Conductivity and performance of hydraulic fractures partially filled with compressible proppant packs

• We investigate the proppant compressibility effect on the hydraulic fracture conductivity.
• A mathematical model is developed and solved numerically.
• Proppant compressibility and in-situ stresses influence well production rate.
• Production rate of fractured wells might be significantly less than the value predicted by overly simplistic models.

Hydraulic or fluid-driven fracturing techniques are often utilised to enhance the production of oil or gas from hydrocarbon reservoirs. There are a number of engineering guidelines to identify the optimum fracture dimensions (i.e. length and average opening) and optimum fracture conductivity, which maximize the efficiency of a given hydraulic fracturing procedure. However, the fracture dimensions as well as conductivity during the production stage may be below the expected design values due to the compressive in-situ stresses, the non-uniform distribution of the proppant within the fracture, as well as the compressibility of the fractured rock and proppant pack.In this paper, the performance of the hydraulic fracture, which is partially filled with a compressible proppant pack, is evaluated using a simple mathematical model. The mathematical model incorporates the aforementioned effects of proppant compressibility and in-situ stresses. A case study is conducted to investigate phenomena such as: the residual opening of fracture faces not supported by the proppant pack, the compaction of the proppant pack under the action of the confining stresses and the subsequent reduction in the permeability of the proppant pack.