The present invention relates to the injection of water and gas, either simultaneously or alternately, into subsea wells in order to enhance production and the oil recovery level. Thus, the present invention provides a subsea system for pressurizing a subsea oil reservoir injecting at least one of water and gas, comprising (i) at least two subsea injection wells (4, 4′), each subsea injection well (4, 4′) being connected to a production unit (5) by means of a single subsea line (1, 2) which is connected to the respective subsea injection well (4, 4′) by a main injection mandrel (6, 6′), and (ii) at least one jumper (3), each jumper (3) hydraulically connecting two of the at least two adjacent subsea injection wells (4, 4′) through annular mandrels (7, 7′). The present invention further provides a subsea reservoir pressurization method associated with the above-described system.

Estimates of global total “liquid” hydrocarbon resources are dominated by structures known as oil sands or tar sands which represent approximately two-thirds of the total recoverable resources. This is despite that the Canadian Athabasca Oil Sands, which dominate these oil sand based recoverable oil reserves at 1.7 trillion barrels, are calculated at only a 10% recovery rate. However, irrespective of whether it is the 3.6 trillion barrels recoverable from the oil sands or the 1.75 trillion barrels from conventional oil reservoirs worldwide, it is evident that significant financial return and extension of the time oil as resource is available to the world arise from increasing the recoverable percentage of such resources. According to embodiments of the invention pressure differentials are exploited to advance production of wells, adjust the evolution of the depletion chambers formed laterally between laterally spaced wells to increase the oil recovery percentage, and provide recovery in deeper reservoirs.

Described herein are methods and techniques for deep reservoir stimulation of a hydrocarbon-containing subsurface formation. The methods may comprise introducing or injecting a formation-dissolving fluid, such as a wet acid-forming gas, into the subsurface formation; allowing the formation-dissolving fluid, such as the wet acid-forming gas, to react with the subsurface formation for a period of time; and producing hydrocarbons from the subsurface formation.

A resource exploration and recovery system including a first system, and a second system extending into a wellbore. The second system includes a completion having a casing defining a wellbore internal diameter. Chemical injection tubing extends from the first system into the completion. The chemical injection tubing includes a terminal end portion. A chemical introduction system is arranged at the first system and fluidically connected to the chemical injection tubing. The chemical introduction system is operable to deliver a chemical into the chemical injection tubing. A chemical injection assembly is mounted to the terminal end portion. The chemical injection system includes an anchor system operable to secure the chemical injection assembly to the casing.

A resource exploration and recovery system includes a first system and a second system extending into a wellbore. The second system includes a completion having a casing defining a wellbore internal diameter. Chemical injection tubing extends from the first system into the completion. The chemical injection tubing includes a terminal end portion. A chemical introduction system is arranged at the first system and fluidically connected to the chemical injection tubing. The chemical introduction system is operable to deliver a chemical into the chemical injection tubing. A chemical injector assembly is mounted to the terminal end portion. The chemical injector assembly includes a propulsion system.

Treatment fluids including a base fluid; and fly ash microspheres, wherein the fly ash microspheres are of a material selected from the group consisting of Class C fly ash, Class F fly ash, and any combination thereof, wherein the fly ash microspheres have a diameter in the range of from about 0.1μηη to about 150μηη, and wherein the fly ash microspheres are present in the treatment fluid in an amount in the range of from about 0.001 ppg to about 1 ppg of the treatment fluid.

Systems and methods for enhanced or improved oil recovery includes injecting a Y-Grade NGL enhanced oil recovery fluid through an injection well into a hydrocarbon bearing reservoir to mobilize and displace hydrocarbons. The Y-Grade NGL enhanced oil recovery fluid comprises an unfractionated hydrocarbon mixture. Simultaneously and/or subsequently, a mobility control fluid is injected into the hydrocarbon bearing formation. Hydrocarbons from the hydrocarbon bearing reservoir are produced through a production well or the same injection well.

A system for pressurization of an underwater oil reservoir by independent injection of water and gas comprise: at least first and second underwater injection wells, wherein at least one of the first and second underwater injection wells is linked to a production unit by means of an individual underwater line; and at least two jumpers: a first jumper hydraulically connecting a wet Christmas tree of the first underwater injection well to a wet Christmas tree of the second underwater injection well, and a second jumper hydraulically the wet Christmas tree of the second underwater injection well to the wet Christmas tree of the first underwater injection well.

A system and method of performing oil displacement by a water-gas dispersion system includes a micro-bubble generation apparatus, a gas source, an ultrasonic oscillation controller, a protective barrel and a support. A first opening is provided in a top end of the protective barrel, into which an internal apparatus enters and is extracted, the first opening is sealed by an end cover. A second opening communicating with a water flooding pipeline is provided in a side wall of the protective barrel, into which fluid flows and from which the fluid exits. The micro-bubble generation apparatus is fixed within the protective barrel by the support. The gas source is connected with the micro-bubble generation apparatus through a gas pipeline, for transporting gas to the micro-bubble generation apparatus. The ultrasonic oscillation controller is connected to the micro-bubble generation apparatus through a signal line, for controlling the micro-bubble generation apparatus to generate micro-bubbles.

Embodiments of the disclosure provide compositions and methods suitable for injection of a nanosurfactant-based foam composition into a hydrocarbon-bearing formation for enhanced recovery operations. The nanosurfactant-based foam composition includes a gaseous component and nanoassemblies. The nanoassemblies contain a petroleum sulfonate surfactant, mineral oil, and a zwitterionic co-surfactant.