view:29646 Last Update: 2019-9-1
Lakirouhani, A., A. Fahimifar
Compressibility- Toughness Dominated Propagation Regime of a Fluid- Driven Fracture from a Borehole
This paper is concerned with the problem of plane strain hydraulic fracture growing transverse to a borenhole in an impermeableelastic medium under condition of compressibility toughness dominated propagation regime.compressibility andnear borehole effects are considered to explain the early unstable phase of the fracture growth observed in laboratory experiments conducted with viscosity fluids . A solution is obtained in terms of dimensionless fluid net pressure, fracture length and borehole radius under conditions where it can be assumed that the fluid is inviscid. It is shown that the problem depends only on a dimensionless time and on a dimensionless borehole radius.With time, the solution evolves between two asymptotic region where the solution in self similar . Compressibility effects control the solution of smalltime while the solution at large time is dominated by material toughness. An instability is identified in the problem after breakdown. The potential unstable growth depends on the initial flaw lengyh fluid compressibility volume of fluid and the material elastic modulus.It is also seen that the deviatoric in situ stress reduces the breakdown pressure.