--> Hydraulic Fracturing: What Do We Often Do Wrong And What Could We Do Better?

AAPG Asia Pacific Region GTW, Pore Pressure & Geomechanics: From Exploration to Abandonment

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Hydraulic Fracturing: What Do We Often Do Wrong And What Could We Do Better?

Abstract

Hydraulic fractures are designed and created in tight reservoirs to increase production. In many cases, the production prediction at the fracture design stage and later from the post-fracture pressure matching exercise is never realized. The underperformance of fracture treatments is often attributed to either formation damage, proppant crushing and embedment, or to the poor reservoir quality despite a reasonably good reservoir property indicator from all sources including mini-fracture pressure decline. There are several issues that are generally responsible for underperformance of fracture treatments. The understanding and mitigation of these issues require the application of comprehensive geomechanics. Issues that are generally responsible for lower than expected production include (1) out of zone fracture growth which cannot be predicted using a oversimplified geomechanics model; (2) poor connection between wellbores and fractures for unfavourably oriented wells; (3) non-optimum perforation intervals that cause non-optimum fracture growth and near-perforation low conductivity; (4) malpractices in treatment execution that result in disconnected fractures with the perforations; and (5) suboptimal treatments for the given reservoir. Having a comprehensive geomechanical model for the target reservoir and its bounding formations, the fracture growth simulation can identify which of the above issues may be responsible for post-fracture underperformance. Using the results of such several investigative case studies around the world, this presentation will demonstrate the adverse effects and misunderstanding of hydraulic fracture performance due to the use of over-simplified geomechanics. Given a good geomechanical model for a field, the presentation will systematically discuss what could go wrong with the well trajectory, perforations, proppant, fracturing fluid and pumping schedule to achieve the growth of a productive fracture. On the hand, the presentation will demonstrate how post-treatment simulations of fractures with a sound geomechanical model reveals the reasons for underperformance, which helps in devising for the correct mitigation strategies for the current well and calibrated design model for the future fracturing campaigns. More specifically, the presentation will focus on the following points: • Common industry perceptions towards geomechanics in hydraulic fracturing • Impact of stress regimes on fracture growth • Effects of geomechanics on fracture growth in deviated wells and mitigation of fracture complexities • Exploiting geomechanics to design the most productive fractures and wells • Understanding of post-treatment production performance and model calibration for future operations • Geomechanics in multistage fracturing of horizontal wells • Benefits of 3D Geomechanics in hydraulic fracturing Among several, one significant observation will be highlighted in this presentation is that several oversimplified techniques currently used in the industry create significantly different stress contrast profiles than that is found based on fundamental physics of geomechanics, though all these profiles can be calibrated with the same closure pressure from a mini-fracture test. The use of such inaccurate stress contrast profiles is primarily responsible for unrealistic fracture and production prediction.