Marathon Oil Company

Karl D Dreher

William B Gogarty

Robert D Sydansk

Paul S Ossip

A process utilizing an emulsion of a carbon dioxide phase and an aqueous phase is provided to enhance oil recovery from a subterranean formation. The aqueous phase is in a liquid state and is made up of a water-soluble polymer and surfactant dissolved within an aqueous solvent. The emulsion is prepared by condensing the carbon dioxide to a supercritical state under elevated pressure either at the surface or in situ. The carbon dioxide phase is mixed with the aqueous phase either prior to, simultaneous with, or subsequent to the condensation step. Placement of the emulsion in the formation via an injection well enables recovery of oil from the formation via a production well in accordance with one of several embodiments. In one embodiment, the emulsion functions as an oil displacement fluid. In other embodiments, the emulsion functions as a mobility control fluid or a conformance improvement treatment composition in conjunction with an oil displacement flood.

Oil recovery process utilizing a supercritical carbon dioxide emulsion

A fluidic fluid composition containing lamellar micelles and which exhibits retro-viscous properties at noncryogenic temperatures is composed of 7.00-7.35% of a surfactant (preferably petroleum sulfonate having an average equivalent weight of 350-525), 50.00-54.00% of liquid hydrocarbon, 24.80-28.00% of water and optionally up to 13.00-13.95% of a cosurfactant (preferably an alcohol containing 1-20 carbon atoms) and/or electrolyte (preferably inorganic salt). The micelles within the composition must have an axial ratio of at least 3.5. The composition is substantially optically clear, phase stable, birefrigent, and the flow properties are such that substantially large increases in flow rates, e.g. 20-fold, can be realized at very small pressure increases, e.g. 5%. Additional additives to impart desired properties can be included with the composition.

Retro-viscous fluidic fluid

Fluids are injected into porous strata for many purposes. These include, for example, well stimulation, secondary-type oil recovery, mobility control, regulation of formation 'wetness' and regulation of the encroachment of fluids. Fluids used for the above purposes are readily selected using nuclear magnetic resonance (NMR) measurements in the laboratory to measure the interaction between the fluids being injected into the reservoir rock and the in situ fluids or between injected fluids and the porous material. NMR measurements are taken for each component of sample fluids proposed to be injected in the reservoir for a desired purpose, or the sample fluid per se and each of the in situ fluids. NMR measurements are then taken of the interaction between the nuclei of sample fluids injected, the reservoir rock, and the nuclei of fluids in situ. If the injected fluid is to be used for some purposes, for example, well stimulation or secondary-type oil recovery, the fluids are selected which interact least with the rock and with in situ fluids. If the wetness of the reservoir is to be changed, then the fluid is selected which interacts well with the reservoir rock. If a material is to be precipitated or formed in situ, the fluid is selected which interacts well with either the reservoir rock or the formation fluids. Additionally, the best combination of components for a particular fluid to be injected can also be determined using NMR, preferably pulsed, detection devices.

Method of selecting oil recovery fluids using nuclear magnetic resonance

Compositions containing lamellar micelles and which exhibit retro-viscous property at noncryogenic temperatures are prepared by mixing 4-15 percent of a surfactant (preferably an alkaryl sulfonate having an average equivalent weight of 350-525), 30-70 percent of a liquid hydrocarbon, 15-66 percent of water and optionally up to 20 percent of a cosurfactant, preferably an alcohol containing 1-20 carbon atoms, and/or electrolyte (preferably inorganic salt). The micelles have an axial ratio of at least 3.5 and preferably the composition has a viscosity of at least 75 cp. at a shear rate of 10 sec.sup.- .sup.1 at 23.degree.C. The composition is substantially optically clear, phase stable, birefringent, and the flow properties are such that substantially large increases in flow rate, e.g. 20-fold, can be realized at very small increases in pressure drop, e.g. 5 percent. Uses for the compositions include stimulation of wells (e.g. fracturing fluids), drilling fluids, carrier fluids in pipelines, fluidics, cutting oils, and similar applications.

Lamellar micelle containing compositions which exhibit retro-viscous

An improved method of pipelining solids is effected by suspending the solids in a liquid containing lamellar micelles and pumping the mixture at flow rates predetermined to produce retro-viscous behavior in the liquid at noncryogenic temperatures. The liquid is a composition containing 4-15% surfactant (preferably petroleum sulfonate having an average equivalent weight of 350-525), and at least two substantially immiscible liquids (e.g. 30-70% liquid hydrocarbon and 15-66% water) and optionally up to 20% cosurfactant (preferably an alcohol containing 1-20 carbon atoms) and/or electrolyte (preferably inorganic salt). The micelles have an axial ratio of at least 3.5. Preferably, the composition has a viscosity of at least 75 cp at a shear rate of 10.sup.-.sup.1 seconds at 23.degree.C. The composition is substantially optically clear, phase stable, birefringent, and the flow properties are such that substantially large increases in flow rates, e.g. 20-fold, can be realized at very small pressure increases, e.g. 5%. Concentration of the solids can be up to about 60% by weight of the composition.

High fluidity liquid for pipelining solids

An improved method of drilling a well is effected by circulating in the well a drilling fluid containing lamellar micelles at flow rates predetermined to produce retro-viscous behavior in the drilling fluid at noncryogenic temperatures. The composition contains 4-15% surfactant (preferably petroleum sulfonate having an average equivalent weight of 350-525), 30-70% liquid hydrocarbon, 15-66% water and optionally up to 20% cosurfactant (preferably an alcohol containing 1-20 carbon atoms) and/or electrolyte (preferably inorganic salt) and the micelles have an axial ratio of at least 3.5. Preferably, the composition has a viscosity of at least 75 cp at a shear rate of 10.sup.-.sup.1 seconds at 23.degree.C. The composition is substantially optically clear, phase stable, birefrigent, and the flow properties are such that substantially large increases in flow rates, e.g., 20-fold, can be realized at very small pressure increases, e.g., 5%. Additional additives to impart desired drilling properties can be included with the composition.

Drilling with low viscosity fluids

Micellar systems which are neither oil-external nor water-external can be formed from petroleum sulfonates, e.g., crude oil sulfonates formulated with water and, optionally, cosurfactants, e.g., hexanol. Because such micellar systems resist uptake of both oil and water, they are suitable for long distance displacement in which injection wells are spaced at least about 300 feet from production wells.

Growing community of inventors

Littleton, CO, United States of America

Karl D Dreher