Patent ID: 8180602
Filing Date: 2012-05-15
Classification: E21B

Abstract:
1. A method for evaluating seal capacity in order to determine hydrocarbon column heights, and optionally associated probable errors, for a subject hydrocarbon trap containing oil, gas, or both oil and gas, said method comprising: (a) estimating a probability-weighted distribution for capillary entry pressure values at one or more calibration locations by equating capillary entry pressure with hydrocarbon buoyancy estimated through inversion of trap and fluid property data; (b) estimating a probability-weighted distribution for hydraulic fracture pressure values from calculations using theoretical calculation or from empirical data collected from one or more calibration locations; (c) obtaining probability-weighted distributions for anticipated fluid properties and trap geometry parameters at the subject hydrocarbon trap, said properties and parameters including: (d) for a current realization, determining a current realization value for each of the fluid properties and trap geometry parameters of the subject trap by randomly selecting from their respective probability-weighted distributions; (e) using a computer, determining a current realization value for the subject trap's capillary entry pressure by: (f) using a computer, determining a current realization value for the subject trap's hydraulic fracture pressure by: (g) using a computer, calculating a column height for each hydrocarbon phase present in the subject trap using the randomly selected fluid properties and trap geometry parameters of the subject trap for the current realization, said calculation equating hydrocarbon buoyancy with total seal capacity, said total seal capacity being obtained by combining the adjusted hydraulic fracture pressure gradient and capillary entry pressure values determined for the current realization, and said each hydrocarbon phase comprises one of oil and gas; (h) repeating steps (d)-(g) a predetermined number of times; and (i) using a computer, averaging results from step (h) and optionally calculating an uncertainty for each column height from spread within the results.