PT Pertamina EP Cepu (PEPC) is regional leader for managing the upstream oil and gas business within Pertamina. Its business portfolio consists of various types of assets including exploration, development and production assets. The assets maturity also varies greatly from green field to brown field. PEPC has at least 3 unitization fields under its control, but the SKW Field has its own complexities because apart from having a different fiscal term regime between the 2 work area operators and also has concern for stakeholders. Unitization Field in the upstream oil and gas business has definition that the condition where one field has a distribution of hydrocarbons covering 2 different blocks. In this case, the analysis becomes more complex because the two blocks are not managed by the same operator. Even though PHE and PEP are Pertamina's subsidiaries, in accordance with Law No. 22 of 2001, each entity managing the Oil and Gas Working Area must be separate. The complexity of the problems that occur due to this unitization is also driven by the application of a gross split mechanism that is different from the previous PSC generation, namely Cost Recovery. This research is intended to assist stakeholders, especially from the company side, in order to determine optimal amount of share/participating interest that meets techno-commercial principles and is supported by compliance aspects for unitization fields. This research can be used as a reference to reduce the potential for future disputes. The Analytical Hierarchy Process (AHP) method assisted by the Focus Group Discussion method by Subject Matter Experts (SME) can assist the process of selecting the most optimal options and support the decision-making process.