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US 10,626,717 B2Granted
System and program for predicting the shearing by fluid pressure
AssigneeSeoul National University R&Db Foundation
InventorsKi-Bok Min, Sehyeok Park, Linmao Xie
Life of this patent
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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 Pcm required for hydraulic shearing, the sufficient pressure Pco for hydraulic shearing, and the optimal shearing direction using input information including the vertical stress σv, 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 ρr, an injected fluid density, and a coefficient of the sufficient pressure for hydraulic shearing α.
Claims15
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 σv, 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 ρr, 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 Pcm required for hydraulic shearing, the sufficient pressure Pco for hydraulic shearing, and a minimum pressure shearing direction using the input information,
- wherein the minimum pressure Pem 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 σ1 is a maximum principal stress which is greatest among the vertical stress σv, 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 σv, 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 σ1 towards the minimum principal stress σ3, and the sufficient pressure Pco for hydraulic shearing is predicted by the following equation:
- Pco=Pcm+α(Pcf−Pcm)
- wherein Pcf is the minimum principal stress σ3, 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 Pco 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.
43 more elements
A program for predicting shearing by fluid pressure, the program comprising the following steps:
- inputting input information including a vertical stress σv, 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 ρr, an injected fluid density, and a coefficient α of a sufficient pressure for hydraulic shearing;
- and
- predicting and providing shearing information included in a fast calculation menu, using the input information,
- wherein the shearing information included in the fast calculation menu includes one or more of a minimum pressure Pcm required for hydraulic shearing, a sufficient pressure Pco for hydraulic shearing, and a minimum pressure shearing direction, and the minimum pressure, the sufficient pressure and the minimum pressure shearing direction are computed using the input information, based on an assumption that joints are distributed uniformly in all directions of a reservoir,
- wherein the minimum pressure Pcm required for hydraulic shearing is predicted by the following equation:
- wherein σ1 is a maximum principal stress which is greatest
- P
- cm
- =
- k
- c
- -
- k
- k
- c
- -
- 1
-
- σ
- 3
- ,
- k
- =
- σ
- 1
- σ
- 3
- ,
- k
- c
- =
- 1
- +
- sin
-
-
- ϕ
- 1
- -
- sin
-
-
- ϕ
- among the vertical stress σv, the maximum horizontal stress, and the minimum horizontal stress of the rock, and σ3 is a minimum principal stress which is smallest among the vertical stress σv, 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 σ1 towards the minimum principal stress σ3, and
- the sufficient pressure Pco for hydraulic shearing is predicted by the following equation:
- Pco=Pcm+α(Pcf−Pcm)
- wherein Pcf is the minimum principal stress σ3, and the coefficient α of the sufficient pressure for hydraulic shearing has a range of 0≤α≤1;
- and
- visualizing, by a visualization unit, 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 Pco for each point on the stress polygon using a color indicating a level of pressure required for hydraulic shearing in a stress state at the corresponding point on the stress polygon.
47 more elements
Dependencies are inferred from the claim text.