Disclosed herein are methods for producing hydrocarbons from a subterranean reservoir that is penetrated by an injection well and a production well. The methods comprise operating the injection well under a set of injection parameters and operating the production well under a set of production parameters to produce a production fluid that has an API gravity that changes over time (ΔAPI) as the method is advanced towards an ultimate recovery factor (RF.sub.o,u) for the reservoir. The methods further comprises modulating the injection parameters, the production parameters, or a combination thereof to decrease or increase the API gravity of the production fluid depending on whether ΔAPI and RF.sub.o,u satisfy a set of requirements as disclosed herein.

Disclosed techniques include a method of obtaining an enhanced oil recovery fluid from a hydrocarbon reservoir, comprising producing a hydrocarbon stream from the hydrocarbon reservoir, separating an associated gas stream from the hydrocarbon stream, and condensing at least a portion of the associated gas stream to obtain an enriched hydrocarbon fluid suitable for injecting into a liquid layer of the hydrocarbon reservoir to enhance recovery of hydrocarbons from the hydrocarbon reservoir.

A method of enhanced oil recovery may comprise placing into a subterranean formation a production enhancement fluid comprising a short chain hydrocarbon phase and a silane based wettability modifier, wherein the short chain hydrocarbon phase comprises hydrocarbons having 5 or less carbon atoms; allowing the production enhancement fluid to remain in the subterranean formation for a shut-in period; and producing hydrocarbons from the subterranean formation.

Provided are methods of recovering oil from a reservoir using carbon dioxide foam flooding in which a carbon dioxide foam of increased strength is used.

Methods of stimulating biogenic production of a metabolic product with enhanced hydrogen content are described. The methods may include accessing a consortium of microorganisms in a geologic formation that includes a carbonaceous material. They may also include providing hydrogen and one or more phosphorous compounds to the microorganisms. The combination of the hydrogen and phosphorous compounds stimulates the consortium to metabolize the carbonaceous material into the metabolic product with enhanced hydrogen content. Also, methods of stimulating biogenic production of a metabolic product with enhanced hydrogen content by providing a carboxylate compound, such as acetate, to a consortium of microorganisms is described. The carboxylate compound stimulates the consortium to metabolize carbonaceous material in the formation into the metabolic product with enhanced hydrogen content.

A method and an apparatus for oil production by increasing resistance of borehole wall for improving an energy utilization rate of injection gas includes injecting gas into an oil reservoir so that a gas pressure in the oil reservoir reaches an initial oil reservoir pressure. The initial oil seepage pressure is present at a position where the inside of the production well is in communication with the oil reservoir. The initial oil seepage pressure is less than the initial oil reservoir pressure. The method also includes monitoring gas production and oil production of the production well and increasing the initial oil seepage pressure to an increased oil seepage pressure when a ratio of the gas production to the oil production is higher than a predetermined ratio. The increased oil seepage pressure is smaller than the initial oil reservoir pressure.

A pressure-up blow-down method for recovering oil from an underground hydrocarbon formation, comprising the steps of: injecting an injection fluid into alternatingly-spaced multiple-induced fractures which extend radially outwardly and along a horizontal portion of a wellbore in the formation; ceasing injection of said injection fluid; recovering to surface oil which flows from remaining of the multiple induced fractures into the wellbore; and successively repeating the foregoing steps one or more times. Gas preferentially is initially used as the injection fluid and after one successive iteration water is then used. A sliding sleeve or sleeves which may be selectively slid open and closed within the wellbore in accordance with the method to allow and prevent, at various time periods in the method, fluid communication with fluid injection fractures and oil production fractures.

Devices and systems for tissue engagement and methods of using the same. In at least one embodiment of a device of the present disclosure, the device comprises an elongated body having a proximal end, a distal end, and at least one lumen extending from the proximal end to the distal end; an engagement portion at the distal end of the elongated body, the engagement portion configured to engage a tissue adjacent thereto when the engagement portion contacts the tissue while suction is applied through the device; and at least one electrode present along the engagement portion and configured to contact the tissue when the engagement portion contacts the tissue and to obtain bioimpedance data from the tissue while suction is applied through the device

In some embodiments, a method for locally lumped equation of state fluid characterization can include determining a set of components for the material balance calculations for a plurality of grid blocks of a reservoir. The plurality of grid blocks can experience different recovery methods between them. Lumping schemes can be determined for the plurality of grid blocks. Phase behavior calculations can be performed on the plurality of grid blocks, wherein different lumping schemes can be used across the plurality of grid blocks.

A method of producing hydrocarbons from an underground formation having an array of horizontal wells has the steps of: inserting one or more heater strings into at least one heater well section, the heater string comprising a heating element and a flow passage for transporting fluid from a fluid input to at least one injection port; activating the heating element of the heater string to heat the formation sufficient to produce hydrocarbons from the formation immediately adjacent to the at least one heater well section; heating and injecting a solvent into the at least one heater well in the gaseous phase through the at least one injection port of the heater string such that the solvent is injected into the voidage in the at least one heater well section created by the produced hydrocarbons; and producing hydrocarbons from at least one producer well.