Using Dynamic Simulations to Optimize the Start-Up of Horizontal Wells and Evaluate Plunger Lift Capability: Horn River Shale Gas Trajectory-Based Case Study

Abstract

Abstract During the start-up of a horizontal multi-staged shale gas well, the fluid distribution within the well changes from a static segregated phase column to a flowing two-phase multiphase mixture. For the start-up to succeed, the well must overcome the hydrostatic head associated with this phase segregation in the vertical portion well as well as the liquid hold up in the lateral section of the well. The latter is heavily dependent on the well trajectory. The initial start-up procedure is critical to the life of the shale well since well clean up efficiency can be maximized at this stage. If the well is not properly cleaned up, the presence of liquid in the wellbore may increase which can make subsequent start-up attempts even more difficult. As reservoir pressure declines with production, the gas flow rate also decreases with time. This eventually leads to liquid loading where the well can no longer effectively lift the associated liquids to surface. Liquid loading has a detrimental impact on production and a suitable deliquification or artificial lift method is required to sustain production and maximize recovery. In the planning phase of shale gas development, it is important to evaluate the artificial lift method that will be implemented to maximize the shale well's productive life. It was studied three Horn River shale gas wells, each with different trajectories. A transient multiphase simulator is used to: 1) simulate the gas well liquid loading process in the three wells; 2) simulate gas well deliquification with plunger lift; 3) optimize the start-up procedure of the wells. These simulations provided valuable insight into the flow and pressure transients that characterize shale production. The results of this study provide guidelines for optimizing the start-up of horizontal shale wells and for designing the optimum shale well trajectory for plunger lift operations. This approach has not been presented before in literature and emphasizes the role of transient simulation in the planning phase of shale developments.