3D Modeling of Multistage Hydraulic Fractures and Two-Way-Coupling Geomechanics/Fluid-Flow Simulation of a Horizontal Well in the Nikanassin Tight Gas Formation, Western Canada Sedimentary Basin

Abstract

Summary Unconventional gas is stored in extensive areas known as basin-centered continuous-gas accumulations. Although the estimated worldwide figures differ significantly, the consensus among the studies relating to unconventional gas resources is that the volumes are gigantic. However, the low permeability in these types of reservoirs usually results in a very low recovery factor. To help unlock these resources, this paper presents a new and more accurate way of simulating multistage hydraulic fracturing in horizontal wells in three dimensions by use of single- and dual-porosity reservoir models. In this approach, the geometry (not necessarily symmetric) and orientation of the multiple hydraulic fractures are driven by the prevailing stress state in the drainage volume of the horizontal well. Once the hydraulic-fracturing job is accurately modeled in three dimensions, two-way geomechanical coupling is used to history match the produced gas from a horizontal well drilled in the Nikanassin naturally fractured tight gas formation of the Western Canada Sedimentary Basin (WCSB). Traditionally, the most widely used approaches have their roots in semianalytical calculations simplifying the fracturing system to a planar feature propagating symmetrically away from a line source of injection. In contrast, the computed results presented in this study show that the incorporation of geomechanical effects gives a more realistic representation of the orientation and geometry of hydraulic fractures. Reduction in permeability of the natural and hydraulic fractures because of pressure depletion results in more-realistic production predictions compared with the case in which geomechanical effects are ignored. The telling conclusion, in light of the computed results, is that the field of hydraulic fracturing provides an object lesson in the need for coupled 3D geomechanical approaches. The method presented in this paper will help to improve gas rates and recoveries from reservoirs with permeability values in the nanodarcy scale.

Advances in the study of naturally fractured hydrocarbon reservoirs: a broad integrated interdisciplinary applied topic

“…Given the challenges of quantitatively characterizing fracture networks from subsurface and outcrop data, it is predicted that the use of geomechanical simulations, based on geologically appropriate approaches, will serve to underpin efforts to understand or create discrete fracture network models, which can then be incorporated into reservoir flow simulations (Gonzalez et al 2014). The rapid and continuing advances in relatively inexpensive computer power will make this approach more practical and less specialized.…”

Reasonable production allocation model of gas wells for deep tight gas reservoirs with the edge water

“…These special gas reservoir characteristics put forward new requirements for reasonable production allocation. There are many recent studies focused on tight gas reservoirs, such as 3D modeling (Gonzalez et al, 2014), an integrated approach with detailed static and dynamic reservoir modeling (Weijermans et al, 2016), and cross-plot multiple regression analysis (Gai et al, 2015).…”

An integrated approach to discretized 3D modeling of geomechanical properties for unconventional mature field appraisal in the western Canadian sedimentary basin

“…Havens (2012) carried out similar approach for Bakken petroleum system to establish the spatial behavior elastic properties and concluded that conventional approach of consideration of small core samples plugs in formulating 3D reservoir geomechanical model is not a practical solution. During fracture modeling of unconventional tight gas reservoirs, Gonzalez et al (2014) and Deng et al (2011) demonstrated that incorporation of 3D geomechanical model gives a more realistic representation of the orientation and geometry of hydraulic fractures compared to traditional way of semi-analytical calculations of fracture geomechanical properties. Other published studies on similar topics in the western Canadian sedimentary basin reveal that spatial distribution of rock mechanical properties is highly heterogeneous in nature and is result of complex basinforming (depositional) process (Ferdous et al 2015;Lavoie and Séjourné 2016;Tong et al 2005).…”