US3412011A - Catalytic cracking and in situ combustion process for producing hydrocarbons - Google Patents

Description

Nov. 19, 1968 R. E. LINDSAY CATALYTIC CRACKING AND IN SITU COMBUSTION PROCESS FOR PRODUCING HYDROCARBONS Filed Sept. 2, 1966 56 54 3 52 S fi J48 40 44 HYDROCARBON SEPARATOR RECOVERY SYSTEM FLUE GAS as 46 50 I r- 22 STEAM I l CATALYST SEPARATION 28 r "I CATALYST 26 rl l- REGENERATIONV i g I AIR /COMBUST|ON ZONE GASES COM BUST ION ZONE A 7' TORNEYS United States Patent 3,412,011 CATALYTIC CRACKING AND IN SITU COMBUSTION PROCESS FOR PRODUC- ING HYDROCARBONS Robert E. Lindsay, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Sept. 2, 1966, Ser. No. 577,062 8 Claims. (Cl. 208-113) ABSTRACT OF THE DISCLOSURE A process for upgrading hydrocarbons produced in vapor form by in situ combustion within the subterranean oil stratum comprising contacting a vaporous hydrocarbon with a fluidized cracking catalyst within a production well, separating the catalyst from the resulting eflluent, recovering the upgraded hydrocarbons, and recycling the catalyst to the subterranean oil stratum to crack the vaporous hydrocarbons.

This invention relates to a process for catalytically cracking vaporous hydrocarbons from a reverse in situ combustion operation in a production well thru which hydrocarbons are being produced from the in situ combustion operation.

Production of hydrocarbons from an oil stratum by reverse burning in situ combustion is being practiced in the petroleum industry. The process comprises initiating combustion 'by any suitable means around a production well penetrating the oil stratum and feeding air to the resulting combustion zone from one or more offset injection wells, preferably a ring of wells surrounding the production well. The injected air arriving in the combustion zone propagates this zone toward the injection wells and away from the production well, leaving burned-out rock or sand behind the combustion front as it progresses thru the stratum. The combustion process is effected in the temperature range of about 750 to 1500 F., usually at least about 1000 F., so that the produced hydrocarbons are in vapor form as they enter the production well. There is substantial upgrading of the crude oil in this process. In one reverse burning in situ combustion operation in an oil field containing API gravity oil, the produced oil was upgraded to about API gravity.

It is desirable to upgrade the hydrocarbons produced from the in situ combustion operation still further. This invention is concerned with such a process.

Accordingly, it is an object of the invention to provide a process for upgrading hydrocarbons produced from a reverse burning in situ combustion process While the hydrocarbons are at an elevated temperature in the cracking range and in the production well. Another object is to utilize the heat of combustion developed in the in situ production of oil in the cracking of heavier hydrocarbons in the product stream to lighter, more valuable hydrocarbons. A further object is to provide a process for catalytically cracking hot vaporous hydrocarbons from a reverse burning in situ combustion operation which makes use of the heat of combustion developed during the in situ combustion operation. Other objects of the invention will become apparent to one skilled in the art upoh consideration of the accompanying disclosure.

A broad aspect of the invention comprises subjecting the hot vaporous effluent from a reverse burning in situ combustion operation to catalytic cracking in contact with a fluidized cracking catalyst within the production well thru which the hydrocarbons from the in situ combustion operation are being produced. A selected cracking catalyst, such as silica-alumina, is injected into the vaporous hydrocarbon effluent from the in situ combustion opoperation either in the casing-tubing annulus or in the tubing string leading from the oil stratum thru the well head. However, it is preferred to inject the fluidized catalyst in a selected gas, such as normally gaseous hydrocarbons or steam, thru the tubing string into the production effluent rising thru the annulus surrounding the tubing.

Any conventional cracking catalyst may be utilized in the process which is amenable to fluidization in a gas. Silica-alumina is the most commonly utilized cracking catalyst in conventional cracking operations but the invention does not lie in a specific catalyst and any cracking catalyst which operates satisfactorily in finely divided fiuidizable form is within the scope of the invention.

The cracked effluent carrying the catalyst in suspension is passed thru a separation zone to recover the catalyst and the catalyst is passed to a catalyst regeneration step which involves burning off the carbonaceous deposits, resulting from the cracking operation, with air at a temperature in the range of about 950-1 F. The resulting hot regenerated catalyst is then admixed with the carrier gas for transport to the well via the tubing or the annulus into the ascending column of in situ combustion effluent.

One aspect of the invention comprises separating a normally gaseous stream of hydrocarbons from the cracked hydrocarbon eflluent and utilizing this stream for suspending and transporting the regenerated catalyst to the cracking zone within the production well. It is also feasible to inject steam into the hydrocarbon stream serving as a transport gas or to use steam entirely as the transport gas.

A more complete understanding of the invention may be had by reference to the accompanying schematic drawing, which is an elevation in partial section of an arrangement of apparatus in combination with a production well in a carbonaceous stratum undergoing inverse in situ combustion for effecting the process of the invention.

Referring to the drawing, an oil stratum 10 is penetrated by a production well 12 which is provided with a casing 14 extending thru the stratum and perforated therein and with a tubing string 16. High temperatureresistant steel should be utilized in the casing within the stratum and the lower end of the turning string. In some reverse in situ combustion operations, a porous refractory liner is utilized in the production well to withstand the temperatures downhole.

A burned-out recovery zone at the stage of operation depicted is bounded by line 18. The combustion front 20 is moving radially away from well 12 toward a ring of offset injection wells (not shown) and the area within the confines of line 18 comprises hot burned-out sand thru which the produced hydrocarbons and combustion gases flow to the production well. Well 12 may also represent one well in a line of production wells flanked on each side by a line of injection wells.

In the embodiment of the invention illustrated in the drawing, casing 14 extends above ground a short but substantial distance and connects with a catalyst separation vessel 22 which is provided with a shield or baffie 24 for disengaging the catalyst from the product gas stream. The catalyst drops to the bottom of vessel 22 and is withdrawn thru line 2-6 which delivers the catalyst to a regeneration vessel 28 for contacting with air or diluted air introduced to the bottom of the vessel thru line 30 under the impetus of pump 32. The regenerated catalyst flows out line 34 and the flue gas is vented thru line 36.

The product gas passes from the top of vessel 22 via line 38 into cyclone separator 40 which knocks down catalyst fines still remaining in the product gas so that these fines are delivered via conduit 43 to the recovered catalyst in the bottom of vessel 22. The substantially catalyst-free product gas passes from separator 40 thru line 44 to hydrocarbon recovery system 46 where a separation is made into normally gaseous hydrocarbons which are recovered thru line 48, normally liquid hydrocarbons recovered thru line 50, and nonhydrocarbon gases and H thru line 52. A portion of the normally gaseous hydrocarbons may be recovered thru line 54 as product and another stream of these gases is passed via line 56 to tubing string 16 at the well head, carrying a suspension of catalyst from line 34. Steam or other transport gas may be introduced thru line 58 to line 46 at a suitable locus as upstream of line 34. An indirect heat exchange vessel 60 is positioned in line 56 for regulating the temperature of the transport gas in operation in which such regulation is needed. Regenerated catalyst can be withdrawn from regenerator 28, heat exchanged, and recycled to the regenerator 28 for temperature control of the system (not shown). Also, the amount of regenerated catalyst flowing to the system thru conduit 34 can be controlled to control the temperature of the system.

A thermocouple 62 downhole in the incipient cracking zone is connected by cable 64 with a temperature recorder 66 above ground for the purpose of determining the temperature downhole in the cracking zone. The sensed cracking temperature can be utilized to control the temperature of the catalyst suspension downstream of line 34 by either adding heat to or extracting heat from the gaseous stream in line 56 upstream of line 34 as by heat exchanger 60 and/or gas introduced thru line 58 and/or by heat exchange of a portion of the regenerated catalyst and/or amount of regenerated catalyst used. It is also feasible to analyze the hot effiuent in line 44 to determine the extent of cracking and adjust the cracking temperature downhole to efiect the desired amount of cracking. One method comprises analyzing the efliuent for olefin concentration or H concentration as an indication of the depth of cracking and regulating the temperature of cracking in response thereto so as to provide the desired amount of cracking.

The following example illustrates a preferred method of operation but it is not to be construed as unnecessarily limiting the invention.

SPECIFIC EXAMPLE Range Specific Rcgenerator (28):

Pressure, p.s.i.g -50 Temperature, F 1, 0504, 1, 100 Tubing (16): Top:

Pressure, p.s.i.g 3-48 18 Temperature, F 950-1, 150 l, 000 Bottom:

Pressure, p.s.i.g (A) 218 Temperature, F (A) 980 Length, feet (A) 400 Annulus (14):

Top:

Pressure, p.s.i.g 20 Temperature, F 900 Bottom:

Pressure, p.s.1.g (A) 80 Temperature, F (A) 980 In Situ Zone:

Pressure, p.s.i.g (A) 300 Temperatur F (A) 1, 200 Catalyst/Hydrocarbon (C), Wt. Ratio 2:1 to 10:1 4:1 Conversion, Vol. Percent Hydrocarbon:

API at F. before combustion 5 .0 API at 60 F. after combustion 25 .0

Liquid Vol. Percent at 60 F.

Hydrocarbon Cracked Products:

Butane and Lighter (measured as liquid) 14 Gasoline (400 F., E.P.) 41 Cycle Oils 50 Total (B) Certain modifications of the invention will become apparent to those skilled in the art and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

I claim:

1. A process for upgrading hydrocarbons from an in situ combustion process conducted in a subterranean oil stratum penetrated by a production well having a casing and a tubing string leading to said stratum, wherein hydrocarbons produced in vapor form around said production well at a temperature of at least 750 F. are recovered through said production well by the steps of:

(a) passing said hot produced hydrocarbons through one of the tubing and the casing-tubing annulae in admixture with a fluidized solid particulate cracking catalyst to substantially crack heavier hydrocarbons to lighter hydrocarbons, the cracking occurring in the absence of added hydrogen;

(b) separating catalyst from the vaporous effluent from said production well;

(c) recovering hydrocarbons from the effiuent of step (b); and

(d) injecting into the other of the tubing and easingtubing annulae at the production well head a hot gaseous suspension of the catalyst of step (a) whereby said catalyst is introduced to said hot hydrocarbons downhole.

2. The process of claim 1 including the steps of:

(e) recovering a stream of normally gaseous hydrocarbons from the hydrocarbons of step (c);

(f) burning deposited coke 011 the catalyst recovered in step (b) to regenerate same; and

(g) suspending regenerated hot catalyst of step (f) in the stream of normally gaseous hydrocarbons of step (e) to provide the suspension of step (d).

3. A process for upgrading hydrocarbons from a reverse in situ combustion process conducted in a subterranean oil stratum penetrated by an injection well and a production well having a casing and a tubing string leading to said stratum, wherein combustion is initiated around said production well, the resulting combustion zone is advanced through said stratum toward said injection well by injecting air through said injection well to feed said combustion, and produced hydrocarbons in vapor form at a temperature of at least 750 F. are recovered through said production well, which comprises the steps of:

(a) passing said hot produced hydrocarbons through one of the tubing and the casing-tubing annulae in admixture with a fluidized solid particulate cracking catalyst to substantially crack heavier hydrocarbons to lighter hydrocarbons, the cracking occurring in the absence of added hydrogen;

(b) separating catalyst from the vaporous effluent from said production well;

(c) recovering hydrocarbons from the effluent of step (d) injecting into the other of the tubing and easingtubing annulae at the production well head a hot gaseous suspension of the catalyst of step (a) whereby said catalyst is introduced to said hot hydrocarbons downhole;

(e) recovering a stream of normally gaseous hydrocarbons from the hydrocarbons of step (c);

(f) burning deposited coke off the catalyst recovered in step (b) to regenerate same; and

(g) suspending regenerated hot catalyst of step (f) in the stream of normally gaseous hydrocarbons of step (e) to provide the suspension of step (d).

4. The process of claim 3 including the steps of:

(h) sensing the temperature of the cracking reaction in step (a); and

(i) regulating the temperature of the catalyst suspension in step (d) so as to maintain a selected reaction temperature in the range of 750 to 950 F.

5. The process of claim 3 wherein the temperature of the hot suspension of step (g) is adjusted to maintain a selected cracking temperature in step (a) in the range of 750 to 950 F.

6. The process of claim 4 wherein the sensed temperature is substantially below the selected temperature and said suspension in step (d) is introduced at a substantially higher temperature than said hot hydrocarbons at initiation of cracking.

7. The process of claim 4 wherein the temperature of the hot hydrocarbons is substantially above the selected cracking temperature and said suspension in step (d) is cooled to a temperature substantially below said selected temperature so as to effect reaction at said selected temperature.

8. The process of claim 3 wherein steam is added to said suspension in step (g).

References Cited UNITED STATES PATENTS DELBERT E. GANTZ, Primary Examiner.

ABRAHAM RIMENS, Assistant Examiner.

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