Abstract—Predictions of fracture initiation and propagation pressure are an essential prerequisite to determine reasonable injection pressure for poorly consolidated sandstone. Most models for hydraulic fracturing based on elasticity mechanics are not applicable for poorly consolidated rocks. The fluid-solid coupling model based on elastic theory of porous media for poorly consolidated sandstone is established to analyze fracturing modes and fracture initiation pressure by adopting the maximum tensile stress criterion and the Mohr-Coulomb criterion, and the calculation methods of water injection fracture pressure and water injection fracture propagation pressure are obtained in this paper. The study shows that fractures are mainly caused by shear failure and propagation direction is parallel to the maximum horizontal stress. The vertical and tangential effective stress are reduced with the increase of bottom-hole injection pressure. But the radial effective stress is just the opposite. So the transformation of the three principal effective stress values will occur with the increase of water injection pressure. The fractures paralleled to the radial direction of borehole are more easily propagate to formation interior when radial stress becomes intermediate principal stress. The work provides important guidance to determine the construction parameters micro-fracturing in water injection wells.
Index Terms—Poorly consolidated sandstone, water injection fracturing pressure, fracture propagation pressure, fracturing mode.
Fan Baitao is with China National Offshore Oil Corporation (CNOOC), senior engineer, the manager of department of well construction and intervention in Bohai Petroleum Administration Bureau in Tianjin, China.
Deng Jingen is with China University of Petroleum (Beijing), Department of Petroleum Engineering, Beijing, China. Meanwhile, he is the director of CNPC well stability laboratory, the director of Science and Technology Department of China University of Petroleum (Beijing).
Lin Hai is with China National Offshore Oil Corporation (CNOOC), Bohai research institute of Bohai Petroleum Administration Bureau in Tianjin, China (email: linhai2007021317@sina.com).
Sun Jin is with Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences since 2016 in Sanya, China. Li Jin is with Bohai research institute in Tianjin, China.
[PDF]
Cite: A. Fan Baitao, B. Deng Jingen, C. Lin Hai, D. Sun Jin, and E. Li Jin, "Water Injection Fracture Pressure and Fracture Propagation Investigating in Poorly Consolidated Sandstone," International Journal of Chemical Engineering and Applications vol. 9, no. 2, pp. 64-70, 2018.
