Although all plug-and-perf systems require frac plugs to isolate zones in the wellbore, there are alternative approaches to hydraulic fracturing using the plug-and-perf method. The availability of dissolvable frac plugs enables operators to weigh the cost and risk of using non-dissolvable frac plugs against the cost and risk of dissolvable frac plugs. This paper analyzes the cost and value of these varying fracturing approaches for applications in North America in traditional and extended reach wellbores.
Frac plugs must be removed from the wellbore before production begins. Non-dissolving frac plugs are removed by milling; this step increases the cost of the overall completion and can sometimes lead to production delays. Risks associated with the milling operation include becoming stuck in the wellbore, damage from the milling debris, and the requirement for larger amounts of water. Consequently, the cost of milling is an added cost to non-dissolvable fracture products. Dissolvable solutions, however, have a larger upfront cost because dissolvable materials are more expensive than non-dissolving materials.
There is a trade-off between the larger upfront costs of dissolvable fracturing technology and the milling costs and risks of non-dissolvable fracturing technology. This trade-off depends on the number of stages, wellbore fluids, formation parameters, operational costs, cost of delayed production, and the operator's willingness to accept risk. The trade-offs also vary between operators and regional geographies. The costs of non-dissolving frac plugs are acquired from historical data and include tools, milling, materials, and the time delay to production, as well as the weighted risk of potential formation damage and lost time incidents. The costs of dissolvable fracture plugs are estimated from the experience in the use of this dissolvable technology. These dissolvable costs are modeled for a typical wellbore in North America for both full wellbore and extended reach laterals. The result is an estimate of the trade-off between cost and risk for non-dissolving and dissolvable fracture technology.
A dissolvable frac plug adds both cost and value to fracturing operations in the unconventional market. A key advantage for dissolvable frac plugs is the ability to fracture longer extended reach wellbores. This paper enables the operator to balance the tool cost with the value of eliminating operational mill-out steps, overall cost of the completion, risk associated with the completion, and the time necessary to begin production.