Super heavy oil development method for strengthening SAGD steam chamber to break through low physical property reservoir

Patent metadata

Field	Value
Publication number	US-11078768-B2
Application number	US-201916605068-A
Country	US
Kind code	B2
Filing date	Apr 4, 2019
Priority date	May 14, 2018
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

Disclosed belongs to the technical field of oil and gas field development engineering, and particularly relates to a super heavy oil development method for strengthening an SAGD steam chamber to break through a low physical property reservoir. The super heavy oil development method for strengthening the SAGD steam chamber to break through the low physical property reservoir includes the following steps: (1) selection of a developed oil reservoir; (2) well distribution; (3) steam chamber forming; (4) steam chamber expansion; (5) steam chamber strengthening. The method may enhance the ability of the steam chamber to break through the low physical property reservoir, enlarge the development height of the steam chamber, and further improve the SAGD development effect of super heavy oil.

First claim

What is claimed is:

1. A super heavy oil development method for strengthening an SAGD steam chamber to break through a low physical property reservoir, comprising the following steps:
(1) selection of a developed oil reservoir: according to geological characteristics and development status of an oil reservoir, roughly screening the oil reservoir applicable to development method according to the following conditions: an oil layer is a middle-deep oil reservoir, a buried depth is less than 1000 m, the remaining oil saturation is greater than 0.5, the thickness of the oil layer is greater than 20 m, the horizontal permeability is greater than 1000 mD, a ratio of vertical permeability to horizontal permeability is greater than 0.35, the porosity of the oil layer is greater than 0.20, a continuously or discontinuously developed low physical property reservoir exists in the oil layer, and the permeability of the low physical property reservoir is greater than 100 mD;
(2) well distribution: drilling two vertically opposite horizontal wells in the oil layer, wherein the horizontal well at an upper part is a steam injection well, the horizontal well at a lower part is a production well, the horizontal well at the lower part is 3-5 m away from the bottom of the oil layer, and the vertical distance between the two horizontal wells is 4-6 m;
(3) steam chamber forming: forming, by the steam injection well and the production well, thermal communication in a steam huff and puff or steam injection circulation preheating mode, and after forming the thermal communication, continuously injecting, by the steam injection well, high-dryness steam, wherein the steam dryness is greater than 70%, the injected steam develops to the upper part of the oil layer to form a steam chamber, and the production well continuously produces;
(4) steam chamber expansion: continuously expanding the steam chamber formed in step (3), and when the steam chamber is expanded to reach the low physical property reservoir, condensing steam to form hot water, so that the steam chamber may not break through the low physical property reservoir and may not be continuously expanded upwards; and
(5) steam chamber strengthening: strengthening the steam chamber by injecting gas into the steam injection well, so that the steam chamber breaks through the low physical property reservoir and is continuously expanded upwards; wherein the gas is injected into the steam injection well by injecting gas and steam into the steam injection well simultaneously as follows: a gas slug and a steam slug are simultaneously injected into a steam injection well, during the injection process, a ratio of a gas injection speed to a steam injection speed is less than 0.1 and a gas injection amount is less than 0.01 PV under an oil layer condition, the steam is continuously injected after the gas injection is completed, if an oil production speed is increased, the steam chamber is expanded, it indicates that the injected gas strengthens the expansion of the steam chamber and breaks through the low physical property reservoir, no gas is injected, and steam is continuously injected; and if the oil production speed and the expansion condition of the steam chamber are not improved, that is, the oil production speed is not increased and the steam chamber is not expanded, the gas slug and the steam slug are simultaneously injected into the steam injection well again, a ratio of a gas injection speed to a steam injection speed is less than 0.1 and a gas injection amount is less than 0.01 PV under an oil layer condition, steam is continuously injected after the gas injection is completed, and the oil production speed and the expansion condition of the steam chamber are observed.

2. The super heavy oil development method for strengthening the SAGD steam chamber to break through the low physical property reservoir according to claim 1 , wherein the gas in step (5) is nitrogen, carbon dioxide or flue gas from a steam injection boiler.

3. The super heavy oil development method for strengthening the SAGD steam chamber to break through the low physical property reservoir according to claim 1 , wherein the gas is injected into the steam injection well in step (5) by injecting gas and steam into the steam injection well alternately.

4. The super heavy oil development method for strengthening the SAGD steam chamber to break through the low physical property reservoir according to claim 3 , wherein the step of injecting gas and steam into the steam injection well alternately is as follows: a gas slug is injected firstly, the gas injection amount is less than 0.01 PV, a steam slug is then injected, a volume ratio of the gas slug to the steam slug is less than 0.1 under the oil layer condition, the oil production speed of firstly injecting the gas slug and then injecting the steam slug and the expansion condition of the steam chamber are observed, if the oil production speed is increased, the steam chamber is expanded, it indicates that the injected gas strengthens the expansion of the steam chamber and breaks through the low physical property reservoir, no gas is injected, and steam is continuously injected; and if the oil production speed and the expansion condition of the steam chamber are not improved, a gas slug and a steam slug are again injected into the steam injection well alternately, the gas slug is injected firstly, the gas injection amount is less than 0.01 PV, the steam slug is then injected, a volume ratio of the gas slug to the steam slug is less than 0.1 under the oil layer condition, and the oil production speed of firstly injecting the gas slug and then injecting the steam slug and the expansion condition of the steam chamber are observed.

Assignees

• Univ China Petroleum
• Univ China Petroleum East China

Inventors

• Lu Teng
• Li Zhaomin
• Yang Jianping
• Wang Hongyuan
• Wang Shizhong
• Wei Yao
• Wang Zhuangzhuang
• Hou Dawei
• Xu Yajie

Classifications

• E21B43/24 Primary

  using heat, e.g. steam injection · CPC title

• E21B43/2406 Primary

  Steam assisted gravity drainage [SAGD] · CPC title

• E21B43/168

  Injecting a gaseous medium · CPC title

• E21B43/305

  comprising at least one inclined or horizontal well · CPC title

• B23K35/0266 Primary

  flux-cored · CPC title