Evaluating the Application of Natural Gas-Based Foamed Fracturing Fluid in Unconventional Reservoirs
Foamed fracturing fluids have been used in unconventional reservoirs to reduce the water usage and minimize deleterious impact on water-sensitive formations. As part of a Department of Energy (DOE) sponsored program, we have previously identified an optimal thermodynamic pathway to transform wellhead natural gas (NG) into pressurized NG suitable for use as the internal phase in a foamed fracturing fluid. This study now aims extends the work to determine the impact of using NG Foam frac fluid on hydraulic fracture geometry and the productivity from the unconventional reservoirs. The current study is focused on investigating the impact of the natural gas-based foam of various foam qualities in hydraulic fracture geometries and their production through simulation models. Field data and lab based measurements for NG foam fluid properties are incorporated in the study. In addition, the transient response of the fluid flowback from foam based fluid is studied using numerical simulation. Comparative analysis is done with typical Slickwater, linear gel and full crosslinked fluid application for hydraulic fracturing using 3D-complex hydraulic fracture models. 1D and 2D particle transport models have been used to verify the differences in proppant distribution in the hydraulic fractures. Rapid wellbore clean-up, low clay damage, and effect of the relative permeability difference between the NG foam and rock matrix is an added advantage apart from reducing the water requirements for hydraulic fracturing. In addition to logistical benefit of using wellsite liberated low pressure gas utilization, NG foamed fracturing fluid has a dynamic fluid leak-off behavior and increase effective viscosity over the base fluid that allows pump and transport sand at least 10% farther in the hydraulic fractures than linear gel. Slickwater displays poor proppant transport and hence poses inability to pump higher concentrations of sand. NG foam fracturing fluid on the other hand displays improved proppant transport and has shown to create more complexity than Slickwater (Hall et al.). Use of NG foamed fracturing fluid is a concept that has not been practiced widely over the well sites due to safety concerns. However, the applications to under-pressured reservoirs, logistical benefits, improved production performance are found lucrative in this study. Hence operators can invest in creating safer handling environment for wellsite application of NG foam to reap the benefits.
AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018