Minimize Formation Damage in Water-Sensitive Unconventional Reservoirs by Using Energized Fracturing Fluid

Abstract

Abstract Slickwater has been widely used for hydraulic fracturing as it is inexpensive and able to carry proppants into the fracture. However, such fluid is unsuitable for water-sensitive formations, such as Montney. Water saturation around the fracture increases and clay swells when water leaks-off into matrix, both hindering natural gas flowing from matrix into fractures. N2 or CO2 energized water-based fracturing fluids have been widely used in water-sensitive formation as they can minimize fluid leak off during fracturing and achieve higher load fluid recovery during flow back. In this paper, multi-phase numerical simulations are applied to study the formation damage mitigation in Montney tight reservoir by using energized fracturing fluid. A simulation model is built and history matched with flow back and early production data of a typical Montney tight gas well. The behavior of multi-phase fluid leak off and flow back is studied, and the sensitivity of foam quality of fracturing fluid on load fluid recovery and well after stimulation productivity is analyzed. Statistical analysis is conducted on the stimulation and production data of over 5000 Montney wells to study the performance of energized fracturing in water-sensitive Montney formation. It is found that multi-phase fracturing fluid has less dynamic fluid leak off than that of a single phase fracturing fluid (i.e., water), and the major fluid leak off occurs during the static leak off period between the end of the stimulation processes and start of the flow back. Gas phase penetrates deeper and faster into the reservoir matrix in comparison with the liquid phase, which greatly contributes to flow back of fracturing fluid. Formation damage caused by fracturing fluid leak off can affect both early and long term production. In addition, N2-foam leads to the highest load fluid recovery in Montney formation, which is 1.6 times of that of CO2-foam. This work provides critical insights into understanding the performance of using energized fracturing fluid to mitigate formation damage in tight formations.