Comparative assessment of mechanical and chemical fluid diversion techniques during hydraulic fracturing in horizontal wells

The application of fluid diversion during hydraulic fracturing is an evolving technology and has become popular amongst E&P operators over the past few years. The primary objective of the fluid diversion is to improve hydraulic fracturing treatment by increasing stimulated reservoir volume and improving hydrocarbon recovery. This is possible by achieving any of the following objectives: creating uniform distribution of treatment slurry within the target zone; treating unstimulated and under-stimulated zones; or by increasing fracture density by creating a complex fracture network. The fluid diversion application is also helpful in decreasing the number of stages (by increasing stage length) for multi-stage plug-n-perf (PnP) fracturing treatment. It is also applied to prevent fracture-driven interactions between adjacent wells, which is currently a major issue, especially in shale. In addition, for successful refracturing treatment, the diverter application is essential for isolating the existing fractures and redirecting the treatment slurry to the desired unstimulated zones. The diversion methods can be broadly categorized into the mechanical and chemical diversion. Several established mechanical diversion techniques are frac plugs, expandable casing patches, expandable liners, swellable packers, straddle packer assembly, sand plugs, frac sleeves, perforation ball sealers, and limited entry technique. The different chemical diversion techniques are particulates, fibers, gels, surfactants, perforation pods, and composite diverting. This paper describes the current status of established mechanical and chemical diverter technologies and examines their comparative advantages and challenges. Various techniques are suitable for diverter application, but the technique is selected based on the desired objective and conditions of the wellbore and reservoir. The general guidelines for selecting diversion techniques and operational considerations are also provided in the paper. The diagnosis of diversion treatment plays an essential role in diversion technique selection and optimization of selection parameters for the subsequent treatments. Therefore, the application of conventional surface pressure monitoring techniques and advanced diagnostic tools to evaluate diversion effectiveness are briefly described. Presently no standard laboratory testing method is established for the performance evaluation of diverting agents. Therefore, researchers have implemented various laboratory methods, which are briefly summarized in the paper. Significant insight into the diversion technology and guidelines for its selection and successful implementation is provided to help engineers to increase the effectiveness of hydraulic fracturing treatments. The limitations of individual diversion techniques are clarified, which provide the future scope of research for improvement in various diversion technologies. (c) 2023 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).