Our invention pertains to a method of treating an oil well completed in an oil containing consolidated limestone or dolomite formation, to form a fluid impermeable barrier in the formation some distance from the oil well. The barrier may be a cone or pancake shaped barrier below the perforation to prevent bottom water coning, or a cylindrical barrier may be formed opposite portions of the well perforations. An aqueous hydrcarbon emulsion treating fluid is used which comprises a hydrocarbon, water and surfactant, whose pH is in the rqnge of from 2 to 6 and preferably adjusted to a level determined experimentally to cause precipitation of hydrocarbon after exposure to the formation from 7 to 14 days. First the emulsion and then the displacement fluid are injected into the formation at a predetermined injection rate which causes the polyvalent metal ions to be extracted from said formation and accumulated in the treating fluid at a controlled rate. The level of polyvalent metal ions in the treating fluid reaches a critical concentration for precipitating hydrocarbon from the treating fluid after the treating fluid has been displaced away from the wellbore to the desired location.

Disclosed is a method of treating an oil well completed in an oil formation overlying and in contact with a water formation to form a barrier below the communications of the well to prevent water moving upward from the underlying water containing formation into the well. An acid solution capable of extracting metal ions from the formation is prepared, having dissolved therein sufficient nonionic soluble solids such as sucrose or other sugar to raise the density of the acid solution to a value greater than the density of the aqueous fluid in the formation. The weighted acid solution is injected through the well into the formation. An acidified resin emulsion comprising a hydrocarbon resin, acidified water and acid stable surfactant, is formulated using a resin emulsion which is susceptible to demulsification on contact with polyvalent metal ions. Sufficient soluble nonionic solid material such as sucrose or other sugar is added to the emulsion to raise its density to a value greater than the density of the aqueous fluid in the underlying formation. The acidified resin emulsion is injected into the formation whereupon the resin emulsion demulsifies in the formation below the perforations of the wellbore. Since the region contains extractable polyvalent metal ions, demulsification occurs to establish an area having greatly reduced permeability.

A method and apparatus to protect explosive components used in various tools, such as tools for use in wellbores, includes a component with an adsorptive material. Example tools include perforating gun strings that include shaped charges, detonating cords, and booster explosives. Other tools may include surface tools containing explosive components. The adsorptive material is placed inside a container. A temperature-activated mechanism is used to open the container. The temperature-activated mechanism includes an element formed of a shape memory metal or plural layers with different coefficients of thermal expansion, such as a bi-metallic strip.

The effect of various chemical or biological agents in well treatment fluids can be delayed by sequestering the agents in the discontinuous phase of an emulsion for a period of time, before the emulsion is destabilized by exposure to at least one of: (1) a change in temperature, (2) a change in pH, (3) a change in salinity, (4) a change in alcohol concentration, (5) a change in stabilizing surfactant concentration, (6) a change in organic ion concentration, (7) a change in destabilizing surfactant concentration, (8) a change in surfactant adsorbent material concentration, (9) an ultrasonic pulse, and (10) an electrical field. Upon exposure to the emulsion destabilizing condition, the agent sequestered in the discontinuous phase of the emulsion is released into the continuous phase of the fluid composition, where it can have its intended effect.

Pumpable multiple phase compositions for carrying agents and components downhole and controllably releasing them by breaking the suspensions are described. The multiple phase composition may have an external or third phase, which in turn has a first pumpable emulsion internally. The first pumpable emulsion has a second phase containing a first phase which bears the agent to be controllably released. The entire pumpable multiple phase composition may thus be an oil phase-in-aqueous phase-in-oil phase emulsion, or an aqueous phase-in-oil phase-in-aqueous phase emulsion. The agent may be released by one or more of a variety of mechanisms. For example, a water-soluble shale stabilizer could be delivered downhole in an aqueous phase-in-oil phase-in-aqueous phase multiple phase emulsion by injecting the multiple phase composition into a water-based drilling fluid, and then the suspension broken by rotary bit nozzles under high shear stress to release the shale stabilizer at the drilling zone. The multiple phase emulsion compositions of this invention may also be used to deliver agents to remote locations along a conduit.