drill-in fluid, which results in improved filter cake performance and/or filter cake removal.

The present invention relates to the well drilling field in petrochemical industry, and discloses an environment-friendly water-based drilling fluid applicable to horizontal shale gas wells comprising a nano-plugging agent, a bionic wall bracing agent, a bionic shale inhibitor, a filler, an emulsifier, and an amphiphobic wettability reversal agent, wherein, the nano-plugging agent is modified silicon dioxide nano-particle, and its modifying group includes an acrylic copolymer chain; the bionic wall bracing agent is carboxymethyl chitosan with a dopamine-derived group grafted on its main chain; the bionic shale inhibitor is composed of structural units of arginine and structural units of lysine; the filler consists of calcium carbonate of 1,600-2,500 mesh, calcium carbonate of 1,050-1,500 mesh, and calcium carbonate of 500-1,000 mesh at a weight ratio of 1:0.55-6:0.55-6; and the amphiphobic wettability reversal agent is a dual-cation fluorocarbon surfactant. The drilling fluid provided in the present invention has high temperature-resistance, high plugging and high inhibition performance, is environment friendly, especially has high density, and is applicable to shale gas mining.

The present disclosure relates to a well treatment fluid comprising finger millet, a breaker package, and a continuous aqueous phase. The present disclosure also relates to a method for treating at least a portion of a subterranean well comprising forming an aqueous treatment fluid comprising (i) finger millet, (ii) a breaker package comprising at least one breaker, and (iii) a continuous aqueous phase; and introducing the treatment fluid into at least a portion of the subterranean well.

The present disclosure relates to a well treatment fluid comprising finger millet, a breaker package, and a continuous aqueous phase. The present disclosure also relates to a method for treating at least a portion of a subterranean well comprising forming an aqueous treatment fluid comprising (i) finger millet, (ii) a breaker package comprising at least one breaker, and (iii) a continuous aqueous phase; and introducing the treatment fluid into at least a portion of the subterranean well.

Various embodiments disclosed relate to crosslinkers for treatment of a subterranean formation and methods of using the same. In various embodiments, the present invention provides a method of treating a subterranean formation. The method includes placing in a subterranean formation a composition that includes polysaccharide viscosifier. The composition also includes a crosslinker including a silica bonded to at least one crosslinking group that includes at least one amine group including at least one of a boronic acid and an ester thereof.