Methods of optimizing well spacing for shale gas development

Patent metadata

Field	Value
Publication number	US-10822938-B2
Application number	US-202016833806-A
Country	US
Kind code	B2
Filing date	Mar 30, 2020
Priority date	Dec 3, 2018
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

A method of optimizing well spacing for shale gas development is provided. It belongs to the technical field of hydrocarbon reservoir exploration and development. The method comprises: firstly verifying block area based on the explored geological structure; analyzing the connection situation of a shale reservoir, identifying the minimum developing area units; calculating the recoverable reserves of the units, confirming the candidate units; drilling representative shale cores and analyzing related physical properties; calculating seepage field and pressure field using unified multi-field, multi-flow-regime, and multi-scale mathematical models; calculating the effective recoverable area of each well; and arranging wells based on the rule that the interference among wells is not larger than 10%. Considering the fluid-solid coupling effects, the method can define appropriately well spacing for shale gas exploration and enhance effectively the output of shale gas.

First claim

What is claimed is:

1. A method of optimizing well spacing for shale gas development, comprising:
identifying the geological structure of a shale reservoir, verifying area of blocks based on explored geological structure,
analyzing connection situation of the shale reservoir, selecting blocks with good connectivity as minimum developing area units,
calculating recoverable reserves of each minimum developing area unit, selecting minimum developing area units satisfying an economic criterion as alternative options, or abandoning the minimum developing area units failing to satisfy the economic criterion,
drilling representative shale cores in the minimum developing area units that are selected, performing experiments on the representative shale cores, and identifying related parameters via experiments,
establishing mathematical models, and integrating the related parameters into the mathematical models for calculating seepage field and pressure field, and calculating effective recoverable boundary of each well based on the seepage field and pressure field, calculating effective recoverable area of each well based on the effective recoverable boundary of each well, and arranging wells according to the effective recoverable area of each well.

2. The method of optimizing well spacing for shale gas development as defined in claim 1 , wherein verifying area of blocks comprises: drawing the outline of the blocks proportionally on grid paper, of which the grids are squares, verifying the number of grids, which is multiplied by the area of a single grid, and obtaining area of blocks.

3. The method of optimizing well spacing for shale gas development as defined in claim 1 , wherein the recoverable reserve V of each minimum developing area unit is
V=Ah ϕ(1− S wc )

wherein A is the area of a recoverable block, h is reservoir thickness, ϕ is stress-affected rock porosity, expressing the percentage of pores in the apparent volume of rock, and S wc is the saturation of bound water.

4. The method of optimizing well spacing for shale gas development as defined claim 1 , wherein the economic criterion is

(

Economic
⁢

⁢
value
⁢

⁢
of
⁢

⁢
recoverable
⁢

⁢
reserve

-

Developing
⁢

⁢
cost

)

Developing
⁢

⁢
cost

×
100
⁢
%

≥

10
⁢

%
.

5. The method of optimizing well spacing for shale gas development as defined in claim 1 , wherein the related parameters include permeability, rock porosity, shale desorption curves, gas viscosity, gas density, and pore compressibility.

6. The method of optimizing well spacing for shale gas development as defined in claim 5 , wherein the mathematical models compromise: stress-affected rock porosity
ϕ=ϕ 0 e −αC ϕ σ

wherein ϕ is stress-affected rock porosity; ϕ 0 is rock porosity without being affected by stress; C ϕ is pore compressibility, expressing the variation in porosity with a unit decrease in formation pressure; σ is effective stress, atm; α is correction coefficient, α>0,
the expression of stress-sensitive permeability
K=K 0 e −βC ϕ σ

wherein K is stress-affected permeability of porous media, μm 2 ; K 0 is permeability without being affected by stress, μm 2 ; β is correction coefficient, β>0,
the stress-affected seepage velocity of shale gas v

v
=

-

K
0

⁢

e

-
β

⁢

⁢

C
ϕ

⁢
σ

μ

⁢

(

1
+

3
⁢
π
⁢

⁢
a
⁢

⁢

ϕ
0

⁢

e

(

β
-
α

)

⁢

C
ϕ

⁢
σ

16
⁢

K
0

⁢

μ
⁢

Assignees

• Univ Beijing Science & Technology

Inventors

• Zhu Weiyao
• Huang Kun
• Chen Zhen
• Yue Ming
• Song Zhiyong
• Li Hua
• Wang Baichuan
• Kong Debin

Classifications

• E21B2200/20

  Computer models or simulations, e.g. for reservoirs under production, drill bits · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• E21B43/305 Primary

  comprising at least one inclined or horizontal well · CPC title

• E21B43/30 Primary

  Specific pattern of wells, e.g. optimising the spacing of wells · CPC title

• E21B41/0092

  Fixed Constructions · mapped topic