Abstract This study documents the first HPHT appraisal and testing campaign in Iran’s first HPHT gas well in the north of the country. Targeting deep, tight formations (Jurassic TI Formation and Permian SH Formation at 3600-5000 m, 15,000 psi, 350 °F), the objective was to evaluate reservoir quality and gas deliverability through fullbore drill-stem testing (FBDST), overcoming severe environmental, logistical, and technical constraints using advanced engineering simulations and adaptive workflows. The FBDST campaign involved multi-zone testing with a custom-designed 15 kpsi-rated string, dual packers, and 3.5″ PH6 tubing. Engineering efforts included thermal modeling based on offset wells (X-01/02), perforation design using HMX charges (no HNS available), and CT string design using stress simulations to mitigate lock-up and control overpull/snub limits. Mud systems were optimized to balance cost and function—using conventional and hi-vis gel instead of high-cost fluids like cesium formate or zinc bromide. Wellbore Multiphase Simulators and PTA Software defined shut-in pressures, temperatures, and test types. Full stackup working pressure assessments ensured safety for both DST and CT operations. Four FBDSTs were executed. FBDST #1 (5050 m, open-hole SH-2 Formation) recovered sour gas intermittently, with shut-in pressures close to reservoir pressure, suggesting limited but present near-wellbore permeability. FBDSTs #2 and #3 (4700 m, cased SH-1 Formation) yielded only trace gas and showed rapid shut-in pressure buildup—confirming ultra-low permeability (≤0.01 mD). Despite staged acidizing and N₂ lifting, no sustained flow was achieved. FBDST #4 (3723 m, TI Formation) showed no flow or pressure buildup, indicating near-zero effective permeability even after stimulation and lift attempts. Key engineering adaptations—rubber swaps on packers, acid pre-heating, timely N₂ logistics, low-solids mud. Perforation margins were adjusted to the available charge performance under HPHT conditions. Real-time decisions—such as skipping shut-ins when pressure response was inadequate—helped optimize rig time. The study concludes that SH Formation exhibits marginal deliverability under current stimulation capabilities, while TI Formation is effectively impermeable. The engineering workflow proved crucial for test execution in a challenging remote HPHT setting. This work delivers the first documented HPHT FBDST campaign in Iran, integrating advanced engineering design—including stress simulations for CT and DST strings, test and flow assurance modeling, and unconventional perforation strategies. It demonstrates how real-time test management and customized engineering solutions can extend testing and evaluation into ultra-deep, tight-gas HPHT reservoirs where local infrastructure and equipment availability are limited.
Zareiforoush et al. (Mon,) studied this question.