the present invention relates to methods and apparatus for recovering hydrocarbons from geological formations ; more particularly , to a method for recovering hydrocarbons from formations wherein oil has been previously extracted to exhaustion by prior art methods ; and most particularly , to a method for recovering hydrocarbons from geological formations by injection of an aqueous oxidant under pressure into the formation to cause electrochemical dissociation of the oil phase from the mineral phase . conventional production of oil accumulated in geologic reservoirs , using natural pressure found in the reservoirs , typically recovers only about 15 % of the oil present . this recovery is known in the art as “ primary recovery .” it is known to increase the recovery percentage from wells by injecting water or gas under pressure to drive out more oil from the formations , which recovery is known in the art as “ secondary recovery .” however , it is estimated that even secondary recovery leaves approximately two thirds of the original oil unrecovered ; this residual oil is known in the art as “ heavy oil .” methodologies employed to recover oil beyond secondary recovery are known in the art as “ enhanced oil recovery ” ( eor ) processes . various processes have been disclosed for improving secondary recovery percentages and for extracting heavy oil . secondary flooding of geological formations using chemical additives can reduce the interfacial forces binding the oil to mineral substrates , thus freeing more oil for recovery . it is known to use organic polymers to control oil mobility , organic surfactants to reduce capillary forces , or alkaline agents to reduce interfacial tension and wettability between oil / water / substrate surfaces . although the effectiveness of these techniques may vary from reservoir to reservoir , the effects on the dissociation constants and displacement efficiencies are well known and are standard practice in the industry . oil recovery can be enhanced by introduction of pressurized gas which is miscible with the oil and which can thus replace the natural gas originally present , permeating through the oil deposit . one such gas commonly used is carbon dioxide , which is commercially available from industrial processes or from natural deposits such as those found at the mcelmo dome and sheep mountain reservoirs in colorado . this technique typically recovers an additional 7 % of the original oil . oil recovery can be enhanced by thermal techniques which heat the oil , thus reducing the viscosity in situ and allowing more oil to flow from the rock formations . steam injection , in situ combustion , electrical / electromagnetic heating , and even nuclear explosive fracturing are known to enhance oil recovery . all of the known techniques still recover only an additional few percent , as noted above , leaving more than half of the original oil unrecovered and unrecoverable by prior art methods . what is needed is a method for mobilizing and recovering a substantial additional percentage of oil beyond the amounts recoverable by the prior art . it is a principal object of the invention to provide an improved process for liberating and mobilizing additional oil from oil deposits exhausted by prior art technology . it is a further object of the invention to provide an improved process for increasing the volume of known recoverable reserves of oil . briefly described , residual heavy oil is released from mineral substrates in geological formations through application of a dilute solution of hydrogen peroxide , formed preferably by combination of sodium peroxide and water during injection into the geological formation . the oil residue is partially oxidized by the peroxide , hydroxyl radicals , and free oxygen , generating heat , carbon dioxide , and low molecular weight hydrocarbons , and especially ketone moieties . because the amount of peroxide is far less than stoichiometric for complete oxidation of the hydrocarbons , significant amounts of ketones are produced which are soluble in the oil residue . fragmenting the heavy oil residues , as well as heating them and diluting them with ketones and other low - molecular weight fractionation products , reduces the residue viscosity . further , hydrogen peroxide acts as an inorganic surfactant to break the electrostatic association of oil droplets with mineral substrates and water , thus suppressing the capillary forces in pores of the oil reservoir and creating a foam emulsion of hydrocarbons , water , and solids which may be pumped from the reservoir . the foam is treated further with hydrogen peroxide , preferably with addition of a low - molecular weight cutter stock such as pentane or natural gas , to reduce the density of the product and allow for mechanical separation of oil from the water and mineral residues . a ) to recover heavy oil residues from otherwise exhausted oil wells and oil fields ; b ) to perform such recovery using much less peroxide than is disclosed in the prior art , to reduce the cost of such recovery ; and c ) to recover more oil from exhausted oil wells and fields than is possible in the prior art , and therefore the foregoing and other objects , features , and advantages of the invention , as well as presently preferred embodiments thereof , will become more apparent from a reading of the following description in connection with the accompanying drawings , in which : fig1 is a schematic diagram showing the relationships of substrate solid , oil , and water , and the interfaces therebetween , at the microscopic level in a residual oil deposit ; fig2 is a schematic diagram of the capillary forces and young &# 39 ; s equation with respect to the relationships shown in fig1 ; fig3 is a schematic diagram showing the electrostatic relationships in the diagram shown in fig1 ; fig4 is a schematic diagram like that shown in fig3 , showing the electrostatic surfactant effect of adding hydrogen peroxide to the water ; fig5 is a schematic diagram showing the effect on zeta potential a of the decomposition of hydrogen peroxide into water and oxygen anions at the water / substrate interface ; fig6 is a schematic diagram showing an enlarged view of the relationship of alkane molecules in the oil residue to the negatively - charged mineral substrate ; and fig7 is a schematic diagram showing the effect of partially oxidizing alkane molecules at the surface of the oil phase to ketones or acids , breaking the colloidal suspension between oil and water . the use of hydrogen peroxide to treat oil / water / mineral colloidal mixtures in order to separate and recover the oil is well known . see u . s . pat . nos . 5 , 797 , 701 ; 5 , 928 , 522 ; 6 , 096 , 227 ; and 6 , 251 , 290 , the relevant disclosures of which are hereby incorporated by reference . those disclosures deal with treatment of residues in above - ground processes ; however , the physical / chemical basis for the success of those processes is applicable to underground in situ oil recovery as well , as described below . the incorporated references show that , using quite modest concentrations of hydrogen peroxide rather than the massive amounts required in the prior art in accordance with fenton &# 39 ; s reaction , a controlled partial cleavage of hydrocarbon residues may be achieved in which a significant amount of various ketones is produced as expressed by the following generalized equation : wherein r is an aliphatic moiety , rch 3 represents an alkane molecule , and rc = o represents a ketone molecule formed from the alkane molecule . ketone molecules so produced typically are small enough as to be gaseous or nearly so at atmospheric pressure and are readily soluble in the remaining heavy oil , thus reducing the viscosity of that residue . in a preferred embodiment of the invention , the oxidizing starting material is sodium peroxide rather than hydrogen peroxide as disclosed in the prior art ( see u . s . pat . no . 4 , 867 , 238 issued to bayless et al .). sodium peroxide is a solid which may be more readily transported and handled than hydrogen peroxide which , as disclosed by bayliss , is most conveniently produced at the wellhead , but which therefore requires significant additional onsite apparatus and controls . ther method of bayliss et al . further requires controlled injection of both acid and base into the geological formation to control the timing of peroxide decomposition . in the present invention , no acids or additional bases , other than that generated by the hydrolysis of sodium peroxide , are required . in the preferred embodiment , sodium peroxide and water are mixed and injected into a geological formation retaining heavy oil . the sodium peroxide is hydrolyzed to yield hydrogen peroxide and hydroxyl cations in accordance with the following generalized equation : na 2 o 2 + 2h 2 o → 2na + + 2o h − + 2h 2 o 2 ( eq . 2 ) the hydroxyl cations produced by dissolution of sodium peroxide additionally enhance the cleavage of hydrocarbons and create a desirably high - ph solution for the partial oxidation of hydrocarbons by hydrogen peroxide . the prior art method disclosed by bayliss et al . requires very high concentrations of hydrogen peroxide ( between 10 and about 90 weight percent ) in order to generate large amounts of carbon dioxide to help mobilize the heavy oil residues , by complete oxidation of a portion of those residues , including the beneficial ketones first produced as intermediaries . in contrast , the present improved recovery method requires only modest amounts of peroxide ( between about 0 . 5 and about 5 weight percent ) and preferably does not generate significant amounts of co 2 . rather , the heat generated by dissolution of sodium hydroxide in water combined with the exothermic partial oxidation of hydrocarbons results is a very large increase in temperature within the residues in the formation and thus , in combination with the ketones as just described , reduces significantly the viscosity of the heavy oil and enhances its mobility for extraction . an extremely important requirement of any recovery method is the ability to break the polar / electrostatic bonds which bind the hydrocarbons to the mineral substrate and thus to reduce the capillary forces which hold the oil residues within the pores of the mineral substrate . while not essential to the present invention , the following description is currently believed to explain the success of the claimed recovery method . referring to fig1 and 2 , there is shown , at the microscopic pore - size scale , a schematic relationship 10 among the principal three constituents of a hydrated residual oil deposit : mineral substrate 12 , which may be clay , sand , or rock such as shale ; oil , heavy oil , or hydrocarbons in general 14 ; and water 16 . interface 18 is between substrate 12 and oil 14 ; interface 20 is between oil 14 and water 16 ; and interface 22 is between substrate 12 and water 16 . the surface of substrate 12 is inherently electronegative ; water is inherently electropositive at its surface , thus it readily wets substrate 12 ; and oil 14 also is inherently electropositive and thus wets substrate 12 . the polar charged microscopic layers between the components are known as “ gegenion ” layers . the key to breaking the polar bond between the oil and the substrate is to make the water more wettable of the substrate surface than is the oil ; thus , the water can displace the oil from the substrate surface , freeing the oil . referring to fig3 , the capillary forces in the interface spaces are shown and defined by arrow δ 1s in interface 22 ; arrow δ 2s in interface 18 ; and arrow δ 1 , 2 in interface 20 , each of which represents the value , per unit length of contact line , of the interfacial tension of its respective interface . the tension forces exerted are perpendicular to the contact lines between the components 12 , 14 , 16 and are tangential to the interfaces . the capillary forces are related by young &# 39 ; s equation : we here further define oil bound to the substrate surface as “ entrained oil ” and oil in contact with the water surface as “ free oil .” therefore , an increased ability for water to wet the substrate surface can overcome the capillary force δ 2s and permit water to encroach on and displace oil from such surface , thereby converting entrained oil to free oil which may be recovered along with the water and subsequently separated . hydrogen peroxide functions as an inorganic surfactant or wetting agent for water , providing the needed increased ability to wet the mineral substrate surface . such wetting is characterized by an enhanced zeta potential of the water / substrate interface 22 when compared to the oil / substrate interface 18 . the zeta potential ç is defined as : where q is the charge per unit area , d is the distance into the gegenion layer , and d is the dielectric constant of the layer . referring to fig4 , the enhanced zeta potential of the water 16 ′ including hydrogen peroxide is shown schematically by compression of the gegenion layer between the water and the substrate . referring to fig5 and 6 , a progressive change and enhancement in zeta potential a along the gegenion layer in the water / solid interface 22 is shown with the progressive effect of h 2 o 2 addition to the water . no such change is seen in zeta potential b along the gegenion layer in the oil / solid interface 18 , as shown in fig5 . thus , water so fortified with hydrogen peroxide 16 ′ is capable of displacing oil from the mineral substrate surface by preferential binding with the substrate , thereby converting entrained oil 14 to free oil 14 ′ ( fig7 ). referring to fig7 , free oil so recovered as by pumping from a geological formation is typically in the form of a metastable foam or froth containing oil , water , and finely divided mineral substrate such as clay and sand , similar to the reaction product experienced in recovering oil from bituminous tar sands in accordance with u . s . pat . no . 6 , 251 , 290 , (&# 39 ; 290 ), incorporated by reference hereinabove . the froth is further intensified by low - molecular weight ketones formed in the recovery process which boil out of solution as the pressure is reduced during extraction . this froth can be reduced by the further addition of hydrogen peroxide , as fully disclosed in the &# 39 ; 290 patent . such separation is believed to involve , among other things , the generation of additional ketone moieties 24 , as shown in fig7 , which serve to make the water and oil more mutually repellant to break down the colloidal stabilization therebetween . the ketones themselves may be conveniently stripped from the reaction mixture and recovered conventionally or reused in a continuous process . preferably , the separation process also includes dissolving a low - molecular weight hydrocarbon cutter stock into the oil phase which further reduces the density of the oil phase and aids in separation from the water phase by flotation . the hydrocarbon may be , but is not limited to , an alkane such as methane , ethane , propane , butane , pentane , or combinations thereof . natural gas makes a convenient cutter in this process . the cutter may be stripped from the separated oil product and recovered in known fashion . the process may be carried out successfully at temperatures as low as 50 ° c ., and in some cases , as low as 20 ° c . further , the separation process may be carried out conveniently while the foam or froth is being transported in a slurry pipeline . from the foregoing description it will be apparent that there has been provided an improved method for recovery of heavy oil from geological formations . variations and modifications of the herein described method , in accordance with the invention , will undoubtedly suggest themselves to those skilled in this art . accordingly , the foregoing description should be taken as illustrative and not in a limiting sense .