Controlled Pulse Fracturing (CPF) is an alternative stimulation technique that differs significantly from conventional hydraulic fracturing. Instead of injecting fluid continuously, CPF generates a rapid, high-pressure gas pulse in the wellbore using a propellant-based tool. When the tool is ignited, it produces a short-duration pressure pulse that propagates into the surrounding formation and initiates fracturing near the wellbore. This method was described by Hunt and Shu (1989) as a way to improve stimulation efficiency while avoiding some of the limitations of traditional techniques.
One of the key characteristics of CPF is the creation of multiple short, radial fractures rather than a single dominant fracture. These fractures typically extend only a short distance from the wellbore but are distributed in multiple directions, improving connectivity between the well and the surrounding formation. Because the pressure pulse is carefully controlled, it remains below the rock’s yield stress, helping to avoid severe wellbore damage often associated with explosive stimulation methods.
The CPF process can be understood in three main stages: wellbore pressurization, rupture of existing flaws in the formation, and fracture extension. The rate at which pressure builds, known as the loading rate, is a critical parameter. If the pressure rises too quickly, it can damage the formation; if it rises too slowly, the process behaves more like conventional hydraulic fracturing and produces fewer fractures. An intermediate loading rate is therefore required to generate multiple fractures effectively (Hunt and Shu, 1989).
Another important feature of CPF is that it minimizes fluid contact with the formation, since the process relies on gas rather than large volumes of injected liquid. This reduces the risk of formation damage caused by fluid invasion. In addition, CPF can be used to target specific zones, making it useful for selective stimulation or for improving near-wellbore connectivity before applying other treatments such as acidizing or hydraulic fracturing.
Despite its advantages, CPF remains less widely used than conventional hydraulic fracturing. Field data are still relatively limited, and the technique requires careful control of pressure and tool design. However, it offers a promising alternative for stimulating low-permeability formations, particularly in cases where traditional methods are ineffective or too costly.
