Abstract
Historically, operators in tight oil carbonate resources, following the shale gas paradigm, drill and stimulate most wells in the same way. Typical wells are single laterals, hydraulically fractured near the reservoir top with no clear understanding of the fluid segregation mechanism. Since this reservoir is producing with very high water cuts (normally above 90%), deployment of electric submersible pumps (ESP) has been widely applied. As pressure declines, difficulties with high gas volumes and slugging have been an operational and cost challenge. By applying an integrated, multi-disciplinary approach, The Event Solution, a project team combined all available data types to fully understand the reservoir mechanisms. Geological and simulation models were utilized to understand and test reservoir development concepts, including operational and cost parameters. A pilot well design was applied for testing and acquiring knowledge implementing an innovative well design with the maximum reservoir contact (MRC) concept. The design consists of one upper hydraulically fractured horizontal well, one hydraulically fractured middle horizontal well and a lower well with five unstimulated open-hole laterals. The upper well ESP sump provides the best way to produce high gas-cut liquids while minimizing gas slugging and interventions. The lower well laterals (with MRC configuration) provide the means to create gravity segregation across the reservoir, pulling water down while still producing low oil cuts. The middle well is the main oil producer with higher oil cuts. Stimulation tracers, well testing and simulation show a geo-mechanical pressure dependency on production indicating that below certain bottom-hole flowing pressures fractures tend to close somewhat and vertical communication is lost; above that pressure, fractures and vertical communication open. Managing communication between all existing laterals at multiple levels in the reservoir is possible. With these understandings, optimized and consistent development with higher oil recovery can be achieved at lower costs. It is envisioned that MRC designs are widely applicable to other tight oil carbonate resources.
