New developments in hydrofracturing stress measurements at Luleå University of technology

Bjarnason, B.; Ljunggren, Christer; Stephansson, Ove

doi:10.1016/0148-9062(89)91438-1

Cited by 19 publications

(7 citation statements)

References 7 publications

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“…7.6a schematic, 7.6b nature). A second early field system was the Swedish multihose hydrofrac field system (Bjarnason et al 1989). One advantage of hydraulic fracturing is that the deformation behaviour of the rock (constitutive equations) is not necessary to calculate stresses.…”

Section: Practice Of Hydrofracturingmentioning

confidence: 99%

Stress Field of the Earth’s Crust

2010

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Section: Practice Of Hydrofracturingmentioning

confidence: 99%

Stress Field of the Earth’s Crust

2010

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“…Hydraulic fracturing reopening tests are simulated by injecting fluid at a constant rate. The well storage capacity S w (Figure 1) is assumed to be 3.1⋅10 -10 m 3 /Pa according to an existing hydraulic fracturing equipment [13]. The initial 7 fracture length is 1 meter, according to field measurements by Rutqvist et al [4].…”

Section: Modeling Of Fracture Reopening Testsmentioning

confidence: 99%

Uncertainty in the maximum principal stress estimated from hydraulic fracturing measurements due to the presence of the induced fracture

Rutqvist

Tsang

Stephansson

2000

International Journal of Rock Mechanics and Mining Sciences

113

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The classical theory for hydraulic fracturing stress measurements assumes an ideal case with a linear elastic, homogenous, and isotropic medium; and a fracture that reopens distinctly when the minimum tangential borehole stress is exceeded. The induced fracture disturbs this ideal picture in several aspects, which are important for the evaluation of the maximum horizontal principal stress using the fracture reopening pressure. This disturbance can be attributed to the fracture normal stiffness and the initial hydraulic fracture permeability. In this paper, the hydraulic fracturing reopening test is studied by coupled hydromechanical modeling that takes into account an induced fracture that is incompletely closed. The result shows that with realistic equipment compliance, the apparent fracture reopening evaluated from the well-pressure is close to the magnitude of the minimum horizontal principal stress with little or no correlation to the maximum horizontal principal stress. This observation suggests that determination of maximum principal stress by hydraulic fracturing using the reopening pressure is very uncertain.

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“…The reasons for this are that the solution is in terms of the difference of the horizontal stresses (aH -ah), and the conditions are in terms of inequalities. Ljunggren and Amadei (1989) and Bjarnason et al (1989) faced this problem in calculating the virgin state of stress at Lavia in Finland when the fractures were horizontal. The ranges of the predicted maximum and minimum horizontal stress were typically 15 MPa (see Tables 2 and 4 in Ljunggren and Amadei 1989).…”

Section: Strength Properties Have Been Obtained By Ljunggren Andmentioning

confidence: 98%

The interpretation of horizontal and mixed-mode fractures in hydraulic fracturing tests in rocks

Hefny¹,

Lo²

1992

Can. Geotech. J.

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For the design of underground structures in rocks, the states of initial stresses in the rock mass are required. For structures located at great depths, the hydraulic fracturing test for stress measurements is the only practical method. For vertical fractures, existing solutions for calculation of stresses from test results are satisfactory. For horizontal or mixed-mode fractures, appropriate solutions are required. Closed-form solutions for horizontal and mixed-mode fractures including strength anisotrophy are presented. The method enables the determination of which fracture (horizontal or vertical) occurs first at the first breakdown pressure during the test, so appropriate stress calculation may be carried out. Results of hydraulic fracturing tests in three case histories have been reanalyzed using the method developed. It is shown that for horizontal fractures the ranges of stress values computed are considerably reduced compared with existing solutions. The reinterpreted horizontal stresses in a case record are consistent with results of field observations in underground excavations. Experimental requirements for the measurements of rock parameters relevant to the specific stress paths in hydraulic fracturing tests are discussed.Pour la conception des structures souterraines dans les roches, les Ctats de contraintes initiales dans le massif rocheux sont requis. Pour les structures localisees a de grandes profondeurs, l'essai de fracturation hydraulique est la seule methode pour mesurer les contraintes. Pour les fractures verticales, les solutions existantes pour le calcul des contraintes en partant de resultats d'essais sont satisfaisantes. Pour les fractures horizontales ou en mode mixte, des solutions appropriees sont requises. Des solutions exactes pour des fractures horizontales et en mode mixte incluant l'anisotropie de resistance sont presentees. La methode permet de determiner laquelle fracture (horizontale ou verticale) se produit en premier lors de la premikre chute de pression durant l'essai, de sorte que le calcul approprie des contraintes peut Ctre fait. Des resultats d'essais de fracturation hydraulique de trois histoires de cas ont Cte re-analysCs en utilisant la methode developpee. I1 est montre que pour les fractures horizontales, les plages des valeurs de contrainte calculees sont considkrablement reduites par rapport aux solutions existantes. La re-interpretation des contraintes horizontales dans le dossier d'un cas est consistante avec les resultats des observations sur le chantier dans les excavations souterraines. L'on discute les exigences experimentales pour les mesures des paramktres de roche pertinents aux cheminements de contrainte specifiques dans les essais de fracturation hydraulique.Mots clPs : fracturation hydraulique, mesures de contrainte, fractures en mode mixte, structures souterraines, resistance de la roche.[Traduit par la redaction]Can. Geotech. J. 29, 902-917 (1992)

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New developments in hydrofracturing stress measurements at Luleå University of technology

Cited by 19 publications

References 7 publications

Stress Field of the Earth’s Crust

Stress Field of the Earth’s Crust

Uncertainty in the maximum principal stress estimated from hydraulic fracturing measurements due to the presence of the induced fracture

The interpretation of horizontal and mixed-mode fractures in hydraulic fracturing tests in rocks

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