Method for enhancing the recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point

Patent metadata

Field	Value
Publication number	US-11536123-B1
Application number	US-202217694508-A
Country	US
Kind code	B1
Filing date	Mar 14, 2022
Priority date	Jul 14, 2021
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

The present invention discloses a method for enhancing the recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point, and the method is aimed at the development of heavy oil reservoir by water injection under the condition that the performance parameters of crude oil emulsion meet the following three specific requirements: (A) The viscosity of the crude oil is less than 6,000 mPa·s; (B) At the reservoir temperature, the phase inversion point of the crude oil emulsion is greater than or equal to 70%, and the emulsion viscosity corresponding to the phase inversion point is 2-6 times of the crude oil viscosity; (C) At the reservoir temperature, when the water cut is less than or equal to the phase inversion point, the flow rate ratio of crude oil emulsion to crude oil is 0.2 to 0.9.

First claim

What is claimed is:

1. A method for enhancing a recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point to develop a heavy oil reservoir comprising:
performing water injection into a heavy oil reservoir under a condition when performance parameters of a crude oil emulsion meet three specific requirements, wherein the three specific requirements comprise:
(A) viscosity of the crude oil is less than 6,000 mPa·s;
(B) phase inversion point of the crude oil emulsion at reservoir temperature, is greater than or equal to 70%, and emulsion viscosity corresponding to the phase inversion point is two-to-six times of the crude oil viscosity; and
(C) at the reservoir temperature, when water content is less than or equal to the phase inversion point, a flow rate ratio of crude oil emulsion to crude oil is 0.2 to 0.9.

2. The method for enhancing a recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point according to claim 1 , wherein the condition of performance parameters of crude oil emulsion meeting the three specific requirements is determined using the following steps:
Step 1: taking a crude oil sample from the heavy oil reservoir, determining the crude oil viscosity, and determining whether the crude oil viscosity meets the requirement of less than 6,000 mPa·s; if it does, proceed to Step 2;
Step 2: measuring the phase inversion point of the crude oil emulsion at the reservoir temperature, and determining whether the phase inversion point is greater than or equal to 70% and whether the emulsion viscosity corresponding to the phase inversion point is two-to-six times of the crude oil viscosity; if it does, proceed to Step 3;
Step 3: measuring the flow rate ratio of crude oil emulsion to crude oil when the water content is less than or equal to the phase inversion point at the reservoir temperature, and then determining whether the flow rate ratio of crude oil emulsion to crude oil is within a range of 0.2 to 0.9, which indicates that water injection is applicable to the development of the heavy oil reservoir.

3. The method for enhancing a recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point according to claim 2 , wherein at the reservoir temperature in Step 2, the phase inversion point of the crude oil emulsion is determined using the steps of:
Step (1) preheating the crude oil and produced water of the heavy oil reservoir to the reservoir temperature respectively;
Step (2) mixing the preheated crude oil and produced water in different volume ratios to form a system with different measures of water content, and stirring the system with an emulsifier for 60 minutes at the reservoir temperature and shear rate of 150 s −1 to form a crude oil emulsion;
Step (3) measuring the viscosity of the crude oil emulsion at 7.34 s −1 and reservoir temperature with a rotary viscometer; forming a curve based on a relationship between the crude oil emulsion viscosity and the different measures of water content, wherein the water content of the system is plotted on an x-axis and the crude oil emulsion viscosity on a y-axis; and determining a water content percentage corresponding to a maximum viscosity of the crude oil emulsion as the phase inversion point.

4. The method for enhancing a recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point according to claim 2 , wherein at the reservoir temperature in Step 3, the method for determining the flow rate ratio of crude oil emulsion to crude oil is as follows:
(1) Select natural or artificial cores that represent porosity and permeability of the reservoir, and vacuum the cores and saturate them with water;
(2) Inject crude oil into the cores at a flow rate ν corresponding to a shear rate of 150 s −1 until a pressure is stable and record a stable pressure value P crude oil , then co-inject the crude oil and water produced in the cores with a specific oil-water flow rate ratio at the same flow rate ν into the cores to simulate formation of in-situ crude oil emulsion at a specific water content, continue to inject until the pressure is stable, and record a stable pressure value P emulsion ; calculate a ratio of P crude oil to P emulsion , which is the flow rate ratio of crude oil emulsion to crude oil at the specific water content;
(3) Repeat Step (1), then change the oil-water flow rate ratio, and repeat Step (2) to obtain the flow rate ratios of crude oil emulsion to crude oil at different measures of water content.

5. The method for enhancing a recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point according to claim 4 , wherein the flow rate ν is calculated as follows:

v
=

4
⁢
n

3
⁢
n

+
1

⁢

γ
⁢

150
⁢
K
⁢
ϕ

12

,

where, n is a flow behavior index, K is permeability, in D, ϕ is porosity, and γ is shear rate.

6. The method for enhancing a recovery factor of heavy oil by in-situ oil-water emulsion with high phase inversion point according to claim 4 , wherein the natural or artificial cores are 3.8 cm×8 cm in size.

Assignees

• Univ Southwest Petroleum

Inventors

• Pu Wanfen
• Sun Lin
• Xie Jianyong
• Pang Shishi
• Shi Yan
• Chu Yanjie
• Liu Rui
• Du Daijun

Classifications

• E21B43/20 Primary

  Displacing by water · CPC title

• G01N33/2823 Primary

  Raw oil, drilling fluid or polyphasic mixtures · CPC title

• Y10T436/21

  Hydrocarbon · CPC title