# US 11,306,571 B2 · Method for injecting non-condensable gas or in-situ combustion to recover remaining oil in a heavy oil reservoir with bottom water

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- Number: US 11,306,571 B2
- Document ID: US11306571B2
- Status: Granted
- Kind: B2
- Application number: 16/823,665
- Filed: 2020-03-19
- Published: 2020-09-24
- Granted: 2022-04-19
- Earliest claimed: 2019-03-19
- Assignees: Southwest Petroleum University; Heavy Oil Development Institute, Liaohe Oilfield Exploration and Development Research Institute Petrochina Oilfield
- Applicants: Southwest Petroleum University; Heavy Oil Development Institute, Liaohe Oilfield Exploration and Development Research Institute, PetroChina Oilfield
- Inventors: Qi Jiang; Changhao Hu; Zhongyuan Wang; Siyuan Huang; Zhibin Wang; Dong Wang
- Web page: https://patentgrep.com/patent/US11306571B2

## CPC

- E21B 43/243: Combustion in situ
- E21B 43/168: {Injecting a gaseous medium}
- E21B 43/24: using heat, e.g. steam injection
- E21B 43/2401: {by means of electricity}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A method for injecting non-condensable gas or application of in-situ combustion to recover remaining oil in a heavy oil reservoir with bottom water includes: drilling a new horizontal well in an oil layer between the existing horizontal production well location and the bottom water layer; preheating the new horizontal well; after the horizontal section of the horizontal well is in thermal communication with the upper steam/gas chamber, performing gas injection in existing wells to maintain pressure slightly higher or similar to the pressure of the bottom water layer, and converting the horizontal well into a continuous production well; drilling a vertical well in the unswept reservoir area; establishing a fluid communication in the oil layer between the vertical well and the horizontal well, injecting air or oxygen into the vertical well; and in the later stage of the horizontal well, stopping gas injection and gradually reducing the pressure in the steam/gas chamber.

## Claims

### Claim 1

A method for injecting non-condensable gas or application of in-situ combustion to recover remaining oil in a heavy oil reservoir with bottom water, comprising the following steps:
Step S10: drilling a new horizontal well in an oil layer between an existing horizontal production well location and a top of a bottom water layer;
Step S20: preheating the new horizontal well, wherein during the preheating stage, an operating pressure at a bottom hole of the new horizontal well is equal to a pressure of the bottom water layer to prevent an injected fluid from entering the bottom water layer, including using an existing vertical gas injection well to inject air or flue gas into an existing steam chamber, and increasing a pressure in the steam chamber to be the same as the bottom water pressure;
Step S30: after a horizontal section of the new horizontal well is preheated, converting the new horizontal well into a continuous production well, including shutting in the original upper horizontal well when the steam/gas chamber is too low;
Step S40: after an initial stage of producing from the new horizontal well, drilling a new vertical well in an unswept reservoir area, wherein the newly drilled vertical well and the new horizontal well form a new vertical well and new horizontal well combination;
Step S41: achieving fluid communication in the oil layer between the new vertical well and the new horizontal well;
Step S50: after achieving fluid communication in the oil layer between the new vertical well and the new horizontal well, injecting air or oxygen into the new vertical well to create a combustion condition underground, and producing a heated crude oil and combustion gas from the new horizontal well; and
Step S60: when producing from the new horizontal well reaches an economic limit, stopping gas injection and reducing the pressure in the steam/gas chamber until an end of oil production.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the horizontal section of the horizontal well in the step S10 is placed in the oil layer having a distance of 2-5 meters above the top of the bottom water layer.

### Claim 3 (depends on 2)

The method according to claim 2, wherein in the step S20, preheating is performed by any of steam circulation, electric heating, solvent injecting or the combination thereof.

### Claim 4 (depends on 1)

The method according to claim 1, wherein in the step S40, in the initial stage of producing from the new horizontal well, the pressure of the steam/gas chamber is higher than the pressure of the bottom water layer by 300-500 kPa, in order to push the upper preheated crude oil to the lower new horizontal well, and after stable production is reached, the pressure in the steam/gas chamber is controlled at the balanced pressure level of the bottom water layer.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the distance between the new vertical well and a toe of the new horizontal well is 5-10 meters in the step S40, and the distance between a bottom of a perforation interval of the new vertical well and the toe level of the new horizontal well is 3-5 meters.

### Claim 6 (depends on 5)

The method according to claim 5, wherein in the step S41, the fluid communication is established in the oil layer between the new vertical well and the new horizontal well by any of thermal circulation, injection of light oil, injection of chemical solvents, injection of a viscosity reducer, or electric heating.

### Claim 7 (depends on 6)

The method according to claim 6, wherein the pressure of the new horizontal well is kept equal to the pressure of the bottom water layer during the entire fluid communication process, thereby reducing the risk of bottom water invading a production well and the steam/gas chamber.