Influence of pore pressure on the development of a hydraulic fracture in poroelastic medium

Abstract

In this paper we demonstrate the influence of the pore pressure to the development of a hydraulically-driven fracture in a poroelastic medium. We present a novel numerical model for propagation of a planar hydraulic fracture and prove its correctness by demonstration of the numerical convergence and by comparison with known solutions. The advantage of the algorithm is that it does not require the distinguishing of the fracture's tips and reconstruction of the numerical mesh according to the fracture propagation. Next, we perform a thorough analysis of the interplay of fluid filtration and redistribution of stresses near the fracture. We demonstrate that the fracture length decreases with the increase of the Biot's number (the parameter that determines the contribution of the pore pressure to the stress) and explain this effect by analysing the near-fracture pore pressure, rock deformation and stresses. We conclude, that the correct account for the fluid exchange between the fracture and the rock should be based not only on physical parameters of the rock and fluid, but also on the analysis of stresses near the fracture.

Dynamic bridging of proppant particles in a hydraulic fracture

“…Numerical solution to Eqs. (32), (33) is carried out using the finite-difference method and staggered uniform rectangular mesh. IMPES strategy for splitting the governing equations is considered.…”

Sensitivity of the pressure decline curve during the hydraulic fracturing to poroelastic effects

“…The mathematical model presented in this paper was proposed and analyzed in authors' earlier works [1,6,2]. Here for consistency, we give only a brief outline of the model.…”

“…Nevertheless, the results of [6,2] indicate that under the plain strain condition the influence of pore fluid pressure on the rock deformation, as well as the reverse effect on fluid filtration, may significantly affect the fracture opening development. The earlier study [3] of the pressure field data in mini-frac tests also confirms the significance of poroelastic effects.…”

“…This information can be obtained from the solution of the inverse problem by analyzing of the pressure decline curve (PDC) in pump-in/shut-in tests. The goal of the present work is to demonstrate that poroelastic effect can have significant influence on the behavior of the PDC and, hence, to results of its analysis.For computer simulations we use the mathematical model of the hydraulic fracture in poroelastic medium developed in [6]. We investigate the dependence of the PDC on the closure stress and of the rock permeability.…”

“…For computer simulations we use the mathematical model of the hydraulic fracture in poroelastic medium developed in [6]. We investigate the dependence of the PDC on the closure stress and of the rock permeability.…”