Royalty Lease Evaluation (RLE) distillation analysis was performed on six hundred (600) wells in Petrotrin's Soldado acreage. This data has been traditionally generated for use by Petrotrin's refinery to determine if the crude oil feedstock is compatible to the refinery configuration or if the crude oil could cause yield, quality and production problems. These made for refinery reports have become part of Petrotrin's legacy data. The authors decided to examine this dormant dataset to ascertain what hidden stories it may tell about the oilfields from which they came.

In this investigation no data is generated, but an existing and dormant dataset will be analysed. Several components in a RLE distillation report on crude oil samples will be observed for trends, patterns and relationships. Ternary diagrams and cross-plots will be employed. Specific geochemical revelations from the RLE data will be validated by comparison to conventional gas chromatography data.

This investigation will illustrate how evaporative fractionation, which is a later charge of light hydrocarbons mixing with an emplaced biodegraded oil is evidenced by a phenomenon called the" Gas Oil Anomaly", seen in the RLE data. Essentially this is the absence of any gas oil fraction combined with the presence of light hydrocarbons in the distillation data. It will also be demonstrated that presence of the later charge of light hydrocarbons has been the key factor in the prolific production from the Soldado reservoirs.

Additional analysis of the light oil and gas oil fractions of a crude oil will reveal properties and characteristics that suggest there were different sources for both the originally emplaced oils and the later charge of light hydrocarbons. The data also shows that due to the evaporative fractionation phenomenon there is no correlation with API Gravity, oil viscosity, Sulphur content and depth of the reservoirs in Soldado. It will also be demonstrated that the data can be used as a qualitative tool leading to exploration plays in the Soldado acreage.

Explorationists at Petrotrin will find the results of this investigation to be both useful and provocative as it directs their attention to specific Trinmar Soldado oilfields as deep exploration play areas in a manner that traditional geochemical analyses have not been able to. It also allows the practioners in the Petrotrin Soldado acreage to better understand the productivity and complex fluid distributions in the Soldado reservoirs.

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