US2288857A - Process for the removal of bitumen from bituminous deposits - Google Patents

Description

gg zsu Patented July 7, 1942.

UHUQO [\Lil'ill'lllllbll (UNITED STATES PATIENT OFFICE PROCESS FOR THE REMOVAL OF BITUMEN FROM BITUMINOUS DPPOSITS Philip'snbkow, Los Angeles, Calif assignor to" Union Oil Company of California, Los Angeles, Calif., a corporation of California I No Drawing. Application October 18, 1937,

Serial No. 189,754

3 Claims. (01. lea-i4).-

, duce a fluent oil-in-water type emulsion.

- found close to the top of the ground in such 10- calit'ies as Utah, California and Northern Canada, from which a viscous asphalt or maltha maybe obtained. Fluid bitumen, such as'high gravity petroleum, may be removed from such formations by natural drainage, or by suitable pressure drives imposed by gas or water. Heretofore, no practical process has been developed for. the removal of. viscous bitumens from deep subterranean formations. In the case of deposits consisting mainly of viscous bitumens in conjunction with sand whichcarry no great overburden, mining has sometimes been successfully resorted to. vIn this latter case, the mined oil sands are subsequently treated with a'hydro-' carbon solvent or with aqueous solutions designed to strip the asphalt from the sand without emulsiflcation in order to recover the bitumen by mining methods from its natural position. and recovering the bitumen as a fluent oil-in-J free from associated mineral oil matter.

It is an object of the present invention to provide a process for the removal of bitumen from mineral matter associated with it in its natural deposits by a process comprising the formation of water continuous emulsionsof bitumen. It is furthermore an object of the present invention facial tension between the bitumen and the water and the sameor other solutes which effect emulsiiication of the bitumen and endow the emulsion with suflicient stability to remain unbroken during its subsequent mechanical handling or contact with electrolytes present in the formation or in the water. The invention further resides in h the use of a small proportion of alkali hydroxides, carbonates, phosphates, silicates, soaps, sulphonated materials, such as Turkey red oil, proteins and carbohydrate materials suchas casein 'or vegetable gums, and alkali salts or tan nic acids, cresol, phenols and the like. The invention further resides in the provision for a positive movement of the aqueous solution against or through the formation which movement is adapted to scour, remove and emulsify the bitumen. The invention further resides in effecting the emulsification at elevated temperatures, or in the presence of hydrocarbon solvents, designed to soften and/or liquefy the bitumen. The invention further resides in such a process in which the emulsion with or without a preliminary treatment to decrease the quantity of admixed mineral matter is broken to recover the bitumen as a separate phase.

The aqueous solution used in my process should be adapted to depress the surface tension between the bitumen and water thereby facilitating the stripping of the bitumen from the mechanical handling and agitation. In many to provide a process for the emulsification of the bitumen in situ whereby the bitum'en is stripped from the formation whether in situ or removed water emulsion. It is, furthermore, an object of the present invention to provide a suitable emulsifying agent for such a process and also to provide means forheating, agitation and the like, designed to effect said emulsiflcation.

The invention further resides in the use of aqueous solutions for said emulsification which contains solutes aiding in the stripping of the bitumen from the sand by depressing the inter- 55 instances, both functions may be combined in one solute-thus, for example, emulsifying agents such as sodium oleate, sodium resinate and Turkey red oil-soap both reduce the interfacial tension and emulsify the bitumen. A surface\ tension depressant, such as alcohol, may be used in conjunction with a separate emulsifying agent, such as sodium naphthenate. The emulsifying agent may be formed by a reaction bethe bitumen. This type of emulsifying agent is useful mainly with restricted types of asphaltic crudes having su'ficicnt acids of the proper cannon mime molecular weight to yield an emulsifying agent on reaction with alkali.

With regard to the function of lowering the interfacial tension between the bitumen and water, the quantity of solute need not be limited; thus concentrations of a few thousandths of a percent are effective and concentrations of several percent are still more effective. The concentration of the solute should be limited however with regard to its function as an emulsify-- ing agent. The emulsifying agent should be present in suflicient concentration to effect emulsification of the bitumen and to stabilize the emulsion thus produced against breaking on subsequent mechanical handling and passage through the formation and against contact with such electrolytes as may be present in the formation or the connate water. Concentrations of from 1; of a percent'to 2% or 3% are usually sufiicient for this purpose. Excessive concentrations are in most instances to be avoided as wasteful, or as inimical to proper emulsification,

The choice of the proper emulsifying agent, as

well as its proper concentration and the amount and character of stabilizing agent, must be ascertained by trial. The choice of the conditions are well understood in the art. Asphalts are now emulsified for use in road construction and the conditions of emulsification are part of the commorrreference in this art. In order to determine these conditions, it will be desirable to obtain a sample of the formation. If near the surface, this may be done by ordinary sampling as practised in mining methods. If the formation is a deep-lying one, coreing as used in oil well practice can be resorted to. With such samples at hand, the conditions. of temperature, concentration and emulsifier composition can be determined by trial and the best conditions for stripping the asphalt or oil from the mineral matter and the condition for forming an oil-inwater emulsion of proper stability may be determined.

In general, a suitably adjusted aqueoussolution of the stability and type described is found to have a relatively fine particle size, which property is of advantage in permitting the emulsion to be transferred through porous formations in which the interstices are relatively small.

The emulsification takes place more readily when bitumen is naturally fiuid or has been rendered fluid by the application of heat or by solution in hydrocarbon solvents. When an oil sand containing viscous bitumen has been brought to the surface by mining, it may be comminuted and heated directly with the aqueous solution and agitated therewith to effect emulsification of the bitumen. As an alternative method, the oil sand may be commingled prior to agitation with the aqueous solution with a hydrocarbon solvent, such as kerosene, or the aqueous solution may contain emulsified therein a light hydrocarbon solvent Deep lying formations, for instance, those about 3000 feet, are

naturally hot and the asphalt, if not actually thin enough to flow by drainage, gas or water drive may be sufficiently soft to emulsify if it be of a nature to emulsify spontaneously. Such deposits may be those which emulsify spontaneously on contact with caustic soda or potash of proper concentration-that is, of about 0.08% to 0.18%.

When operating on deep deposits reached only by wells, the formation, if desired, may be first fluxed with a hydrocarbon solvent. This may be accomplished by introducing light solvents, such as kerosene or naphtha, into the formation by means of a drive from centrally located wells in conventional manner. In general, the direct application of heat through the medium of a heated aqueous solution of the type described suflices to liquefy and emulsify the bitumen. In this latter instance, the aqueous solution may carry, if desired, more or less emulsified hydrocarbon solvent,

In operating on undisturbed formation insitu. I may cause a' positive movement of the aqueous solution to take place which is adapted to scour the bitumen from the sands and to provide the agitation necessary for emulsification. The character of the process which can be applied depends to a large extent on the porosity of the formation. When dealing with a sufficiently porous formation, I may usea process somewhat akin to a water drive. By sinking a central pressuring well in the formation, and around it sinking several other collecting wells, I may force the aqueous solution, preferably at an elevated temperature, for instance at 212 F., down the central well and by means of the applied pressure cause it to migrate to the neighboring collecting wells. In the passage of the hot aqueous solution through the porous sands, the bitumen is stripped free from the sand and'emulsified in the. form of small discrete particles surrounded by the aqueous solution. By properly adjusting the character and quantity of the emulsifying agent, this emulsion is rendered sufficiently stable to remain'unbroken during its passage through the sands to the neighboring wells and its subsequent mechanical transfer to the surface, for example, by means of pumps. Factors tending to break the emulsion are the intimate mechanical contact with the sand and the admixture of the 7 solution with electrolytes present in the formation or in the whole system. By the addition of sufficient amountpf emulsifying agent, how-- ever, in the form of a soap, or by the use of a stabilizing agent in conjunction with the emulsifying agent, for example, by using a mixture of alkali and casein, I am able to prevent the breakdown of the emulsion under these conditions.

salts present in the formation of well systems,

or an emulsion which would be resolved by the mechanical handling or pumping of the emulslon.

In the case of less porous formations which are permeated by the aqueous solution only with difficulty, I prefer to use a surging .or'pulsatin'g back and forth motion of the aqueous solution which effects the emulsification of the bitumen .at the outer bounds of the zone penetrated by the water and subsequently provides for the removal of this relatively concentrated emulsionv and its replacement by a fresh solution or at least a diluted emulsion. By this means, the

forward surge. of the emulsifying solution iseffective in causing a limited penetration of the formation, which, when followed by the momentary withdrawal of the solution and repetition of the cycle, causes the bitumen to be removed in an emulsified form from a gradually increasing zone. type of surging motion can be induced by a variety of means, for example, by the action of a pulsating gas pressuring means, such as air ornatural gas on a body of the emulsifying solution lying at the bottom of the drill hole. In carrying out this process, a heated aqueous solution of emulsifying and stabilizingagent is introduced into the well and agitated by means of injection of natural gas or air. The surface of the formation is scoured. Gas is then introduced above the water surface and the water solution is driven into the formation. Under certain conditions of residual gas pressure in the formations, the water may then be drained back into the well by releasing pressure and employing gas lift to withdraw the emulsion. If desired,

a reverse gas drive from surrounding wells may be employed to force the emulsion back into the well. The repeated washing of the formation and stripping the formations may be accomplished.

Various means may be used for heating the aqueous solution and/or the formation. Hot aqueous solution, for example, may be pumped down the drill hole into contact with the forma- I 2 tion and recycled backto the surface for further heating; If desired, the system may be maintained under pressure to provide for the use of superheated water. This may be accomplished by heating the solution'under high pressure, such as 300 to 1,000 pounds and pumping the solution into wells under the high pressure.

I Live steam may bebrought into contact with men. The emulsion may then be removed bypumping or. gas lift.

emulsifying solution on the formation in situ contains but little, if any, associated mineral. matter and may be broken or resolved directly to obtain bitumen as a separate phase. Suitable methods of breaking the emulsion comprises the addition of electrolytes, particularly polyvalent electrolytes, such as 02301:, or breaking by freezing. Other methods may also be used for breaking, for

example, substantial quantities, e. g., from 10 to 50%, or methyl or ethyl alcohol may be added to the emulsion whereby the bitumen breaks out as a separate phase. The aqueous phase containing the alcohol may be fractionally distilled to recover the alcohol and an emulsifying solution substantially free from alcohol and suitable for reuse.

In operating onsands which have been brought I to the surface by mining, agitation of the sand with the emulsifying solution may be afforded by any suitable device,-as for example, by means of a paddle mixer, a ball mill, or the like. This agitation should be conducted attemperatures at which the bitumen associated with the sand is sumciently liquid to emulsify. Asset forth above, a hydrocarbon solventinay be used during the agitation process to liquefy the bitumen by solution rather than by heat.

The emulsionas obtained by the action of the In the case of mined sands which have been agitated during the process of emulsiflcation, more or less mineral matter may remain admixed with or suspended in the emulsion. By settling and decantation, as for example, in a Dorr type of thickener, the greater part of this suspended mineral matter may be separated from the emulsion. Further separation may also be effected by centrifuging or filtering the emulsion through fine meshed screens, dilute with further quantities of water, and the like. In breaking an emulsion which contains more or less associated mineral matter, it is desirable to diminish only the emulsifying properties of the solution without substantially' increasing the interfacial tension between the bitumen and the water. By this means, the sand or mineral still remains preferentially wet by the water and sinks to the bottom, while the bituminous material separates as a water repellant phase free from both sand 1 and water. This condition can be realized by the addition of properly 'adjusted amounts of breaking agent, for examplecalcium chloride,

.whereby the emulsion is broken while at the same time the tendency of the sand to be wet by .the[

water rather than the bitumen is conserved. The process of adding alcohol to break the emulsion, as set forth above, is well adapted for this purpose.

While the process has been described as applicable to relatively viscous bituminous deposits, such as'asphalts and heavy oils, it is also applicable to removal of the residual oil deposits fromexhausted oil fields. It is -well known that but a fraction of the oil is recovered by present methods. The oilformations contain a large percentage of the original oil. The invention here described makes possible the recovery'of additional oil. The fluidity of the 011 makes the emulsification more easy. Many of .the formations are of sufficient porposity to make the use of a water device from centrally located wells to surrounding wells feasible. The use of a proper emulsifying agent determined as hereunder cited will result in the stripping of the formations and theiremulsiflcation inthe water to form oil-inwater emulsions. The emulsion is collected in the collecting wells and removed as by pumping and'gas lift. The emulsions are then broken as described above.

The foregoing exemplary description of my invention is not to'be considered as limiting since .many variations may be made within the scope of the following claims by those skilled in the art without departing from the spirit thereof.

I claim:

' 1. A process for removing bitumen such as oil or asphalt from formations whichcomprises introducing an aqueous solution containing an emulsifying agent into the formation, agitating said solution in said formation by surging said solution back and forth in the formation to eifect intimate contact of said solution with bitumen in said formation, emulsifying said bitumen by said agitation to form a fluid oil-in-water emulsion, withdrawing said emulsion from said formation and resolving the emulsion to separate the bitumen from the emulsion.

2. A process for removing bitumen such as oil or asphalt from formations which comprises introducing an aqueous solution containing an emulsifying agent into the formation, agitating said solution in said formation by surging said solution back and forth in the formation by means of a gas under pressure to effect intimate contact of said solution with bitumen in said formation, emulsifying said bitumen by said agitation to form a fluid oil-in-water emulsion, withdrawing said emulsion from said formation and resolving the emulsion to separate the bitumen from the emulsion.

3. A process for removing bitumen such as oil or asphalt from subterranean formations which comprises forming a central shaft to said formation, forming surrounding shafts to said formation, forcing an aqueous solution containing an emulsifying agent down said central shaft, applying pressure down said central shaft to cause said solution to migrate to said surrounding shafts and therebi causing said solution to mix with bitumen in said formation and emulsify the same to form an oil-in-water emulsion, withdrawing said emulsion from said surrounding shafts and separating the bitumen from said emulsion. I

PHILIP SUBKOW.