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Two－Dimensional　Model　of　Hydraulic　Fracturing　in　Geosciences：Effects　of　Fluid　Buoyancy

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Journal of Earth Science 1996年第2期15卷 216-222页

作者： Yoshito Nakashima Mitsuhiro Toriumi(Geological Institute, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan)

Hydraulic fracturing occurs in diverse fields of geosciences. We introduce effects of fluid buoyancy into the CGDD (Christianovich-Geertsma-DeKlerk-Daneshy) model of hydranlic fracturing. In the model, a two-dimensional one-sided crack in impermeable rock propagates from a horizontally lying wellbore or fluid reservoir at depth; the crack plane is inclined at a prescribed angle to the horizontal; incompressible and Newtonian fluid less dense than the surrounding rock is injected consecutively from the wellbore or fluid reservoir into the crack at a given injection rate. A solution of the crack propagation is obtained using lubrication theory for turbulent or laminar film flow and linear elastic fracture mechanics. The solution shows the importance of the buoyancy of the fluid in the crack as a driving force or a resisting force of the crack propagation. For example,when the water injection rate into a vertical fracture is 10-2 m2/s and the vertical length of the propagating fracture exceeds 100 m, the fluid buoyancy is important (1) as a driving force if the fracture is formed by the upward propagation of a vertical crack and (2) as a resisting force if it is formed by the downward propagation.

关键词： buoyancy crack propagation dyke hydraulic fracturing hydrofracturing vein

Failure pressure calculation of fracturing well based on fluid-structure interaction

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Journal of Rock Mechanics and Geotechnical Engineering 2011年第S1期3卷 450-456页

作者： Jinzhou Zhao Lan Ren Min Li Yongming Li State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China

Failure pressure is a key parameter in reservoir hydrofracturing operation. Existing analytical methods for calculating the failure pressure are based on the assumption that borehole fluid is under two extreme conditions: non-infiltration or complete infiltration. The assumption is not suitable for the actual infiltration process, and this will cause a great error in practical calculation. It shows that during the injection process, the dynamic variation in effective stress-dependent permeability has an influence on the infiltration, and the influence also brings about calculation errors. Based on the fluid-structure interaction and finite element method (FEM), considering partial infiltration during injection process, a numerical model for calculating rock failure pressure is established. According to the analysis of permeability test results and response-surface method, a new variation rule of rock permeability with the change of effective stress is presented, and the relationships among the permeability, confining pressure and pore pressure are proposed. There are some differences between the dynamic value of permeability-effective-stress coefficient observed herein and the one obtained by the classical theory. Combining with the numerical model and the dynamic permeability, a coupling method for calculating failure pressure is developed. Comparison of field data and calculated values obtained by various methods shows that accurate values can be obtained by the coupling method. The coupling method can be widely applied to the calculation of failure pressure of reservoirs and complex wells to achieve effective fracturing operation.

关键词： failure pressure fluid-structure interaction hydrofracturing coupling method response-surface method

Conduit System and formation mechanism of heat fluids in diapiric belt of Yinggehai basin,China

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Science China Earth Sciences 1999年第6期42卷 561-571页

作者：解习农李思田胡祥云董伟良张敏强 Faculty of Earth Resources China University of Geosciences China Offshore Petroleum Nanhai West Corporation

The conduit system of heat fluids in diapiric belt of Yinggehai basin is dominantly vertical faults and fractures . Detailed research on the formation mechanism and their occurrence features shows that the faults and fractures can be classified into three types: intrastratal dispersive hydrofracture, puncturing fault and upwarping-extensional fault. The development of the fault and fracture system not only resulted in the changes of the temperature and pressure fields in the basin, but also affected the hydrocarbon migration in the overpressured system. These faults and fractures constituted the main pathways for vertical hydrocarbon migration, and opening and closing intermittently led to episodic expulsion of overpressured fluid compartment. Thus there formed the pool-forming model of multi-source mixing and ploy-stage migration and accumulation for hydrocarbons in the Yinggehai basin.

关键词： Yinggehai basin overpressured system hydrofracturing episodic hydrocarbon expulsion.

STUDY ON IN-SITU STRESS DISTRIBUTION LAW IN DEEP UNDERGROUND COAL MINING AREAS Paper No.184

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STUDY ON IN-SITU STRESS DISTRIBUTION LAW IN DEEP UNDERGROUND...