A very informative paper.

Thanks for the link Lanman, it sure does help to understand the unitization laws.

C. Circumstances Triggering Unitization

In the United States, the fractionalized pattern of private ownership of a common reservoir creates its own circumstance justifying unitization. The unitization statutes of the various states typically require a finding that persons own separate interests in a common field, a finding easily made in almost all instances. (56)

Similarly, in international practice, the universal trigger for requiring unitization is geological: A petroleum reservoir is found to extend underneath contiguous contract areas, so different parties have rights over the common reservoir (57) (although the language does differ among countries, and Angola and China in particular have two triggering events, as discussed further below).