The persistent industry problem of poor pump efficiency associated with lifting foamy crude under maximum drawdown conditions is particularly adverse in S. Oklahoma's E. Velma field. Field tests supplemented with a research laboratory investigation of defoaming agents have been conducted during the past 2 yr. The objectives were: (1) to develop laboratory screening techniques for selecting the best defoaming agent, considering concentration and viscosity as the primary variables involved in breaking the foam; and (2) based on field results, attempt to optimize the treating technique required to break the foam column and influence the downhole fluid compressibility. Substantial production increases have been realized from field application, even though the treating technique with respect to volume and frequency has not been fully optimized. Out of 43 wells field tested with dimethyl silicone (1,000 centistokes), 21 wells were considered successful, yielding a 1,360-bpod increased in production. Field tests have involved wells equipped with hydraulic, beam, and electric submersible pumping equipment.