Abstract: The 10000-meter deep formation is an important field for intra source rock gas exploration in Kuqa Depression, which is a potential replacement field benefit from its large resource amount, good preservation conditions and near-source hydrocarbon charging. However, there is unclear understanding of structural traps, reservoir scale and oil and gas reservoir types. Based on geological study of deep structures, hydrocarbon generation potential evaluation, physical simulation of reservoir diagenesis and comprehensive analysis of hydrocarbon accumulation mode, the key conditions for gas accumulation in 10000-meter deep formations have been analyzed and favorable replacement fields have been optimally selected. The results show that, controlled by three detachment layers such as coal measure strata, huge thick mudstone, and Paleozoic unconformity, large fault anticlines, anticlines and fault block structures were developed in 10000-meter deep formations in Kuqa Depression, and mostly concentrated in Kelasu thrust belt. The huge thick Triassic–Lower Jurassic highly-over mature coal measures and lacustrine mudstone source rocks were developed in 10000-meter formations, with a hydrocarbon generation capacity of (1000–3000)×10⁸ m³/km². Jointly controlled by the large-area braided river delta plain–front huge thick sand bodies, rapidly deep burial in the late stage, ultra-high temperature and ultra-high pressure, and intense tectonic compressive stress, the large-scale fractured–porosity type reservoirs still have good physical properties at a depth of 10000 m, with a porosity of 5%–10% and a permeability of higher than 1 mD. The Triassic-Lower Jurassic regional near/intra source rock hydrocarbon accumulation combination was dominant in 10000-meter deep formation, generally forming structural-lithologic tight sandstone gas reservoirs. The Kelasu thrust belt is optimally selected as a strategic exploration zone, with an area of 4200 km², and gas resources of up to 1.5×10¹² m³, and the traps below Keshen Gas Field are favorable targets. The research results provide basic understanding for gas exploration in clastic rocks with a depth of 10000 meters in China, and lay geological theoretical foundation for further discovery of large gas fields below Kela–Keshen in Kuqa foreland basin thrust belt.

Key words: 10000-meter deep gas, key condition, replacement field, Kuqa Depression, Tarim Basin