Method and system for determining single-well dynamic reserve and recoverable reserve of gas-drive reservoir

Patent metadata

Field	Value
Publication number	US-11320564-B1
Application number	US-202117314133-A
Country	US
Kind code	B1
Filing date	May 7, 2021
Priority date	May 7, 2021
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

A method and system determines a single-well dynamic reserve and recoverable reserve of a gas-drive reservoir. An example method includes: calculating a gas saturation of a gas-drive reservoir based on a principle of material balance; establishing a relationship between an oil-gas relative permeability ratio and oil-gas flow rates based on Darcy's law; fitting a binomial relationship between the oil-gas relative permeability ratio and the gas saturation based on an oil-gas seepage law; and establishing a gas-drive characteristic curve relationship between a produced gas-oil ratio and a cumulative oil production under a steady seepage flow of the gas-drive reservoir based on the above relationships and the gas saturation, and calculating a single-well dynamic reserve and recoverable reserve of the gas-drive reservoir based on binomial regression coefficients of the binomial relationship and the gas-drive characteristic curve relationship.

First claim

What is claimed is:

1. A method for determining a single-well dynamic reserve and a recoverable reserve of a gas-drive reservoir, comprising:
a processor establishing a gas saturation formula of the gas-drive reservoir based on a principle of material balance;
the processor establishing a relationship between an oil-gas relative permeability ratio and oil-gas flow rates based on Darcy's law;
the processor fitting a binomial relationship between the oil-gas relative permeability ratio and a gas saturation based on an oil-gas seepage law;
the processor establishing a gas-drive characteristic curve relationship between a produced gas-oil ratio and a cumulative oil production under a steady seepage flow of the gas-drive reservoir based on relationships between oil-gas formation flow rates and surface flow rates, the relationship between the oil-gas relative permeability ratio and the oil-gas flow rates, the binomial relationship between the oil-gas relative permeability ratio and the gas saturation, as well as the gas saturation formula;
the processor obtaining oil-gas relative permeability curves, wherein the oil-gas relative permeability curves comprise a curve of a relative permeability of oil relative to the gas saturation, and a curve of a relative permeability of gas relative to the gas saturation;
the processor calculating binomial regression coefficients of the binomial relationship between the oil-gas relative permeability ratio and the gas saturation based on the oil-gas relative permeability curves and the binomial relationship between the oil-gas relative permeability ratio and the gas saturation;
the processor obtaining actual cumulative oil production data and actual produced gas-oil ratio data of the gas-drive reservoir;
the processor calculating binomial regression coefficients of the gas-drive characteristic curve relationship based on the actual cumulative oil production data, the actual produced gas-oil ratio data and the gas-drive characteristic curve relationship;
the processor obtaining an irreducible water saturation, an economic-limit produced gas-oil ratio and an initial solution gas-oil ratio;
the processor determining the single-well dynamic reserve of the gas-drive reservoir based on the binomial regression coefficients of the binomial relationship between the oil-gas relative permeability ratio and the gas saturation, the irreducible water saturation and the binomial regression coefficients of the gas-drive characteristic curve relationship; and
the processor determining the recoverable reserve of the gas-drive reservoir based on the economic-limit produced gas-oil ratio, the initial solution gas-oil ratio and the binomial regression coefficients of the gas-drive characteristic curve relationship.

2. The method according to claim 1 , wherein establishing the gas saturation formula of the gas-drive reservoir based on the principle of material balance specifically comprises:
the processor establishing an oil saturation formula of the gas-drive reservoir based on the principle of material balance:

S
o

=

(

N
-

N
p

)

⁢

B
o

N
⁢

B
oi

/

(

1
-

S
wi

)

=

(

N
-

N
p

)

⁢

B
o

N
⁢

B
oi

⁢

(

1
-

S
wi

)

;

wherein, S o represents an oil saturation; N represents a geologic reserve of oil; N p represents the cumulative oil production; B o represents an oil formation volume factor; B oi represents an initial oil formation volume factor; S wi represents the irreducible water saturation; and

the processor establishing the gas saturation formula based on the oil saturation formula: S g =1−S wi −S o , wherein S g represents the gas saturation.

3. The method according to claim 1 , wherein the relationship between the oil-gas relative permeability ratio and the oil-gas flow rates is:

q
g

q
o

=

μ
o

μ
g

·

k

r
⁢
g

k

r
⁢
o

;

wherein, q g represents a gas flow rate under a formation condition; q o represents an oil flow rate under the formation condition; μ o represents an oil viscosity under the formation condition; μ g represents a gas viscosity under the formation condition; k ro represents the relative permeability of oil; k rg represents the relative permeability of gas.

4. The method according to claim

Assignees

• Univ Southwest Petroleum

Inventors

• Hu Shuyong
• Zheng Bingyang
• Song Nana
• Guo Xueqiang

Classifications

• E21B49/00 Primary

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title

• E21B49/0875

  determining specific fluid parameters · CPC title

• G01V99/00 Primary

  Subject matter not provided for in other groups of this subclass · CPC title