Abstract Production wells in mature offshore fields encounter many challenges. In this study the main consideration is avoidance of early water breakthrough driven by injection/production. Encountering water complicates effective completion and production operations. Real-time understanding of geology and fluids, particularly water saturation variance, is required to optimize well placement. This case study is from a recent well in a mature field offshore UAE. Reservoir fluid identification solution utilizing the latest technology was recognized as the most effective method to confront the challenges in this well. The well target was planned for approximately 12,100 feet, targeting a specific carbonate layer in an 8.5″ open hole horizontal section. Precise geosteering required that is a combination of logging while drilling technologies: Triple Combo; and a borehole Imaging Azimuthal Density tool (for detailed formation evaluation). The focus on real-time fluid identification supported any increasing proximity to the conductive water zone, highlighting areas that could cause water flooding during production. During well placement and steering operations, it has been provided for this well through the whole operation from the planning stage; through the execution stage (Realtime Modelling); and post well analysis as validation of steering actions post TD. During drilling the 8.5″ hole section several geological and drilling challenges were encountered. Pro-active maneuvering of the trajectory to land in the reservoir's optimum zone was required in the early interval due to setting of the previous section's casing shoe in the dense layer above the target reservoir. The top boundary above the target formation was mapped allowing continual interpretation of formation dip, which was in the range of 1.2 – 1.7 deg up towards the toe. Simultaneously, the bottom boundary of the target reservoir was continuously mapped to TD 7 – 9 ft below trajectory and this is where the main challenge was identified with the identification of a conductive water zone with increased proximity to the wellbore. Effective action by utilizing double latch to the ORA tool in tough logging condition had enabled the oil water contact to be identified and acquiring the optimum hydrocarbon bearing zone and evaluating the toe of the horizontal hole to verify the water existence. Geosteering services and quick decision making had facilitated the rapid and critical decision to obtain and deliver the well objective, to allow the possibility of water leg to be seen in the well and all over the field. To continue drilling and completion without identifying nearby water movement in this section would result in significant water production that will enhance the injection mechanism. This would be possible using conventional electromagnetic tools. In later stage, production of this well had provide promising results, securing at least 4 years of maximizing well life and expanding the hydrocarbon reserve column. This practice shall set a new standard for future appraisal and mature reservoir wells.
Al-Shehhi et al. (Mon,) studied this question.