Hydrocarbon Accumulation Model of Carbonate Reservoirs in Palaeogene in Kekeya Area, Southwest Depression in the Tarim Basin, China

Abstract

As a rare marine carbonate reservoir developed after the Eocene in the world, the oil and gas source of Palaeogene carbonate reservoirs in Kekeya area and the evolution process and mechanism of hydrocarbon accumulation are not clear, restricting the reasonable and effective development of Kekeya area. By the use of drilling cores and experimental data, oil and gas source correlation, reservoir evaluation, accumulation period and reservoir formation process were studied. Results show that the source rocks in the study area are mainly Permian lacustrine mudstone and Jurassic coal-bearing source rocks. The Palaeogene carbonate reservoirs are generally low porosity and ultra-low permeability, with secondary dissolution pores as the main reservoir space. The oil–gas source correlation shows that the Palaeogene crude oil is derived from the Permian source rock, and the natural gas is derived from the Jurassic source rock. The ancient and present reservoirs have experienced two oil and gas filling stages. The first stage is the middle and late Pliocene and the second stage is the early Pleistocene. The hydrocarbon accumulation mode was built as ‘source-reservoir separation, fracture dredging, multi-stage filling’. The research results guide exploration in Tarim Basin and similar basins.

Keywords

accumulation model / carbonatite / Kekeya region / Palaeogene / Tarim Basin

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2026 Geological Society of China.