Because oils are susceptible to many transformations during expulsion and [[migration]] and in the reservoir—including cracking, phase separation, and biodegradation—correlation techniques and parameters must be selected to minimize complications due to postgenetic transformations. In general, oil–[[source rock]] correlations are more difficult than oil–oil correlations, largely because we seldom have samples from the effective (mature) [[source rocks]] themselves. Problems arise from variations in facies between the basin center and the sampling point as well as from potentially large maturity differences. Condensates can be difficult to correlate because they have lost much of their valuable information during cracking, phase separation, or both. | Because oils are susceptible to many transformations during expulsion and [[migration]] and in the reservoir—including cracking, phase separation, and biodegradation—correlation techniques and parameters must be selected to minimize complications due to postgenetic transformations. In general, oil–[[source rock]] correlations are more difficult than oil–oil correlations, largely because we seldom have samples from the effective (mature) [[source rocks]] themselves. Problems arise from variations in facies between the basin center and the sampling point as well as from potentially large maturity differences. Condensates can be difficult to correlate because they have lost much of their valuable information during cracking, phase separation, or both. |