| Popis: |
Hydraulic fracturing is one of the major techniques in modern well stimulation practices. The purpose of the current contribution is to gain novel insights on utilization of cold water for fracturing services in Western Siberia aiming to reduce non-productive time and price while maintaining excellent quality of service delivery. The study covers the hydration of non-modified guar gum and borate crosslinking in cold water conditions, the associated risks and plausible benefits are also considered. Among all fracturing services, conventional borate crosslinked guar gum fluids remain the most widely utilized due to their economical profitability, availability, ease of viscosifying and handling. The reduced temperature of water affects the guar swelling and hydration during linear gel preparation and influences the crosslinking reaction rate for delayed borate systems. One of the obvious drawbacks of the guar-based fracturing fluids is the necessity for a water heat-up process, especially during winter period. Within the scope of present study we are discussing the opportunities and perspectives of non-modified guar fluids for cold water fracturing applications. This original research details the comprehensive laboratory evaluation and thorough theoretical study, which presents a variety of fracturing fluids available to hydrate and crosslink in water temperatures starting from 5 degrees Celsius. It was revealed that the hydration of guar polymer (loading 3.6 kg/m3) in water varies between 82-88% at 5 degrees Celsius. The optimized borate-crosslinked fluids provide viscosity greater than 400 cP at 96 degrees Celsius. The versatility of proposed fracturing fluids was proven by exceptional viscosity recovery to 400 cP in less than one minute after high shear regime in the range of 10-50 degrees Celsius, simulating the fluid behavior in near-wellbore area at ambient temperature. The scope of work included the development of cold water implementation criteria and evaluation of possible associated risks, e.g. the additional cooling effect upon contact with proppant. The results presented in the current work pave the way for implementation of conventional borate-crosslinked guar gum fluids for cold water fracturing. Without significant price increase the proposed approach allows to decrease 30% of non-productive time and reduce heating expenses. The approach is significantly beneficial in areas exposed to cold winter conditions like Russia, Alaska or Canada. |
