Coupled Fluid-Solid Geomechanical Modeling of Multiple Hydraulic Fractures Interacting with Natural Fractures and the Resulting Proppant Distribution

Abstract

The application of a new Material Point Method (MPM) approach to model the proppant distribution in a reservoir where hydraulic fractures interact with natural fractures is presented and validated with an Eagle Ford well. The new MPM approach uses particles to represent the slurry and its effects on the hydraulic and natural fractures. The particles are injected in the hydraulic fractures and their action causes the hydraulic fractures to propagate and interact with the natural fractures thus providing new pathways for the proppant to move away from the wellbore when optimal natural fracture orientations are encountered. Elementary tests, conducted with the new MPM approach show that fractures oriented in certain directions close to the hydraulic fracture orientation facilitate the proppant placement while other fracture orientations that are perpendicular to the hydraulic fracture or close to perpendicular direction appear to cause screen out. When using the new MPM approach on multiple interacting natural fractures with different orientations the same conclusions observed with one single fractures still hold and only those close to the orientation of the hydraulic fractures promote the placement of the proppant. The application of the new technology to an Eagle Ford well shows that the simulated proppant travels the farthest in the frac stage that is known from other methods and measurements to be the one with the best half fracture length. Furthermore, the examination of the simulated proppant concentration curve versus time shows striking similarities with the actual slurry concentration measured at the same well. These encouraging results show that the macroscopic modeling of proppant distribution using the new MPM technology could help improve our understanding of the complex hydraulic fracturing process and the resulting proppant distribution.

Estimation of the Propped Volume Through the Geomechanical Modeling of Multiple Hydraulic Fractures Interacting with Natural Fractures

“…To better explain these observations and prevent the poor placement of proppant by simulating the impact of natural fractures, the macroscopic proppant modeling using the MPM approach was introduced and validated with real field data (Raymond et al, 2015). A brief summary of this method and its use to better understand the role of fracture length and stress anisotropy is described in the following sections.…”

“…Unlike the previous model Nairn, 2014, Aimene and where the effect of the fluid in the hydraulic fractures was modeled by a traction law mimicking the fluid pressure on the fracture surfaces, Raymond et al (2015) introduced a new model that takes into account the complex multiphysics of hydraulic fracturing, by explicitly including the effect of the injected mixture of fluid and proppant (slurry) in the hydraulic fractures. The slurry represents the proppant as particles that are injected inside the hydraulic fractures.…”

“…2-4 show the final time step for the simulation of proppant injection into a hydraulic fracture that propagates, intersects the natural fracture then dilate it by placing proppant. The dynamic evolution of this process can be found in Raymond et al (2015) and in this paper we compare only the last time step of the various cases where the natural fracture length or the stress anisotropy varies.…”

“…7 (left). With these new tests added to those described in Raymond et al (2015), it is becoming clear that multiple natural fracture characteristics could have an impact on the propped volume which means that in real well examples where multiple fracture lengths and orientations and varying differential stress conditions exist, the resulting propped volume will be a complex result. To illustrate this complexity and its impact on the well performance, we will consider an Eagle Ford well and its nine stages to estimate the propped volume.…”

“…However, the well performance is also controlled by the proppant placement beyond the near-wellbore thus the need to introduce a new approach. Raymond et al (2015) introduced a new macroscopic approach based on the use of the Material Point Method (MPM) to model the proppant placement at the scale of the entire well thus providing the opportunity to evaluate the effects of natural fractures on the resulting proppant placement which ultimately will assist shale operators better understand their well performance. To better illustrate the importance of this topic, three actual case studies from current unconventional plays where the natural fractures are playing a major role in controlling the proppant placement are summarized.…”