Intelligent identification method of aquifer distribution in complex edge-water oil and gas reservoirs

1 . An intelligent identification method of aquifer distribution in complex edge-water oil and gas reservoirs, implemented by a device comprising a processor, a display and a memory storing instructions executed by the processor, wherein the intelligent identification method comprising:

discretizing, by the processor, an edge aquifer into an aquifer unit communicated with a production well unit;

discretizing, by the processor, a position with clear geological knowledge into an infill unit;

based on the aquifer unit, the production well unit and the infill unit, establishing, by the processor, a simple edge-water oil and gas reservoir unit system, wherein the aquifer unit is characterized by a volume and a water influx of the aquifer unit;

based on the aquifer unit, the production well unit and the infill unit, calculating, by the processor, pressure of each unit by a material balance equation; and according to the calculated pressure of each unit, calculating, by the processor, saturation and water cut of each unit by using a waterflood front advancing equation to establish a numerical simulation model of a water influx unit to be stored in the memory;

establishing, by the processor, characteristic parameter vectors and an objective function of the aquifer unit according to the established numerical simulation model of the water influx unit;

setting, by the processor, constraints on the volume of the aquifer unit, the volume of the aquifer unit equal to a size of an entire edge-water aquifer;

automatically fitting, by the processor, the volume and the water influx of the aquifer unit by a genetic algorithm, until an error value between data predicted by the established numerical simulation model and actual dynamic production data is minimum, thereby obtaining a corrected volume and a corrected water influx of the aquifer unit;

assigning, by the processor, the corrected volume and corrected water influx of the aquifer unit to a discretized aquifer unit to establish and display an aquifer unit bar chart in the display, wherein an aquifer distribution is determined by the bar height of each unit; and

based on the determined aquifer distribution, adjusting a production schedule of the production well unit to improve an oil reservoir recovery factor.

2 . The intelligent identification method of aquifer distribution in complex edge-water oil and gas reservoirs according to claim 1 , wherein the material balance equation is

∑

j

=

1

n

well

T

ji

t

(

p

j

t

-

p

i

t

)

+

w

i

t

=

c

t

·

V

i

t

·

dp

i

t

dt

,

where

T

ij

t

is an average conductivity between the aquifer unit i and the production well unit j at time t, m 3 /(d·MPa); nwell is a number of the production well units and infill units, dimensionless;

p

i

t

 is aquifer pressure of the aquifer unit i at time t, MPa;

p

j

t

 is average bottom hole pressure of the production well unit j at time t, MPa;

w

i

t

is the water influx of the aquifer unit i at time t, m 3 /d; ct is a comprehensive formation compressibility, MPa −1 ; and

V

j

t

 is the aquifer volume of the aquifer unit i at time t, m 3 .

3 . The intelligent identification method of aquifer distribution in complex edge-water oil and gas reservoirs according to claim 1 , wherein the waterflood front advancing equation

(

dx

dt

)

Sw

=

Q

A

⁢

ϕ

·

∂

f

w

∂

S

w

,

where x is a position of a water influx channel, m; Q is total flow of fluid, m 3 ; S w is water saturation at position x, dimensionless; f w is partial flow of a water phase, dimensionless; A is a cross-sectional area of a seepage, m 2 ; and φ is porosity, dimensionless.

4 . The intelligent identification method of aquifer distribution in complex edge-water oil and gas reservoirs according to claim 1 , wherein the dynamic production data comprises bottom hole pressure of a single well and water cut of the single well.