Downhole tools, systems, and methods for electric-based fracturing are disclosed. A downhole tool for electric-based fracturing may include an outer enclosure, an insulator chamber disposed at least partially within the enclosure, and an electrode disposed at least partially within the insulator chamber. The electrode may extend out from the insulator chamber and the enclosure, and may be configured to transfer electric energy to an exterior environment surrounding the downhole tool. The insulator chamber may be configured to thermally and electrically insulate at least a portion of the electrode from the exterior environment.

A method of treating a subterranean formation by contacting the formation with the following: (a) ammonium compound; (b) an oxidizing agent selected from a perchlorate or a nitrite or combinations thereof; and (c) sulfamic acid.

Disclosed herein are compositions and methods for reducing fluid loss in a well bore, methods for wellbore strengthening and increasing the integrity of the borehole of an oil or gas well. Also disclosed are methods for artificially increasing the temperature of a subsurface formation in the wellbore to increase the apparent wellbore strength. The mechanism for accomplishing this revolves around increasing fracture propagation pressure by actively manipulating thermal wellbore stresses.

A steam diverter apparatus for forming part of a downhole tubing string is provided. The apparatus may be used in a SAGD operation to control flow of steam into a formation. The apparatus includes a tubular housing defining steam-admitting ports, and containing a moveable shift sleeve. The apparatus is modifiable for use with position shifting tools of different outer diameters by interchanging first and second sets of the shift sleeve and insert rings having different minimum inner diameters within the housing. The open flow area of the apparatus is modifiable by plugs that block the ports and are removably attached to the housing. The plug, the shift sleeve, or both of them may be made of a dissolvable material, so that they can be dissolved by a chemical solution injected into the tubing string, for the purpose of controlling steam flow through the ports.

A method of hydraulic fracturing of an oil producing formation includes the provision of a heating apparatus which is transportable and that has a vessel for containing water. A water stream of cool or cold water is transmitted from a source to a mixer, the cool or cold water stream being at ambient temperature. The mixer has an inlet that receives cool or cold water from the source and an outlet that enables a discharge of a mix of cool or cold water and the hot water. After mixing in the mixer, the water assumes a temperature that is suitable for mixing with chemicals that are used in the fracturing process, such as a temperature of about 40°-120° F.+ (4.4-48.9 C+). An outlet discharges a mix of the cool or cold and hot water to surge tanks or to mixing tanks. In the mixing tanks, a proppant and an optional selected chemical or chemicals are added to the water which has been warmed. From the mixing tanks, the water with proppant and optional chemicals is injected into the well for part of the hydraulic fracturing operation.

A method for stimulating a well includes mixing at least one thermochemical with fracturing fluid to create a fracturing fluid mixture, injecting the fracturing fluid mixture into the well, creating an exothermic reaction with the fracturing fluid mixture, generating a pressure pulse in the well from the exothermic reaction, and fracturing a formation around the well with pressure from the pressure pulse and a hydraulic pressure source.

A method of increasing hydrocarbon recovery from a wellbore in a tight formation with greater breakdown pressures, the method including using hydro-jetting to effect a plurality of oriented cavities or discoidal grooves in the horizontal portion of the wellbore to overcome near-wellbore stresses, injecting a thermally controlled fluid into the wellbore to alter the temperature of the formation and lower stresses, and then fracturing the formation to generate a series of fractures that can be formed in a planar formation.

An embodiment in accordance with the present invention includes an EGS configured to allow the commercial production of electrical energy. One criteria of an EGS according to the present invention is that the temperature and volume of the fluids extracted are sufficiently high and large enough as to allow the commercial production of electrical energy. The system is able to operate for at least N years before the extracted fluid falls below the minimum temperature needed for energy production. Additionally, fractures are separated from each other by a sufficiently large volume of rock (V.sub.crit) relative to the fractures surface area such that the ratio of the rate of heat extraction to the rate of heat supply controlled by the thermal conductivity of the rock is such that the intervening rock is cooled at a rate that is sufficiently slow to be economic.

A wellbore is drilled in a formation using a drill string assembly that includes a drill string. A drill bit is connected to a downhole end of the drill string. A notching tool is connected to the drill string. After drilling the wellbore to a depth from a surface in the formation, the drilling is paused. The notching tool is rotated. a notch is formed with the rotating notching tool. In subsequent operations, DSA is removed from the well and the fracturing fluid pumped from the surface can create fractures at the locations of notches. These fractures would improve wellbore connectivity with the reservoir for better oil and gas recovery.

Petroleum may be recovered from a sub-surface reservoir by reducing the break-down pressure of a geological formation from an original break-down pressure to a reduced break-down pressure by exothermically reacting one or more reaction components in a carrier fluid adjacent to or within the geological formation, and forming fractures in the geological formation by hydraulic fracturing the geological formation.