Benefits of the Novel Fiber-Laden Low-Viscosity Fluid System in Fracturing Low- Permeability Tight Gas Formations

摘要

Most of the low-permeability tight gas market that is treated by low-viscosity slickwater fracturing treatments results in ineffective propped fractures due to rapid proppant settling. Currently hybrid fracturing and ultra-lightweight proppants are employed for improving performance of slickwater treatments. The hybrid fracturing methodology uses a combination of linear and crosslinked gels to improve proppant placement. The disadvantages of existing lightweight proppants are their high cost and applicability only to reservoirs characterized by low closure stresses. Novel fiber-laden low-viscosity fluid technology has been developed to improve proppant transport for hydraulic fracturing in low-temperature tight gas formations. Such a system creates a fiber-based network within the fracturing fluid that decouples proppant settling from fluid viscosity. This network entangles proppant, dramatically reduces proppant settling, and provides a mechanical means to transport and place the proppant at greater distances from the wellbore. An additional advantage of the new system lies in fiber degradability, which leads to a nondamaged fracture conductivity with time. Fluid rheology of fiber-laden fluids was measured over a 150–230 °F temperature range under various fiber loadings. Studies showed that under bottomhole temperature and fluid pH fiber decompose and form a water-soluble species. During fiber degradation, the permeability of the fiber-laden system approaches the value of permeability for the baseline system without fiber. Compatibility study of the degradation byproducts with formation water showed no precipitate formation in high salinity environments. The results demonstrate that the new fiber technology ensures uniform proppant placement within a long fracture, provides permeability equal to pure proppant pack values, andoffers higher production rates in comparison with conventional fracturing treatments.