Enhanced oil recovery apparatus and method

• US 4,378,846 A
• Filed: 12/15/1980
• Issued: 04/05/1983
• Est. Priority Date: 12/15/1980
• Status: Expired due to Fees

• Current Assignee: Kurtis B. Brock
• Original Assignee: Kurtis B. Brock
• Inventors: Brock, Kurtis B.
• Primary Examiner(s): Leppink, James A.
• Assistant Examiner(s): Suchfield, George A.
• Application Number:
  US06/216,425
• Time in Patent Office: 841 Days
• Field of Search: 166/57, 166/60, 166/65 R, 166/272, 166/302, 166/303, 219/277, 219/278, 219/279, 219/291, 219/292, 219/293
• US Class Current: 166/303
• CPC Class Codes: E21B 36/00 Heating, cooling or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones
• CPC Class Codes: E21B 36/04 using electrical heaters

Abstract

Apparatus for heating hydrocarbons, and the like, in an underground reservoir for the purpose of lowering the viscosity of the substance in the reservoir and facilitating the flow thereof has a flow channel arrangement disposable in a reservoir of the material to be treated for forming a flow path for a working fluid that is heated by a heating system associated with the flow channel arrangement. The heated working fluid is then discharged from the flow path and into the reservoir of material to be heated for the purpose of lowering the viscosity and improving the flowability of the material in the reservoir.

The heating system includes an electrical resistance heating unit comprising an electrical circuit including at least one pair of opposed electrodes electrically connected in series and arranged along and partially forming the flow path for the working fluid, with the portion of the electrical circuit between the electrodes being completed through the working fluid. The series connection of the electrodes provide for efficient downhole use of electrical energy even at depths below 2,000 feet, by minimizing line losses to the electrodes and by creating, with accurate control, a very high resistance at the bottom of the well in which the device is disposed.

Claims

1. Apparatus for heating hydrocarbons in an underground reservoir and facilitating flow of the hydrocarbons, comprising, in combination:

(a) flow channel means disposable in a reservoir of hydrocarbons for forming a flow path for a working fluid; and

(b) heating means associated with the flow channel means for heating the working fluid prior to discharging the heated working fluid from the flow path and into a reservoir of hydrocarbons to be heated, the flow channel means including, in combination;

(1) a housing having an exterior and defining a hollow chamber; and

(2) conduit means arranged in the chamber of the housing and communicating with the exterior of the housing for forming the flow path, the conduit means including a fluid inlet to the chamber, a restricted fluid flow circuit through the chamber and a fluid outlet from the chamber, the housing being provided with connector means for attaching the housing to a lower end of a pipe string, the fluid inlet and fluid outlet being respectively located in the maximum spaced portions of the housing, and the fluid flow circuit of the conduit means forming a tortious path, substantially "S" shaped, between the fluid inlet and fluid outlet and arrangeable relative to an associated pipe string to form three substantially parallel, vertically disposed legs, the working fluid being a liquid, and the heating means including a pair of series connected electrodes at least partially forming a middle one of the legs, the latter being arranged forming an upwardly directed flow path means passing between the pair of electrodes for assuring that the liquid of the working fluid completely fills the associated one of the legs.

2. Apparatus for heating hydrocarbons in an underground reservoir and facilitating flow of the hydrocarbons, comprising, in combination:

(a) flow channel means disposable in a reservoir of hydrocarbons for forming a flow path for a working fluid; and

(b) heating means associated with the flow channel means for heating the working fluid prior to discharging the heated working fluid from the flow path and into a reservoir of hydrocarbons to be heated, the flow channel means including, in combination;

a housing having an exterior and defining a hollow chamber; and

conduit means arranged in the chamber of the housing and communicating with the exterior of the housing for forming the flow path, the conduit means including a fluid inlet to the chamber, a restricted fluid flow circuit through the chamber and a fluid outlet from the chamber, the housing being provided with connector means for attaching same to a lower end of a pipe string, the fluid inlet and fluid outlet being respectively located in maximum distally spaced portions of the housing, and the fluid flow circuit of the conduit means forming a tortious path, substantially "S" shaped, between the fluid inlet and fluid outlet and arrangeable relative to an associated pipe string to form three substantially parallel, vertically disposed legs, the heating means including a series electrical resistant heating unit comprising an electrical circuit including a pair of opposed electrodes arranged along and partially forming the flow path of a working fluid, a portion of the electrical circuit between the electrodes being completed through the working fluid, the pair of electrodes being one of a plurality of pairs of opposed electrodes and spaced along the flow path of the working fluid, each of the electrodes of the pairs being electrically connected in series with all of the other electrodes in the electrical circuit.

3. Apparatus for heating hydrocarbons in an underground reservoir and facilitating flow of the hydrocarbons, comprising, in combination:

(a) flow channel means disposable in a reservoir of hydrocarbons for forming a flow path for a working fluid; and

(b) heating means associated with the flow channel means for heating the working fluid prior to discharging the heated working fluid from the flow path and into a reservoir of hydrocarbons to be heated, the heating means including an electrical resistance heating unit comprising a series electrical circuit including a pair of opposed electrodes arranged along and partially forming the flow path of a working fluid, the electrical current between the electrodes being completed through the working fluid, with most of the resistance in the circuit being between the electrodes, the pair of electrodes being one of a plurality of pairs of opposed electrodes included in the electrical circuit and spaced along the flow path of the working fluid, each of the electrodes of the pairs being electrically connected in series with all of the other electrodes.

4. Apparatus as defined in claim 3 wherein the flow channel means includes, in combination:

(a) a housing having an exterior and defining a hollow chamber; and

(b) conduit means arranged in the chamber of the housing and communicating with the exterior of the housing for forming the flow path, the conduit means including a fluid inlet to the chamber, a restricted fluid flow circuit through the chamber and a fluid outlet from the chamber.

5. Apparatus as defined in claim 4, wherein the housing is provided with connector means for attaching same to a lower end of a pipe string.

6. A method for facilitating the recovery from wells of hydrocarbons having relatively high viscosities, comprising the steps of:

(a) arranging a heating unit at the bottom of a pipe string in a reservoir of hydrocarbons;

(b) passing through the heating unit a fluid heat transfer medium;

(c) heating the fluid as it passes through the heating unit;

(d) injecting the heated fluid into the reservoir of hydrocarbons for reducing viscisity of the hydrocarbons;

(e) recovering by conventional techniques the reduced viscosity hydrocarbons;

the step of heating the fluid including the step of passing the fluid between a plurality of pairs of series connected electrodes and using the fluid as part of an electrical circuit connecting the pairs of electrodes; and

(f) maximizing a resistance in a path through the working fluid between the electrodes in relation to a total resistance of the associated circuit for causing a maximum voltage to occur in the working fluid.

7. A method as defined in claime 6, wherein the step of passing the fluid includes the step of directing the fluid upwardly between the electrodes.