Stacked Mechanism EOR Frac Flood Delivered with Novel Surface Module

Over half of US oil production is from low permeability sands and shale plays in the Permian, Williston and Eagle Ford Basins with an estimated oil in place of over 3 trillion barrels. So far, this production is limited to “drill and drain” methods with the associated rapid decline and low ultimate recoveries. Improving “base production” has recently become a key area of emphasis as many horizontal wells move into late life with substantial hydrocarbons remaining in the reservoir. Methods to restore production to existing wells, with existing pads and processing facilities are especially attractive. This paper details a new Enhanced Oil Recovery (EOR) method that has been successfully piloted by several operators in the Bakken and has recently been implemented in the Midland play of the Permian basin. This EOR method uses a patented co-injection process injecting both produced water and natural gas. Single-well tests have established a Gas Utilization Factor (GUF) in the 4 Mscf/BO range which is excellent when compared with other EOR processes. Also, pilots have demonstrated the robust operation of the surface module and the ability to exceed Minimum Miscibility Pressure (MMP) using low-pressure produced gas coming directly from the existing gas lift distribution systems and water coming from produced water distribution systems. Also, the co-injected water has been shown to improve gas conformance in the reservoir and reduce breakthrough in adjacent wells. This paper presents a review of both gas and surfactant Huff & Puff style EOR processes before detailing the co-injection method. This paper highlights the advantage of a co-injection method that mobilizes oil within smaller pores using surfactant and capillary effects, while also mobilizing oil in the larger diameter pores using a multi-contact miscible process. The paper highlights the full-scale potential of this method using multiple injection cycles on a 5-well pad, over a 15-month period of time with injection of a total of 900 MMscf. The model utilizes the GUF and other information from pilot projects to estimate a Cost of Supply (CoS) in the $10-15/BO range, which is competitive for capital, especially in a lower oil price environment. This patented process provides a continuous EOR process, which builds pressure and adds EOR oil for a given pad or area as a tertiary stage of production.