METHODS AND APPARATUS FOR ESTIMATING PHYSICAL PARAMETERS OF RESERVOIRS USING PRESSURE TRANSIENT FRACTURE INJECTION/FALLOFF TEST ANALYSIS

摘要

A before-closure pressure-transient leakoff analysis for a fracture-injection/falloff test is used to mitigate the detrimental effects of pressure-dependent fluid properties on the evaluation of physical parameters of areservoir. A fracture-injection/falloff test consists of an injection ofliquid, gas, or a combination (foam, emulsion, etc.) containing desirableadditives for compatibility with the formation at an injection pressureexceeding the formation fracture pressure followed by a shut-in period. Thepressure falloff during the shut-in period is measured and analyzed todetermine permeability and fracture-face resistance by preparing a specializedCartesian graph from the shut-in data using adjusted pseudodata such asadjusted pseudopressure data and time as variables in a first method, andadjusted pseudopressure and adjusted pseudotime data as variables in a secondmethod. This analysis allows the data on the graph to fall along a straightline with either constant or pressure-dependent fluid properties. The slopeand the intercept of the straight line are respectively indicative of thepermeability k and fracture-face resistance evaluations R0.