Abstract: A single-use pressure-controlled actuator for downhole well tools or mechanisms is provided. The actuator is configured for control of activation/deactivation by agency of wellbore fluid pressure (e.g., pressure levels of drilling fluid or drilling mud in the wellbore). The actuator is further configured for hydraulic actuation by agency of the wellbore fluid. The actuator comprises a plunger displaceably mounted on a sealed cylinder body, with a non-reclosable frangible device closing off wellbore fluid access to an interior of the cylinder body. The frangible device is configured for automatic in response to exposure of wellbore fluid pressures exceeding a predetermined activation threshold. Failure of the frangible device causes exposure of the plunger to the wellbore fluid, resulting in actuated movement of the plunger by hydraulic action of the wellbore fluid.

Abstract: Boronated biopolymer crosslinking agents useful in producing viscosified treatment fluids that include an aqueous fluid, a base polymer, and the boronated biopolymer crosslinking agent, wherein the boronated biopolymer crosslinking agent comprises a biopolymer derivatized with a boronic acid, a boronate ester, or both. Such viscosified treatment fluids may be useful in fracturing operations, gravel packing operations, drilling operations, and the like.