Successful development of unconventional resources (UCR) depends on the planning and execution of economic and efficient hydraulic fracturing stimulation. In the last decade, multistage hydraulic fracturing technologies have significantly improved and matured with more than 50,000 wells being drilled and completed every year across different UCR resources. Still, opportunities exist for continuous improvement and optimization of multiple design parameters of hydraulic fracturing job planning and execution. Solutions have been developed for these opportunities to maximize productivity and Estimated Ultimate Recovery (EUR) with economic development practices.
The key components of hydraulic fracturing in UCR wells were reviewed to identify opportunities for improvement in efficiency and effectiveness. This covered design and decisions regarding horizontal well landing, number of fracture clusters per stage, proppant and frac fluid type and quantity, propped and unpropped fracture contribution, fracture interaction and stress evolution during well life. Collection & analysis of various diagnostic data along with application of fit-for-purpose software tools in area of numerical geomechanics, fracture modeling, Computational Fluid Dynamics (CFD) modeling and reservoir simulations were used to study the mechanisms and gain learnings. In-house tools and integrated workflows are developed to achieve solutions for optimum stimulation design and develop best practices for each of opportunities identified in hydraulic fracture stimulation of UCR wells.
The integrated solution has provided economic and efficient design to maximize productivity and EUR by capturing all segments of hydraulic fracturing process. The integrated workflow showed the importance of incorporating geomechanical parameters in addition to geologic and geophysical properties while selecting best rock for horizontal well landing to ensure maximum coverage of good quality rock with fracture and fracture to wellbore connectivity. The case specific optimum perforation cluster design using in-house developed fracture entry optimization tool reduced cost with ability to successfully pump up to 15 cluster per stage with increased fracture placement efficiency. The proppant transport study in wellbore and fracture using CFD modeling highlighted the optimum combination of fracture fluid viscosity range and proppant type (size and density) to maximize proppant transport for required propped and unpropped conductivity as per formation petrophysical properties. The analysis of stress evolution during fracturing and production life of well due to depletion using numerical coupled geomechanics provided quantification of effective stress on proppant for selection of low-cost local sand as proppant and drawdown management solution.
The integrated analysis of individual component of overall stimulation process provided many key learnings and best practices to achieve economic improvement of productivity and EUR. The fit-for-purpose tools and workflows provided optimum economic solution to maximize both early time production and EUR with ability to successfully pump 10-14 clusters per stage using smaller local sands and slickwater in horizontal wells landed in best rock and produced at optimum drawdown.