Large Scale Geologic Controls on Hydraulic Stimulation

When simulating a hydraulic fracturing, the analyst has historically prescribed a single planar fracture. Originally (in the 1950s through the 1970s) this was necessitated by computational restrictions. In the latter part of the twentieth century, hydraulic fracture simulation evolved to incorporate vertical propagation controlled by modulus, fluid loss, and the minimum principal stress. With improvements in software, computational capacity, and recognition that in-situ discontinuities are relevant, fully three-dimensional hydraulic simulation is now becoming possible.

Advances in simulation capabilities enable coupling structural geologic data (three-dimensional representation of stresses, natural fractures, and stratigraphy) with decision making processes for stimulation – volumes, rates, fluid types, completion zones. Without this interaction between simulation capabilities and geological information, low permeability formation exploitation may linger on the fringes of real economic viability.

Comparative simulations have been undertaken in varying structural environments where the stress contrast and the frequency of natural discontinuities causes varying patterns of multiple, hydraulically generated or reactivated flow paths. Stress conditions and nature of the discontinuities are selected as variables and are used to simulate how fracturing can vary in different structural regimes. The basis of the simulations is commercial distinct element software (Itasca Corporation’s 3DEC).