Proppant Simulation in 3DEC 5.2
Hydraulic fracturing is a technique, used in the oil and gas industry, to stimulate resource production. The fracturing treatment often involves the injection of proppant as a suspension in the fracturing fluid. After the end of injection, the fracture closes onto the proppant, and a conductive conduit is formed to allow the oil/gas/heated-water to flow productively.
The transport and placement of proppant within the fracture is usually modeled by representing the proppant and fracturing fluid as a mixture, and this is the approach taken by 3DEC 5.2. It is assumed that the proppant particles are small compared to the fracture opening, and the proppant in the mixture is given by its volumetric concentration.
- The proppant logic (Detournay et al., 2016) takes into account fluid-mechanical coupling and several effects are represented, such as:
- pack-formation (when the concentration reaches a given value, the proppant forms a pack, leaving only the fracturing fluid to flow through)
- bridging (when the proppant stops if the fracture width is small enough, compared to the particle size)
- proppant convection (when density gradients cause fluid motion in the fluid loaded with proppant)
- settling (when there is a slip in velocity between slurry and proppant, caused by gravity)
- viscosity changes as a function of proppant concentration
For more information about the proppant logic and its numerical implementation in 3DEC, download the paper "Development of a proppant transport logic in 3DEC".
The following video shows simulation of proppant flowing within a single crack between two blocks (in- and out-of-the plane). Proppant concentration and fluid discharge rates are shown over the course of 40 seconds. The simulation is shown twice in the video.