DISCOVERY OF NEW HORIZONS IN A 36 YEARS OLD CONVENTIONAL OIL AND GAS PLAY BY UTILIZATION OF STATE-OF-THE-ART FORMATION EVALUATION APPROACHES: A CASE STUDY FROM THE THRACE BASIN, TURKEY

摘要

Due to relatively low hydrocarbon prices in recent years, making most out of each well has become crucial to increase the profit margins of oil and gas companies. One effective way to strengthen the economics of the oil and gas companies is through the delineation of new prospective zones using pre-existing wells. This study shows an example of a very successful formation evaluation case, which totally changed the economic perspective of a mature conventional oil and gas field. The re-evaluation of formations via utilization of low resistivity pay (LRP) approach led to the discovery of new gas bearing zones in a legacy gas well drilled in 2006 (Yesilgol-O1), which was on the verge of abandonment. The insight from Yesilgol-O1 also led to the opening of a new production horizon for a nearby legacy oil well (Yesilgol-1), drilled in 1982, which never produced at economic rates. The current saturation of the shallow gas reservoir in Yesilgol-1 was evaluated with a pulsed neutron logging operation. The interpretation of the logs was supported by five different data sources (seismic cross sections, lithology recordings, X-ray Diffraction (XRD) analysis of drill cuttings, gas readings in mud logging unit (MLU), sonic (DT) and deep resistivity (LLD) logs recorded in open hole). The re-evaluation led to the discovery of several new reservoir intervals with considerably high gas rates in the 36 years old Yesigol-1 well.