A reservoir that has formed through millions of years of sedimentation almost never conforms to the established borderlines that define political entities or legal jurisdictions of neighboring countries. The term shared reservoir is given to such hydrocarbon deposits. After the discovery of shared reservoirs, the neighboring countries could jointly develop a cross-border hydrocarbon deposit or disagree on any framework for unitizing or jointly developing the reservoir. Furthermore, in order for any negotiation to take place, the contending sides need to settle on an unbiased agreement. This can only be done after the term “unbiased” is defined quantitatively in technical terms. Although defining a reservoir before thorough exploration is challenging and rather unreliable, understanding the behavior of shared reservoirs is highly valued since many reservoirs around the globe, including the world’s largest condensate gas reservoir, in under such collaborative ownership. It is evident that optimized production from such reservoirs will benefit their rightful possessors and the rest of the world. This study investigates all main factors that influence production from a shared oil reservoir and demonstrates how each neighboring country is affected by variations of each of these factors. Displays of simulated reservoir at potential production conditions complement our quantitative analysis throughout this study. © 2014, The Author(s).