In 2021, PPL spudded well X-1 targeting Basal Sands in 12.25" hole section, Massive Deep and Sembar Sands in 8.5" hole section. The well faced multitude challenges including borehole stability issues while drilling both reservoir sections. Nevertheless, despite the poor hole conditions, wireline formation testing was able to provide important information about the tight nature of the shallow formation penetrated by the well in 12.25" section. Consequently, reservoirs across the deeper 8.5" section were vital to the evaluation of this well. Accordingly, this paper sheds light on the deployment of an effective formation testing strategy, complemented by advanced, flexural attenuation-based cased hole cement evaluation logs.

Deteriorating hole conditions excluded the option of open hole reservoir testing, hence cased hole formation testing with Dual Packer was planned to achieve formation evaluation objectives in a comprehensive manner. Furthermore, routinely used ultrasonic pulse-echo based cement evaluation technique was upgraded to advanced flexural waves (Solid Liquid Gas mapping) methodology to gain confidence pertaining isolation between reservoir zones to be tested. Perforation intervals for testing were optimized based on cement evaluation results that led to efficient execution of the cased hole formation testing job. In addition, Interval-Pressure-Transient-Testing (IPTT) was performed to determine reservoir characteristics including permeability, skin, average pressure among others. Finally, well deliverability analysis was performed using steady-state wellbore simulator.

The implemented formation testing plan ultimately proved hydrocarbon presence across Massive Deep Sands, while Sembar was evaluated as depicting tight/dry behavior. Point forward, using IPTT analysis, elaborate characterization of Massive Deep Sands was performed, yielding parameters for tuning reservoir model and estimate reservoir deliverability. Moreover, formation testing results were also in-line with the DST outcome. Integrative findings from formation testing job yielded concrete conclusion with respect to the well’s potential by providing downhole gas samples for analysis, zone wise reservoir pressure, permeability, and skin, ultimately leading to reservoir deliverability estimations.

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