| dc.description.abstract | Unconventional reservoirs such as the tight Bakken reservoirs have become an important topic
in the oil industry due to the discoveries of enormous volumes of hydrocarbons. The
permeability in these formations can typically be described as ultra-low, meaning that
conventional recovery techniques rarely provide enough production to yield economic
feasibility. By taking advantage of horizontal drilling with hydraulic fracturing along the well, oil companies have managed to increase the recovery, but the initial high production rates are often reduced dramatically after a short period of time. Therefore, it has proven necessary to employ Enhanced Oil Recovery (EOR) techniques as attempts to maintain a sustainable recovery level, and natural gas injection is an interesting area in this context.
Cyclic SWEOR (Cyclic Same-Well Enhanced Oil recovery) and Same-Well Huff n Puff EOR are two gas EOR methods that include injection and production from the same well, with both injected and produced fluids flowing in one single tubing. These solutions are thought to be implemented in already existing horizontal well configurations, thus representing low-cost
initiatives for recovery improvement. When such strategies are put into operation, it is required to perform injection and production in separate cycles, as the processes can t be performed simultaneously.
This study aims to present and exemplify a cycle optimization strategy, where both Cyclic
SWEOR and Same-Well Huff n Puff EOR are under examination. The cycle part refers to three
cycle parameters that act as user input in the strategy, while the optimization aspect refers to chosen Key Performance Indicators (KPIs) and the desire of ideally affecting them based on
the cycle parameters. How one can go about performing this in a systematic way is then covered in the strategy part. Central KPIs in this context are incremental oil production and incremental net present value (NPV), as these are of particular interest to uncover to which extent the EOR methods can give additional recovery and if the projects are economically sustainable.
The work presented applies SENSOR reservoir simulation to exemplify the strategy with
generated data, where a reservoir model reflecting the Bakken reservoirs is utilized including a horizontal well with hydraulic fractures. Ordinary pressure depletion production is run in parallel to the EOR simulations to give a base for calculating incremental production. In order to chain together user input, reservoir model, simulation and financial computations into an integrated process, the Pipe-It software developed by Petrostreamz AS plays a central role. The optimization method is demonstrated as a brute force strategy that relies on numerous simulation runs to suggest ideal cycle parameter values to influence the KPIs as desired | en |
