SEISMIC AMPLITUDE ANOMALIES AND AVO ANALYSES AT MESTENA GRANDE FIELD, JIM-HOGG-COUNTY, TEXAS

Mestena Grande field produces gas and condensate, primarily from the middle member of the Middle Eocene Queen City formation. The producing zone is a deep, thin, high impedance sandstone which generates amplitude anomalies on the stacked data. AVO (amplitude versus offset) analyses were performed to investigate those anomalies and determine if they could aid in field development or exploration along the trend. Modelling the AVO response of a productive well has predicted an amplitude decrease with offset from a high impedance sandstone. However, amplitudes increase with offset on the crest of the field. The disagreement between the results of the modelling and the real data is attributed to the lack of accurate shear wave velocities and the presence of very thin beds. -from Author