Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
권호 표지

Modeling of Highly Segmented Fluid-Driven Natural Fractures

다중으로 분할된 자연수압파쇄 균열 모델링

  • 심영종 (대한주택공사 주택도시연구원)
  • Received : 2009.08.26
  • Accepted : 2009.09.15
  • Published : 2009.10.01
Download PDF
⟨ Previous Next ⟩

Abstract

Fracturing technique using fluid injection into the borehole is widely used technology in the industry for the geothermal heat, oil, and gas extraction. Dealing with fluid-driven natural fractures such as dike and vein indirectly, design technology would be improved by adapting their principles. In this paper, mechanical interaction between the segments is evaluated by modeling highly segmented and closely spaced fluid-driven natural fractures. The number of segments is 71 with 3,339 measured apertures in which the interaction is considerably predicted. To evaluate mechanical interaction, boundary collocation method is used and the net pressure is calculated by using least square method to fit measured apertures. As a result, in case that mechanical interaction is considered, two pressures as fitting parameters are sufficient to capture measured apertures.

수압파쇄기술은 주로 지열, 석유, 가스 추출 시 지반의 투수성을 증가시키기 위해 사용되는 공법으로 자연에서 생성된 수압파쇄균열의 원리를 적용함으로써 실제 설계기법을 발전시켜 나아가고 있다. 본 논문에서는 균열간 거리가 아주 근접한 다중으로 분할 생성된 자연 수압파쇄균열을 대상으로 균열간 기계적 상호작용의 영향을 평가하였다. 균열의 수는 71개이며 여기에 사용된 균열폭 자료는 3,339개로 균열간 아주 근접하여 생성 당시 상당한 기계적 상호작용이 예상되었던 균열이다. 이러한 상호작용을 정량적으로 평가하기 위해서 경계병치법을 사용하였으며 측정된 균열폭에 가까운 형상을 얻기 위해 최소자승법을 통한 압력(net pressure)을 계산하였다. 그 결과 상호작용을 고려한 경우 단 2개의 압력변수만으로도 측정치에 가까운 균열폭을 얻을 수 있음을 증명하였다.

Keywords

References

  1. 심영종, 김홍택 (2005), 다중으로 분할된 수압파쇄균열의 상호작용에 관한 연구, 한국지반공학회논문집, 제21권, 9호,, pp. 45-52.
  2. Bai, T., Pollard, D.D. and Gross, M.R. (2000), Mechanical Prediction of Fracture Aperture in Layered Rocks, Journal of Geophysical Research, Vol. 105, No. B1, pp. 707-721. https://doi.org/10.1029/1999JB900303
  3. Delaney, P.T. and Pollard, D.D. (1981), Deformation of Host Rocks and Rlow of Magma during Growth of Minette Dikes and Breccia-bearing Intrusions near Ship Rock, New Mexico, Geological Survey Professional Paper 1202, p. 61.
  4. Jeffrey, R.G., Vandamme, L., and Roegiers, J.-C. (1987), Mechanical Interactions in Branched or Subparallel Hydraulic Fractures, SPE 16422.
  5. Naceur, K.B. and Roegiers, J.-C. (1990), Design of Fracturing Treatments in Multilayered Formations, SPE Production Engineering, pp. 21-26.
  6. Nolte, K.G. (1987), Discussion of Influence of Geologic Discontinuities on Hydraulic Fracture Propagation, Journal of Petroleum Technology, pp. 998.
  7. Olson, J.E. and Pollard, D.D. (1991), The Initiation and Growth of En echelon veins, Journal of Structural Geology, Vol. 13, No. 5, pp. 595-608. https://doi.org/10.1016/0191-8141(91)90046-L
  8. Pollard, D.D. and Muller, O.H. (1976), The Effect of Gradients in Regional Stress and Magma Pressure on the Form of Sheet Intrusions in Cross-section, Journal of Geophysical Research, Vol. 81, No. 5, pp. 975-984. https://doi.org/10.1029/JB081i005p00975
  9. Secor, D.T. and Pollard, D.D. (1975), On the Stability of Open Hydraulic Fractures in the Earth's Crust, Geophysical Research Letters, Vol. 2, No. 11, pp. 510-513. https://doi.org/10.1029/GL002i011p00510
  10. Tada, H., Paris, P.C. and Irwin, G.R. (2000), The Stress Analysis of Cracks Handbook, American Society of Mechanical Engineers, 3rd Ed., p. 696.
  11. Vermilye, J.M. (1996), The Growth of Natural Fracture Systems: A Fracture Mechanics Approach, Ph.D. Dissertation, Columbia University, p. 236.
  12. Vermilye, J.M. and Scholz, C.H. (1995), Relation between Vein Length and Aperture, Journal of Structural Geology, Vol. 17, No. 3, pp. 423-434. https://doi.org/10.1016/0191-8141(94)00058-8
  13. Wawrzynek, P.A. and Ingraffea, A.R. (1987), Interactive Finite Element Analysis of Fracture Processes: an Integrated Approach. Theoretical and Applied Fracture Mechanics, Vol. 8, pp. 137-150. https://doi.org/10.1016/0167-8442(87)90007-3