Selecting Optimal Fracture Fluids, Breaker System, and Proppant Type for Successful Hydraulic Fracturing and Enhanced Gas Production – Case Studies

摘要

Hydraulic fracturing is required to commercially produce low to moderate permeability gas reservoirs. The selection of fracturing fluids, additives, and proppant types are major components when designing and implementing a hydraulic fracturing treatment. A viscous, unbroken fracture fluid that remains after the treatment compounds the effects of fracture face skin and causes severe deterioration to proppant conductivity. With the advancement of technology, many novel fracture fluid systems are available in the industry with reduced polymer concentration to preserve reservoir and proppant integrity. The advantages of these fluids include less formation damage, low cost, and reduced treatment pressure. Subsequent to the fracture operation, an aggressive breaker treatment is often necessary to effectively clean up the fracture and restore proppant conductivity. Proppant conductivity plays a tremendous role in the post-fracture production enhancement and any damage left from the fluids can impair well potential considerably. Similarly, correct choice of proppant based on the rock strength, reservoir fluid properties, expected production rate, pressure, and temperature is important. Proppant type and scheduling determine the ultimate propped fracture geometry that controls the gas flow from the reservoir to the wellbore. Application of new technologies in combination with better job design to obtain improved results in the deep sandstone reservoirs of Saudi Arabia is ongoing. In the process of optimization, fluids along with its gel type, polymer concentration, and additives have been modified and changed to provide better results. Similarly proppant size, types, and schedule have been optimized. Different types of aqueous-based fracturing fluids used with various polymer loadings as well as the use of hybrid systems and viscoelastic fluids (VES) used in deep and high temperature reservoirs are currently in use. Several case studies provided in this paper demonstrate how the critical fracturing parameters have progressed with time, been customized, and made to fit the reservoir conditions to make a noticeable impact on well productivity and recovery.