System and program for predicting the shearing by fluid pressure

Patent metadata

Field	Value
Publication number	US-10626717-B2
Application number	US-201615348750-A
Country	US
Kind code	B2
Filing date	Nov 10, 2016
Priority date	Oct 13, 2016
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

The present disclosure relates to a system and program for predicting shearing by fluid pressure, the system and program capable of predicting shearing information such as the minimum pressure P cm required for hydraulic shearing, the sufficient pressure P co for hydraulic shearing, and the optimal shearing direction using input information including the vertical stress σ v , the maximum horizontal stress and the minimum horizontal stress of a rock to which fluid is to be injected, a joint friction angle ϕ, a reservoir rock density ρ r , an injected fluid density, and a coefficient of the sufficient pressure for hydraulic shearing α.

First claim

What is claimed is:

1. A system for predicting shearing by fluid pressure, the system comprising:
an interactor interaction unit configured to provide a screen for inputting information necessary for shearing prediction and to provide a user with shearing information predicted according to input information;
a data processor configured to receive the input information from the interaction unit and to perform computation for predicting the shearing information,

wherein the input information includes a vertical stress σ v , a maximum horizontal stress and a minimum horizontal stress of a rock to which fluid is to be injected, a joint friction angle Φ, a reservoir rock density ρ r , an injected fluid density, and a coefficient of a sufficient pressure a for hydraulic shearing, and based on an assumption that joints are distributed uniformly in all directions of a reservoir, the data processing unit predicts and provides a minimum pressure P cm required for hydraulic shearing, the sufficient pressure P co for hydraulic shearing, and a minimum pressure shearing direction using the input information,
wherein the minimum pressure P em required for hydraulic shearing is predicted by the following equation:

P
cm

=

k
c

-
k

k
c

-
1

⁢

σ
3

,

k
=

σ
1

σ
3

,

k
c

=

1
+

sin
⁢

⁢
ϕ

1
-

sin
⁢

⁢
ϕ

wherein σ 1 is a maximum principal stress which is greatest among the vertical stress σ v , the maximum horizontal stress, and the minimum horizontal stress of the rock, and a is a minimum principal stress which is smallest among the vertical stress σ v , the maximum horizontal stress, and the minimum horizontal stress of the rock, the minimum pressure shearing direction is predicted by two planes tilted at an angle θ (=45°−Φ/2) in a direction from the maximum principal stress σ 1 towards the minimum principal stress σ 3 , and the sufficient pressure P co for hydraulic shearing is predicted by the following equation:
P co =P cm +α( P cf −P cm )

wherein P cf is the minimum principal stress σ 3 , and the coefficient α of the sufficient pressure for hydraulic shearing has a range of 0≤α≤1; and
and a visualization unit visualizing the distribution of the minimum pressure Pcm on a stress polygon using a color indicating a level of pressure required for hydraulic shearing in a corresponding stress state, visualizing a distribution on a stereonet of a level of pressure required for hydraulic shearing for each joint direction at each point in the stereonet using a color indicating a level of pressure required for hydraulic shearing in a corresponding joint direction, and visualizing a distribution on a stress polygon of the predicted pressure P co for each point on the stress polygon using a color indicating a level of pressure required for hydraulic shearing in a stress state at a corresponding point of the stress polygon.

2. The system according to claim 1 ,
wherein the input information further comprises rock joint network data, and the data processing unit predicts and provides a pressure P c required for hydraulic shearing, a shearing initiation location in a wellbore and propagation direction, for each rock joint direction of the rock joint network data using the input information.

3. The system according to claim 2 ,
wherein the pressure P c required for hydraulic shearing is predicted by the following equation:

P
c

=

σ
-

τ

tan
⁢

⁢
ϕ

σ
=

l
2

⁢

σ
1

+

m
2

⁢

σ
2

+

n
2

⁢

σ
3

τ
=

(

σ
1

-

σ
2

)

2

⁢

l
2

⁢

m
2

+

(

σ
2

-

σ
3

Assignees

• Seoul Nat Univ R&Db Foundation

Inventors

• Min Ki-Bok
• Park Sehyeok
• Xie Linmao

Classifications

• G01N2013/0216

  by measuring skin friction or shear force · CPC title

• E21B47/06 Primary

  Measuring temperature or pressure · CPC title

• G01N13/02

  Investigating surface tension of liquids · CPC title

• G01N3/24 Primary

  by applying steady shearing forces (G01N3/26, G01N3/28 take precedence) · CPC title

• G01N3/10

  generated by pneumatic or hydraulic pressure (G01N3/18 takes precedence) · CPC title