An 18-well numerical-simulation model was built to represent an operator’s Lower Shaunavon waterflood-pilot area. Numerical simulation was used, and a history match on the pilot area was performed. By use of parameters obtained from the history match, a representative model was built and a sensitivity study was performed on hydraulic-fracture spacing and well spacing in both primary-depletion and waterflood scenarios.
The Shaunavon is partitioned into lower and upper members. The lower member is an authigenic carbonate shelf, while the upper member has a strong clastic influence from the west. Oil is trapped hydrodynamically; the oil fairway crosses both stratigraphic and structural trends.
The Lower Shaunavon is divided into four intervals in the study area. The lowest interval is a calcareous cryptocrystalline mudstone. Sitting above this interval is the B Marker, which is a slightly more energetic environment. The A Marker marks a regressive lag as a result of a sea-level drop. It consists of wackestone to some packstone rock and is bounded above and below by mudstones. The uppermost interval represents a high-energy environment.
A geological model was developed for the lower Shaunavon pilot area on the basis of well logs, petrophysical data, and surface maps. The model was developed further into a dynamic simulation model by incorporating pressure/volume/temperature data, relative permeability, well trajectory, well completion, and historical well-production and -injection information for all wells located within the pilot area.
Understanding Waterflood Response in Tight Oil Formations: A Saskatchewan Case Study
20 September 2015