Evaluation and optimization of degradable-fiber-assisted slurry for fracturing thick and tight formation with high stress

Economically producing hydrocarbon from tight formations requires fracturing with a large volume of water and proppants to ensure a highly conductive fracture network. Proppant settling can hinder proppant transportation within fractures, limiting dimensions of the propped fractures and well production rates. This problem is more serious in thick formations that tall fractures are needed. In deep reservoirs with high closure stresses, using high pumping rate or viscous cross-linked gel have their own limitations, while adding degradable fibers can solve the problem. However, no visualized flow experiments have been conducted that can fill the gap between the benchtop measurements and the field tests, thus providing reliable mechanisms to guide the optimization of this technique for a chosen reservoir. In this study, a systematic screening and evaluation procedure is developed to quantify the effectiveness of degradable fibers on suspending proppants and enhancing fracture conductivity, so as to explore the mechanisms behind this technique. Results indicate that a dilute concentration of fibers in proppant slurry can double proppant placement efficiency without blocking perforation holes on the wellbore; fiber degradation leaves no residue that damages fracture conductivity; fiber degradation does not cause the closure of propped fractures even at high closure stresses.