A Look at History-Match Non-Uniqueness Through the Lens of Model Simplifications - Delta Reservoir Case Study

Abstract

Reservoir simulation is one subject with different "schools of thought" for its ability to predict the future performance of a reservoir. An important topic in reservoir simulation workflow is the parameters used to achieve history-match. The non-uniqueness of history-match parameters creates an opportunity for reservoir simulation engineers and geologists to engage in collaborations that ensure geological and engineering interpretations are incorporated in history-match parameters. Simple history-match parameters are often times preferred by practitioners to complex history-match parameters. This paper will discuss Delta reservoir history-match parameters used in a 2014 reservoir simulation study which was later updated in 2016 with simplified history-match parameters. The parameters that were simplified are permeability multipliers, oil/water relative permeability and the use of Land's constant. Also, vertical grid refinement was implemented to reduce it from 8ft to 2ft to enable the simulation model reproduce the reservoir fluid distributions in the two lobes of the reservoir. With all these modifications, there were no significant differences with the wells’ static reservoir pressure and fluid saturation matches between the 2014 simulation study and the 2016 simulation update. This paper demonstrates the non-uniqueness of reservoir simulation history match parameters and the value to consider simple grid and fluid parameters’ modification before considering complex approach. With the simplified history-match parameters, the Asset Team had more confidence in the simulation result. The updated Delta reservoir simulation model was used to assess future development opportunities and identified two oil-well producers and one water injector well with EUR of 13.3 MMSTBO.